Commit bf57d8a7e3

Andrew Kelley <superjoe30@gmail.com>
2017-04-13 09:07:58
typedefpocalypse
closes #314
1 parent bf67427
doc/langref.md
@@ -9,9 +9,7 @@ TopLevelItem = ErrorValueDecl | CompTimeExpression(Block) | TopLevelDecl | TestD
 
 TestDecl = "test" String Block
 
-TopLevelDecl = option(VisibleMod) (FnDef | ExternDecl | GlobalVarDecl | TypeDecl | UseDecl)
-
-TypeDecl = "type" Symbol "=" TypeExpr ";"
+TopLevelDecl = option(VisibleMod) (FnDef | ExternDecl | GlobalVarDecl | UseDecl)
 
 ErrorValueDecl = "error" Symbol ";"
 
@@ -155,7 +153,7 @@ GotoExpression = "goto" Symbol
 
 GroupedExpression = "(" Expression ")"
 
-KeywordLiteral = "true" | "false" | "null" | "break" | "continue" | "undefined" | "error" | "type" | "this" | "unreachable"
+KeywordLiteral = "true" | "false" | "null" | "break" | "continue" | "undefined" | "error" | "this" | "unreachable"
 
 ContainerDecl = option("extern" | "packed") ("struct" | "enum" | "union") "{" many(ContainerMember) "}"
 ```
src/all_types.hpp
@@ -254,7 +254,6 @@ enum TldId {
     TldIdVar,
     TldIdFn,
     TldIdContainer,
-    TldIdTypeDef,
     TldIdCompTime,
 };
 
@@ -303,12 +302,6 @@ struct TldContainer {
     TypeTableEntry *type_entry;
 };
 
-struct TldTypeDef {
-    Tld base;
-
-    TypeTableEntry *type_entry;
-};
-
 struct TldCompTime {
     Tld base;
 };
@@ -330,7 +323,6 @@ enum NodeType {
     NodeTypeReturnExpr,
     NodeTypeDefer,
     NodeTypeVariableDeclaration,
-    NodeTypeTypeDecl,
     NodeTypeErrorValueDecl,
     NodeTypeTestDecl,
     NodeTypeBinOpExpr,
@@ -369,7 +361,6 @@ enum NodeType {
     NodeTypeStructValueField,
     NodeTypeArrayType,
     NodeTypeErrorType,
-    NodeTypeTypeLiteral,
     NodeTypeVarLiteral,
     NodeTypeTryExpr,
     NodeTypeInlineExpr,
@@ -448,12 +439,6 @@ struct AstNodeVariableDeclaration {
     AstNode *expr;
 };
 
-struct AstNodeTypeDecl {
-    VisibMod visib_mod;
-    Buf *symbol;
-    AstNode *child_type;
-};
-
 struct AstNodeErrorValueDecl {
     Buf *name;
 
@@ -790,9 +775,6 @@ struct AstNodeArrayType {
 struct AstNodeErrorType {
 };
 
-struct AstNodeTypeLiteral {
-};
-
 struct AstNodeVarLiteral {
 };
 
@@ -816,7 +798,6 @@ struct AstNode {
         AstNodeReturnExpr return_expr;
         AstNodeDefer defer;
         AstNodeVariableDeclaration variable_declaration;
-        AstNodeTypeDecl type_decl;
         AstNodeErrorValueDecl error_value_decl;
         AstNodeTestDecl test_decl;
         AstNodeBinOpExpr bin_op_expr;
@@ -856,7 +837,6 @@ struct AstNode {
         AstNodeUnreachableExpr unreachable_expr;
         AstNodeArrayType array_type;
         AstNodeErrorType error_type;
-        AstNodeTypeLiteral type_literal;
         AstNodeVarLiteral var_literal;
         AstNodeInlineExpr inline_expr;
     } data;
@@ -1026,11 +1006,6 @@ struct TypeTableEntryBoundFn {
     TypeTableEntry *fn_type;
 };
 
-struct TypeTableEntryTypeDecl {
-    TypeTableEntry *child_type;
-    TypeTableEntry *canonical_type;
-};
-
 enum TypeTableEntryId {
     TypeTableEntryIdInvalid,
     TypeTableEntryIdVar,
@@ -1054,11 +1029,11 @@ enum TypeTableEntryId {
     TypeTableEntryIdEnumTag,
     TypeTableEntryIdUnion,
     TypeTableEntryIdFn,
-    TypeTableEntryIdTypeDecl,
     TypeTableEntryIdNamespace,
     TypeTableEntryIdBlock,
     TypeTableEntryIdBoundFn,
     TypeTableEntryIdArgTuple,
+    TypeTableEntryIdOpaque,
 };
 
 struct TypeTableEntry {
@@ -1083,7 +1058,6 @@ struct TypeTableEntry {
         TypeTableEntryEnumTag enum_tag;
         TypeTableEntryUnion unionation;
         TypeTableEntryFn fn;
-        TypeTableEntryTypeDecl type_decl;
         TypeTableEntryBoundFn bound_fn;
     } data;
 
src/analyze.cpp
@@ -186,6 +186,8 @@ bool type_is_complete(TypeTableEntry *type_entry) {
             return type_entry->data.enumeration.complete;
         case TypeTableEntryIdUnion:
             return type_entry->data.unionation.complete;
+        case TypeTableEntryIdOpaque:
+            return false;
         case TypeTableEntryIdMetaType:
         case TypeTableEntryIdVoid:
         case TypeTableEntryIdBool:
@@ -202,7 +204,6 @@ bool type_is_complete(TypeTableEntry *type_entry) {
         case TypeTableEntryIdErrorUnion:
         case TypeTableEntryIdPureError:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
@@ -240,12 +241,12 @@ bool type_has_zero_bits_known(TypeTableEntry *type_entry) {
         case TypeTableEntryIdErrorUnion:
         case TypeTableEntryIdPureError:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
         case TypeTableEntryIdEnumTag:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             return true;
     }
     zig_unreachable();
@@ -254,18 +255,17 @@ bool type_has_zero_bits_known(TypeTableEntry *type_entry) {
 
 uint64_t type_size(CodeGen *g, TypeTableEntry *type_entry) {
     assert(type_is_complete(type_entry));
-    TypeTableEntry *canon_type = get_underlying_type(type_entry);
 
     if (!type_has_bits(type_entry))
         return 0;
 
-    if (canon_type->id == TypeTableEntryIdStruct && canon_type->data.structure.layout == ContainerLayoutPacked) {
+    if (type_entry->id == TypeTableEntryIdStruct && type_entry->data.structure.layout == ContainerLayoutPacked) {
         uint64_t size_in_bits = type_size_bits(g, type_entry);
         return (size_in_bits + 7) / 8;
-    } else if (canon_type->id == TypeTableEntryIdArray) {
-        TypeTableEntry *canon_child_type = get_underlying_type(canon_type->data.array.child_type);
-        if (canon_child_type->id == TypeTableEntryIdStruct &&
-            canon_child_type->data.structure.layout == ContainerLayoutPacked)
+    } else if (type_entry->id == TypeTableEntryIdArray) {
+        TypeTableEntry *child_type = type_entry->data.array.child_type;
+        if (child_type->id == TypeTableEntryIdStruct &&
+            child_type->data.structure.layout == ContainerLayoutPacked)
         {
             uint64_t size_in_bits = type_size_bits(g, type_entry);
             return (size_in_bits + 7) / 8;
@@ -277,27 +277,26 @@ uint64_t type_size(CodeGen *g, TypeTableEntry *type_entry) {
 
 uint64_t type_size_bits(CodeGen *g, TypeTableEntry *type_entry) {
     assert(type_is_complete(type_entry));
-    TypeTableEntry *canon_type = get_underlying_type(type_entry);
 
     if (!type_has_bits(type_entry))
         return 0;
 
-    if (canon_type->id == TypeTableEntryIdStruct && canon_type->data.structure.layout == ContainerLayoutPacked) {
+    if (type_entry->id == TypeTableEntryIdStruct && type_entry->data.structure.layout == ContainerLayoutPacked) {
         uint64_t result = 0;
-        for (size_t i = 0; i < canon_type->data.structure.src_field_count; i += 1) {
-            result += type_size_bits(g, canon_type->data.structure.fields[i].type_entry);
+        for (size_t i = 0; i < type_entry->data.structure.src_field_count; i += 1) {
+            result += type_size_bits(g, type_entry->data.structure.fields[i].type_entry);
         }
         return result;
-    } else if (canon_type->id == TypeTableEntryIdArray) {
-        TypeTableEntry *canon_child_type = get_underlying_type(canon_type->data.array.child_type);
-        if (canon_child_type->id == TypeTableEntryIdStruct &&
-            canon_child_type->data.structure.layout == ContainerLayoutPacked)
+    } else if (type_entry->id == TypeTableEntryIdArray) {
+        TypeTableEntry *child_type = type_entry->data.array.child_type;
+        if (child_type->id == TypeTableEntryIdStruct &&
+            child_type->data.structure.layout == ContainerLayoutPacked)
         {
-            return canon_type->data.array.len * type_size_bits(g, canon_child_type);
+            return type_entry->data.array.len * type_size_bits(g, child_type);
         }
     }
 
-    return LLVMSizeOfTypeInBits(g->target_data_ref, canon_type->type_ref);
+    return LLVMSizeOfTypeInBits(g->target_data_ref, type_entry->type_ref);
 }
 
 static bool type_is_copyable(CodeGen *g, TypeTableEntry *type_entry) {
@@ -360,10 +359,9 @@ TypeTableEntry *get_pointer_to_type_extra(CodeGen *g, TypeTableEntry *child_type
                 bit_offset + unaligned_bit_count, const_str, volatile_str, buf_ptr(&child_type->name));
     }
 
-    TypeTableEntry *canon_child_type = get_underlying_type(child_type);
-    assert(canon_child_type->id != TypeTableEntryIdInvalid);
+    assert(child_type->id != TypeTableEntryIdInvalid);
 
-    entry->zero_bits = !type_has_bits(canon_child_type);
+    entry->zero_bits = !type_has_bits(child_type);
 
     if (!entry->zero_bits) {
         entry->type_ref = LLVMPointerType(child_type->type_ref, 0);
@@ -766,17 +764,22 @@ TypeTableEntry *get_slice_type(CodeGen *g, TypeTableEntry *child_type, bool is_c
     }
 }
 
-TypeTableEntry *get_typedecl_type(CodeGen *g, const char *name, TypeTableEntry *child_type) {
-    TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdTypeDecl);
+TypeTableEntry *get_opaque_type(CodeGen *g, Scope *scope, AstNode *source_node, const char *name) {
+    TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdOpaque);
 
     buf_init_from_str(&entry->name, name);
 
-    entry->is_copyable = type_is_copyable(g, child_type);
-    entry->type_ref = child_type->type_ref;
-    entry->di_type = child_type->di_type;
-    entry->zero_bits = child_type->zero_bits;
-    entry->data.type_decl.child_type = child_type;
-    entry->data.type_decl.canonical_type = get_underlying_type(child_type);
+    ImportTableEntry *import = scope ? get_scope_import(scope) : nullptr;
+    unsigned line = source_node ? (unsigned)(source_node->line + 1) : 0;
+
+    entry->is_copyable = false;
+    entry->type_ref = LLVMInt8Type();
+    entry->di_type = ZigLLVMCreateDebugForwardDeclType(g->dbuilder,
+        ZigLLVMTag_DW_structure_type(), buf_ptr(&entry->name),
+        import ? ZigLLVMFileToScope(import->di_file) : nullptr,
+        import ? import->di_file : nullptr,
+        line);
+    entry->zero_bits = false;
 
     return entry;
 }
@@ -968,14 +971,6 @@ TypeTableEntry *get_partial_container_type(CodeGen *g, Scope *scope, ContainerKi
     return entry;
 }
 
-TypeTableEntry *get_underlying_type(TypeTableEntry *type_entry) {
-    if (type_entry->id == TypeTableEntryIdTypeDecl) {
-        return type_entry->data.type_decl.canonical_type;
-    } else {
-        return type_entry;
-    }
-}
-
 static IrInstruction *analyze_const_value(CodeGen *g, Scope *scope, AstNode *node, TypeTableEntry *type_entry, Buf *type_name) {
     size_t backward_branch_count = 0;
     return ir_eval_const_value(g, scope, node, type_entry,
@@ -1066,6 +1061,7 @@ static TypeTableEntry *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *c
             case TypeTableEntryIdUndefLit:
             case TypeTableEntryIdNullLit:
             case TypeTableEntryIdArgTuple:
+            case TypeTableEntryIdOpaque:
                 add_node_error(g, param_node->data.param_decl.type,
                     buf_sprintf("parameter of type '%s' not allowed", buf_ptr(&type_entry->name)));
                 return g->builtin_types.entry_invalid;
@@ -1099,7 +1095,6 @@ static TypeTableEntry *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *c
             case TypeTableEntryIdEnum:
             case TypeTableEntryIdUnion:
             case TypeTableEntryIdFn:
-            case TypeTableEntryIdTypeDecl:
             case TypeTableEntryIdEnumTag:
                 ensure_complete_type(g, type_entry);
                 if (!fn_type_id.is_extern && !type_is_copyable(g, type_entry)) {
@@ -1123,6 +1118,7 @@ static TypeTableEntry *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *c
         case TypeTableEntryIdUndefLit:
         case TypeTableEntryIdNullLit:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             add_node_error(g, fn_proto->return_type,
                 buf_sprintf("return type '%s' not allowed", buf_ptr(&fn_type_id.return_type->name)));
             return g->builtin_types.entry_invalid;
@@ -1155,7 +1151,6 @@ static TypeTableEntry *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *c
         case TypeTableEntryIdEnum:
         case TypeTableEntryIdUnion:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdEnumTag:
             break;
     }
@@ -1173,8 +1168,6 @@ bool type_is_invalid(TypeTableEntry *type_entry) {
             return type_entry->data.enumeration.is_invalid;
         case TypeTableEntryIdUnion:
             return type_entry->data.unionation.is_invalid;
-        case TypeTableEntryIdTypeDecl:
-            return type_is_invalid(type_entry->data.type_decl.canonical_type);
         default:
             return false;
     }
@@ -1380,8 +1373,7 @@ static void resolve_enum_type(CodeGen *g, TypeTableEntry *enum_type) {
 }
 
 static bool type_allowed_in_packed_struct(TypeTableEntry *type_entry) {
-    TypeTableEntry *canon_type = get_underlying_type(type_entry);
-    switch (canon_type->id) {
+    switch (type_entry->id) {
         case TypeTableEntryIdInvalid:
         case TypeTableEntryIdVar:
             zig_unreachable();
@@ -1395,11 +1387,11 @@ static bool type_allowed_in_packed_struct(TypeTableEntry *type_entry) {
         case TypeTableEntryIdPureError:
         case TypeTableEntryIdEnum:
         case TypeTableEntryIdEnumTag:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             return false;
         case TypeTableEntryIdVoid:
         case TypeTableEntryIdBool:
@@ -1411,11 +1403,11 @@ static bool type_allowed_in_packed_struct(TypeTableEntry *type_entry) {
         case TypeTableEntryIdFn:
             return true;
         case TypeTableEntryIdStruct:
-            return canon_type->data.structure.layout == ContainerLayoutPacked;
+            return type_entry->data.structure.layout == ContainerLayoutPacked;
         case TypeTableEntryIdMaybe:
             {
-                TypeTableEntry *canon_child_type = get_underlying_type(canon_type->data.maybe.child_type);
-                return canon_child_type->id == TypeTableEntryIdPointer || canon_child_type->id == TypeTableEntryIdFn;
+                TypeTableEntry *child_type = type_entry->data.maybe.child_type;
+                return child_type->id == TypeTableEntryIdPointer || child_type->id == TypeTableEntryIdFn;
             }
     }
     zig_unreachable();
@@ -2037,15 +2029,6 @@ void scan_decls(CodeGen *g, ScopeDecls *decls_scope, AstNode *node) {
                 add_top_level_decl(g, decls_scope, &tld_var->base);
                 break;
             }
-        case NodeTypeTypeDecl:
-            {
-                Buf *name = node->data.type_decl.symbol;
-                VisibMod visib_mod = node->data.type_decl.visib_mod;
-                TldTypeDef *tld_typedef = allocate<TldTypeDef>(1);
-                init_tld(&tld_typedef->base, TldIdTypeDef, name, visib_mod, node, &decls_scope->base);
-                add_top_level_decl(g, decls_scope, &tld_typedef->base);
-                break;
-            }
         case NodeTypeFnProto:
             {
                 // if the name is missing, we immediately announce an error
@@ -2126,7 +2109,6 @@ void scan_decls(CodeGen *g, ScopeDecls *decls_scope, AstNode *node) {
         case NodeTypeStructValueField:
         case NodeTypeArrayType:
         case NodeTypeErrorType:
-        case NodeTypeTypeLiteral:
         case NodeTypeVarLiteral:
         case NodeTypeTryExpr:
         case NodeTypeInlineExpr:
@@ -2154,10 +2136,7 @@ static void resolve_decl_container(CodeGen *g, TldContainer *tld_container) {
 }
 
 TypeTableEntry *validate_var_type(CodeGen *g, AstNode *source_node, TypeTableEntry *type_entry) {
-    TypeTableEntry *underlying_type = get_underlying_type(type_entry);
-    switch (underlying_type->id) {
-        case TypeTableEntryIdTypeDecl:
-            zig_unreachable();
+    switch (type_entry->id) {
         case TypeTableEntryIdInvalid:
             return g->builtin_types.entry_invalid;
         case TypeTableEntryIdUnreachable:
@@ -2168,8 +2147,9 @@ TypeTableEntry *validate_var_type(CodeGen *g, AstNode *source_node, TypeTableEnt
         case TypeTableEntryIdNullLit:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             add_node_error(g, source_node, buf_sprintf("variable of type '%s' not allowed",
-                buf_ptr(&underlying_type->name)));
+                buf_ptr(&type_entry->name)));
             return g->builtin_types.entry_invalid;
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdMetaType:
@@ -2328,17 +2308,6 @@ static void resolve_decl_var(CodeGen *g, TldVar *tld_var) {
     g->global_vars.append(tld_var);
 }
 
-static void resolve_decl_typedef(CodeGen *g, TldTypeDef *tld_typedef) {
-    AstNode *typedef_node = tld_typedef->base.source_node;
-    assert(typedef_node->type == NodeTypeTypeDecl);
-    AstNode *type_node = typedef_node->data.type_decl.child_type;
-    Buf *decl_name = typedef_node->data.type_decl.symbol;
-
-    TypeTableEntry *child_type = analyze_type_expr(g, tld_typedef->base.parent_scope, type_node);
-    tld_typedef->type_entry = (child_type->id == TypeTableEntryIdInvalid) ?
-        child_type : get_typedecl_type(g, buf_ptr(decl_name), child_type);
-}
-
 void resolve_top_level_decl(CodeGen *g, Tld *tld, bool pointer_only) {
     if (tld->resolution != TldResolutionUnresolved)
         return;
@@ -2370,12 +2339,6 @@ void resolve_top_level_decl(CodeGen *g, Tld *tld, bool pointer_only) {
                 resolve_decl_container(g, tld_container);
                 break;
             }
-        case TldIdTypeDef:
-            {
-                TldTypeDef *tld_typedef = (TldTypeDef *)tld;
-                resolve_decl_typedef(g, tld_typedef);
-                break;
-            }
         case TldIdCompTime:
             {
                 TldCompTime *tld_comptime = (TldCompTime *)tld;
@@ -2589,6 +2552,7 @@ static bool is_container(TypeTableEntry *type_entry) {
     switch (type_entry->id) {
         case TypeTableEntryIdInvalid:
         case TypeTableEntryIdVar:
+        case TypeTableEntryIdOpaque:
             zig_unreachable();
         case TypeTableEntryIdStruct:
         case TypeTableEntryIdEnum:
@@ -2610,7 +2574,6 @@ static bool is_container(TypeTableEntry *type_entry) {
         case TypeTableEntryIdErrorUnion:
         case TypeTableEntryIdPureError:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
@@ -2659,7 +2622,6 @@ void resolve_container_type(CodeGen *g, TypeTableEntry *type_entry) {
         case TypeTableEntryIdErrorUnion:
         case TypeTableEntryIdPureError:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
@@ -2667,6 +2629,7 @@ void resolve_container_type(CodeGen *g, TypeTableEntry *type_entry) {
         case TypeTableEntryIdVar:
         case TypeTableEntryIdEnumTag:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             zig_unreachable();
     }
 }
@@ -3062,6 +3025,7 @@ bool handle_is_ptr(TypeTableEntry *type_entry) {
         case TypeTableEntryIdBoundFn:
         case TypeTableEntryIdVar:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
              zig_unreachable();
         case TypeTableEntryIdUnreachable:
         case TypeTableEntryIdVoid:
@@ -3086,8 +3050,6 @@ bool handle_is_ptr(TypeTableEntry *type_entry) {
              return type_has_bits(type_entry->data.maybe.child_type) &&
                     type_entry->data.maybe.child_type->id != TypeTableEntryIdPointer &&
                     type_entry->data.maybe.child_type->id != TypeTableEntryIdFn;
-        case TypeTableEntryIdTypeDecl:
-             return handle_is_ptr(type_entry->data.type_decl.canonical_type);
     }
     zig_unreachable();
 }
@@ -3165,6 +3127,8 @@ bool fn_type_id_eql(FnTypeId *a, FnTypeId *b) {
 static uint32_t hash_const_val(ConstExprValue *const_val) {
     assert(const_val->special == ConstValSpecialStatic);
     switch (const_val->type->id) {
+        case TypeTableEntryIdOpaque:
+            zig_unreachable();
         case TypeTableEntryIdBool:
             return const_val->data.x_bool ? (uint32_t)127863866 : (uint32_t)215080464;
         case TypeTableEntryIdMetaType:
@@ -3254,8 +3218,6 @@ static uint32_t hash_const_val(ConstExprValue *const_val) {
         case TypeTableEntryIdFn:
             return hash_ptr(const_val->data.x_fn.fn_entry) +
                 (const_val->data.x_fn.is_inline ? 4133894920 : 3983484790);
-        case TypeTableEntryIdTypeDecl:
-            return hash_ptr(const_val->data.x_type);
         case TypeTableEntryIdNamespace:
             return hash_ptr(const_val->data.x_import);
         case TypeTableEntryIdBlock:
@@ -3359,10 +3321,10 @@ bool type_has_bits(TypeTableEntry *type_entry) {
 }
 
 bool type_requires_comptime(TypeTableEntry *type_entry) {
-    switch (get_underlying_type(type_entry)->id) {
+    switch (type_entry->id) {
         case TypeTableEntryIdInvalid:
         case TypeTableEntryIdVar:
-        case TypeTableEntryIdTypeDecl:
+        case TypeTableEntryIdOpaque:
             zig_unreachable();
         case TypeTableEntryIdNumLitFloat:
         case TypeTableEntryIdNumLitInt:
@@ -3603,14 +3565,14 @@ ConstExprValue *create_const_arg_tuple(CodeGen *g, size_t arg_index_start, size_
 
 
 void init_const_undefined(CodeGen *g, ConstExprValue *const_val) {
-    TypeTableEntry *canon_wanted_type = get_underlying_type(const_val->type);
-    if (canon_wanted_type->id == TypeTableEntryIdArray) {
+    TypeTableEntry *wanted_type = const_val->type;
+    if (wanted_type->id == TypeTableEntryIdArray) {
         const_val->special = ConstValSpecialStatic;
-        size_t elem_count = canon_wanted_type->data.array.len;
+        size_t elem_count = wanted_type->data.array.len;
         const_val->data.x_array.elements = allocate<ConstExprValue>(elem_count);
         for (size_t i = 0; i < elem_count; i += 1) {
             ConstExprValue *element_val = &const_val->data.x_array.elements[i];
-            element_val->type = canon_wanted_type->data.array.child_type;
+            element_val->type = wanted_type->data.array.child_type;
             init_const_undefined(g, element_val);
             ConstParent *parent = get_const_val_parent(element_val);
             if (parent != nullptr) {
@@ -3619,15 +3581,15 @@ void init_const_undefined(CodeGen *g, ConstExprValue *const_val) {
                 parent->data.p_array.elem_index = i;
             }
         }
-    } else if (canon_wanted_type->id == TypeTableEntryIdStruct) {
-        ensure_complete_type(g, canon_wanted_type);
+    } else if (wanted_type->id == TypeTableEntryIdStruct) {
+        ensure_complete_type(g, wanted_type);
 
         const_val->special = ConstValSpecialStatic;
-        size_t field_count = canon_wanted_type->data.structure.src_field_count;
+        size_t field_count = wanted_type->data.structure.src_field_count;
         const_val->data.x_struct.fields = allocate<ConstExprValue>(field_count);
         for (size_t i = 0; i < field_count; i += 1) {
             ConstExprValue *field_val = &const_val->data.x_struct.fields[i];
-            field_val->type = canon_wanted_type->data.structure.fields[i].type_entry;
+            field_val->type = wanted_type->data.structure.fields[i].type_entry;
             assert(field_val->type);
             init_const_undefined(g, field_val);
             ConstParent *parent = get_const_val_parent(field_val);
@@ -3678,6 +3640,8 @@ bool const_values_equal(ConstExprValue *a, ConstExprValue *b) {
     assert(a->special == ConstValSpecialStatic);
     assert(b->special == ConstValSpecialStatic);
     switch (a->type->id) {
+        case TypeTableEntryIdOpaque:
+            zig_unreachable();
         case TypeTableEntryIdEnum:
             {
                 ConstEnumValue *enum1 = &a->data.x_enum;
@@ -3767,8 +3731,6 @@ bool const_values_equal(ConstExprValue *a, ConstExprValue *b) {
             }
         case TypeTableEntryIdErrorUnion:
             zig_panic("TODO");
-        case TypeTableEntryIdTypeDecl:
-            zig_panic("TODO");
         case TypeTableEntryIdNamespace:
             return a->data.x_import == b->data.x_import;
         case TypeTableEntryIdBlock:
@@ -3857,9 +3819,9 @@ void render_const_value(Buf *buf, ConstExprValue *const_val) {
     }
     assert(const_val->type);
 
-    TypeTableEntry *canon_type = get_underlying_type(const_val->type);
-    switch (canon_type->id) {
-        case TypeTableEntryIdTypeDecl:
+    TypeTableEntry *type_entry = const_val->type;
+    switch (type_entry->id) {
+        case TypeTableEntryIdOpaque:
             zig_unreachable();
         case TypeTableEntryIdInvalid:
             buf_appendf(buf, "(invalid)");
@@ -3926,7 +3888,7 @@ void render_const_value(Buf *buf, ConstExprValue *const_val) {
                         return;
                     }
                 case ConstPtrSpecialHardCodedAddr:
-                    buf_appendf(buf, "(&%s)(%" PRIx64 ")", buf_ptr(&canon_type->data.pointer.child_type->name),
+                    buf_appendf(buf, "(&%s)(%" PRIx64 ")", buf_ptr(&type_entry->data.pointer.child_type->name),
                             const_val->data.x_ptr.data.hard_coded_addr.addr);
                     return;
                 case ConstPtrSpecialDiscard:
@@ -3949,8 +3911,8 @@ void render_const_value(Buf *buf, ConstExprValue *const_val) {
             }
         case TypeTableEntryIdArray:
             {
-                TypeTableEntry *child_type = canon_type->data.array.child_type;
-                uint64_t len = canon_type->data.array.len;
+                TypeTableEntry *child_type = type_entry->data.array.child_type;
+                uint64_t len = type_entry->data.array.len;
 
                 // if it's []u8, assume UTF-8 and output a string
                 if (child_type->id == TypeTableEntryIdInt &&
@@ -3973,7 +3935,7 @@ void render_const_value(Buf *buf, ConstExprValue *const_val) {
                     return;
                 }
 
-                buf_appendf(buf, "%s{", buf_ptr(&canon_type->name));
+                buf_appendf(buf, "%s{", buf_ptr(&type_entry->name));
                 for (uint64_t i = 0; i < len; i += 1) {
                     if (i != 0)
                         buf_appendf(buf, ",");
@@ -4021,22 +3983,22 @@ void render_const_value(Buf *buf, ConstExprValue *const_val) {
             }
         case TypeTableEntryIdStruct:
             {
-                buf_appendf(buf, "(struct %s constant)", buf_ptr(&canon_type->name));
+                buf_appendf(buf, "(struct %s constant)", buf_ptr(&type_entry->name));
                 return;
             }
         case TypeTableEntryIdEnum:
             {
-                buf_appendf(buf, "(enum %s constant)", buf_ptr(&canon_type->name));
+                buf_appendf(buf, "(enum %s constant)", buf_ptr(&type_entry->name));
                 return;
             }
         case TypeTableEntryIdErrorUnion:
             {
-                buf_appendf(buf, "(error union %s constant)", buf_ptr(&canon_type->name));
+                buf_appendf(buf, "(error union %s constant)", buf_ptr(&type_entry->name));
                 return;
             }
         case TypeTableEntryIdUnion:
             {
-                buf_appendf(buf, "(union %s constant)", buf_ptr(&canon_type->name));
+                buf_appendf(buf, "(union %s constant)", buf_ptr(&type_entry->name));
                 return;
             }
         case TypeTableEntryIdPureError:
@@ -4046,7 +4008,7 @@ void render_const_value(Buf *buf, ConstExprValue *const_val) {
             }
         case TypeTableEntryIdEnumTag:
             {
-                TypeTableEntry *enum_type = canon_type->data.enum_tag.enum_type;
+                TypeTableEntry *enum_type = type_entry->data.enum_tag.enum_type;
                 TypeEnumField *field = &enum_type->data.enumeration.fields[const_val->data.x_bignum.data.x_uint];
                 buf_appendf(buf, "%s.%s", buf_ptr(&enum_type->name), buf_ptr(field->name));
                 return;
@@ -4095,6 +4057,7 @@ uint32_t type_id_hash(TypeId x) {
     switch (x.id) {
         case TypeTableEntryIdInvalid:
         case TypeTableEntryIdVar:
+        case TypeTableEntryIdOpaque:
         case TypeTableEntryIdMetaType:
         case TypeTableEntryIdVoid:
         case TypeTableEntryIdBool:
@@ -4112,7 +4075,6 @@ uint32_t type_id_hash(TypeId x) {
         case TypeTableEntryIdEnumTag:
         case TypeTableEntryIdUnion:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
@@ -4157,11 +4119,11 @@ bool type_id_eql(TypeId a, TypeId b) {
         case TypeTableEntryIdEnumTag:
         case TypeTableEntryIdUnion:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             zig_unreachable();
         case TypeTableEntryIdPointer:
             return a.data.pointer.child_type == b.data.pointer.child_type &&
@@ -4211,10 +4173,10 @@ bool zig_llvm_fn_key_eql(ZigLLVMFnKey a, ZigLLVMFnKey b) {
 
 ConstParent *get_const_val_parent(ConstExprValue *value) {
     assert(value->type);
-    TypeTableEntry *canon_type = get_underlying_type(value->type);
-    if (canon_type->id == TypeTableEntryIdArray) {
+    TypeTableEntry *type_entry = value->type;
+    if (type_entry->id == TypeTableEntryIdArray) {
         return &value->data.x_array.parent;
-    } else if (canon_type->id == TypeTableEntryIdStruct) {
+    } else if (type_entry->id == TypeTableEntryIdStruct) {
         return &value->data.x_struct.parent;
     }
     return nullptr;
src/analyze.hpp
@@ -24,7 +24,6 @@ TypeTableEntry **get_int_type_ptr(CodeGen *g, bool is_signed, uint32_t size_in_b
 TypeTableEntry *get_int_type(CodeGen *g, bool is_signed, uint32_t size_in_bits);
 TypeTableEntry **get_c_int_type_ptr(CodeGen *g, CIntType c_int_type);
 TypeTableEntry *get_c_int_type(CodeGen *g, CIntType c_int_type);
-TypeTableEntry *get_typedecl_type(CodeGen *g, const char *name, TypeTableEntry *child_type);
 TypeTableEntry *get_fn_type(CodeGen *g, FnTypeId *fn_type_id);
 TypeTableEntry *get_maybe_type(CodeGen *g, TypeTableEntry *child_type);
 TypeTableEntry *get_array_type(CodeGen *g, TypeTableEntry *child_type, uint64_t array_size);
@@ -34,11 +33,11 @@ TypeTableEntry *get_partial_container_type(CodeGen *g, Scope *scope, ContainerKi
 TypeTableEntry *get_smallest_unsigned_int_type(CodeGen *g, uint64_t x);
 TypeTableEntry *get_error_type(CodeGen *g, TypeTableEntry *child_type);
 TypeTableEntry *get_bound_fn_type(CodeGen *g, FnTableEntry *fn_entry);
+TypeTableEntry *get_opaque_type(CodeGen *g, Scope *scope, AstNode *source_node, const char *name);
 bool handle_is_ptr(TypeTableEntry *type_entry);
 void find_libc_include_path(CodeGen *g);
 void find_libc_lib_path(CodeGen *g);
 
-TypeTableEntry *get_underlying_type(TypeTableEntry *type_entry);
 bool type_has_bits(TypeTableEntry *type_entry);
 
 
src/ast_render.cpp
@@ -166,8 +166,6 @@ static const char *node_type_str(NodeType node_type) {
             return "Defer";
         case NodeTypeVariableDeclaration:
             return "VariableDeclaration";
-        case NodeTypeTypeDecl:
-            return "TypeDecl";
         case NodeTypeErrorValueDecl:
             return "ErrorValueDecl";
         case NodeTypeTestDecl:
@@ -234,8 +232,6 @@ static const char *node_type_str(NodeType node_type) {
             return "ArrayType";
         case NodeTypeErrorType:
             return "ErrorType";
-        case NodeTypeTypeLiteral:
-            return "TypeLiteral";
         case NodeTypeVarLiteral:
             return "VarLiteral";
         case NodeTypeTryExpr:
@@ -394,7 +390,6 @@ static void render_node_extra(AstRender *ar, AstNode *node, bool grouped) {
 
                 if (child->type == NodeTypeUse ||
                     child->type == NodeTypeVariableDeclaration ||
-                    child->type == NodeTypeTypeDecl ||
                     child->type == NodeTypeErrorValueDecl ||
                     child->type == NodeTypeFnProto)
                 {
@@ -507,14 +502,6 @@ static void render_node_extra(AstRender *ar, AstNode *node, bool grouped) {
                 }
                 break;
             }
-        case NodeTypeTypeDecl:
-            {
-                const char *pub_str = visib_mod_string(node->data.type_decl.visib_mod);
-                const char *var_name = buf_ptr(node->data.type_decl.symbol);
-                fprintf(ar->f, "%stype %s = ", pub_str, var_name);
-                render_node_grouped(ar, node->data.type_decl.child_type);
-                break;
-            }
         case NodeTypeBinOpExpr:
             if (!grouped) fprintf(ar->f, "(");
             render_node_ungrouped(ar, node->data.bin_op_expr.op1);
@@ -668,9 +655,6 @@ static void render_node_extra(AstRender *ar, AstNode *node, bool grouped) {
         case NodeTypeErrorType:
             fprintf(ar->f, "error");
             break;
-        case NodeTypeTypeLiteral:
-            fprintf(ar->f, "type");
-            break;
         case NodeTypeVarLiteral:
             fprintf(ar->f, "var");
             break;
@@ -1034,6 +1018,12 @@ static void ast_render_tld_var(AstRender *ar, Buf *name, TldVar *tld_var) {
             fprintf(ar->f, "union {");
             fprintf(ar->f, "TODO");
             fprintf(ar->f, "}");
+        } else if (type_entry->id == TypeTableEntryIdOpaque) {
+            if (buf_eql_buf(&type_entry->name, name)) {
+                fprintf(ar->f, "@OpaqueType()");
+            } else {
+                fprintf(ar->f, "%s", buf_ptr(&type_entry->name));
+            }
         } else {
             fprintf(ar->f, "%s", buf_ptr(&type_entry->name));
         }
@@ -1047,15 +1037,6 @@ static void ast_render_tld_var(AstRender *ar, Buf *name, TldVar *tld_var) {
     fprintf(ar->f, ";\n");
 }
 
-static void ast_render_tld_typedef(AstRender *ar, Buf *name, TldTypeDef *tld_typedef) {
-    TypeTableEntry *type_entry = tld_typedef->type_entry;
-    TypeTableEntry *canon_type = get_underlying_type(type_entry);
-
-    fprintf(ar->f, "pub type ");
-    print_symbol(ar, name);
-    fprintf(ar->f, " = %s;\n", buf_ptr(&canon_type->name));
-}
-
 void ast_render_decls(FILE *f, int indent_size, ImportTableEntry *import) {
     AstRender ar = {0};
     ar.f = f;
@@ -1087,9 +1068,6 @@ void ast_render_decls(FILE *f, int indent_size, ImportTableEntry *import) {
             case TldIdContainer:
                 fprintf(stdout, "container\n");
                 break;
-            case TldIdTypeDef:
-                ast_render_tld_typedef(&ar, entry->key, (TldTypeDef *)tld);
-                break;
             case TldIdCompTime:
                 fprintf(stdout, "comptime\n");
                 break;
src/codegen.cpp
@@ -649,12 +649,9 @@ static void add_bounds_check(CodeGen *g, LLVMValueRef target_val,
     LLVMPositionBuilderAtEnd(g->builder, ok_block);
 }
 
-static LLVMValueRef gen_widen_or_shorten(CodeGen *g, bool want_debug_safety, TypeTableEntry *actual_type_non_canon,
-        TypeTableEntry *wanted_type_non_canon, LLVMValueRef expr_val)
+static LLVMValueRef gen_widen_or_shorten(CodeGen *g, bool want_debug_safety, TypeTableEntry *actual_type,
+        TypeTableEntry *wanted_type, LLVMValueRef expr_val)
 {
-    TypeTableEntry *actual_type = get_underlying_type(actual_type_non_canon);
-    TypeTableEntry *wanted_type = get_underlying_type(wanted_type_non_canon);
-
     assert(actual_type->id == wanted_type->id);
 
     uint64_t actual_bits;
@@ -852,7 +849,7 @@ static LLVMValueRef gen_struct_memcpy(CodeGen *g, LLVMValueRef src, LLVMValueRef
 static LLVMValueRef gen_assign_raw(CodeGen *g, LLVMValueRef ptr, TypeTableEntry *ptr_type,
         LLVMValueRef value)
 {
-    TypeTableEntry *child_type = get_underlying_type(ptr_type->data.pointer.child_type);
+    TypeTableEntry *child_type = ptr_type->data.pointer.child_type;
 
     if (!type_has_bits(child_type))
         return nullptr;
@@ -1111,7 +1108,7 @@ static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
     IrInstruction *op2 = bin_op_instruction->op2;
 
     assert(op1->value.type == op2->value.type);
-    TypeTableEntry *canon_type = get_underlying_type(op1->value.type);
+    TypeTableEntry *type_entry = op1->value.type;
 
     bool want_debug_safety = bin_op_instruction->safety_check_on &&
         ir_want_debug_safety(g, &bin_op_instruction->base);
@@ -1133,22 +1130,22 @@ static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
         case IrBinOpCmpGreaterThan:
         case IrBinOpCmpLessOrEq:
         case IrBinOpCmpGreaterOrEq:
-            if (canon_type->id == TypeTableEntryIdFloat) {
+            if (type_entry->id == TypeTableEntryIdFloat) {
                 LLVMRealPredicate pred = cmp_op_to_real_predicate(op_id);
                 return LLVMBuildFCmp(g->builder, pred, op1_value, op2_value, "");
-            } else if (canon_type->id == TypeTableEntryIdInt) {
-                LLVMIntPredicate pred = cmp_op_to_int_predicate(op_id, canon_type->data.integral.is_signed);
+            } else if (type_entry->id == TypeTableEntryIdInt) {
+                LLVMIntPredicate pred = cmp_op_to_int_predicate(op_id, type_entry->data.integral.is_signed);
                 return LLVMBuildICmp(g->builder, pred, op1_value, op2_value, "");
-            } else if (canon_type->id == TypeTableEntryIdEnum) {
-                if (canon_type->data.enumeration.gen_field_count == 0) {
+            } else if (type_entry->id == TypeTableEntryIdEnum) {
+                if (type_entry->data.enumeration.gen_field_count == 0) {
                     LLVMIntPredicate pred = cmp_op_to_int_predicate(op_id, false);
                     return LLVMBuildICmp(g->builder, pred, op1_value, op2_value, "");
                 } else {
                     zig_unreachable();
                 }
-            } else if (canon_type->id == TypeTableEntryIdPureError ||
-                    canon_type->id == TypeTableEntryIdPointer ||
-                    canon_type->id == TypeTableEntryIdBool)
+            } else if (type_entry->id == TypeTableEntryIdPureError ||
+                    type_entry->id == TypeTableEntryIdPointer ||
+                    type_entry->id == TypeTableEntryIdBool)
             {
                 LLVMIntPredicate pred = cmp_op_to_int_predicate(op_id, false);
                 return LLVMBuildICmp(g->builder, pred, op1_value, op2_value, "");
@@ -1157,15 +1154,15 @@ static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
             }
         case IrBinOpAdd:
         case IrBinOpAddWrap:
-            if (canon_type->id == TypeTableEntryIdFloat) {
+            if (type_entry->id == TypeTableEntryIdFloat) {
                 return LLVMBuildFAdd(g->builder, op1_value, op2_value, "");
-            } else if (canon_type->id == TypeTableEntryIdInt) {
+            } else if (type_entry->id == TypeTableEntryIdInt) {
                 bool is_wrapping = (op_id == IrBinOpAddWrap);
                 if (is_wrapping) {
                     return LLVMBuildAdd(g->builder, op1_value, op2_value, "");
                 } else if (want_debug_safety) {
-                    return gen_overflow_op(g, canon_type, AddSubMulAdd, op1_value, op2_value);
-                } else if (canon_type->data.integral.is_signed) {
+                    return gen_overflow_op(g, type_entry, AddSubMulAdd, op1_value, op2_value);
+                } else if (type_entry->data.integral.is_signed) {
                     return LLVMBuildNSWAdd(g->builder, op1_value, op2_value, "");
                 } else {
                     return LLVMBuildNUWAdd(g->builder, op1_value, op2_value, "");
@@ -1182,36 +1179,36 @@ static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
         case IrBinOpBitShiftLeft:
         case IrBinOpBitShiftLeftWrap:
             {
-                assert(canon_type->id == TypeTableEntryIdInt);
+                assert(type_entry->id == TypeTableEntryIdInt);
                 bool is_wrapping = (op_id == IrBinOpBitShiftLeftWrap);
                 if (is_wrapping) {
                     return LLVMBuildShl(g->builder, op1_value, op2_value, "");
                 } else if (want_debug_safety) {
-                    return gen_overflow_shl_op(g, canon_type, op1_value, op2_value);
-                } else if (canon_type->data.integral.is_signed) {
+                    return gen_overflow_shl_op(g, type_entry, op1_value, op2_value);
+                } else if (type_entry->data.integral.is_signed) {
                     return ZigLLVMBuildNSWShl(g->builder, op1_value, op2_value, "");
                 } else {
                     return ZigLLVMBuildNUWShl(g->builder, op1_value, op2_value, "");
                 }
             }
         case IrBinOpBitShiftRight:
-            assert(canon_type->id == TypeTableEntryIdInt);
-            if (canon_type->data.integral.is_signed) {
+            assert(type_entry->id == TypeTableEntryIdInt);
+            if (type_entry->data.integral.is_signed) {
                 return LLVMBuildAShr(g->builder, op1_value, op2_value, "");
             } else {
                 return LLVMBuildLShr(g->builder, op1_value, op2_value, "");
             }
         case IrBinOpSub:
         case IrBinOpSubWrap:
-            if (canon_type->id == TypeTableEntryIdFloat) {
+            if (type_entry->id == TypeTableEntryIdFloat) {
                 return LLVMBuildFSub(g->builder, op1_value, op2_value, "");
-            } else if (canon_type->id == TypeTableEntryIdInt) {
+            } else if (type_entry->id == TypeTableEntryIdInt) {
                 bool is_wrapping = (op_id == IrBinOpSubWrap);
                 if (is_wrapping) {
                     return LLVMBuildSub(g->builder, op1_value, op2_value, "");
                 } else if (want_debug_safety) {
-                    return gen_overflow_op(g, canon_type, AddSubMulSub, op1_value, op2_value);
-                } else if (canon_type->data.integral.is_signed) {
+                    return gen_overflow_op(g, type_entry, AddSubMulSub, op1_value, op2_value);
+                } else if (type_entry->data.integral.is_signed) {
                     return LLVMBuildNSWSub(g->builder, op1_value, op2_value, "");
                 } else {
                     return LLVMBuildNUWSub(g->builder, op1_value, op2_value, "");
@@ -1221,15 +1218,15 @@ static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
             }
         case IrBinOpMult:
         case IrBinOpMultWrap:
-            if (canon_type->id == TypeTableEntryIdFloat) {
+            if (type_entry->id == TypeTableEntryIdFloat) {
                 return LLVMBuildFMul(g->builder, op1_value, op2_value, "");
-            } else if (canon_type->id == TypeTableEntryIdInt) {
+            } else if (type_entry->id == TypeTableEntryIdInt) {
                 bool is_wrapping = (op_id == IrBinOpMultWrap);
                 if (is_wrapping) {
                     return LLVMBuildMul(g->builder, op1_value, op2_value, "");
                 } else if (want_debug_safety) {
-                    return gen_overflow_op(g, canon_type, AddSubMulMul, op1_value, op2_value);
-                } else if (canon_type->data.integral.is_signed) {
+                    return gen_overflow_op(g, type_entry, AddSubMulMul, op1_value, op2_value);
+                } else if (type_entry->data.integral.is_signed) {
                     return LLVMBuildNSWMul(g->builder, op1_value, op2_value, "");
                 } else {
                     return LLVMBuildNUWMul(g->builder, op1_value, op2_value, "");
@@ -1238,9 +1235,9 @@ static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
                 zig_unreachable();
             }
         case IrBinOpDiv:
-            return gen_div(g, want_debug_safety, op1_value, op2_value, canon_type, false);
+            return gen_div(g, want_debug_safety, op1_value, op2_value, type_entry, false);
         case IrBinOpRem:
-            return gen_rem(g, want_debug_safety, op1_value, op2_value, canon_type);
+            return gen_rem(g, want_debug_safety, op1_value, op2_value, type_entry);
     }
     zig_unreachable();
 }
@@ -1644,7 +1641,7 @@ static LLVMValueRef ir_render_store_ptr(CodeGen *g, IrExecutable *executable, Ir
     LLVMValueRef value = ir_llvm_value(g, instruction->value);
 
     assert(instruction->ptr->value.type->id == TypeTableEntryIdPointer);
-    TypeTableEntry *ptr_type = get_underlying_type(instruction->ptr->value.type);
+    TypeTableEntry *ptr_type = instruction->ptr->value.type;
 
     gen_assign_raw(g, ptr, ptr_type, value);
 
@@ -1685,9 +1682,9 @@ static LLVMValueRef ir_render_elem_ptr(CodeGen *g, IrExecutable *executable, IrI
         if (array_ptr_type->data.pointer.unaligned_bit_count != 0) {
             return array_ptr_ptr;
         }
-        TypeTableEntry *canon_child_type = get_underlying_type(array_type->data.array.child_type);
-        if (canon_child_type->id == TypeTableEntryIdStruct &&
-            canon_child_type->data.structure.layout == ContainerLayoutPacked)
+        TypeTableEntry *child_type = array_type->data.array.child_type;
+        if (child_type->id == TypeTableEntryIdStruct &&
+            child_type->data.structure.layout == ContainerLayoutPacked)
         {
             size_t unaligned_bit_count = instruction->base.value.type->data.pointer.unaligned_bit_count;
             if (unaligned_bit_count != 0) {
@@ -1701,7 +1698,7 @@ static LLVMValueRef ir_render_elem_ptr(CodeGen *g, IrExecutable *executable, IrI
                     byte_offset
                 };
                 LLVMValueRef elem_byte_ptr = LLVMBuildInBoundsGEP(g->builder, u8_array_ptr, indices, 1, "");
-                return LLVMBuildBitCast(g->builder, elem_byte_ptr, LLVMPointerType(canon_child_type->type_ref, 0), "");
+                return LLVMBuildBitCast(g->builder, elem_byte_ptr, LLVMPointerType(child_type->type_ref, 0), "");
             }
         }
         LLVMValueRef indices[] = {
@@ -2206,8 +2203,8 @@ static LLVMValueRef ir_render_div_exact(CodeGen *g, IrExecutable *executable, Ir
 
 static LLVMValueRef ir_render_truncate(CodeGen *g, IrExecutable *executable, IrInstructionTruncate *instruction) {
     LLVMValueRef target_val = ir_llvm_value(g, instruction->target);
-    TypeTableEntry *dest_type = get_underlying_type(instruction->base.value.type);
-    TypeTableEntry *src_type = get_underlying_type(instruction->target->value.type);
+    TypeTableEntry *dest_type = instruction->base.value.type;
+    TypeTableEntry *src_type = instruction->target->value.type;
     if (dest_type == src_type) {
         // no-op
         return target_val;
@@ -2228,7 +2225,7 @@ static LLVMValueRef ir_render_memset(CodeGen *g, IrExecutable *executable, IrIns
 
     LLVMValueRef dest_ptr_casted = LLVMBuildBitCast(g->builder, dest_ptr, ptr_u8, "");
 
-    TypeTableEntry *ptr_type = get_underlying_type(instruction->dest_ptr->value.type);
+    TypeTableEntry *ptr_type = instruction->dest_ptr->value.type;
     assert(ptr_type->id == TypeTableEntryIdPointer);
 
     LLVMValueRef is_volatile = ptr_type->data.pointer.is_volatile ?
@@ -2256,8 +2253,8 @@ static LLVMValueRef ir_render_memcpy(CodeGen *g, IrExecutable *executable, IrIns
     LLVMValueRef dest_ptr_casted = LLVMBuildBitCast(g->builder, dest_ptr, ptr_u8, "");
     LLVMValueRef src_ptr_casted = LLVMBuildBitCast(g->builder, src_ptr, ptr_u8, "");
 
-    TypeTableEntry *dest_ptr_type = get_underlying_type(instruction->dest_ptr->value.type);
-    TypeTableEntry *src_ptr_type = get_underlying_type(instruction->src_ptr->value.type);
+    TypeTableEntry *dest_ptr_type = instruction->dest_ptr->value.type;
+    TypeTableEntry *src_ptr_type = instruction->src_ptr->value.type;
 
     assert(dest_ptr_type->id == TypeTableEntryIdPointer);
     assert(src_ptr_type->id == TypeTableEntryIdPointer);
@@ -2407,7 +2404,7 @@ static LLVMValueRef ir_render_frame_address(CodeGen *g, IrExecutable *executable
 }
 
 static LLVMValueRef render_shl_with_overflow(CodeGen *g, IrInstructionOverflowOp *instruction) {
-    TypeTableEntry *int_type = get_underlying_type(instruction->result_ptr_type);
+    TypeTableEntry *int_type = instruction->result_ptr_type;
     assert(int_type->id == TypeTableEntryIdInt);
 
     LLVMValueRef op1 = ir_llvm_value(g, instruction->op1);
@@ -2444,7 +2441,7 @@ static LLVMValueRef ir_render_overflow_op(CodeGen *g, IrExecutable *executable,
             return render_shl_with_overflow(g, instruction);
     }
 
-    TypeTableEntry *int_type = get_underlying_type(instruction->result_ptr_type);
+    TypeTableEntry *int_type = instruction->result_ptr_type;
     assert(int_type->id == TypeTableEntryIdInt);
 
     LLVMValueRef fn_val = get_int_overflow_fn(g, int_type, add_sub_mul);
@@ -2467,8 +2464,8 @@ static LLVMValueRef ir_render_overflow_op(CodeGen *g, IrExecutable *executable,
 }
 
 static LLVMValueRef ir_render_test_err(CodeGen *g, IrExecutable *executable, IrInstructionTestErr *instruction) {
-    TypeTableEntry *err_union_type = get_underlying_type(instruction->value->value.type);
-    TypeTableEntry *child_type = get_underlying_type(err_union_type->data.error.child_type);
+    TypeTableEntry *err_union_type = instruction->value->value.type;
+    TypeTableEntry *child_type = err_union_type->data.error.child_type;
     LLVMValueRef err_union_handle = ir_llvm_value(g, instruction->value);
 
     LLVMValueRef err_val;
@@ -2484,11 +2481,11 @@ static LLVMValueRef ir_render_test_err(CodeGen *g, IrExecutable *executable, IrI
 }
 
 static LLVMValueRef ir_render_unwrap_err_code(CodeGen *g, IrExecutable *executable, IrInstructionUnwrapErrCode *instruction) {
-    TypeTableEntry *ptr_type = get_underlying_type(instruction->value->value.type);
+    TypeTableEntry *ptr_type = instruction->value->value.type;
     assert(ptr_type->id == TypeTableEntryIdPointer);
     bool is_volatile = ptr_type->data.pointer.is_volatile;
-    TypeTableEntry *err_union_type = get_underlying_type(ptr_type->data.pointer.child_type);
-    TypeTableEntry *child_type = get_underlying_type(err_union_type->data.error.child_type);
+    TypeTableEntry *err_union_type = ptr_type->data.pointer.child_type;
+    TypeTableEntry *child_type = err_union_type->data.error.child_type;
     LLVMValueRef err_union_ptr = ir_llvm_value(g, instruction->value);
     LLVMValueRef err_union_handle = get_handle_value(g, err_union_ptr, err_union_type, is_volatile);
 
@@ -2501,11 +2498,11 @@ static LLVMValueRef ir_render_unwrap_err_code(CodeGen *g, IrExecutable *executab
 }
 
 static LLVMValueRef ir_render_unwrap_err_payload(CodeGen *g, IrExecutable *executable, IrInstructionUnwrapErrPayload *instruction) {
-    TypeTableEntry *ptr_type = get_underlying_type(instruction->value->value.type);
+    TypeTableEntry *ptr_type = instruction->value->value.type;
     assert(ptr_type->id == TypeTableEntryIdPointer);
     bool is_volatile = ptr_type->data.pointer.is_volatile;
-    TypeTableEntry *err_union_type = get_underlying_type(ptr_type->data.pointer.child_type);
-    TypeTableEntry *child_type = get_underlying_type(err_union_type->data.error.child_type);
+    TypeTableEntry *err_union_type = ptr_type->data.pointer.child_type;
+    TypeTableEntry *child_type = err_union_type->data.error.child_type;
     LLVMValueRef err_union_ptr = ir_llvm_value(g, instruction->value);
     LLVMValueRef err_union_handle = get_handle_value(g, err_union_ptr, err_union_type, is_volatile);
 
@@ -2941,9 +2938,9 @@ static LLVMValueRef pack_const_int(CodeGen *g, LLVMTypeRef big_int_type_ref, Con
             break;
     }
 
-    TypeTableEntry *canon_type = get_underlying_type(const_val->type);
-    assert(!canon_type->zero_bits);
-    switch (canon_type->id) {
+    TypeTableEntry *type_entry = const_val->type;
+    assert(!type_entry->zero_bits);
+    switch (type_entry->id) {
         case TypeTableEntryIdInvalid:
         case TypeTableEntryIdVar:
         case TypeTableEntryIdMetaType:
@@ -2956,12 +2953,12 @@ static LLVMValueRef pack_const_int(CodeGen *g, LLVMTypeRef big_int_type_ref, Con
         case TypeTableEntryIdPureError:
         case TypeTableEntryIdEnum:
         case TypeTableEntryIdEnumTag:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
         case TypeTableEntryIdArgTuple:
         case TypeTableEntryIdVoid:
+        case TypeTableEntryIdOpaque:
             zig_unreachable();
         case TypeTableEntryIdBool:
             return LLVMConstInt(big_int_type_ref, const_val->data.x_bool ? 1 : 0, false);
@@ -2975,7 +2972,7 @@ static LLVMValueRef pack_const_int(CodeGen *g, LLVMTypeRef big_int_type_ref, Con
             {
                 LLVMValueRef float_val = gen_const_val(g, const_val);
                 LLVMValueRef int_val = LLVMConstFPToUI(float_val,
-                        LLVMIntType((unsigned)canon_type->data.floating.bit_count));
+                        LLVMIntType((unsigned)type_entry->data.floating.bit_count));
                 return LLVMConstZExt(int_val, big_int_type_ref);
             }
         case TypeTableEntryIdPointer:
@@ -2992,11 +2989,11 @@ static LLVMValueRef pack_const_int(CodeGen *g, LLVMTypeRef big_int_type_ref, Con
             zig_panic("TODO bit pack a union");
         case TypeTableEntryIdStruct:
             {
-                assert(canon_type->data.structure.layout == ContainerLayoutPacked);
+                assert(type_entry->data.structure.layout == ContainerLayoutPacked);
 
                 LLVMValueRef val = LLVMConstInt(big_int_type_ref, 0, false);
-                for (size_t i = 0; i < canon_type->data.structure.src_field_count; i += 1) {
-                    TypeStructField *field = &canon_type->data.structure.fields[i];
+                for (size_t i = 0; i < type_entry->data.structure.src_field_count; i += 1) {
+                    TypeStructField *field = &type_entry->data.structure.fields[i];
                     if (field->gen_index == SIZE_MAX) {
                         continue;
                     }
@@ -3012,37 +3009,35 @@ static LLVMValueRef pack_const_int(CodeGen *g, LLVMTypeRef big_int_type_ref, Con
 }
 
 static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
-    TypeTableEntry *canon_type = get_underlying_type(const_val->type);
-    assert(!canon_type->zero_bits);
+    TypeTableEntry *type_entry = const_val->type;
+    assert(!type_entry->zero_bits);
 
     switch (const_val->special) {
         case ConstValSpecialRuntime:
             zig_unreachable();
         case ConstValSpecialUndef:
-            return LLVMGetUndef(canon_type->type_ref);
+            return LLVMGetUndef(type_entry->type_ref);
         case ConstValSpecialStatic:
             break;
     }
 
-    switch (canon_type->id) {
-        case TypeTableEntryIdTypeDecl:
-            zig_unreachable();
+    switch (type_entry->id) {
         case TypeTableEntryIdInt:
         case TypeTableEntryIdEnumTag:
-            return LLVMConstInt(canon_type->type_ref, bignum_to_twos_complement(&const_val->data.x_bignum), false);
+            return LLVMConstInt(type_entry->type_ref, bignum_to_twos_complement(&const_val->data.x_bignum), false);
         case TypeTableEntryIdPureError:
             assert(const_val->data.x_pure_err);
             return LLVMConstInt(g->builtin_types.entry_pure_error->type_ref,
                     const_val->data.x_pure_err->value, false);
         case TypeTableEntryIdFloat:
             if (const_val->data.x_bignum.kind == BigNumKindFloat) {
-                return LLVMConstReal(canon_type->type_ref, const_val->data.x_bignum.data.x_float);
+                return LLVMConstReal(type_entry->type_ref, const_val->data.x_bignum.data.x_float);
             } else {
                 double x = (double)const_val->data.x_bignum.data.x_uint;
                 if (const_val->data.x_bignum.is_negative) {
                     x = -x;
                 }
-                return LLVMConstReal(canon_type->type_ref, x);
+                return LLVMConstReal(type_entry->type_ref, x);
             }
         case TypeTableEntryIdBool:
             if (const_val->data.x_bool) {
@@ -3052,7 +3047,7 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
             }
         case TypeTableEntryIdMaybe:
             {
-                TypeTableEntry *child_type = canon_type->data.maybe.child_type;
+                TypeTableEntry *child_type = type_entry->data.maybe.child_type;
                 if (child_type->zero_bits) {
                     return LLVMConstInt(LLVMInt1Type(), const_val->data.x_maybe ? 1 : 0, false);
                 } else if (child_type->id == TypeTableEntryIdPointer ||
@@ -3082,12 +3077,12 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
             }
         case TypeTableEntryIdStruct:
             {
-                LLVMValueRef *fields = allocate<LLVMValueRef>(canon_type->data.structure.gen_field_count);
-                size_t src_field_count = canon_type->data.structure.src_field_count;
-                if (canon_type->data.structure.layout == ContainerLayoutPacked) {
+                LLVMValueRef *fields = allocate<LLVMValueRef>(type_entry->data.structure.gen_field_count);
+                size_t src_field_count = type_entry->data.structure.src_field_count;
+                if (type_entry->data.structure.layout == ContainerLayoutPacked) {
                     size_t src_field_index = 0;
                     while (src_field_index < src_field_count) {
-                        TypeStructField *type_struct_field = &canon_type->data.structure.fields[src_field_index];
+                        TypeStructField *type_struct_field = &type_entry->data.structure.fields[src_field_index];
                         if (type_struct_field->gen_index == SIZE_MAX) {
                             src_field_index += 1;
                             continue;
@@ -3095,7 +3090,7 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
 
                         size_t src_field_index_end = src_field_index + 1;
                         for (; src_field_index_end < src_field_count; src_field_index_end += 1) {
-                            TypeStructField *it_field = &canon_type->data.structure.fields[src_field_index_end];
+                            TypeStructField *it_field = &type_entry->data.structure.fields[src_field_index_end];
                             if (it_field->gen_index != type_struct_field->gen_index)
                                 break;
                         }
@@ -3104,11 +3099,11 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
                             fields[type_struct_field->gen_index] =
                                 gen_const_val(g, &const_val->data.x_struct.fields[src_field_index]);
                         } else {
-                            LLVMTypeRef big_int_type_ref = LLVMStructGetTypeAtIndex(canon_type->type_ref,
+                            LLVMTypeRef big_int_type_ref = LLVMStructGetTypeAtIndex(type_entry->type_ref,
                                     (unsigned)type_struct_field->gen_index);
                             LLVMValueRef val = LLVMConstInt(big_int_type_ref, 0, false);
                             for (size_t i = src_field_index; i < src_field_index_end; i += 1) {
-                                TypeStructField *it_field = &canon_type->data.structure.fields[i];
+                                TypeStructField *it_field = &type_entry->data.structure.fields[i];
                                 if (it_field->gen_index == SIZE_MAX) {
                                     continue;
                                 }
@@ -3126,14 +3121,14 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
                     }
                 } else {
                     for (uint32_t i = 0; i < src_field_count; i += 1) {
-                        TypeStructField *type_struct_field = &canon_type->data.structure.fields[i];
+                        TypeStructField *type_struct_field = &type_entry->data.structure.fields[i];
                         if (type_struct_field->gen_index == SIZE_MAX) {
                             continue;
                         }
                         fields[type_struct_field->gen_index] = gen_const_val(g, &const_val->data.x_struct.fields[i]);
                     }
                 }
-                return LLVMConstNamedStruct(canon_type->type_ref, fields, canon_type->data.structure.gen_field_count);
+                return LLVMConstNamedStruct(type_entry->type_ref, fields, type_entry->data.structure.gen_field_count);
             }
         case TypeTableEntryIdUnion:
             {
@@ -3141,7 +3136,7 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
             }
         case TypeTableEntryIdArray:
             {
-                uint64_t len = canon_type->data.array.len;
+                uint64_t len = type_entry->data.array.len;
                 LLVMValueRef *values = allocate<LLVMValueRef>(len);
                 for (uint64_t i = 0; i < len; i += 1) {
                     ConstExprValue *elem_value = &const_val->data.x_array.elements[i];
@@ -3151,13 +3146,13 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
             }
         case TypeTableEntryIdEnum:
             {
-                LLVMTypeRef tag_type_ref = canon_type->data.enumeration.tag_type->type_ref;
+                LLVMTypeRef tag_type_ref = type_entry->data.enumeration.tag_type->type_ref;
                 LLVMValueRef tag_value = LLVMConstInt(tag_type_ref, const_val->data.x_enum.tag, false);
-                if (canon_type->data.enumeration.gen_field_count == 0) {
+                if (type_entry->data.enumeration.gen_field_count == 0) {
                     return tag_value;
                 } else {
-                    TypeTableEntry *union_type = canon_type->data.enumeration.union_type;
-                    TypeEnumField *enum_field = &canon_type->data.enumeration.fields[const_val->data.x_enum.tag];
+                    TypeTableEntry *union_type = type_entry->data.enumeration.union_type;
+                    TypeEnumField *enum_field = &type_entry->data.enumeration.fields[const_val->data.x_enum.tag];
                     assert(enum_field->value == const_val->data.x_enum.tag);
                     LLVMValueRef union_value;
                     if (type_has_bits(enum_field->type_entry)) {
@@ -3261,7 +3256,7 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
             }
         case TypeTableEntryIdErrorUnion:
             {
-                TypeTableEntry *child_type = canon_type->data.error.child_type;
+                TypeTableEntry *child_type = type_entry->data.error.child_type;
                 if (!type_has_bits(child_type)) {
                     uint64_t value = const_val->data.x_err_union.err ? const_val->data.x_err_union.err->value : 0;
                     return LLVMConstInt(g->err_tag_type->type_ref, value, false);
@@ -3296,6 +3291,7 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
         case TypeTableEntryIdBoundFn:
         case TypeTableEntryIdVar:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             zig_unreachable();
 
     }
@@ -4107,7 +4103,7 @@ static void define_builtin_types(CodeGen *g) {
     g->builtin_types.entry_i64 = get_int_type(g, true, 64);
 
     {
-        g->builtin_types.entry_c_void = get_typedecl_type(g, "c_void", g->builtin_types.entry_u8);
+        g->builtin_types.entry_c_void = get_opaque_type(g, nullptr, nullptr, "c_void");
         g->primitive_type_table.put(&g->builtin_types.entry_c_void->name, g->builtin_types.entry_c_void);
     }
 
@@ -4747,6 +4743,7 @@ static void get_c_type(CodeGen *g, TypeTableEntry *type_entry, Buf *out_buf) {
                     zig_unreachable();
                 }
             }
+        case TypeTableEntryIdOpaque:
         case TypeTableEntryIdArray:
         case TypeTableEntryIdStruct:
         case TypeTableEntryIdErrorUnion:
@@ -4754,7 +4751,6 @@ static void get_c_type(CodeGen *g, TypeTableEntry *type_entry, Buf *out_buf) {
         case TypeTableEntryIdEnum:
         case TypeTableEntryIdUnion:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdEnumTag:
             zig_panic("TODO implement get_c_type for more types");
         case TypeTableEntryIdInvalid:
src/ir.cpp
@@ -5323,11 +5323,6 @@ static IrInstruction *ir_gen_continue(IrBuilder *irb, Scope *scope, AstNode *nod
     return ir_build_br(irb, scope, node, dest_block, is_comptime);
 }
 
-static IrInstruction *ir_gen_type_literal(IrBuilder *irb, Scope *scope, AstNode *node) {
-    assert(node->type == NodeTypeTypeLiteral);
-    return ir_build_const_type(irb, scope, node, irb->codegen->builtin_types.entry_type);
-}
-
 static IrInstruction *ir_gen_error_type(IrBuilder *irb, Scope *scope, AstNode *node) {
     assert(node->type == NodeTypeErrorType);
     return ir_build_const_type(irb, scope, node, irb->codegen->builtin_types.entry_pure_error);
@@ -5600,8 +5595,6 @@ static IrInstruction *ir_gen_node_raw(IrBuilder *irb, AstNode *node, Scope *scop
             return ir_lval_wrap(irb, scope, ir_gen_goto(irb, scope, node), lval);
         case NodeTypeCompTime:
             return ir_gen_comptime(irb, scope, node, lval);
-        case NodeTypeTypeLiteral:
-            return ir_lval_wrap(irb, scope, ir_gen_type_literal(irb, scope, node), lval);
         case NodeTypeErrorType:
             return ir_lval_wrap(irb, scope, ir_gen_error_type(irb, scope, node), lval);
         case NodeTypeBreak:
@@ -5628,8 +5621,6 @@ static IrInstruction *ir_gen_node_raw(IrBuilder *irb, AstNode *node, Scope *scop
             zig_panic("TODO IR gen NodeTypeFnDecl");
         case NodeTypeErrorValueDecl:
             zig_panic("TODO IR gen NodeTypeErrorValueDecl");
-        case NodeTypeTypeDecl:
-            zig_panic("TODO IR gen NodeTypeTypeDecl");
         case NodeTypeTestDecl:
             zig_panic("TODO IR gen NodeTypeTestDecl");
     }
@@ -5753,13 +5744,6 @@ static ErrorMsg *ir_add_error(IrAnalyze *ira, IrInstruction *source_instruction,
     return ir_add_error_node(ira, source_instruction->source_node, msg);
 }
 
-static void ir_add_typedef_err_note(IrAnalyze *ira, ErrorMsg *msg, TypeTableEntry *type_entry) {
-    if (type_entry->id == TypeTableEntryIdTypeDecl) {
-        // requires tracking source_node in the typedecl type
-        zig_panic("TODO add error note about typedecls");
-    }
-}
-
 static IrInstruction *ir_exec_const_result(CodeGen *codegen, IrExecutable *exec) {
     IrBasicBlock *bb = exec->basic_block_list.at(0);
     for (size_t i = 0; i < bb->instruction_list.length; i += 1) {
@@ -5791,27 +5775,25 @@ static bool ir_emit_global_runtime_side_effect(IrAnalyze *ira, IrInstruction *so
 }
 
 static bool ir_num_lit_fits_in_other_type(IrAnalyze *ira, IrInstruction *instruction, TypeTableEntry *other_type) {
-    TypeTableEntry *other_type_underlying = get_underlying_type(other_type);
-
-    if (type_is_invalid(other_type_underlying)) {
+    if (type_is_invalid(other_type)) {
         return false;
     }
 
     ConstExprValue *const_val = &instruction->value;
     assert(const_val->special != ConstValSpecialRuntime);
-    if (other_type_underlying->id == TypeTableEntryIdFloat) {
+    if (other_type->id == TypeTableEntryIdFloat) {
         return true;
-    } else if (other_type_underlying->id == TypeTableEntryIdInt &&
+    } else if (other_type->id == TypeTableEntryIdInt &&
                const_val->data.x_bignum.kind == BigNumKindInt)
     {
-        if (bignum_fits_in_bits(&const_val->data.x_bignum, other_type_underlying->data.integral.bit_count,
-                    other_type_underlying->data.integral.is_signed))
+        if (bignum_fits_in_bits(&const_val->data.x_bignum, other_type->data.integral.bit_count,
+                    other_type->data.integral.is_signed))
         {
             return true;
         }
-    } else if ((other_type_underlying->id == TypeTableEntryIdNumLitFloat &&
+    } else if ((other_type->id == TypeTableEntryIdNumLitFloat &&
                 const_val->data.x_bignum.kind == BigNumKindFloat) ||
-               (other_type_underlying->id == TypeTableEntryIdNumLitInt &&
+               (other_type->id == TypeTableEntryIdNumLitInt &&
                 const_val->data.x_bignum.kind == BigNumKindInt))
     {
         return true;
@@ -6890,12 +6872,9 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
     TypeTableEntry *wanted_type, IrInstruction *value)
 {
     TypeTableEntry *actual_type = value->value.type;
-    TypeTableEntry *wanted_type_canon = get_underlying_type(wanted_type);
-    TypeTableEntry *actual_type_canon = get_underlying_type(actual_type);
-
     TypeTableEntry *usize_type = ira->codegen->builtin_types.entry_usize;
 
-    if (type_is_invalid(wanted_type_canon) || type_is_invalid(actual_type_canon)) {
+    if (type_is_invalid(wanted_type) || type_is_invalid(actual_type)) {
         return ira->codegen->invalid_instruction;
     }
 
@@ -6908,36 +6887,36 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
     }
 
     // explicit cast from bool to int
-    if (wanted_type_canon->id == TypeTableEntryIdInt &&
-        actual_type_canon->id == TypeTableEntryIdBool)
+    if (wanted_type->id == TypeTableEntryIdInt &&
+        actual_type->id == TypeTableEntryIdBool)
     {
         return ir_resolve_cast(ira, source_instr, value, wanted_type, CastOpBoolToInt, false);
     }
 
     // explicit cast from pointer to usize
-    if (wanted_type_canon == usize_type && type_is_codegen_pointer(actual_type_canon)) {
+    if (wanted_type == usize_type && type_is_codegen_pointer(actual_type)) {
         return ir_analyze_ptr_to_int(ira, source_instr, value, wanted_type);
     }
 
     // explicit widening or shortening cast
-    if ((wanted_type_canon->id == TypeTableEntryIdInt &&
-        actual_type_canon->id == TypeTableEntryIdInt) ||
-        (wanted_type_canon->id == TypeTableEntryIdFloat &&
-        actual_type_canon->id == TypeTableEntryIdFloat))
+    if ((wanted_type->id == TypeTableEntryIdInt &&
+        actual_type->id == TypeTableEntryIdInt) ||
+        (wanted_type->id == TypeTableEntryIdFloat &&
+        actual_type->id == TypeTableEntryIdFloat))
     {
         return ir_analyze_widen_or_shorten(ira, source_instr, value, wanted_type);
     }
 
     // explicit cast from int to float
-    if (wanted_type_canon->id == TypeTableEntryIdFloat &&
-        actual_type_canon->id == TypeTableEntryIdInt)
+    if (wanted_type->id == TypeTableEntryIdFloat &&
+        actual_type->id == TypeTableEntryIdInt)
     {
         return ir_resolve_cast(ira, source_instr, value, wanted_type, CastOpIntToFloat, false);
     }
 
     // explicit cast from float to int
-    if (wanted_type_canon->id == TypeTableEntryIdInt &&
-        actual_type_canon->id == TypeTableEntryIdFloat)
+    if (wanted_type->id == TypeTableEntryIdInt &&
+        actual_type->id == TypeTableEntryIdFloat)
     {
         return ir_resolve_cast(ira, source_instr, value, wanted_type, CastOpFloatToInt, false);
     }
@@ -7070,17 +7049,17 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
                 return ira->codegen->invalid_instruction;
 
             return cast2;
-        } else if (ir_num_lit_fits_in_other_type(ira, value, wanted_type_canon)) {
+        } else if (ir_num_lit_fits_in_other_type(ira, value, wanted_type)) {
             CastOp op;
             if ((actual_type->id == TypeTableEntryIdNumLitFloat &&
-                 wanted_type_canon->id == TypeTableEntryIdFloat) ||
+                 wanted_type->id == TypeTableEntryIdFloat) ||
                 (actual_type->id == TypeTableEntryIdNumLitInt &&
-                 wanted_type_canon->id == TypeTableEntryIdInt))
+                 wanted_type->id == TypeTableEntryIdInt))
             {
                 op = CastOpNoop;
-            } else if (wanted_type_canon->id == TypeTableEntryIdInt) {
+            } else if (wanted_type->id == TypeTableEntryIdInt) {
                 op = CastOpFloatToInt;
-            } else if (wanted_type_canon->id == TypeTableEntryIdFloat) {
+            } else if (wanted_type->id == TypeTableEntryIdFloat) {
                 op = CastOpIntToFloat;
             } else {
                 zig_unreachable();
@@ -7475,7 +7454,7 @@ static TypeTableEntry *ir_analyze_bin_op_cmp(IrAnalyze *ira, IrInstructionBinOp
         case TypeTableEntryIdPointer:
         case TypeTableEntryIdPureError:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
+        case TypeTableEntryIdOpaque:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
@@ -7709,15 +7688,14 @@ static TypeTableEntry *ir_analyze_bin_op_math(IrAnalyze *ira, IrInstructionBinOp
     TypeTableEntry *resolved_type = ir_resolve_peer_types(ira, bin_op_instruction->base.source_node, instructions, 2);
     if (type_is_invalid(resolved_type))
         return resolved_type;
-    TypeTableEntry *canon_resolved_type = get_underlying_type(resolved_type);
     IrBinOp op_id = bin_op_instruction->op_id;
 
-    if (canon_resolved_type->id == TypeTableEntryIdInt ||
-        canon_resolved_type->id == TypeTableEntryIdNumLitInt)
+    if (resolved_type->id == TypeTableEntryIdInt ||
+        resolved_type->id == TypeTableEntryIdNumLitInt)
     {
         // int
-    } else if ((canon_resolved_type->id == TypeTableEntryIdFloat ||
-                canon_resolved_type->id == TypeTableEntryIdNumLitFloat) &&
+    } else if ((resolved_type->id == TypeTableEntryIdFloat ||
+                resolved_type->id == TypeTableEntryIdNumLitFloat) &&
         (op_id == IrBinOpAdd ||
             op_id == IrBinOpSub ||
             op_id == IrBinOpMult ||
@@ -7751,7 +7729,7 @@ static TypeTableEntry *ir_analyze_bin_op_math(IrAnalyze *ira, IrInstructionBinOp
         bin_op_instruction->base.other = &bin_op_instruction->base;
 
         int err;
-        if ((err = ir_eval_math_op(canon_resolved_type, op1_val, op_id, op2_val, out_val))) {
+        if ((err = ir_eval_math_op(resolved_type, op1_val, op_id, op2_val, out_val))) {
             if (err == ErrorDivByZero) {
                 ir_add_error_node(ira, bin_op_instruction->base.source_node,
                         buf_sprintf("division by zero is undefined"));
@@ -7776,13 +7754,13 @@ static TypeTableEntry *ir_analyze_bin_op_math(IrAnalyze *ira, IrInstructionBinOp
 
 static TypeTableEntry *ir_analyze_array_cat(IrAnalyze *ira, IrInstructionBinOp *instruction) {
     IrInstruction *op1 = instruction->op1->other;
-    TypeTableEntry *op1_canon_type = get_underlying_type(op1->value.type);
-    if (type_is_invalid(op1_canon_type))
+    TypeTableEntry *op1_type = op1->value.type;
+    if (type_is_invalid(op1_type))
         return ira->codegen->builtin_types.entry_invalid;
 
     IrInstruction *op2 = instruction->op2->other;
-    TypeTableEntry *op2_canon_type = get_underlying_type(op2->value.type);
-    if (type_is_invalid(op2_canon_type))
+    TypeTableEntry *op2_type = op2->value.type;
+    if (type_is_invalid(op2_type))
         return ira->codegen->builtin_types.entry_invalid;
 
     ConstExprValue *op1_val = ir_resolve_const(ira, op1, UndefBad);
@@ -7797,22 +7775,22 @@ static TypeTableEntry *ir_analyze_array_cat(IrAnalyze *ira, IrInstructionBinOp *
     size_t op1_array_index;
     size_t op1_array_end;
     TypeTableEntry *child_type;
-    if (op1_canon_type->id == TypeTableEntryIdArray) {
-        child_type = op1_canon_type->data.array.child_type;
+    if (op1_type->id == TypeTableEntryIdArray) {
+        child_type = op1_type->data.array.child_type;
         op1_array_val = op1_val;
         op1_array_index = 0;
-        op1_array_end = op1_canon_type->data.array.len;
-    } else if (op1_canon_type->id == TypeTableEntryIdPointer &&
-        op1_canon_type->data.pointer.child_type == ira->codegen->builtin_types.entry_u8 &&
+        op1_array_end = op1_type->data.array.len;
+    } else if (op1_type->id == TypeTableEntryIdPointer &&
+        op1_type->data.pointer.child_type == ira->codegen->builtin_types.entry_u8 &&
         op1_val->data.x_ptr.special == ConstPtrSpecialBaseArray &&
         op1_val->data.x_ptr.data.base_array.is_cstr)
     {
-        child_type = op1_canon_type->data.pointer.child_type;
+        child_type = op1_type->data.pointer.child_type;
         op1_array_val = op1_val->data.x_ptr.data.base_array.array_val;
         op1_array_index = op1_val->data.x_ptr.data.base_array.elem_index;
         op1_array_end = op1_array_val->type->data.array.len - 1;
-    } else if (is_slice(op1_canon_type)) {
-        TypeTableEntry *ptr_type = op1_canon_type->data.structure.fields[slice_ptr_index].type_entry;
+    } else if (is_slice(op1_type)) {
+        TypeTableEntry *ptr_type = op1_type->data.structure.fields[slice_ptr_index].type_entry;
         child_type = ptr_type->data.pointer.child_type;
         ConstExprValue *ptr_val = &op1_val->data.x_struct.fields[slice_ptr_index];
         assert(ptr_val->data.x_ptr.special == ConstPtrSpecialBaseArray);
@@ -7822,15 +7800,14 @@ static TypeTableEntry *ir_analyze_array_cat(IrAnalyze *ira, IrInstructionBinOp *
     } else {
         ir_add_error(ira, op1,
             buf_sprintf("expected array or C string literal, found '%s'", buf_ptr(&op1->value.type->name)));
-        // TODO if meta_type is type decl, add note pointing to type decl declaration
         return ira->codegen->builtin_types.entry_invalid;
     }
 
     ConstExprValue *op2_array_val;
     size_t op2_array_index;
     size_t op2_array_end;
-    if (op2_canon_type->id == TypeTableEntryIdArray) {
-        if (op2_canon_type->data.array.child_type != child_type) {
+    if (op2_type->id == TypeTableEntryIdArray) {
+        if (op2_type->data.array.child_type != child_type) {
             ir_add_error(ira, op2, buf_sprintf("expected array of type '%s', found '%s'",
                         buf_ptr(&child_type->name),
                         buf_ptr(&op2->value.type->name)));
@@ -7839,8 +7816,8 @@ static TypeTableEntry *ir_analyze_array_cat(IrAnalyze *ira, IrInstructionBinOp *
         op2_array_val = op2_val;
         op2_array_index = 0;
         op2_array_end = op2_array_val->type->data.array.len;
-    } else if (op2_canon_type->id == TypeTableEntryIdPointer &&
-        op2_canon_type->data.pointer.child_type == ira->codegen->builtin_types.entry_u8 &&
+    } else if (op2_type->id == TypeTableEntryIdPointer &&
+        op2_type->data.pointer.child_type == ira->codegen->builtin_types.entry_u8 &&
         op2_val->data.x_ptr.special == ConstPtrSpecialBaseArray &&
         op2_val->data.x_ptr.data.base_array.is_cstr)
     {
@@ -7853,8 +7830,8 @@ static TypeTableEntry *ir_analyze_array_cat(IrAnalyze *ira, IrInstructionBinOp *
         op2_array_val = op2_val->data.x_ptr.data.base_array.array_val;
         op2_array_index = op2_val->data.x_ptr.data.base_array.elem_index;
         op2_array_end = op2_array_val->type->data.array.len - 1;
-    } else if (is_slice(op2_canon_type)) {
-        TypeTableEntry *ptr_type = op2_canon_type->data.structure.fields[slice_ptr_index].type_entry;
+    } else if (is_slice(op2_type)) {
+        TypeTableEntry *ptr_type = op2_type->data.structure.fields[slice_ptr_index].type_entry;
         if (ptr_type->data.pointer.child_type != child_type) {
             ir_add_error(ira, op2, buf_sprintf("expected array of type '%s', found '%s'",
                         buf_ptr(&child_type->name),
@@ -7869,7 +7846,6 @@ static TypeTableEntry *ir_analyze_array_cat(IrAnalyze *ira, IrInstructionBinOp *
     } else {
         ir_add_error(ira, op2,
             buf_sprintf("expected array or C string literal, found '%s'", buf_ptr(&op2->value.type->name)));
-        // TODO if meta_type is type decl, add note pointing to type decl declaration
         return ira->codegen->builtin_types.entry_invalid;
     }
 
@@ -7878,7 +7854,7 @@ static TypeTableEntry *ir_analyze_array_cat(IrAnalyze *ira, IrInstructionBinOp *
     TypeTableEntry *result_type;
     ConstExprValue *out_array_val;
     size_t new_len = (op1_array_end - op1_array_index) + (op2_array_end - op2_array_index);
-    if (op1_canon_type->id == TypeTableEntryIdArray || op2_canon_type->id == TypeTableEntryIdArray) {
+    if (op1_type->id == TypeTableEntryIdArray || op2_type->id == TypeTableEntryIdArray) {
         result_type = get_array_type(ira->codegen, child_type, new_len);
 
         out_array_val = out_val;
@@ -7931,14 +7907,13 @@ static TypeTableEntry *ir_analyze_array_mult(IrAnalyze *ira, IrInstructionBinOp
     if (!ir_resolve_usize(ira, op2, &mult_amt))
         return ira->codegen->builtin_types.entry_invalid;
 
-    TypeTableEntry *array_canon_type = get_underlying_type(op1->value.type);
-    if (array_canon_type->id != TypeTableEntryIdArray) {
+    TypeTableEntry *array_type = op1->value.type;
+    if (array_type->id != TypeTableEntryIdArray) {
         ir_add_error(ira, op1, buf_sprintf("expected array type, found '%s'", buf_ptr(&op1->value.type->name)));
-        // TODO if meta_type is type decl, add note pointing to type decl declaration
         return ira->codegen->builtin_types.entry_invalid;
     }
 
-    uint64_t old_array_len = array_canon_type->data.array.len;
+    uint64_t old_array_len = array_type->data.array.len;
 
     BigNum array_len;
     bignum_init_unsigned(&array_len, old_array_len);
@@ -7961,7 +7936,7 @@ static TypeTableEntry *ir_analyze_array_mult(IrAnalyze *ira, IrInstructionBinOp
     }
     assert(i == new_array_len);
 
-    TypeTableEntry *child_type = array_canon_type->data.array.child_type;
+    TypeTableEntry *child_type = array_type->data.array.child_type;
     return get_array_type(ira->codegen, child_type, new_array_len);
 }
 
@@ -8033,7 +8008,7 @@ static TypeTableEntry *ir_analyze_instruction_decl_var(IrAnalyze *ira, IrInstruc
     AstNode *source_node = decl_var_instruction->base.source_node;
 
     IrInstruction *casted_init_value = ir_implicit_cast(ira, init_value, explicit_type);
-    TypeTableEntry *result_type = get_underlying_type(casted_init_value->value.type);
+    TypeTableEntry *result_type = casted_init_value->value.type;
     if (type_is_invalid(result_type)) {
         result_type = ira->codegen->builtin_types.entry_invalid;
     }
@@ -8041,8 +8016,6 @@ static TypeTableEntry *ir_analyze_instruction_decl_var(IrAnalyze *ira, IrInstruc
     bool is_comptime_var = ir_get_var_is_comptime(var);
 
     switch (result_type->id) {
-        case TypeTableEntryIdTypeDecl:
-            zig_unreachable();
         case TypeTableEntryIdInvalid:
             break; // handled above
         case TypeTableEntryIdNumLitFloat:
@@ -8057,6 +8030,7 @@ static TypeTableEntry *ir_analyze_instruction_decl_var(IrAnalyze *ira, IrInstruc
         case TypeTableEntryIdVar:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdNullLit:
+        case TypeTableEntryIdOpaque:
             ir_add_error_node(ira, source_node,
                 buf_sprintf("variable of type '%s' not allowed", buf_ptr(&result_type->name)));
             result_type = ira->codegen->builtin_types.entry_invalid;
@@ -8670,14 +8644,11 @@ static TypeTableEntry *ir_analyze_unary_prefix_op_err(IrAnalyze *ira, IrInstruct
     IrInstruction *value = un_op_instruction->value->other;
 
     TypeTableEntry *meta_type = ir_resolve_type(ira, value);
-    TypeTableEntry *underlying_meta_type = get_underlying_type(meta_type);
-
-    if (type_is_invalid(underlying_meta_type))
+    if (type_is_invalid(meta_type))
         return ira->codegen->builtin_types.entry_invalid;
 
 
-    switch (underlying_meta_type->id) {
-        case TypeTableEntryIdTypeDecl:
+    switch (meta_type->id) {
         case TypeTableEntryIdInvalid: // handled above
             zig_unreachable();
 
@@ -8712,9 +8683,9 @@ static TypeTableEntry *ir_analyze_unary_prefix_op_err(IrAnalyze *ira, IrInstruct
         case TypeTableEntryIdUnreachable:
         case TypeTableEntryIdVar:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             ir_add_error_node(ira, un_op_instruction->base.source_node,
                     buf_sprintf("unable to wrap type '%s' in error type", buf_ptr(&meta_type->name)));
-            // TODO if meta_type is type decl, add note pointing to type decl declaration
             return ira->codegen->builtin_types.entry_invalid;
     }
     zig_unreachable();
@@ -8756,13 +8727,11 @@ static TypeTableEntry *ir_analyze_dereference(IrAnalyze *ira, IrInstructionUnOp
 static TypeTableEntry *ir_analyze_maybe(IrAnalyze *ira, IrInstructionUnOp *un_op_instruction) {
     IrInstruction *value = un_op_instruction->value->other;
     TypeTableEntry *type_entry = ir_resolve_type(ira, value);
-    TypeTableEntry *canon_type = get_underlying_type(type_entry);
-    if (type_is_invalid(canon_type))
+    if (type_is_invalid(type_entry))
         return ira->codegen->builtin_types.entry_invalid;
-    switch (canon_type->id) {
+    switch (type_entry->id) {
         case TypeTableEntryIdInvalid:
         case TypeTableEntryIdVar:
-        case TypeTableEntryIdTypeDecl:
             zig_unreachable();
         case TypeTableEntryIdMetaType:
         case TypeTableEntryIdVoid:
@@ -8793,9 +8762,9 @@ static TypeTableEntry *ir_analyze_maybe(IrAnalyze *ira, IrInstructionUnOp *un_op
                 return ira->codegen->builtin_types.entry_type;
             }
         case TypeTableEntryIdUnreachable:
+        case TypeTableEntryIdOpaque:
             ir_add_error_node(ira, un_op_instruction->base.source_node,
                     buf_sprintf("type '%s' not nullable", buf_ptr(&type_entry->name)));
-            // TODO if it's a type decl, put an error note here pointing to the decl
             return ira->codegen->builtin_types.entry_invalid;
     }
     zig_unreachable();
@@ -9406,23 +9375,6 @@ static TypeTableEntry *ir_analyze_decl_ref(IrAnalyze *ira, IrInstruction *source
             return ir_analyze_const_ptr(ira, source_instruction, const_val, fn_entry->type_entry,
                     ConstPtrMutComptimeConst, ptr_is_const, ptr_is_volatile);
         }
-        case TldIdTypeDef:
-        {
-            TldTypeDef *tld_typedef = (TldTypeDef *)tld;
-            assert(tld_typedef->type_entry);
-
-            // TODO instead of allocating this every time, put it in the tld value and we can reference
-            // the same one every time
-            ConstExprValue *const_val = allocate<ConstExprValue>(1);
-            const_val->special = ConstValSpecialStatic;
-            const_val->type = ira->codegen->builtin_types.entry_type;
-            const_val->data.x_type = tld_typedef->type_entry;
-
-            bool ptr_is_const = true;
-            bool ptr_is_volatile = false;
-            return ir_analyze_const_ptr(ira, source_instruction, const_val, ira->codegen->builtin_types.entry_type,
-                    ConstPtrMutComptimeConst, ptr_is_const, ptr_is_volatile);
-        }
     }
     zig_unreachable();
 }
@@ -9726,9 +9678,9 @@ static TypeTableEntry *ir_analyze_instruction_typeof(IrAnalyze *ira, IrInstructi
         case TypeTableEntryIdEnum:
         case TypeTableEntryIdUnion:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdEnumTag:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             {
                 ConstExprValue *out_val = ir_build_const_from(ira, &typeof_instruction->base);
                 out_val->data.x_type = type_entry;
@@ -9990,12 +9942,10 @@ static TypeTableEntry *ir_analyze_instruction_slice_type(IrAnalyze *ira,
     bool is_const = slice_type_instruction->is_const;
 
     TypeTableEntry *resolved_child_type = ir_resolve_type(ira, child_type);
-    TypeTableEntry *canon_child_type = get_underlying_type(resolved_child_type);
-    if (type_is_invalid(canon_child_type))
+    if (type_is_invalid(resolved_child_type))
         return ira->codegen->builtin_types.entry_invalid;
 
-    switch (canon_child_type->id) {
-        case TypeTableEntryIdTypeDecl:
+    switch (resolved_child_type->id) {
         case TypeTableEntryIdInvalid: // handled above
             zig_unreachable();
         case TypeTableEntryIdVar:
@@ -10004,9 +9954,9 @@ static TypeTableEntry *ir_analyze_instruction_slice_type(IrAnalyze *ira,
         case TypeTableEntryIdNullLit:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             ir_add_error_node(ira, slice_type_instruction->base.source_node,
                     buf_sprintf("slice of type '%s' not allowed", buf_ptr(&resolved_child_type->name)));
-            // TODO if this is a typedecl, add error note showing the declaration of the type decl
             return ira->codegen->builtin_types.entry_invalid;
         case TypeTableEntryIdMetaType:
         case TypeTableEntryIdVoid:
@@ -10100,11 +10050,9 @@ static TypeTableEntry *ir_analyze_instruction_array_type(IrAnalyze *ira,
 
     IrInstruction *child_type_value = array_type_instruction->child_type->other;
     TypeTableEntry *child_type = ir_resolve_type(ira, child_type_value);
-    TypeTableEntry *canon_child_type = get_underlying_type(child_type);
-    if (type_is_invalid(canon_child_type))
+    if (type_is_invalid(child_type))
         return ira->codegen->builtin_types.entry_invalid;
-    switch (canon_child_type->id) {
-        case TypeTableEntryIdTypeDecl:
+    switch (child_type->id) {
         case TypeTableEntryIdInvalid: // handled above
             zig_unreachable();
         case TypeTableEntryIdVar:
@@ -10113,9 +10061,9 @@ static TypeTableEntry *ir_analyze_instruction_array_type(IrAnalyze *ira,
         case TypeTableEntryIdNullLit:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             ir_add_error_node(ira, array_type_instruction->base.source_node,
                     buf_sprintf("array of type '%s' not allowed", buf_ptr(&child_type->name)));
-            // TODO if this is a typedecl, add error note showing the declaration of the type decl
             return ira->codegen->builtin_types.entry_invalid;
         case TypeTableEntryIdMetaType:
         case TypeTableEntryIdVoid:
@@ -10172,15 +10120,13 @@ static TypeTableEntry *ir_analyze_instruction_size_of(IrAnalyze *ira,
 {
     IrInstruction *type_value = size_of_instruction->type_value->other;
     TypeTableEntry *type_entry = ir_resolve_type(ira, type_value);
-    TypeTableEntry *canon_type_entry = get_underlying_type(type_entry);
 
     ensure_complete_type(ira->codegen, type_entry);
-    if (type_is_invalid(canon_type_entry))
+    if (type_is_invalid(type_entry))
         return ira->codegen->builtin_types.entry_invalid;
 
-    switch (canon_type_entry->id) {
+    switch (type_entry->id) {
         case TypeTableEntryIdInvalid: // handled above
-        case TypeTableEntryIdTypeDecl:
             zig_unreachable();
         case TypeTableEntryIdVar:
         case TypeTableEntryIdUnreachable:
@@ -10193,9 +10139,9 @@ static TypeTableEntry *ir_analyze_instruction_size_of(IrAnalyze *ira,
         case TypeTableEntryIdMetaType:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             ir_add_error_node(ira, size_of_instruction->base.source_node,
                     buf_sprintf("no size available for type '%s'", buf_ptr(&type_entry->name)));
-            // TODO if this is a typedecl, add error note showing the declaration of the type decl
             return ira->codegen->builtin_types.entry_invalid;
         case TypeTableEntryIdVoid:
         case TypeTableEntryIdBool:
@@ -10516,15 +10462,13 @@ static TypeTableEntry *ir_analyze_instruction_switch_target(IrAnalyze *ira,
         if (pointee_val->special == ConstValSpecialRuntime)
             pointee_val = nullptr;
     }
-    TypeTableEntry *canon_target_type = get_underlying_type(target_type);
     ensure_complete_type(ira->codegen, target_type);
-    if (type_is_invalid(canon_target_type))
+    if (type_is_invalid(target_type))
         return ira->codegen->builtin_types.entry_invalid;
 
-    switch (canon_target_type->id) {
+    switch (target_type->id) {
         case TypeTableEntryIdInvalid:
         case TypeTableEntryIdVar:
-        case TypeTableEntryIdTypeDecl:
             zig_unreachable();
         case TypeTableEntryIdMetaType:
         case TypeTableEntryIdVoid:
@@ -10576,9 +10520,9 @@ static TypeTableEntry *ir_analyze_instruction_switch_target(IrAnalyze *ira,
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             ir_add_error(ira, &switch_target_instruction->base,
                 buf_sprintf("invalid switch target type '%s'", buf_ptr(&target_type->name)));
-            // TODO if this is a typedecl, add error note showing the declaration of the type decl
             return ira->codegen->builtin_types.entry_invalid;
     }
     zig_unreachable();
@@ -10630,9 +10574,8 @@ static TypeTableEntry *ir_analyze_instruction_switch_var(IrAnalyze *ira, IrInstr
         return get_pointer_to_type(ira->codegen, field->type_entry,
                 target_value_ptr->value.type->data.pointer.is_const);
     } else {
-        ErrorMsg *msg = ir_add_error(ira, &instruction->base,
+        ir_add_error(ira, &instruction->base,
             buf_sprintf("switch on type '%s' provides no expression parameter", buf_ptr(&target_type->name)));
-        ir_add_typedef_err_note(ira, msg, target_type);
         return ira->codegen->builtin_types.entry_invalid;
     }
 }
@@ -10743,13 +10686,13 @@ static TypeTableEntry *ir_analyze_instruction_array_len(IrAnalyze *ira,
         IrInstructionArrayLen *array_len_instruction)
 {
     IrInstruction *array_value = array_len_instruction->array_value->other;
-    TypeTableEntry *canon_type = get_underlying_type(array_value->value.type);
-    if (type_is_invalid(canon_type)) {
+    TypeTableEntry *type_entry = array_value->value.type;
+    if (type_is_invalid(type_entry)) {
         return ira->codegen->builtin_types.entry_invalid;
-    } else if (canon_type->id == TypeTableEntryIdArray) {
+    } else if (type_entry->id == TypeTableEntryIdArray) {
         return ir_analyze_const_usize(ira, &array_len_instruction->base,
-                canon_type->data.array.len);
-    } else if (is_slice(canon_type)) {
+                type_entry->data.array.len);
+    } else if (is_slice(type_entry)) {
         if (array_value->value.special != ConstValSpecialRuntime) {
             ConstExprValue *len_val = &array_value->value.data.x_struct.fields[slice_len_index];
             if (len_val->special != ConstValSpecialRuntime) {
@@ -10757,7 +10700,7 @@ static TypeTableEntry *ir_analyze_instruction_array_len(IrAnalyze *ira,
                         len_val->data.x_bignum.data.x_uint);
             }
         }
-        TypeStructField *field = &canon_type->data.structure.fields[slice_len_index];
+        TypeStructField *field = &type_entry->data.structure.fields[slice_len_index];
         IrInstruction *len_ptr = ir_build_struct_field_ptr(&ira->new_irb, array_len_instruction->base.scope,
                 array_len_instruction->base.source_node, array_value, field);
         len_ptr->value.type = get_pointer_to_type(ira->codegen, ira->codegen->builtin_types.entry_usize, true);
@@ -10766,7 +10709,6 @@ static TypeTableEntry *ir_analyze_instruction_array_len(IrAnalyze *ira,
     } else {
         ir_add_error_node(ira, array_len_instruction->base.source_node,
             buf_sprintf("type '%s' has no field 'len'", buf_ptr(&array_value->value.type->name)));
-        // TODO if this is a typedecl, add error note showing the declaration of the type decl
         return ira->codegen->builtin_types.entry_invalid;
     }
 }
@@ -11049,29 +10991,28 @@ static TypeTableEntry *ir_analyze_min_max(IrAnalyze *ira, IrInstruction *source_
         IrInstruction *target_type_value, bool is_max)
 {
     TypeTableEntry *target_type = ir_resolve_type(ira, target_type_value);
-    TypeTableEntry *canon_type = get_underlying_type(target_type);
-    if (type_is_invalid(canon_type))
+    if (type_is_invalid(target_type))
         return ira->codegen->builtin_types.entry_invalid;
-    switch (canon_type->id) {
+    switch (target_type->id) {
         case TypeTableEntryIdInvalid:
             zig_unreachable();
         case TypeTableEntryIdInt:
             {
                 ConstExprValue *out_val = ir_build_const_from(ira, source_instruction);
-                eval_min_max_value(ira->codegen, canon_type, out_val, is_max);
+                eval_min_max_value(ira->codegen, target_type, out_val, is_max);
                 return ira->codegen->builtin_types.entry_num_lit_int;
             }
         case TypeTableEntryIdFloat:
             {
                 ConstExprValue *out_val = ir_build_const_from(ira, source_instruction);
-                eval_min_max_value(ira->codegen, canon_type, out_val, is_max);
+                eval_min_max_value(ira->codegen, target_type, out_val, is_max);
                 return ira->codegen->builtin_types.entry_num_lit_float;
             }
         case TypeTableEntryIdBool:
         case TypeTableEntryIdVoid:
             {
                 ConstExprValue *out_val = ir_build_const_from(ira, source_instruction);
-                eval_min_max_value(ira->codegen, canon_type, out_val, is_max);
+                eval_min_max_value(ira->codegen, target_type, out_val, is_max);
                 return target_type;
             }
         case TypeTableEntryIdEnumTag:
@@ -11092,18 +11033,17 @@ static TypeTableEntry *ir_analyze_min_max(IrAnalyze *ira, IrInstruction *source_
         case TypeTableEntryIdEnum:
         case TypeTableEntryIdUnion:
         case TypeTableEntryIdFn:
-        case TypeTableEntryIdTypeDecl:
         case TypeTableEntryIdNamespace:
         case TypeTableEntryIdBlock:
         case TypeTableEntryIdBoundFn:
         case TypeTableEntryIdArgTuple:
+        case TypeTableEntryIdOpaque:
             {
                 const char *err_format = is_max ?
                     "no max value available for type '%s'" :
                     "no min value available for type '%s'";
                 ir_add_error(ira, source_instruction,
                         buf_sprintf(err_format, buf_ptr(&target_type->name)));
-                // TODO if this is a typedecl, add error note showing the declaration of the type decl
                 return ira->codegen->builtin_types.entry_invalid;
             }
     }
@@ -11508,14 +11448,11 @@ static TypeTableEntry *ir_analyze_instruction_div_exact(IrAnalyze *ira, IrInstru
     if (type_is_invalid(result_type))
         return ira->codegen->builtin_types.entry_invalid;
 
-    TypeTableEntry *canon_type = get_underlying_type(result_type);
-
-    if (canon_type->id != TypeTableEntryIdInt &&
-        canon_type->id != TypeTableEntryIdNumLitInt)
+    if (result_type->id != TypeTableEntryIdInt &&
+        result_type->id != TypeTableEntryIdNumLitInt)
     {
         ir_add_error(ira, &instruction->base,
                 buf_sprintf("expected integer type, found '%s'", buf_ptr(&result_type->name)));
-        // TODO if meta_type is type decl, add note pointing to type decl declaration
         return ira->codegen->builtin_types.entry_invalid;
     }
 
@@ -11563,49 +11500,42 @@ static TypeTableEntry *ir_analyze_instruction_div_exact(IrAnalyze *ira, IrInstru
 static TypeTableEntry *ir_analyze_instruction_truncate(IrAnalyze *ira, IrInstructionTruncate *instruction) {
     IrInstruction *dest_type_value = instruction->dest_type->other;
     TypeTableEntry *dest_type = ir_resolve_type(ira, dest_type_value);
-    TypeTableEntry *canon_dest_type = get_underlying_type(dest_type);
-
-    if (type_is_invalid(canon_dest_type))
+    if (type_is_invalid(dest_type))
         return ira->codegen->builtin_types.entry_invalid;
 
-    if (canon_dest_type->id != TypeTableEntryIdInt &&
-        canon_dest_type->id != TypeTableEntryIdNumLitInt)
+    if (dest_type->id != TypeTableEntryIdInt &&
+        dest_type->id != TypeTableEntryIdNumLitInt)
     {
         ir_add_error(ira, dest_type_value, buf_sprintf("expected integer type, found '%s'", buf_ptr(&dest_type->name)));
-        // TODO if meta_type is type decl, add note pointing to type decl declaration
         return ira->codegen->builtin_types.entry_invalid;
     }
 
     IrInstruction *target = instruction->target->other;
     TypeTableEntry *src_type = target->value.type;
-    TypeTableEntry *canon_src_type = get_underlying_type(src_type);
-    if (type_is_invalid(canon_src_type))
+    if (type_is_invalid(src_type))
         return ira->codegen->builtin_types.entry_invalid;
 
-    if (canon_src_type->id != TypeTableEntryIdInt &&
-        canon_src_type->id != TypeTableEntryIdNumLitInt)
+    if (src_type->id != TypeTableEntryIdInt &&
+        src_type->id != TypeTableEntryIdNumLitInt)
     {
         ir_add_error(ira, target, buf_sprintf("expected integer type, found '%s'", buf_ptr(&src_type->name)));
-        // TODO if meta_type is type decl, add note pointing to type decl declaration
         return ira->codegen->builtin_types.entry_invalid;
     }
 
-    if (canon_src_type->data.integral.is_signed != canon_dest_type->data.integral.is_signed) {
-        const char *sign_str = canon_dest_type->data.integral.is_signed ? "signed" : "unsigned";
+    if (src_type->data.integral.is_signed != dest_type->data.integral.is_signed) {
+        const char *sign_str = dest_type->data.integral.is_signed ? "signed" : "unsigned";
         ir_add_error(ira, target, buf_sprintf("expected %s integer type, found '%s'", sign_str, buf_ptr(&src_type->name)));
-        // TODO if meta_type is type decl, add note pointing to type decl declaration
         return ira->codegen->builtin_types.entry_invalid;
-    } else if (canon_src_type->data.integral.bit_count < canon_dest_type->data.integral.bit_count) {
+    } else if (src_type->data.integral.bit_count < dest_type->data.integral.bit_count) {
         ir_add_error(ira, target, buf_sprintf("type '%s' has fewer bits than destination type '%s'",
                     buf_ptr(&src_type->name), buf_ptr(&dest_type->name)));
-        // TODO if meta_type is type decl, add note pointing to type decl declaration
         return ira->codegen->builtin_types.entry_invalid;
     }
 
     if (target->value.special == ConstValSpecialStatic) {
         ConstExprValue *out_val = ir_build_const_from(ira, &instruction->base);
         bignum_init_bignum(&out_val->data.x_bignum, &target->value.data.x_bignum);
-        bignum_truncate(&out_val->data.x_bignum, canon_dest_type->data.integral.bit_count);
+        bignum_truncate(&out_val->data.x_bignum, dest_type->data.integral.bit_count);
         return dest_type;
     }
 
@@ -11663,7 +11593,7 @@ static TypeTableEntry *ir_analyze_instruction_memset(IrAnalyze *ira, IrInstructi
     if (type_is_invalid(count_value->value.type))
         return ira->codegen->builtin_types.entry_invalid;
 
-    TypeTableEntry *dest_uncasted_type = get_underlying_type(dest_ptr->value.type);
+    TypeTableEntry *dest_uncasted_type = dest_ptr->value.type;
     bool dest_is_volatile = (dest_uncasted_type->id == TypeTableEntryIdPointer) &&
         dest_uncasted_type->data.pointer.is_volatile;
 
@@ -11749,8 +11679,8 @@ static TypeTableEntry *ir_analyze_instruction_memcpy(IrAnalyze *ira, IrInstructi
     if (type_is_invalid(count_value->value.type))
         return ira->codegen->builtin_types.entry_invalid;
 
-    TypeTableEntry *dest_uncasted_type = get_underlying_type(dest_ptr->value.type);
-    TypeTableEntry *src_uncasted_type = get_underlying_type(src_ptr->value.type);
+    TypeTableEntry *dest_uncasted_type = dest_ptr->value.type;
+    TypeTableEntry *src_uncasted_type = src_ptr->value.type;
     bool dest_is_volatile = (dest_uncasted_type->id == TypeTableEntryIdPointer) &&
         dest_uncasted_type->data.pointer.is_volatile;
     bool src_is_volatile = (src_uncasted_type->id == TypeTableEntryIdPointer) &&
@@ -11866,8 +11796,7 @@ static TypeTableEntry *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstructio
 
     TypeTableEntry *ptr_type = ptr_ptr->value.type;
     assert(ptr_type->id == TypeTableEntryIdPointer);
-    TypeTableEntry *non_canon_array_type = ptr_type->data.pointer.child_type;
-    TypeTableEntry *canon_array_type = get_underlying_type(non_canon_array_type);
+    TypeTableEntry *array_type = ptr_type->data.pointer.child_type;
 
     IrInstruction *start = instruction->start->other;
     if (type_is_invalid(start->value.type))
@@ -11892,22 +11821,21 @@ static TypeTableEntry *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstructio
 
     TypeTableEntry *return_type;
 
-    if (canon_array_type->id == TypeTableEntryIdArray) {
-        return_type = get_slice_type(ira->codegen, canon_array_type->data.array.child_type, instruction->is_const);
-    } else if (canon_array_type->id == TypeTableEntryIdPointer) {
-        return_type = get_slice_type(ira->codegen, canon_array_type->data.pointer.child_type, instruction->is_const);
+    if (array_type->id == TypeTableEntryIdArray) {
+        return_type = get_slice_type(ira->codegen, array_type->data.array.child_type, instruction->is_const);
+    } else if (array_type->id == TypeTableEntryIdPointer) {
+        return_type = get_slice_type(ira->codegen, array_type->data.pointer.child_type, instruction->is_const);
         if (!end) {
             ir_add_error(ira, &instruction->base, buf_sprintf("slice of pointer must include end value"));
             return ira->codegen->builtin_types.entry_invalid;
         }
-    } else if (is_slice(canon_array_type)) {
+    } else if (is_slice(array_type)) {
         return_type = get_slice_type(ira->codegen,
-                canon_array_type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.child_type,
+                array_type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.child_type,
                 instruction->is_const);
     } else {
         ir_add_error(ira, &instruction->base,
-            buf_sprintf("slice of non-array type '%s'", buf_ptr(&non_canon_array_type->name)));
-        // TODO if this is a typedecl, add error note showing the declaration of the type decl
+            buf_sprintf("slice of non-array type '%s'", buf_ptr(&array_type->name)));
         return ira->codegen->builtin_types.entry_invalid;
     }
 
@@ -11919,12 +11847,12 @@ static TypeTableEntry *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstructio
         ConstExprValue *parent_ptr;
         size_t abs_offset;
         size_t rel_end;
-        if (canon_array_type->id == TypeTableEntryIdArray) {
+        if (array_type->id == TypeTableEntryIdArray) {
             array_val = const_ptr_pointee(&ptr_ptr->value);
             abs_offset = 0;
-            rel_end = canon_array_type->data.array.len;
+            rel_end = array_type->data.array.len;
             parent_ptr = nullptr;
-        } else if (canon_array_type->id == TypeTableEntryIdPointer) {
+        } else if (array_type->id == TypeTableEntryIdPointer) {
             parent_ptr = const_ptr_pointee(&ptr_ptr->value);
             switch (parent_ptr->data.x_ptr.special) {
                 case ConstPtrSpecialInvalid:
@@ -11946,7 +11874,7 @@ static TypeTableEntry *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstructio
                     array_val = nullptr;
                     break;
             }
-        } else if (is_slice(canon_array_type)) {
+        } else if (is_slice(array_type)) {
             ConstExprValue *slice_ptr = const_ptr_pointee(&ptr_ptr->value);
             parent_ptr = &slice_ptr->data.x_struct.fields[slice_ptr_index];
             ConstExprValue *len_val = &slice_ptr->data.x_struct.fields[slice_len_index];
@@ -12005,7 +11933,7 @@ static TypeTableEntry *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstructio
             if (array_val) {
                 size_t index = abs_offset + start_scalar;
                 init_const_ptr_array(ira->codegen, ptr_val, array_val, index, instruction->is_const);
-                if (canon_array_type->id == TypeTableEntryIdArray) {
+                if (array_type->id == TypeTableEntryIdArray) {
                     ptr_val->data.x_ptr.mut = ptr_ptr->value.data.x_ptr.mut;
                 }
             } else {
@@ -12045,17 +11973,16 @@ static TypeTableEntry *ir_analyze_instruction_member_count(IrAnalyze *ira, IrIns
     if (type_is_invalid(container->value.type))
         return ira->codegen->builtin_types.entry_invalid;
     TypeTableEntry *container_type = ir_resolve_type(ira, container);
-    TypeTableEntry *canon_type = get_underlying_type(container_type);
 
     uint64_t result;
-    if (type_is_invalid(canon_type)) {
-        return ira->codegen->builtin_types.entry_invalid;
-    } else if (canon_type->id == TypeTableEntryIdEnum) {
-        result = canon_type->data.enumeration.src_field_count;
-    } else if (canon_type->id == TypeTableEntryIdStruct) {
-        result = canon_type->data.structure.src_field_count;
-    } else if (canon_type->id == TypeTableEntryIdUnion) {
-        result = canon_type->data.unionation.src_field_count;
+    if (type_is_invalid(container_type)) {
+        return ira->codegen->builtin_types.entry_invalid;
+    } else if (container_type->id == TypeTableEntryIdEnum) {
+        result = container_type->data.enumeration.src_field_count;
+    } else if (container_type->id == TypeTableEntryIdStruct) {
+        result = container_type->data.structure.src_field_count;
+    } else if (container_type->id == TypeTableEntryIdUnion) {
+        result = container_type->data.unionation.src_field_count;
     } else {
         ir_add_error(ira, &instruction->base, buf_sprintf("no value count available for type '%s'", buf_ptr(&container_type->name)));
         return ira->codegen->builtin_types.entry_invalid;
@@ -12112,14 +12039,12 @@ static TypeTableEntry *ir_analyze_instruction_overflow_op(IrAnalyze *ira, IrInst
     if (type_is_invalid(type_value->value.type))
         return ira->codegen->builtin_types.entry_invalid;
     TypeTableEntry *dest_type = ir_resolve_type(ira, type_value);
-    TypeTableEntry *canon_type = get_underlying_type(dest_type);
-    if (type_is_invalid(canon_type))
+    if (type_is_invalid(dest_type))
         return ira->codegen->builtin_types.entry_invalid;
 
-    if (canon_type->id != TypeTableEntryIdInt) {
+    if (dest_type->id != TypeTableEntryIdInt) {
         ir_add_error(ira, type_value,
             buf_sprintf("expected integer type, found '%s'", buf_ptr(&dest_type->name)));
-        // TODO if this is a typedecl, add error note showing the declaration of the type decl
         return ira->codegen->builtin_types.entry_invalid;
     }
 
@@ -12171,11 +12096,11 @@ static TypeTableEntry *ir_analyze_instruction_overflow_op(IrAnalyze *ira, IrInst
                 out_val->data.x_bool = bignum_shl(dest_bignum, op1_bignum, op2_bignum);
                 break;
         }
-        if (!bignum_fits_in_bits(dest_bignum, canon_type->data.integral.bit_count,
-            canon_type->data.integral.is_signed))
+        if (!bignum_fits_in_bits(dest_bignum, dest_type->data.integral.bit_count,
+            dest_type->data.integral.is_signed))
         {
             out_val->data.x_bool = true;
-            bignum_truncate(dest_bignum, canon_type->data.integral.bit_count);
+            bignum_truncate(dest_bignum, dest_type->data.integral.bit_count);
         }
         pointee_val->special = ConstValSpecialStatic;
         return ira->codegen->builtin_types.entry_bool;
@@ -12191,12 +12116,10 @@ static TypeTableEntry *ir_analyze_instruction_test_err(IrAnalyze *ira, IrInstruc
     if (type_is_invalid(value->value.type))
         return ira->codegen->builtin_types.entry_invalid;
 
-    TypeTableEntry *non_canon_type = value->value.type;
-
-    TypeTableEntry *canon_type = get_underlying_type(non_canon_type);
-    if (type_is_invalid(canon_type)) {
+    TypeTableEntry *type_entry = value->value.type;
+    if (type_is_invalid(type_entry)) {
         return ira->codegen->builtin_types.entry_invalid;
-    } else if (canon_type->id == TypeTableEntryIdErrorUnion) {
+    } else if (type_entry->id == TypeTableEntryIdErrorUnion) {
         if (instr_is_comptime(value)) {
             ConstExprValue *err_union_val = ir_resolve_const(ira, value, UndefBad);
             if (!err_union_val)
@@ -12211,7 +12134,7 @@ static TypeTableEntry *ir_analyze_instruction_test_err(IrAnalyze *ira, IrInstruc
 
         ir_build_test_err_from(&ira->new_irb, &instruction->base, value);
         return ira->codegen->builtin_types.entry_bool;
-    } else if (canon_type->id == TypeTableEntryIdPureError) {
+    } else if (type_entry->id == TypeTableEntryIdPureError) {
         ConstExprValue *out_val = ir_build_const_from(ira, &instruction->base);
         out_val->data.x_bool = true;
         return ira->codegen->builtin_types.entry_bool;
@@ -12233,11 +12156,10 @@ static TypeTableEntry *ir_analyze_instruction_unwrap_err_code(IrAnalyze *ira,
     // This will be a pointer type because unwrap err payload IR instruction operates on a pointer to a thing.
     assert(ptr_type->id == TypeTableEntryIdPointer);
 
-    TypeTableEntry *non_canon_type = ptr_type->data.pointer.child_type;
-    TypeTableEntry *canon_type = get_underlying_type(non_canon_type);
-    if (type_is_invalid(canon_type)) {
+    TypeTableEntry *type_entry = ptr_type->data.pointer.child_type;
+    if (type_is_invalid(type_entry)) {
         return ira->codegen->builtin_types.entry_invalid;
-    } else if (canon_type->id == TypeTableEntryIdErrorUnion) {
+    } else if (type_entry->id == TypeTableEntryIdErrorUnion) {
         if (instr_is_comptime(value)) {
             ConstExprValue *ptr_val = ir_resolve_const(ira, value, UndefBad);
             if (!ptr_val)
@@ -12257,8 +12179,7 @@ static TypeTableEntry *ir_analyze_instruction_unwrap_err_code(IrAnalyze *ira,
         return ira->codegen->builtin_types.entry_pure_error;
     } else {
         ir_add_error(ira, value,
-            buf_sprintf("expected error union type, found '%s'", buf_ptr(&non_canon_type->name)));
-        // TODO if this is a typedecl, add error note showing the declaration of the type decl
+            buf_sprintf("expected error union type, found '%s'", buf_ptr(&type_entry->name)));
         return ira->codegen->builtin_types.entry_invalid;
     }
 }
@@ -12275,12 +12196,11 @@ static TypeTableEntry *ir_analyze_instruction_unwrap_err_payload(IrAnalyze *ira,
     // This will be a pointer type because unwrap err payload IR instruction operates on a pointer to a thing.
     assert(ptr_type->id == TypeTableEntryIdPointer);
 
-    TypeTableEntry *non_canon_type = ptr_type->data.pointer.child_type;
-    TypeTableEntry *canon_type = get_underlying_type(non_canon_type);
-    if (type_is_invalid(canon_type)) {
+    TypeTableEntry *type_entry = ptr_type->data.pointer.child_type;
+    if (type_is_invalid(type_entry)) {
         return ira->codegen->builtin_types.entry_invalid;
-    } else if (canon_type->id == TypeTableEntryIdErrorUnion) {
-        TypeTableEntry *child_type = canon_type->data.error.child_type;
+    } else if (type_entry->id == TypeTableEntryIdErrorUnion) {
+        TypeTableEntry *child_type = type_entry->data.error.child_type;
         TypeTableEntry *result_type = get_pointer_to_type_extra(ira->codegen, child_type,
                 ptr_type->data.pointer.is_const, ptr_type->data.pointer.is_volatile, 0, 0);
         if (instr_is_comptime(value)) {
@@ -12307,8 +12227,7 @@ static TypeTableEntry *ir_analyze_instruction_unwrap_err_payload(IrAnalyze *ira,
         return result_type;
     } else {
         ir_add_error(ira, value,
-            buf_sprintf("expected error union type, found '%s'", buf_ptr(&non_canon_type->name)));
-        // TODO if this is a typedecl, add error note showing the declaration of the type decl
+            buf_sprintf("expected error union type, found '%s'", buf_ptr(&type_entry->name)));
         return ira->codegen->builtin_types.entry_invalid;
     }
 
@@ -12594,22 +12513,6 @@ static TypeTableEntry *ir_analyze_instruction_decl_ref(IrAnalyze *ira,
                 return ref_instruction->value.type;
             }
         }
-        case TldIdTypeDef:
-        {
-            TldTypeDef *tld_typedef = (TldTypeDef *)tld;
-            TypeTableEntry *typedef_type = tld_typedef->type_entry;
-
-            IrInstruction *ref_instruction = ir_create_const_type(&ira->new_irb, instruction->base.scope,
-                    instruction->base.source_node, typedef_type);
-            if (lval.is_ptr) {
-                IrInstruction *ptr_inst = ir_get_ref(ira, &instruction->base, ref_instruction, true, false);
-                ir_link_new_instruction(ptr_inst, &instruction->base);
-                return ptr_inst->value.type;
-            } else {
-                ir_link_new_instruction(ref_instruction, &instruction->base);
-                return ref_instruction->value.type;
-            }
-        }
     }
     zig_unreachable();
 }
src/parseh.cpp
@@ -219,28 +219,8 @@ static Tld *add_container_tld(Context *c, TypeTableEntry *type_entry) {
     return add_const_type(c, &type_entry->name, type_entry);
 }
 
-static Tld *add_typedef_tld(Context *c, TypeTableEntry *type_decl) {
-    assert(type_decl);
-    assert(type_decl->id == TypeTableEntryIdTypeDecl);
-
-    TldTypeDef *tld_typedef = allocate<TldTypeDef>(1);
-    parseh_init_tld(c, &tld_typedef->base, TldIdTypeDef, &type_decl->name);
-    tld_typedef->type_entry = type_decl;
-
-    add_global(c, &tld_typedef->base);
-    c->global_type_table.put(&type_decl->name, type_decl);
-
-    return &tld_typedef->base;
-}
-
 static bool is_c_void_type(Context *c, TypeTableEntry *type_entry) {
-    while (type_entry->id == TypeTableEntryIdTypeDecl) {
-        if (type_entry == c->codegen->builtin_types.entry_c_void) {
-            return true;
-        }
-        type_entry = type_entry->data.type_decl.child_type;
-    }
-    return false;
+    return (type_entry == c->codegen->builtin_types.entry_c_void);
 }
 
 static bool qual_type_child_is_fn_proto(const QualType &qt) {
@@ -369,7 +349,7 @@ static TypeTableEntry *resolve_type_with_table(Context *c, const Type *ty, const
                 const PointerType *pointer_ty = static_cast<const PointerType*>(ty);
                 QualType child_qt = pointer_ty->getPointeeType();
                 TypeTableEntry *child_type = resolve_qual_type(c, child_qt, decl);
-                if (get_underlying_type(child_type)->id == TypeTableEntryIdInvalid) {
+                if (type_is_invalid(child_type)) {
                     emit_warning(c, decl, "pointer to unresolved type");
                     return c->codegen->builtin_types.entry_invalid;
                 }
@@ -410,7 +390,7 @@ static TypeTableEntry *resolve_type_with_table(Context *c, const Type *ty, const
                 } else {
                     auto entry = type_table->maybe_get(type_name);
                     if (entry) {
-                        if (get_underlying_type(entry->value)->id == TypeTableEntryIdInvalid) {
+                        if (type_is_invalid(entry->value)) {
                             return c->codegen->builtin_types.entry_invalid;
                         } else {
                             return entry->value;
@@ -507,7 +487,7 @@ static TypeTableEntry *resolve_type_with_table(Context *c, const Type *ty, const
                     fn_type_id.return_type = c->codegen->builtin_types.entry_unreachable;
                 } else {
                     fn_type_id.return_type = resolve_qual_type(c, fn_proto_ty->getReturnType(), decl);
-                    if (get_underlying_type(fn_type_id.return_type)->id == TypeTableEntryIdInvalid) {
+                    if (type_is_invalid(fn_type_id.return_type)) {
                         emit_warning(c, decl, "unresolved function proto return type");
                         return c->codegen->builtin_types.entry_invalid;
                     }
@@ -522,7 +502,7 @@ static TypeTableEntry *resolve_type_with_table(Context *c, const Type *ty, const
                     QualType qt = fn_proto_ty->getParamType(i);
                     TypeTableEntry *param_type = resolve_qual_type(c, qt, decl);
 
-                    if (get_underlying_type(param_type)->id == TypeTableEntryIdInvalid) {
+                    if (type_is_invalid(param_type)) {
                         emit_warning(c, decl, "unresolved function proto parameter type");
                         return c->codegen->builtin_types.entry_invalid;
                     }
@@ -702,6 +682,7 @@ static void replace_with_fwd_decl(Context *c, TypeTableEntry *struct_type, Buf *
 
     ZigLLVMReplaceTemporary(c->codegen->dbuilder, struct_type->di_type, replacement_di_type);
     struct_type->di_type = replacement_di_type;
+    struct_type->id = TypeTableEntryIdOpaque;
 }
 
 static TypeTableEntry *resolve_enum_decl(Context *c, const EnumDecl *enum_decl) {
@@ -809,7 +790,9 @@ static TypeTableEntry *resolve_enum_decl(Context *c, const EnumDecl *enum_decl)
 
         return enum_type;
     } else {
-        TypeTableEntry *enum_type = get_typedecl_type(c->codegen, buf_ptr(full_type_name), tag_type_entry);
+        // TODO after issue #305 is solved, make this be an enum with tag_type_entry
+        // as the integer type and set the custom enum values
+        TypeTableEntry *enum_type = tag_type_entry;
         c->enum_type_table.put(bare_name, enum_type);
         c->decl_table.put(enum_decl, enum_type);
 
@@ -847,22 +830,8 @@ static void visit_enum_decl(Context *c, const EnumDecl *enum_decl) {
 
     Buf *bare_name = buf_create_from_str(decl_name(enum_decl));
 
-    if (enum_type->id == TypeTableEntryIdEnum) {
-        if (enum_type->data.enumeration.complete) {
-            Tld *tld = add_container_tld(c, enum_type);
-            add_global_weak_alias(c, bare_name, tld);
-        } else {
-            TypeTableEntry *typedecl_type = get_typedecl_type(c->codegen, buf_ptr(&enum_type->name),
-                    c->codegen->builtin_types.entry_u8);
-            Tld *tld = add_typedef_tld(c, typedecl_type);
-            add_global_weak_alias(c, bare_name, tld);
-        }
-    } else if (enum_type->id == TypeTableEntryIdTypeDecl) {
-        Tld *tld = add_typedef_tld(c, enum_type);
-        add_global_weak_alias(c, bare_name, tld);
-    } else {
-        zig_unreachable();
-    }
+    Tld *tld = add_container_tld(c, enum_type);
+    add_global_weak_alias(c, bare_name, tld);
 }
 
 static TypeTableEntry *resolve_record_decl(Context *c, const RecordDecl *record_decl) {
@@ -912,7 +881,7 @@ static TypeTableEntry *resolve_record_decl(Context *c, const RecordDecl *record_
         const FieldDecl *field_decl = *it;
 
         if (field_decl->isBitField()) {
-            emit_warning(c, field_decl, "struct %s demoted to typedef - has bitfield\n", buf_ptr(bare_name));
+            emit_warning(c, field_decl, "struct %s demoted to opaque type - has bitfield\n", buf_ptr(bare_name));
             replace_with_fwd_decl(c, struct_type, full_type_name);
             return struct_type;
         }
@@ -939,7 +908,7 @@ static TypeTableEntry *resolve_record_decl(Context *c, const RecordDecl *record_
         type_struct_field->type_entry = field_type;
 
         if (type_is_invalid(field_type) || !type_is_complete(field_type)) {
-            emit_warning(c, field_decl, "struct %s demoted to typedef - unresolved type\n", buf_ptr(bare_name));
+            emit_warning(c, field_decl, "struct %s demoted to opaque type - unresolved type\n", buf_ptr(bare_name));
             replace_with_fwd_decl(c, struct_type, full_type_name);
             return struct_type;
         }
@@ -1001,23 +970,14 @@ static void visit_record_decl(Context *c, const RecordDecl *record_decl) {
         return;
     }
 
-    assert(struct_type->id == TypeTableEntryIdStruct);
-
     bool is_anonymous = (record_decl->isAnonymousStructOrUnion() || decl_name(record_decl)[0] == 0);
     if (is_anonymous)
         return;
 
     Buf *bare_name = buf_create_from_str(decl_name(record_decl));
 
-    if (struct_type->data.structure.complete) {
-        Tld *tld = add_container_tld(c, struct_type);
-        add_global_weak_alias(c, bare_name, tld);
-    } else {
-        TypeTableEntry *typedecl_type = get_typedecl_type(c->codegen, buf_ptr(&struct_type->name),
-                c->codegen->builtin_types.entry_u8);
-        Tld *tld = add_typedef_tld(c, typedecl_type);
-        add_global_weak_alias(c, bare_name, tld);
-    }
+    Tld *tld = add_container_tld(c, struct_type);
+    add_global_weak_alias(c, bare_name, tld);
 }
 
 static void visit_var_decl(Context *c, const VarDecl *var_decl) {
@@ -1059,8 +1019,7 @@ static void visit_var_decl(Context *c, const VarDecl *var_decl) {
         switch (ap_value->getKind()) {
             case APValue::Int:
                 {
-                    TypeTableEntry *canon_type = get_underlying_type(var_type);
-                    if (canon_type->id != TypeTableEntryIdInt) {
+                    if (var_type->id != TypeTableEntryIdInt) {
                         emit_warning(c, var_decl,
                             "ignoring variable '%s' - int initializer for non int type\n", buf_ptr(name));
                         return;
src/parser.cpp
@@ -710,7 +710,7 @@ static AstNode *ast_parse_try_expr(ParseContext *pc, size_t *token_index, bool m
 
 /*
 PrimaryExpression = Number | String | CharLiteral | KeywordLiteral | GroupedExpression | GotoExpression | BlockExpression(BlockOrExpression) | Symbol | ("@" Symbol FnCallExpression) | ArrayType | (option("extern") FnProto) | AsmExpression | ("error" "." Symbol) | ContainerDecl
-KeywordLiteral = "true" | "false" | "null" | "break" | "continue" | "undefined" | "error" | "type" | "this" | "unreachable"
+KeywordLiteral = "true" | "false" | "null" | "break" | "continue" | "undefined" | "error" | "this" | "unreachable"
 */
 static AstNode *ast_parse_primary_expr(ParseContext *pc, size_t *token_index, bool mandatory) {
     Token *token = &pc->tokens->at(*token_index);
@@ -766,10 +766,6 @@ static AstNode *ast_parse_primary_expr(ParseContext *pc, size_t *token_index, bo
         AstNode *node = ast_create_node(pc, NodeTypeUnreachable, token);
         *token_index += 1;
         return node;
-    } else if (token->id == TokenIdKeywordType) {
-        AstNode *node = ast_create_node(pc, NodeTypeTypeLiteral, token);
-        *token_index += 1;
-        return node;
     } else if (token->id == TokenIdKeywordError) {
         AstNode *node = ast_create_node(pc, NodeTypeErrorType, token);
         *token_index += 1;
@@ -2500,34 +2496,9 @@ static AstNode *ast_parse_test_decl_node(ParseContext *pc, size_t *token_index)
     return node;
 }
 
-/*
-TypeDecl = "type" "Symbol" "=" TypeExpr ";"
-*/
-static AstNode *ast_parse_type_decl(ParseContext *pc, size_t *token_index, VisibMod visib_mod) {
-    Token *first_token = &pc->tokens->at(*token_index);
-
-    if (first_token->id != TokenIdKeywordType) {
-        return nullptr;
-    }
-    *token_index += 1;
-
-    Token *name_tok = ast_eat_token(pc, token_index, TokenIdSymbol);
-    ast_eat_token(pc, token_index, TokenIdEq);
-
-    AstNode *node = ast_create_node(pc, NodeTypeTypeDecl, first_token);
-    node->data.type_decl.symbol = token_buf(name_tok);
-    node->data.type_decl.child_type = ast_parse_type_expr(pc, token_index, true);
-
-    ast_eat_token(pc, token_index, TokenIdSemicolon);
-
-    node->data.type_decl.visib_mod = visib_mod;
-
-    return node;
-}
-
 /*
 TopLevelItem = ErrorValueDecl | CompTimeExpression(Block) | TopLevelDecl | TestDecl
-TopLevelDecl = option(VisibleMod) (FnDef | ExternDecl | GlobalVarDecl | TypeDecl | UseDecl)
+TopLevelDecl = option(VisibleMod) (FnDef | ExternDecl | GlobalVarDecl | UseDecl)
 */
 static void ast_parse_top_level_decls(ParseContext *pc, size_t *token_index, ZigList<AstNode *> *top_level_decls) {
     for (;;) {
@@ -2586,12 +2557,6 @@ static void ast_parse_top_level_decls(ParseContext *pc, size_t *token_index, Zig
             continue;
         }
 
-        AstNode *type_decl_node = ast_parse_type_decl(pc, token_index, visib_mod);
-        if (type_decl_node) {
-            top_level_decls->append(type_decl_node);
-            continue;
-        }
-
         return;
     }
     zig_unreachable();
@@ -2674,9 +2639,6 @@ void ast_visit_node_children(AstNode *node, void (*visit)(AstNode **, void *cont
             visit_field(&node->data.variable_declaration.type, visit, context);
             visit_field(&node->data.variable_declaration.expr, visit, context);
             break;
-        case NodeTypeTypeDecl:
-            visit_field(&node->data.type_decl.child_type, visit, context);
-            break;
         case NodeTypeErrorValueDecl:
             // none
             break;
@@ -2826,9 +2788,6 @@ void ast_visit_node_children(AstNode *node, void (*visit)(AstNode **, void *cont
         case NodeTypeErrorType:
             // none
             break;
-        case NodeTypeTypeLiteral:
-            // none
-            break;
         case NodeTypeVarLiteral:
             // none
             break;
src/tokenizer.cpp
@@ -139,7 +139,6 @@ static const struct ZigKeyword zig_keywords[] = {
     {"this", TokenIdKeywordThis},
     {"true", TokenIdKeywordTrue},
     {"try", TokenIdKeywordTry},
-    {"type", TokenIdKeywordType},
     {"undefined", TokenIdKeywordUndefined},
     {"union", TokenIdKeywordUnion},
     {"unreachable", TokenIdKeywordUnreachable},
@@ -1474,7 +1473,6 @@ const char * token_name(TokenId id) {
         case TokenIdKeywordThis: return "this";
         case TokenIdKeywordTrue: return "true";
         case TokenIdKeywordTry: return "try";
-        case TokenIdKeywordType: return "type";
         case TokenIdKeywordUndefined: return "undefined";
         case TokenIdKeywordUnion: return "union";
         case TokenIdKeywordUnreachable: return "unreachable";
src/tokenizer.hpp
@@ -76,7 +76,6 @@ enum TokenId {
     TokenIdKeywordThis,
     TokenIdKeywordTrue,
     TokenIdKeywordTry,
-    TokenIdKeywordType,
     TokenIdKeywordUndefined,
     TokenIdKeywordUnion,
     TokenIdKeywordUnreachable,
test/cases/typedef.zig
@@ -1,10 +0,0 @@
-const assert = @import("std").debug.assert;
-
-type int = u8;
-
-fn add(a: int, b: int) -> int {
-    a + b
-}
-test "typedef" {
-    assert(add(12, 34) == 46);
-}
test/run_tests.cpp
@@ -2191,7 +2191,7 @@ struct Foo {
     add_parseh_case("struct prototype used in func", AllowWarningsNo, R"SOURCE(
 struct Foo;
 struct Foo *some_func(struct Foo *foo, int x);
-    )SOURCE", 3, R"OUTPUT(pub type struct_Foo = u8;)OUTPUT",
+    )SOURCE", 3, R"OUTPUT(pub const struct_Foo = @OpaqueType();)OUTPUT",
         R"OUTPUT(pub extern fn some_func(foo: ?&struct_Foo, x: c_int) -> ?&struct_Foo;)OUTPUT",
         R"OUTPUT(pub const Foo = struct_Foo;)OUTPUT");
 
@@ -2277,12 +2277,12 @@ void foo(void (__cdecl *fn_ptr)(void));
     )SOURCE", 1, "pub const SDL_INIT_VIDEO = 32;");
 
     add_parseh_case("zig keywords in C code", AllowWarningsNo, R"SOURCE(
-struct type {
+struct comptime {
     int defer;
 };
-    )SOURCE", 2, R"(pub const struct_type = extern struct {
+    )SOURCE", 2, R"(pub const struct_comptime = extern struct {
     @"defer": c_int,
-};)", R"(pub const @"type" = struct_type;)");
+};)", R"(pub const @"comptime" = struct_comptime;)");
 
     add_parseh_case("macro defines string literal with octal", AllowWarningsNo, R"SOURCE(
 #define FOO "aoeu\023 derp"
test/self_hosted.zig
@@ -31,7 +31,6 @@ comptime {
     _ = @import("cases/switch_prong_implicit_cast.zig");
     _ = @import("cases/this.zig");
     _ = @import("cases/try.zig");
-    _ = @import("cases/typedef.zig");
     _ = @import("cases/undefined.zig");
     _ = @import("cases/var_args.zig");
     _ = @import("cases/void.zig");