Commit 137c8f5e8a

Andrew Kelley <superjoe30@gmail.com>
2017-12-03 04:31:42
ability to set tag values of enums
also remove support for enums with 0 values closes #305
1 parent 98237f7
doc/langref.html.in
@@ -5709,7 +5709,7 @@ VariableDeclaration = option("comptime") ("var" | "const") Symbol option(":" Typ
 
 ContainerMember = (ContainerField | FnDef | GlobalVarDecl)
 
-ContainerField = Symbol option(":" Expression) ","
+ContainerField = Symbol option(":" PrefixOpExpression option("=" PrefixOpExpression ","
 
 UseDecl = "use" Expression ";"
 
src/all_types.hpp
@@ -98,7 +98,7 @@ struct ConstParent {
 };
 
 struct ConstEnumValue {
-    uint64_t tag;
+    BigInt tag;
     ConstExprValue *payload;
 };
 
@@ -108,7 +108,7 @@ struct ConstStructValue {
 };
 
 struct ConstUnionValue {
-    uint64_t tag;
+    BigInt tag;
     ConstExprValue *payload;
     ConstParent parent;
 };
@@ -346,14 +346,14 @@ struct TldCompTime {
 struct TypeEnumField {
     Buf *name;
     TypeTableEntry *type_entry;
-    uint32_t value;
+    BigInt value;
     uint32_t gen_index;
 };
 
 struct TypeUnionField {
     Buf *name;
     TypeTableEntry *type_entry;
-    uint32_t value;
+    BigInt value;
     uint32_t gen_index;
 };
 
@@ -780,6 +780,7 @@ struct AstNodeStructField {
     VisibMod visib_mod;
     Buf *name;
     AstNode *type;
+    AstNode *value;
 };
 
 struct AstNodeStringLiteral {
@@ -1014,6 +1015,7 @@ struct TypeTableEntryEnum {
     TypeEnumField *fields;
     bool is_invalid; // true if any fields are invalid
     TypeTableEntry *tag_type;
+    TypeTableEntry *tag_int_type;
     LLVMTypeRef union_type_ref;
 
     ScopeDecls *decls_scope;
src/analyze.cpp
@@ -1390,30 +1390,7 @@ static void resolve_enum_type(CodeGen *g, TypeTableEntry *enum_type) {
         return;
     }
 
-    TypeTableEntry *tag_int_type = get_smallest_unsigned_int_type(g, field_count - 1);
-    if (decl_node->data.container_decl.init_arg_expr != nullptr) {
-        TypeTableEntry *wanted_tag_int_type = analyze_type_expr(g, scope, decl_node->data.container_decl.init_arg_expr);
-        if (type_is_invalid(wanted_tag_int_type)) {
-            enum_type->data.enumeration.is_invalid = true;
-        } else if (wanted_tag_int_type->id != TypeTableEntryIdInt) {
-            enum_type->data.enumeration.is_invalid = true;
-            add_node_error(g, decl_node->data.container_decl.init_arg_expr,
-                buf_sprintf("expected integer, found '%s'", buf_ptr(&wanted_tag_int_type->name)));
-        } else if (wanted_tag_int_type->data.integral.is_signed) {
-            enum_type->data.enumeration.is_invalid = true;
-            add_node_error(g, decl_node->data.container_decl.init_arg_expr,
-                buf_sprintf("expected unsigned integer, found '%s'", buf_ptr(&wanted_tag_int_type->name)));
-        } else if (wanted_tag_int_type->data.integral.bit_count < tag_int_type->data.integral.bit_count) {
-            enum_type->data.enumeration.is_invalid = true;
-            add_node_error(g, decl_node->data.container_decl.init_arg_expr,
-                buf_sprintf("'%s' too small to hold all bits; must be at least '%s'",
-                    buf_ptr(&wanted_tag_int_type->name), buf_ptr(&tag_int_type->name)));
-        } else {
-            tag_int_type = wanted_tag_int_type;
-        }
-    }
-
-
+    TypeTableEntry *tag_int_type = enum_type->data.enumeration.tag_int_type;
     TypeTableEntry *tag_type_entry = create_enum_tag_type(g, enum_type, tag_int_type);
     enum_type->data.enumeration.tag_type = tag_type_entry;
 
@@ -1683,7 +1660,6 @@ static void resolve_struct_type(CodeGen *g, TypeTableEntry *struct_type) {
         TypeTableEntry *field_type = type_struct_field->type_entry;
 
         ensure_complete_type(g, field_type);
-
         if (type_is_invalid(field_type)) {
             struct_type->data.structure.is_invalid = true;
             break;
@@ -2121,6 +2097,18 @@ static void resolve_enum_zero_bits(CodeGen *g, TypeTableEntry *enum_type) {
 
     assert(!enum_type->data.enumeration.fields);
     uint32_t field_count = (uint32_t)decl_node->data.container_decl.fields.length;
+    if (field_count == 0) {
+        add_node_error(g, decl_node, buf_sprintf("enums must have 1 or more fields"));
+
+        enum_type->data.enumeration.src_field_count = field_count;
+        enum_type->data.enumeration.fields = nullptr;
+        enum_type->data.enumeration.is_invalid = true;
+        enum_type->data.enumeration.zero_bits_loop_flag = false;
+        enum_type->data.enumeration.gen_field_count = 0;
+        enum_type->data.enumeration.zero_bits_known = true;
+        return;
+    }
+
     enum_type->data.enumeration.src_field_count = field_count;
     enum_type->data.enumeration.fields = allocate<TypeEnumField>(field_count);
 
@@ -2128,14 +2116,69 @@ static void resolve_enum_zero_bits(CodeGen *g, TypeTableEntry *enum_type) {
 
     Scope *scope = &enum_type->data.enumeration.decls_scope->base;
 
+    HashMap<BigInt, AstNode *, bigint_hash, bigint_eql> occupied_tag_values = {};
+    occupied_tag_values.init(field_count);
+
+    TypeTableEntry *tag_int_type = get_smallest_unsigned_int_type(g, field_count - 1);
+
+    if (decl_node->data.container_decl.init_arg_expr != nullptr) {
+        TypeTableEntry *wanted_tag_int_type = analyze_type_expr(g, scope, decl_node->data.container_decl.init_arg_expr);
+        if (type_is_invalid(wanted_tag_int_type)) {
+            enum_type->data.enumeration.is_invalid = true;
+        } else if (wanted_tag_int_type->id != TypeTableEntryIdInt) {
+            enum_type->data.enumeration.is_invalid = true;
+            add_node_error(g, decl_node->data.container_decl.init_arg_expr,
+                buf_sprintf("expected integer, found '%s'", buf_ptr(&wanted_tag_int_type->name)));
+        } else if (wanted_tag_int_type->data.integral.is_signed) {
+            enum_type->data.enumeration.is_invalid = true;
+            add_node_error(g, decl_node->data.container_decl.init_arg_expr,
+                buf_sprintf("expected unsigned integer, found '%s'", buf_ptr(&wanted_tag_int_type->name)));
+        } else if (wanted_tag_int_type->data.integral.bit_count < tag_int_type->data.integral.bit_count) {
+            enum_type->data.enumeration.is_invalid = true;
+            add_node_error(g, decl_node->data.container_decl.init_arg_expr,
+                buf_sprintf("'%s' too small to hold all bits; must be at least '%s'",
+                    buf_ptr(&wanted_tag_int_type->name), buf_ptr(&tag_int_type->name)));
+        } else {
+            tag_int_type = wanted_tag_int_type;
+        }
+    }
+    enum_type->data.enumeration.tag_int_type = tag_int_type;
+
     uint32_t gen_field_index = 0;
-    for (uint32_t i = 0; i < field_count; i += 1) {
-        AstNode *field_node = decl_node->data.container_decl.fields.at(i);
-        TypeEnumField *type_enum_field = &enum_type->data.enumeration.fields[i];
+    for (uint32_t field_i = 0; field_i < field_count; field_i += 1) {
+        AstNode *field_node = decl_node->data.container_decl.fields.at(field_i);
+        TypeEnumField *type_enum_field = &enum_type->data.enumeration.fields[field_i];
         type_enum_field->name = field_node->data.struct_field.name;
         TypeTableEntry *field_type = analyze_type_expr(g, scope, field_node->data.struct_field.type);
         type_enum_field->type_entry = field_type;
-        type_enum_field->value = i;
+
+        AstNode *tag_value = field_node->data.struct_field.value;
+
+        // In this first pass we resolve explicit tag values.
+        // In a second pass we will fill in the unspecified ones.
+        if (tag_value != nullptr) {
+            IrInstruction *result_inst = analyze_const_value(g, scope, tag_value, tag_int_type, nullptr);
+            if (result_inst->value.type->id == TypeTableEntryIdInvalid) {
+                enum_type->data.enumeration.is_invalid = true;
+                continue;
+            }
+            assert(result_inst->value.special != ConstValSpecialRuntime);
+            assert(result_inst->value.type->id == TypeTableEntryIdInt);
+            auto entry = occupied_tag_values.put_unique(result_inst->value.data.x_bigint, tag_value);
+            if (entry == nullptr) {
+                bigint_init_bigint(&type_enum_field->value, &result_inst->value.data.x_bigint);
+            } else {
+                Buf *val_buf = buf_alloc();
+                bigint_append_buf(val_buf, &result_inst->value.data.x_bigint, 10);
+
+                ErrorMsg *msg = add_node_error(g, tag_value,
+                        buf_sprintf("enum tag value %s already taken", buf_ptr(val_buf)));
+                add_error_note(g, msg, entry->value,
+                        buf_sprintf("other occurrence here"));
+                enum_type->data.enumeration.is_invalid = true;
+                continue;
+            }
+        }
 
         type_ensure_zero_bits_known(g, field_type);
         if (type_is_invalid(field_type)) {
@@ -2155,6 +2198,34 @@ static void resolve_enum_zero_bits(CodeGen *g, TypeTableEntry *enum_type) {
         }
     }
 
+    // Now iterate again and populate the unspecified tag values
+    uint32_t next_maybe_unoccupied_index = 0;
+
+    for (uint32_t field_i = 0; field_i < field_count; field_i += 1) {
+        AstNode *field_node = decl_node->data.container_decl.fields.at(field_i);
+        TypeEnumField *type_enum_field = &enum_type->data.enumeration.fields[field_i];
+        AstNode *tag_value = field_node->data.struct_field.value;
+
+        if (tag_value == nullptr) {
+            if (occupied_tag_values.size() == 0) {
+                bigint_init_unsigned(&type_enum_field->value, next_maybe_unoccupied_index);
+                next_maybe_unoccupied_index += 1;
+            } else {
+                BigInt proposed_value;
+                for (;;) {
+                    bigint_init_unsigned(&proposed_value, next_maybe_unoccupied_index);
+                    next_maybe_unoccupied_index += 1;
+                    auto entry = occupied_tag_values.put_unique(proposed_value, field_node);
+                    if (entry != nullptr) {
+                        continue;
+                    }
+                    break;
+                }
+                bigint_init_bigint(&type_enum_field->value, &proposed_value);
+            }
+        }
+    }
+
     enum_type->data.enumeration.zero_bits_loop_flag = false;
     enum_type->data.enumeration.gen_field_count = gen_field_index;
     enum_type->zero_bits = (gen_field_index == 0 && field_count < 2);
@@ -2162,7 +2233,6 @@ static void resolve_enum_zero_bits(CodeGen *g, TypeTableEntry *enum_type) {
 
     // also compute abi_alignment
     if (!enum_type->zero_bits) {
-        TypeTableEntry *tag_int_type = get_smallest_unsigned_int_type(g, field_count);
         uint32_t align_of_tag_in_bytes = LLVMABIAlignmentOfType(g->target_data_ref, tag_int_type->type_ref);
         enum_type->data.enumeration.abi_alignment = max(align_of_tag_in_bytes, biggest_align_bytes);
     }
@@ -2214,6 +2284,11 @@ static void resolve_struct_zero_bits(CodeGen *g, TypeTableEntry *struct_type) {
         type_struct_field->src_index = i;
         type_struct_field->gen_index = SIZE_MAX;
 
+        if (field_node->data.struct_field.value != nullptr) {
+            add_node_error(g, field_node->data.struct_field.value,
+                    buf_sprintf("enums, not structs, support field assignment"));
+        }
+
         type_ensure_zero_bits_known(g, field_type);
         if (type_is_invalid(field_type)) {
             struct_type->data.structure.is_invalid = true;
@@ -2277,7 +2352,14 @@ static void resolve_union_zero_bits(CodeGen *g, TypeTableEntry *union_type) {
         type_union_field->name = field_node->data.struct_field.name;
         TypeTableEntry *field_type = analyze_type_expr(g, scope, field_node->data.struct_field.type);
         type_union_field->type_entry = field_type;
-        type_union_field->value = i;
+
+        // TODO look for enum arg to union
+        bigint_init_unsigned(&type_union_field->value, i);
+
+        if (field_node->data.struct_field.value != nullptr) {
+            add_node_error(g, field_node->data.struct_field.value,
+                    buf_sprintf("enums, not unions, support field assignment"));
+        }
 
         type_ensure_zero_bits_known(g, field_type);
         if (type_is_invalid(field_type)) {
@@ -3190,6 +3272,29 @@ TypeUnionField *find_union_type_field(TypeTableEntry *type_entry, Buf *name) {
     return nullptr;
 }
 
+static TypeUnionField *find_union_field_by_tag(TypeTableEntry *type_entry, const BigInt *tag) {
+    assert(type_entry->id == TypeTableEntryIdUnion);
+    assert(type_entry->data.unionation.complete);
+    for (uint32_t i = 0; i < type_entry->data.unionation.src_field_count; i += 1) {
+        TypeUnionField *field = &type_entry->data.unionation.fields[i];
+        if (bigint_cmp(&field->value, tag) == CmpEQ) {
+            return field;
+        }
+    }
+    return nullptr;
+}
+
+TypeEnumField *find_enum_field_by_tag(TypeTableEntry *enum_type, const BigInt *tag) {
+    for (uint32_t i = 0; i < enum_type->data.enumeration.src_field_count; i += 1) {
+        TypeEnumField *field = &enum_type->data.enumeration.fields[i];
+        if (bigint_cmp(&field->value, tag) == CmpEQ) {
+            return field;
+        }
+    }
+    return nullptr;
+}
+
+
 static bool is_container(TypeTableEntry *type_entry) {
     switch (type_entry->id) {
         case TypeTableEntryIdInvalid:
@@ -4178,6 +4283,18 @@ ConstExprValue *create_const_c_str_lit(CodeGen *g, Buf *str) {
     return const_val;
 }
 
+void init_const_bigint(ConstExprValue *const_val, TypeTableEntry *type, const BigInt *bigint) {
+    const_val->special = ConstValSpecialStatic;
+    const_val->type = type;
+    bigint_init_bigint(&const_val->data.x_bigint, bigint);
+}
+
+ConstExprValue *create_const_bigint(TypeTableEntry *type, const BigInt *bigint) {
+    ConstExprValue *const_val = create_const_vals(1);
+    init_const_bigint(const_val, type, bigint);
+    return const_val;
+}
+
 void init_const_unsigned_negative(ConstExprValue *const_val, TypeTableEntry *type, uint64_t x, bool negative) {
     const_val->special = ConstValSpecialStatic;
     const_val->type = type;
@@ -4241,13 +4358,13 @@ ConstExprValue *create_const_float(TypeTableEntry *type, double value) {
     return const_val;
 }
 
-void init_const_enum_tag(ConstExprValue *const_val, TypeTableEntry *type, uint64_t tag) {
+void init_const_enum_tag(ConstExprValue *const_val, TypeTableEntry *type, const BigInt *tag) {
     const_val->special = ConstValSpecialStatic;
     const_val->type = type;
-    const_val->data.x_enum.tag = tag;
+    bigint_init_bigint(&const_val->data.x_enum.tag, tag);
 }
 
-ConstExprValue *create_const_enum_tag(TypeTableEntry *type, uint64_t tag) {
+ConstExprValue *create_const_enum_tag(TypeTableEntry *type, const BigInt *tag) {
     ConstExprValue *const_val = create_const_vals(1);
     init_const_enum_tag(const_val, type, tag);
     return const_val;
@@ -4450,20 +4567,35 @@ bool const_values_equal(ConstExprValue *a, ConstExprValue *b) {
     switch (a->type->id) {
         case TypeTableEntryIdOpaque:
             zig_unreachable();
-        case TypeTableEntryIdEnum:
-            {
-                ConstEnumValue *enum1 = &a->data.x_enum;
-                ConstEnumValue *enum2 = &b->data.x_enum;
-                if (enum1->tag == enum2->tag) {
-                    TypeEnumField *enum_field = &a->type->data.enumeration.fields[enum1->tag];
-                    if (type_has_bits(enum_field->type_entry)) {
-                        zig_panic("TODO const expr analyze enum special value for equality");
-                    } else {
-                        return true;
-                    }
+        case TypeTableEntryIdEnum: {
+            ConstEnumValue *enum1 = &a->data.x_enum;
+            ConstEnumValue *enum2 = &b->data.x_enum;
+            if (bigint_cmp(&enum1->tag, &enum2->tag) == CmpEQ) {
+                TypeEnumField *field = find_enum_field_by_tag(a->type, &enum1->tag);
+                assert(field != nullptr);
+                if (type_has_bits(field->type_entry)) {
+                    zig_panic("TODO const expr analyze enum field value for equality");
+                } else {
+                    return true;
                 }
-                return false;
             }
+            return false;
+        }
+        case TypeTableEntryIdUnion: {
+            ConstUnionValue *union1 = &a->data.x_union;
+            ConstUnionValue *union2 = &b->data.x_union;
+
+            if (bigint_cmp(&union1->tag, &union2->tag) == CmpEQ) {
+                TypeUnionField *field = find_union_field_by_tag(a->type, &union1->tag);
+                assert(field != nullptr);
+                if (type_has_bits(field->type_entry)) {
+                    zig_panic("TODO const expr analyze union field value for equality");
+                } else {
+                    return true;
+                }
+            }
+            return false;
+        }
         case TypeTableEntryIdMetaType:
             return a->data.x_type == b->data.x_type;
         case TypeTableEntryIdVoid:
@@ -4544,8 +4676,6 @@ bool const_values_equal(ConstExprValue *a, ConstExprValue *b) {
                     return false;
             }
             return true;
-        case TypeTableEntryIdUnion:
-            zig_panic("TODO");
         case TypeTableEntryIdUndefLit:
             zig_panic("TODO");
         case TypeTableEntryIdNullLit:
@@ -4855,11 +4985,10 @@ void render_const_value(CodeGen *g, Buf *buf, ConstExprValue *const_val) {
 }
 
 TypeTableEntry *make_int_type(CodeGen *g, bool is_signed, uint32_t size_in_bits) {
-    assert(size_in_bits > 0);
-
     TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdInt);
     entry->is_copyable = true;
-    entry->type_ref = LLVMIntType(size_in_bits);
+    entry->type_ref = (size_in_bits == 0) ? LLVMVoidType() : LLVMIntType(size_in_bits);
+    entry->zero_bits = (size_in_bits == 0);
 
     const char u_or_i = is_signed ? 'i' : 'u';
     buf_resize(&entry->name, 0);
@@ -4880,7 +5009,8 @@ TypeTableEntry *make_int_type(CodeGen *g, bool is_signed, uint32_t size_in_bits)
         }
     }
 
-    uint64_t debug_size_in_bits = 8*LLVMStoreSizeOfType(g->target_data_ref, entry->type_ref);
+    uint64_t debug_size_in_bits = (size_in_bits == 0) ?
+        0 : (8*LLVMStoreSizeOfType(g->target_data_ref, entry->type_ref));
     entry->di_type = ZigLLVMCreateDebugBasicType(g->dbuilder, buf_ptr(&entry->name), debug_size_in_bits, dwarf_tag);
     entry->data.integral.is_signed = is_signed;
     entry->data.integral.bit_count = size_in_bits;
src/analyze.hpp
@@ -64,6 +64,8 @@ TypeStructField *find_struct_type_field(TypeTableEntry *type_entry, Buf *name);
 ScopeDecls *get_container_scope(TypeTableEntry *type_entry);
 TypeEnumField *find_enum_type_field(TypeTableEntry *enum_type, Buf *name);
 TypeUnionField *find_union_type_field(TypeTableEntry *type_entry, Buf *name);
+TypeEnumField *find_enum_field_by_tag(TypeTableEntry *enum_type, const BigInt *tag);
+
 bool is_container_ref(TypeTableEntry *type_entry);
 void scan_decls(CodeGen *g, ScopeDecls *decls_scope, AstNode *node);
 void scan_import(CodeGen *g, ImportTableEntry *import);
@@ -109,6 +111,9 @@ ConstExprValue *create_const_str_lit(CodeGen *g, Buf *str);
 void init_const_c_str_lit(CodeGen *g, ConstExprValue *const_val, Buf *c_str);
 ConstExprValue *create_const_c_str_lit(CodeGen *g, Buf *c_str);
 
+void init_const_bigint(ConstExprValue *const_val, TypeTableEntry *type, const BigInt *bigint);
+ConstExprValue *create_const_bigint(TypeTableEntry *type, const BigInt *bigint);
+
 void init_const_unsigned_negative(ConstExprValue *const_val, TypeTableEntry *type, uint64_t x, bool negative);
 ConstExprValue *create_const_unsigned_negative(TypeTableEntry *type, uint64_t x, bool negative);
 
@@ -121,8 +126,8 @@ ConstExprValue *create_const_usize(CodeGen *g, uint64_t x);
 void init_const_float(ConstExprValue *const_val, TypeTableEntry *type, double value);
 ConstExprValue *create_const_float(TypeTableEntry *type, double value);
 
-void init_const_enum_tag(ConstExprValue *const_val, TypeTableEntry *type, uint64_t tag);
-ConstExprValue *create_const_enum_tag(TypeTableEntry *type, uint64_t tag);
+void init_const_enum_tag(ConstExprValue *const_val, TypeTableEntry *type, const BigInt *tag);
+ConstExprValue *create_const_enum_tag(TypeTableEntry *type, const BigInt *tag);
 
 void init_const_bool(CodeGen *g, ConstExprValue *const_val, bool value);
 ConstExprValue *create_const_bool(CodeGen *g, bool value);
src/ast_render.cpp
@@ -677,6 +677,10 @@ static void render_node_extra(AstRender *ar, AstNode *node, bool grouped) {
                         fprintf(ar->f, ": ");
                         render_node_grouped(ar, field_node->data.struct_field.type);
                     }
+                    if (field_node->data.struct_field.value != nullptr) {
+                        fprintf(ar->f, "= ");
+                        render_node_grouped(ar, field_node->data.struct_field.value);
+                    }
                     fprintf(ar->f, ",\n");
                 }
 
src/bigint.cpp
@@ -1224,3 +1224,35 @@ Cmp bigint_cmp_zero(const BigInt *op) {
     }
     return op->is_negative ? CmpLT : CmpGT;
 }
+
+uint32_t bigint_hash(BigInt x) {
+    if (x.digit_count == 0) {
+        return 0;
+    } else {
+        return bigint_ptr(&x)[0];
+    }
+}
+
+bool bigint_eql(BigInt a, BigInt b) {
+    return bigint_cmp(&a, &b) == CmpEQ;
+}
+
+void bigint_incr(BigInt *x) {
+    if (x->digit_count == 0) {
+        bigint_init_unsigned(x, 1);
+        return;
+    }
+    
+    if (x->digit_count == 1 && x->data.digit != UINT64_MAX) {
+        x->data.digit += 1;
+        return;
+    }
+
+    BigInt copy;
+    bigint_init_bigint(&copy, x);
+
+    BigInt one;
+    bigint_init_unsigned(&one, 1);
+
+    bigint_add(x, &copy, &one);
+}
src/bigint.hpp
@@ -88,6 +88,11 @@ size_t bigint_bits_needed(const BigInt *op);
 // convenience functions
 Cmp bigint_cmp_zero(const BigInt *op);
 
+void bigint_incr(BigInt *value);
+
 bool mul_u64_overflow(uint64_t op1, uint64_t op2, uint64_t *result);
 
+uint32_t bigint_hash(BigInt x);
+bool bigint_eql(BigInt a, BigInt b);
+
 #endif
src/codegen.cpp
@@ -1362,8 +1362,12 @@ static LLVMValueRef bigint_to_llvm_const(LLVMTypeRef type_ref, BigInt *bigint) {
     if (bigint->digit_count == 0) {
         return LLVMConstNull(type_ref);
     }
-    LLVMValueRef unsigned_val = LLVMConstIntOfArbitraryPrecision(type_ref,
-            bigint->digit_count, bigint_ptr(bigint));
+    LLVMValueRef unsigned_val;
+    if (bigint->digit_count == 1) {
+        unsigned_val = LLVMConstInt(type_ref, bigint_ptr(bigint)[0], false);
+    } else {
+        unsigned_val = LLVMConstIntOfArbitraryPrecision(type_ref, bigint->digit_count, bigint_ptr(bigint));
+    }
     if (bigint->is_negative) {
         return LLVMConstNeg(unsigned_val);
     } else {
@@ -2420,9 +2424,10 @@ static LLVMValueRef ir_render_union_field_ptr(CodeGen *g, IrExecutable *executab
     if (ir_want_debug_safety(g, &instruction->base)) {
         LLVMValueRef tag_field_ptr = LLVMBuildStructGEP(g->builder, union_ptr, union_type->data.unionation.gen_tag_index, "");
         LLVMValueRef tag_value = gen_load_untyped(g, tag_field_ptr, 0, false, "");
-        LLVMValueRef expected_tag_value = LLVMConstInt(union_type->data.unionation.tag_type->type_ref,
-                field->value, false);
 
+
+        LLVMValueRef expected_tag_value = bigint_to_llvm_const(union_type->data.unionation.tag_type->type_ref,
+                &field->value);
         LLVMBasicBlockRef ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "UnionCheckOk");
         LLVMBasicBlockRef bad_block = LLVMAppendBasicBlock(g->cur_fn_val, "UnionCheckFail");
         LLVMValueRef ok_val = LLVMBuildICmp(g->builder, LLVMIntEQ, tag_value, expected_tag_value, "");
@@ -3364,9 +3369,9 @@ static LLVMValueRef ir_render_enum_tag(CodeGen *g, IrExecutable *executable, IrI
 
 static LLVMValueRef ir_render_init_enum(CodeGen *g, IrExecutable *executable, IrInstructionInitEnum *instruction) {
     TypeTableEntry *enum_type = instruction->enum_type;
-    uint32_t value = instruction->field->value;
     LLVMTypeRef tag_type_ref = enum_type->data.enumeration.tag_type->type_ref;
-    LLVMValueRef tag_value = LLVMConstInt(tag_type_ref, value, false);
+
+    LLVMValueRef tag_value = bigint_to_llvm_const(tag_type_ref, &instruction->field->value);
 
     if (enum_type->data.enumeration.gen_field_count == 0)
         return tag_value;
@@ -3429,8 +3434,9 @@ static LLVMValueRef ir_render_union_init(CodeGen *g, IrExecutable *executable, I
     if (union_type->data.unionation.gen_tag_index != SIZE_MAX) {
         LLVMValueRef tag_field_ptr = LLVMBuildStructGEP(g->builder, instruction->tmp_ptr,
                 union_type->data.unionation.gen_tag_index, "");
-        LLVMValueRef tag_value = LLVMConstInt(union_type->data.unionation.tag_type->type_ref,
-                type_union_field->value, false);
+
+        LLVMValueRef tag_value = bigint_to_llvm_const(union_type->data.unionation.tag_type->type_ref,
+                &type_union_field->value);
         gen_store_untyped(g, tag_value, tag_field_ptr, 0, false);
 
         uncasted_union_ptr = LLVMBuildStructGEP(g->builder, instruction->tmp_ptr,
@@ -4039,7 +4045,8 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
                     return union_value_ref;
                 }
 
-                LLVMValueRef tag_value = LLVMConstInt(type_entry->data.unionation.tag_type->type_ref, const_val->data.x_union.tag, false);
+                LLVMValueRef tag_value = bigint_to_llvm_const(type_entry->data.unionation.tag_type->type_ref,
+                        &const_val->data.x_union.tag);
 
                 LLVMValueRef fields[2];
                 fields[type_entry->data.unionation.gen_union_index] = union_value_ref;
@@ -4055,13 +4062,13 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
         case TypeTableEntryIdEnum:
             {
                 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);
+                LLVMValueRef tag_value = bigint_to_llvm_const(tag_type_ref, &const_val->data.x_enum.tag);
                 if (type_entry->data.enumeration.gen_field_count == 0) {
                     return tag_value;
                 } else {
                     LLVMTypeRef union_type_ref = type_entry->data.enumeration.union_type_ref;
-                    TypeEnumField *enum_field = &type_entry->data.enumeration.fields[const_val->data.x_enum.tag];
-                    assert(enum_field->value == const_val->data.x_enum.tag);
+                    TypeEnumField *enum_field = find_enum_field_by_tag(type_entry, &const_val->data.x_enum.tag);
+                    assert(bigint_cmp(&enum_field->value, &const_val->data.x_enum.tag) == CmpEQ);
                     LLVMValueRef union_value;
 
                     bool make_unnamed_struct;
src/ir.cpp
@@ -8387,7 +8387,7 @@ static IrInstruction *ir_analyze_enum_to_int(IrAnalyze *ira, IrInstruction *sour
             return ira->codegen->invalid_instruction;
         IrInstruction *result = ir_create_const(&ira->new_irb, source_instr->scope,
                 source_instr->source_node, wanted_type);
-        init_const_unsigned_negative(&result->value, wanted_type, val->data.x_enum.tag, false);
+        init_const_bigint(&result->value, wanted_type, &val->data.x_enum.tag);
         return result;
     }
 
@@ -8469,7 +8469,7 @@ static IrInstruction *ir_analyze_int_to_enum(IrAnalyze *ira, IrInstruction *sour
 
         IrInstruction *result = ir_create_const(&ira->new_irb, source_instr->scope,
                 source_instr->source_node, wanted_type);
-        result->value.data.x_enum.tag = bigint_as_unsigned(&val->data.x_bigint);
+        bigint_init_bigint(&result->value.data.x_enum.tag, &val->data.x_bigint);
         return result;
     }
 
@@ -9148,7 +9148,7 @@ static bool ir_resolve_atomic_order(IrAnalyze *ira, IrInstruction *value, Atomic
     if (!const_val)
         return false;
 
-    *out = (AtomicOrder)const_val->data.x_enum.tag;
+    *out = (AtomicOrder)bigint_as_unsigned(&const_val->data.x_enum.tag);
     return true;
 }
 
@@ -9168,7 +9168,27 @@ static bool ir_resolve_global_linkage(IrAnalyze *ira, IrInstruction *value, Glob
     if (!const_val)
         return false;
 
-    *out = (GlobalLinkageId)const_val->data.x_enum.tag;
+    *out = (GlobalLinkageId)bigint_as_unsigned(&const_val->data.x_enum.tag);
+    return true;
+}
+
+static bool ir_resolve_float_mode(IrAnalyze *ira, IrInstruction *value, FloatMode *out) {
+    if (type_is_invalid(value->value.type))
+        return false;
+
+    ConstExprValue *float_mode_val = get_builtin_value(ira->codegen, "FloatMode");
+    assert(float_mode_val->type->id == TypeTableEntryIdMetaType);
+    TypeTableEntry *float_mode_type = float_mode_val->data.x_type;
+
+    IrInstruction *casted_value = ir_implicit_cast(ira, value, float_mode_type);
+    if (type_is_invalid(casted_value->value.type))
+        return false;
+
+    ConstExprValue *const_val = ir_resolve_const(ira, casted_value, UndefBad);
+    if (!const_val)
+        return false;
+
+    *out = (FloatMode)bigint_as_unsigned(&const_val->data.x_enum.tag);
     return true;
 }
 
@@ -11825,13 +11845,13 @@ static TypeTableEntry *ir_analyze_instruction_field_ptr(IrAnalyze *ira, IrInstru
                         bool ptr_is_const = true;
                         bool ptr_is_volatile = false;
                         return ir_analyze_const_ptr(ira, &field_ptr_instruction->base,
-                                create_const_enum_tag(child_type, field->value), child_type,
+                                create_const_enum_tag(child_type, &field->value), child_type,
                                 ConstPtrMutComptimeConst, ptr_is_const, ptr_is_volatile);
                     } else {
                         bool ptr_is_const = true;
                         bool ptr_is_volatile = false;
                         return ir_analyze_const_ptr(ira, &field_ptr_instruction->base,
-                            create_const_unsigned_negative(child_type->data.enumeration.tag_type, field->value, false),
+                            create_const_bigint(child_type->data.enumeration.tag_type, &field->value),
                             child_type->data.enumeration.tag_type,
                             ConstPtrMutComptimeConst, ptr_is_const, ptr_is_volatile);
                     }
@@ -12420,21 +12440,11 @@ static TypeTableEntry *ir_analyze_instruction_set_float_mode(IrAnalyze *ira,
         return ira->codegen->builtin_types.entry_invalid;
     }
 
-    ConstExprValue *float_mode_val = get_builtin_value(ira->codegen, "FloatMode");
-    assert(float_mode_val->type->id == TypeTableEntryIdMetaType);
-    TypeTableEntry *float_mode_enum_type = float_mode_val->data.x_type;
-
     IrInstruction *float_mode_value = instruction->mode_value->other;
-    if (type_is_invalid(float_mode_value->value.type))
-        return ira->codegen->builtin_types.entry_invalid;
-    IrInstruction *casted_value = ir_implicit_cast(ira, float_mode_value, float_mode_enum_type);
-    if (type_is_invalid(casted_value->value.type))
-        return ira->codegen->builtin_types.entry_invalid;
-    ConstExprValue *mode_val = ir_resolve_const(ira, casted_value, UndefBad);
-    if (!mode_val)
-        return ira->codegen->builtin_types.entry_invalid;
 
-    bool want_fast_math = (mode_val->data.x_enum.tag == FloatModeOptimized);
+    FloatMode float_mode_scalar;
+    if (!ir_resolve_float_mode(ira, float_mode_value, &float_mode_scalar))
+        return ira->codegen->builtin_types.entry_invalid;
 
     AstNode *source_node = instruction->base.source_node;
     if (*fast_math_set_node_ptr) {
@@ -12444,7 +12454,7 @@ static TypeTableEntry *ir_analyze_instruction_set_float_mode(IrAnalyze *ira,
         return ira->codegen->builtin_types.entry_invalid;
     }
     *fast_math_set_node_ptr = source_node;
-    *fast_math_off_ptr = !want_fast_math;
+    *fast_math_off_ptr = (float_mode_scalar == FloatModeStrict);
 
     ir_build_const_from(ira, &instruction->base);
     return ira->codegen->builtin_types.entry_void;
@@ -12835,7 +12845,7 @@ static IrInstruction *ir_analyze_enum_tag(IrAnalyze *ira, IrInstruction *source_
                 source_instr->scope, source_instr->source_node);
         const_instruction->base.value.type = tag_type;
         const_instruction->base.value.special = ConstValSpecialStatic;
-        bigint_init_unsigned(&const_instruction->base.value.data.x_bigint, val->data.x_enum.tag);
+        bigint_init_bigint(&const_instruction->base.value.data.x_bigint, &val->data.x_enum.tag);
         return &const_instruction->base;
     }
 
@@ -13005,7 +13015,7 @@ static TypeTableEntry *ir_analyze_instruction_switch_target(IrAnalyze *ira,
                 assert(tag_type != nullptr);
                 if (pointee_val) {
                     ConstExprValue *out_val = ir_build_const_from(ira, &switch_target_instruction->base);
-                    bigint_init_unsigned(&out_val->data.x_bigint, pointee_val->data.x_enum.tag);
+                    bigint_init_bigint(&out_val->data.x_bigint, &pointee_val->data.x_enum.tag);
                     return tag_type;
                 }
 
@@ -13056,9 +13066,9 @@ static TypeTableEntry *ir_analyze_instruction_switch_var(IrAnalyze *ira, IrInstr
 
         TypeEnumField *field;
         if (prong_value->value.type->id == TypeTableEntryIdEnumTag) {
-            field = &target_type->data.enumeration.fields[bigint_as_unsigned(&prong_val->data.x_bigint)];
+            field = find_enum_field_by_tag(target_type, &prong_val->data.x_bigint);
         } else if (prong_value->value.type->id == TypeTableEntryIdEnum) {
-            field = &target_type->data.enumeration.fields[prong_val->data.x_enum.tag];
+            field = find_enum_field_by_tag(target_type, &prong_val->data.x_enum.tag);
         } else {
             zig_unreachable();
         }
@@ -13503,8 +13513,8 @@ static TypeTableEntry *ir_analyze_instruction_container_init_list(IrAnalyze *ira
 
         TypeTableEntry *enum_type = container_type_value->value.type->data.enum_tag.enum_type;
 
-        uint64_t tag_uint = bigint_as_unsigned(&tag_value->data.x_bigint);
-        TypeEnumField *field = &enum_type->data.enumeration.fields[tag_uint];
+        TypeEnumField *field = find_enum_field_by_tag(enum_type, &tag_value->data.x_bigint);
+        assert(field != nullptr);
         TypeTableEntry *this_field_type = field->type_entry;
 
         IrInstruction *init_value = instruction->items[0]->other;
@@ -13520,7 +13530,7 @@ static TypeTableEntry *ir_analyze_instruction_container_init_list(IrAnalyze *ira
             if (!init_val)
                 return ira->codegen->builtin_types.entry_invalid;
             ConstExprValue *out_val = ir_build_const_from(ira, &instruction->base);
-            out_val->data.x_enum.tag = tag_uint;
+            bigint_init_bigint(&out_val->data.x_enum.tag, &tag_value->data.x_bigint);
             out_val->data.x_enum.payload = init_val;
             return enum_type;
         }
@@ -13859,7 +13869,7 @@ static TypeTableEntry *ir_analyze_instruction_type_id(IrAnalyze *ira,
     TypeTableEntry *result_type = var_value->data.x_type;
 
     ConstExprValue *out_val = ir_build_const_from(ira, &instruction->base);
-    out_val->data.x_enum.tag = type_id_index(type_entry->id);
+    bigint_init_unsigned(&out_val->data.x_enum.tag, type_id_index(type_entry->id));
     return result_type;
 }
 
@@ -15117,7 +15127,9 @@ static TypeTableEntry *ir_analyze_instruction_check_switch_prongs(IrAnalyze *ira
 
     if (switch_type->id == TypeTableEntryIdEnumTag) {
         TypeTableEntry *enum_type = switch_type->data.enum_tag.enum_type;
-        AstNode **field_prev_uses = allocate<AstNode *>(enum_type->data.enumeration.src_field_count);
+        HashMap<BigInt, AstNode *, bigint_hash, bigint_eql> field_prev_uses = {};
+        field_prev_uses.init(enum_type->data.enumeration.src_field_count);
+
         for (size_t range_i = 0; range_i < instruction->range_count; range_i += 1) {
             IrInstructionCheckSwitchProngsRange *range = &instruction->ranges[range_i];
 
@@ -15129,41 +15141,52 @@ static TypeTableEntry *ir_analyze_instruction_check_switch_prongs(IrAnalyze *ira
             if (type_is_invalid(end_value->value.type))
                 return ira->codegen->builtin_types.entry_invalid;
 
-            size_t start_index;
-            size_t end_index;
+            BigInt start_index;
+            BigInt end_index;
             if (start_value->value.type->id == TypeTableEntryIdEnumTag) {
-                start_index = bigint_as_unsigned(&start_value->value.data.x_bigint);
+                bigint_init_bigint(&start_index, &start_value->value.data.x_bigint);
             } else if (start_value->value.type->id == TypeTableEntryIdEnum) {
-                start_index = start_value->value.data.x_enum.tag;
+                bigint_init_bigint(&start_index, &start_value->value.data.x_enum.tag);
             } else {
                 zig_unreachable();
             }
             if (end_value->value.type->id == TypeTableEntryIdEnumTag) {
-                end_index = bigint_as_unsigned(&end_value->value.data.x_bigint);
+                bigint_init_bigint(&end_index, &end_value->value.data.x_bigint);
             } else if (end_value->value.type->id == TypeTableEntryIdEnum) {
-                end_index = end_value->value.data.x_enum.tag;
+                bigint_init_bigint(&end_index, &end_value->value.data.x_enum.tag);
             } else {
                 zig_unreachable();
             }
 
-            for (size_t field_index = start_index; field_index <= end_index; field_index += 1) {
-                AstNode *prev_node = field_prev_uses[field_index];
-                if (prev_node != nullptr) {
-                    TypeEnumField *type_enum_field = &enum_type->data.enumeration.fields[field_index];
+            BigInt field_index;
+            bigint_init_bigint(&field_index, &start_index);
+            for (;;) {
+                Cmp cmp = bigint_cmp(&field_index, &end_index);
+                if (cmp == CmpGT) {
+                    break;
+                }
+                auto entry = field_prev_uses.put_unique(field_index, start_value->source_node);
+                if (entry) {
+                    AstNode *prev_node = entry->value;
+                    TypeEnumField *enum_field = find_enum_field_by_tag(enum_type, &field_index);
+                    assert(enum_field != nullptr);
                     ErrorMsg *msg = ir_add_error(ira, start_value,
                         buf_sprintf("duplicate switch value: '%s.%s'", buf_ptr(&enum_type->name),
-                            buf_ptr(type_enum_field->name)));
+                            buf_ptr(enum_field->name)));
                     add_error_note(ira->codegen, msg, prev_node, buf_sprintf("other value is here"));
                 }
-                field_prev_uses[field_index] = start_value->source_node;
+                bigint_incr(&field_index);
             }
         }
         if (!instruction->have_else_prong) {
             for (uint32_t i = 0; i < enum_type->data.enumeration.src_field_count; i += 1) {
-                if (field_prev_uses[i] == nullptr) {
+                TypeEnumField *enum_field = &enum_type->data.enumeration.fields[i];
+
+                auto entry = field_prev_uses.maybe_get(enum_field->value);
+                if (!entry) {
                     ir_add_error(ira, &instruction->base,
                         buf_sprintf("enumeration value '%s.%s' not handled in switch", buf_ptr(&enum_type->name),
-                            buf_ptr(enum_type->data.enumeration.fields[i].name)));
+                            buf_ptr(enum_field->name)));
                 }
             }
         }
src/parser.cpp
@@ -2379,7 +2379,7 @@ static AstNode *ast_parse_use(ParseContext *pc, size_t *token_index, VisibMod vi
 /*
 ContainerDecl = option("extern" | "packed") ("struct" | "union" | ("enum" option(GroupedExpression))) "{" many(ContainerMember) "}"
 ContainerMember = (ContainerField | FnDef | GlobalVarDecl)
-ContainerField = Symbol option(":" Expression) ","
+ContainerField = Symbol option(":" PrefixOpExpression option("=" PrefixOpExpression ","
 */
 static AstNode *ast_parse_container_decl(ParseContext *pc, size_t *token_index, bool mandatory) {
     Token *first_token = &pc->tokens->at(*token_index);
@@ -2414,10 +2414,7 @@ static AstNode *ast_parse_container_decl(ParseContext *pc, size_t *token_index,
     AstNode *node = ast_create_node(pc, NodeTypeContainerDecl, first_token);
     node->data.container_decl.layout = layout;
     node->data.container_decl.kind = kind;
-
-    if (kind == ContainerKindEnum || kind == ContainerKindStruct) {
-        node->data.container_decl.init_arg_expr = ast_parse_grouped_expr(pc, token_index, false);
-    }
+    node->data.container_decl.init_arg_expr = ast_parse_grouped_expr(pc, token_index, false);
 
     ast_eat_token(pc, token_index, TokenIdLBrace);
 
@@ -2456,31 +2453,35 @@ static AstNode *ast_parse_container_decl(ParseContext *pc, size_t *token_index,
             AstNode *field_node = ast_create_node(pc, NodeTypeStructField, token);
             *token_index += 1;
 
+            node->data.container_decl.fields.append(field_node);
             field_node->data.struct_field.visib_mod = visib_mod;
             field_node->data.struct_field.name = token_buf(token);
 
-            Token *token = &pc->tokens->at(*token_index);
-            if (token->id == TokenIdComma || token->id == TokenIdRBrace) {
-                field_node->data.struct_field.type = ast_create_void_type_node(pc, token);
+            Token *colon_token = &pc->tokens->at(*token_index);
+            if (colon_token->id == TokenIdColon) {
                 *token_index += 1;
-                node->data.container_decl.fields.append(field_node);
-
-                if (token->id == TokenIdRBrace) {
-                    break;
-                }
+                field_node->data.struct_field.type = ast_parse_prefix_op_expr(pc, token_index, true);
             } else {
-                ast_eat_token(pc, token_index, TokenIdColon);
-                field_node->data.struct_field.type = ast_parse_expression(pc, token_index, true);
-                node->data.container_decl.fields.append(field_node);
+                field_node->data.struct_field.type = ast_create_void_type_node(pc, colon_token);
+            }
+            Token *eq_token = &pc->tokens->at(*token_index);
+            if (eq_token->id == TokenIdEq) {
+                *token_index += 1;
+                field_node->data.struct_field.value = ast_parse_prefix_op_expr(pc, token_index, true);
+            }
 
-                Token *token = &pc->tokens->at(*token_index);
-                if (token->id == TokenIdRBrace) {
-                    *token_index += 1;
-                    break;
-                } else {
-                    ast_eat_token(pc, token_index, TokenIdComma);
-                }
+            Token *next_token = &pc->tokens->at(*token_index);
+            if (next_token->id == TokenIdComma) {
+                *token_index += 1;
+                continue;
             }
+
+            if (next_token->id == TokenIdRBrace) {
+                *token_index += 1;
+                break;
+            }
+
+            ast_invalid_token_error(pc, next_token);
         } else {
             ast_invalid_token_error(pc, token);
         }
@@ -2812,6 +2813,7 @@ void ast_visit_node_children(AstNode *node, void (*visit)(AstNode **, void *cont
             break;
         case NodeTypeStructField:
             visit_field(&node->data.struct_field.type, visit, context);
+            visit_field(&node->data.struct_field.value, visit, context);
             break;
         case NodeTypeContainerInitExpr:
             visit_field(&node->data.container_init_expr.type, visit, context);
std/sort.zig
@@ -16,7 +16,7 @@ pub fn sort_stable(comptime T: type, array: []T, comptime cmp: fn(a: &const T, b
     }}
 }
 
-/// Unstable sort using O(n) stack space. Currentl implemented as quicksort.
+/// Unstable sort using O(n) stack space. Currently implemented as quicksort.
 pub fn sort(comptime T: type, array: []T, comptime cmp: fn(a: &const T, b: &const T)->Cmp) {
     if (array.len > 0) {
         quicksort(T, array, 0, array.len - 1, cmp);
test/cases/enum.zig
@@ -137,7 +137,6 @@ const AlignTestEnum = enum {
     B: u64,
 };
 
-const ValueCount0 = enum {};
 const ValueCount1 = enum { I0 };
 const ValueCount2 = enum { I0, I1 };
 const ValueCount256 = enum {
@@ -183,7 +182,6 @@ const ValueCount257 = enum {
 
 test "enum sizes" {
     comptime {
-        assert(@sizeOf(ValueCount0) == 0);
         assert(@sizeOf(ValueCount1) == 0);
         assert(@sizeOf(ValueCount2) == 1);
         assert(@sizeOf(ValueCount256) == 1);
@@ -292,3 +290,57 @@ test "casting enum to its tag type" {
 fn testCastEnumToTagType(value: Small2) {
     assert(u2(value) == 1);
 }
+
+const MultipleChoice = enum(u32) {
+    A = 20,
+    B = 40,
+    C = 60,
+    D = 1000,
+};
+
+test "enum with specified tag values" {
+    testEnumWithSpecifiedTagValues(MultipleChoice.C);
+    comptime testEnumWithSpecifiedTagValues(MultipleChoice.C);
+}
+
+fn testEnumWithSpecifiedTagValues(x: MultipleChoice) {
+    assert(u32(x) == 60);
+    assert(1234 == switch (x) {
+        MultipleChoice.A => 1,
+        MultipleChoice.B => 2,
+        MultipleChoice.C => u32(1234),
+        MultipleChoice.D => 4,
+    });
+}
+
+const MultipleChoice2 = enum(u32) {
+    Unspecified1,
+    A = 20,
+    Unspecified2,
+    B = 40,
+    Unspecified3,
+    C = 60,
+    Unspecified4,
+    D = 1000,
+    Unspecified5,
+};
+
+test "enum with specified and unspecified tag values" {
+    testEnumWithSpecifiedAndUnspecifiedTagValues(MultipleChoice2.D);
+    comptime testEnumWithSpecifiedAndUnspecifiedTagValues(MultipleChoice2.D);
+}
+
+fn testEnumWithSpecifiedAndUnspecifiedTagValues(x: MultipleChoice2) {
+    assert(u32(x) == 1000);
+    assert(1234 == switch (x) {
+        MultipleChoice2.A => 1,
+        MultipleChoice2.B => 2,
+        MultipleChoice2.C => 3,
+        MultipleChoice2.D => u32(1234),
+        MultipleChoice2.Unspecified1 => 5,
+        MultipleChoice2.Unspecified2 => 6,
+        MultipleChoice2.Unspecified3 => 7,
+        MultipleChoice2.Unspecified4 => 8,
+        MultipleChoice2.Unspecified5 => 9,
+    });
+}
test/compile_errors.zig
@@ -2307,11 +2307,11 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
 
     cases.add("@memberType enum out of bounds",
         \\comptime {
-        \\    _ = @memberType(Foo, 0);
+        \\    _ = @memberType(Foo, 1);
         \\}
-        \\const Foo = enum {};
+        \\const Foo = enum {A,};
     ,
-        ".tmp_source.zig:2:26: error: member index 0 out of bounds; 'Foo' has 0 members");
+        ".tmp_source.zig:2:26: error: member index 1 out of bounds; 'Foo' has 1 members");
 
     cases.add("@memberName on unsupported type",
         \\comptime {
@@ -2330,11 +2330,11 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
 
     cases.add("@memberName enum out of bounds",
         \\comptime {
-        \\    _ = @memberName(Foo, 0);
+        \\    _ = @memberName(Foo, 1);
         \\}
-        \\const Foo = enum {};
+        \\const Foo = enum {A,};
     ,
-        ".tmp_source.zig:2:26: error: member index 0 out of bounds; 'Foo' has 0 members");
+        ".tmp_source.zig:2:26: error: member index 1 out of bounds; 'Foo' has 1 members");
 
     cases.add("calling var args extern function, passing array instead of pointer",
         \\export fn entry() {
@@ -2447,4 +2447,47 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
         \\}
     ,
         ".tmp_source.zig:1:19: error: expected unsigned integer, found 'i2'");
+
+    cases.add("struct fields with value assignments",
+        \\const MultipleChoice = struct {
+        \\    A: i32 = 20,
+        \\};
+        \\export fn entry() {
+        \\        var x: MultipleChoice = undefined;
+        \\}
+    ,
+        ".tmp_source.zig:2:14: error: enums, not structs, support field assignment");
+
+    cases.add("union fields with value assignments",
+        \\const MultipleChoice = union {
+        \\    A: i32 = 20,
+        \\};
+        \\export fn entry() {
+        \\        var x: MultipleChoice = undefined;
+        \\}
+    ,
+        ".tmp_source.zig:2:14: error: enums, not unions, support field assignment");
+
+    cases.add("enum with 0 fields",
+        \\const Foo = enum {};
+        \\export fn entry() -> usize {
+        \\    return @sizeOf(Foo);
+        \\}
+    ,
+        ".tmp_source.zig:1:13: error: enums must have 1 or more fields");
+
+    cases.add("enum value already taken",
+        \\const MultipleChoice = enum(u32) {
+        \\    A = 20,
+        \\    B = 40,
+        \\    C = 60,
+        \\    D = 1000,
+        \\    E = 60,
+        \\};
+        \\export fn entry() {
+        \\    var x = MultipleChoice.C;
+        \\}
+    ,
+        ".tmp_source.zig:6:9: error: enum tag value 60 already taken",
+        ".tmp_source.zig:4:9: note: other occurrence here");
 }