Commit aafb0b9082

Andrew Kelley <superjoe30@gmail.com>
2017-04-22 18:19:20
slicing now returns correct const-ness
also remove the ability to override constness when slicing closes #334
1 parent 1a0081b
doc/langref.md
@@ -133,7 +133,7 @@ FnCallExpression = "(" list(Expression, ",") ")"
 
 ArrayAccessExpression = "[" Expression "]"
 
-SliceExpression = "[" Expression "..." option(Expression) "]" option("const")
+SliceExpression = "[" Expression "..." option(Expression) "]"
 
 ContainerInitExpression = "{" ContainerInitBody "}"
 
src/all_types.hpp
@@ -532,7 +532,6 @@ struct AstNodeSliceExpr {
     AstNode *array_ref_expr;
     AstNode *start;
     AstNode *end;
-    bool is_const;
 };
 
 struct AstNodeFieldAccessExpr {
@@ -2260,7 +2259,6 @@ struct IrInstructionSlice {
     IrInstruction *ptr;
     IrInstruction *start;
     IrInstruction *end;
-    bool is_const;
     bool safety_check_on;
     LLVMValueRef tmp_ptr;
 };
src/ast_render.cpp
@@ -894,8 +894,6 @@ static void render_node_extra(AstRender *ar, AstNode *node, bool grouped) {
                 if (node->data.slice_expr.end)
                     render_node_grouped(ar, node->data.slice_expr.end);
                 fprintf(ar->f, "]");
-                if (node->data.slice_expr.is_const)
-                    fprintf(ar->f, "const");
                 break;
             }
         case NodeTypeUnwrapErrorExpr:
src/ir.cpp
@@ -1729,13 +1729,12 @@ static IrInstruction *ir_build_memcpy_from(IrBuilder *irb, IrInstruction *old_in
 }
 
 static IrInstruction *ir_build_slice(IrBuilder *irb, Scope *scope, AstNode *source_node,
-    IrInstruction *ptr, IrInstruction *start, IrInstruction *end, bool is_const, bool safety_check_on)
+    IrInstruction *ptr, IrInstruction *start, IrInstruction *end, bool safety_check_on)
 {
     IrInstructionSlice *instruction = ir_build_instruction<IrInstructionSlice>(irb, scope, source_node);
     instruction->ptr = ptr;
     instruction->start = start;
     instruction->end = end;
-    instruction->is_const = is_const;
     instruction->safety_check_on = safety_check_on;
 
     ir_ref_instruction(ptr, irb->current_basic_block);
@@ -1746,10 +1745,10 @@ static IrInstruction *ir_build_slice(IrBuilder *irb, Scope *scope, AstNode *sour
 }
 
 static IrInstruction *ir_build_slice_from(IrBuilder *irb, IrInstruction *old_instruction,
-    IrInstruction *ptr, IrInstruction *start, IrInstruction *end, bool is_const, bool safety_check_on)
+    IrInstruction *ptr, IrInstruction *start, IrInstruction *end, bool safety_check_on)
 {
     IrInstruction *new_instruction = ir_build_slice(irb, old_instruction->scope,
-            old_instruction->source_node, ptr, start, end, is_const, safety_check_on);
+            old_instruction->source_node, ptr, start, end, safety_check_on);
     ir_link_new_instruction(new_instruction, old_instruction);
     return new_instruction;
 }
@@ -5439,7 +5438,7 @@ static IrInstruction *ir_gen_slice(IrBuilder *irb, Scope *scope, AstNode *node)
         end_value = nullptr;
     }
 
-    return ir_build_slice(irb, scope, node, ptr_value, start_value, end_value, slice_expr->is_const, true);
+    return ir_build_slice(irb, scope, node, ptr_value, start_value, end_value, true);
 }
 
 static IrInstruction *ir_gen_err_ok_or(IrBuilder *irb, Scope *parent_scope, AstNode *node) {
@@ -5903,6 +5902,11 @@ static bool is_slice(TypeTableEntry *type) {
     return type->id == TypeTableEntryIdStruct && type->data.structure.is_slice;
 }
 
+static bool slice_is_const(TypeTableEntry *type) {
+    assert(is_slice(type));
+    return type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.is_const;
+}
+
 enum ImplicitCastMatchResult {
     ImplicitCastMatchResultNo,
     ImplicitCastMatchResultYes,
@@ -6778,7 +6782,7 @@ static IrInstruction *ir_analyze_array_to_slice(IrAnalyze *ira, IrInstruction *s
     IrInstruction *array_ptr = ir_get_ref(ira, source_instr, array, true, false);
 
     IrInstruction *result = ir_build_slice(&ira->new_irb, source_instr->scope,
-            source_instr->source_node, array_ptr, start, end, false, false);
+            source_instr->source_node, array_ptr, start, end, false);
     TypeTableEntry *child_type = array_type->data.array.child_type;
     result->value.type = get_slice_type(ira->codegen, child_type, true);
     ir_add_alloca(ira, result, result->value.type);
@@ -12076,17 +12080,17 @@ static TypeTableEntry *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstructio
     TypeTableEntry *return_type;
 
     if (array_type->id == TypeTableEntryIdArray) {
-        return_type = get_slice_type(ira->codegen, array_type->data.array.child_type, instruction->is_const);
+        return_type = get_slice_type(ira->codegen, array_type->data.array.child_type, ptr_type->data.pointer.is_const);
     } else if (array_type->id == TypeTableEntryIdPointer) {
-        return_type = get_slice_type(ira->codegen, array_type->data.pointer.child_type, instruction->is_const);
+        return_type = get_slice_type(ira->codegen, array_type->data.pointer.child_type,
+                array_type->data.pointer.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(array_type)) {
-        return_type = get_slice_type(ira->codegen,
-                array_type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.child_type,
-                instruction->is_const);
+        TypeTableEntry *ptr_type = array_type->data.structure.fields[slice_ptr_index].type_entry;
+        return_type = get_slice_type(ira->codegen, ptr_type->data.pointer.child_type, ptr_type->data.pointer.is_const);
     } else {
         ir_add_error(ira, &instruction->base,
             buf_sprintf("slice of non-array type '%s'", buf_ptr(&array_type->name)));
@@ -12186,7 +12190,8 @@ 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);
+                bool is_const = slice_is_const(return_type);
+                init_const_ptr_array(ira->codegen, ptr_val, array_val, index, is_const);
                 if (array_type->id == TypeTableEntryIdArray) {
                     ptr_val->data.x_ptr.mut = ptr_ptr->value.data.x_ptr.mut;
                 }
@@ -12197,7 +12202,7 @@ static TypeTableEntry *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstructio
                         zig_unreachable();
                     case ConstPtrSpecialRef:
                         init_const_ptr_ref(ira->codegen, ptr_val,
-                                parent_ptr->data.x_ptr.data.ref.pointee, instruction->is_const);
+                                parent_ptr->data.x_ptr.data.ref.pointee, slice_is_const(return_type));
                         break;
                     case ConstPtrSpecialBaseArray:
                         zig_unreachable();
@@ -12216,7 +12221,7 @@ static TypeTableEntry *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstructio
     }
 
     IrInstruction *new_instruction = ir_build_slice_from(&ira->new_irb, &instruction->base, ptr_ptr,
-            casted_start, end, instruction->is_const, instruction->safety_check_on);
+            casted_start, end, instruction->safety_check_on);
     ir_add_alloca(ira, new_instruction, return_type);
 
     return return_type;
src/ir_print.cpp
@@ -642,8 +642,6 @@ static void ir_print_slice(IrPrint *irp, IrInstructionSlice *instruction) {
     if (instruction->end)
         ir_print_other_instruction(irp, instruction->end);
     fprintf(irp->f, "]");
-    if (instruction->is_const)
-        fprintf(irp->f, "const");
 }
 
 static void ir_print_member_count(IrPrint *irp, IrInstructionMemberCount *instruction) {
src/parser.cpp
@@ -986,7 +986,7 @@ static AstNode *ast_parse_inline_expr(ParseContext *pc, size_t *token_index, boo
 SuffixOpExpression = InlineExpression option(FnCallExpression | ArrayAccessExpression | FieldAccessExpression | SliceExpression)
 FnCallExpression : token(LParen) list(Expression, token(Comma)) token(RParen)
 ArrayAccessExpression : token(LBracket) Expression token(RBracket)
-SliceExpression : token(LBracket) Expression token(Ellipsis) option(Expression) token(RBracket) option(token(Const))
+SliceExpression = "[" Expression "..." option(Expression) "]"
 FieldAccessExpression : token(Dot) token(Symbol)
 StructLiteralField : token(Dot) token(Symbol) token(Eq) Expression
 */
@@ -1022,12 +1022,6 @@ static AstNode *ast_parse_suffix_op_expr(ParseContext *pc, size_t *token_index,
 
                 ast_eat_token(pc, token_index, TokenIdRBracket);
 
-                Token *const_tok = &pc->tokens->at(*token_index);
-                if (const_tok->id == TokenIdKeywordConst) {
-                    *token_index += 1;
-                    node->data.slice_expr.is_const = true;
-                }
-
                 inline_expr = node;
             } else if (ellipsis_or_r_bracket->id == TokenIdRBracket) {
                 *token_index += 1;
test/cases/cast.zig
@@ -120,6 +120,11 @@ fn returnNullLitFromMaybeTypeErrorRef() -> %?&A {
 
 test "peer type resolution: ?T and T" {
     assert(??peerTypeTAndMaybeT(true, false) == 0);
+    assert(??peerTypeTAndMaybeT(false, false) == 3);
+    comptime {
+        assert(??peerTypeTAndMaybeT(true, false) == 0);
+        assert(??peerTypeTAndMaybeT(false, false) == 3);
+    }
 }
 fn peerTypeTAndMaybeT(c: bool, b: bool) -> ?usize {
     if (c) {
@@ -128,3 +133,20 @@ fn peerTypeTAndMaybeT(c: bool, b: bool) -> ?usize {
 
     return usize(3);
 }
+
+
+test "peer type resolution: [0]u8 and []const u8" {
+    assert(peerTypeEmptyArrayAndSlice(true, "hi").len == 0);
+    assert(peerTypeEmptyArrayAndSlice(false, "hi").len == 1);
+    comptime {
+        assert(peerTypeEmptyArrayAndSlice(true, "hi").len == 0);
+        assert(peerTypeEmptyArrayAndSlice(false, "hi").len == 1);
+    }
+}
+fn peerTypeEmptyArrayAndSlice(a: bool, slice: []const u8) -> []const u8 {
+    if (a) {
+        return []const u8 {};
+    }
+
+    return slice[0...1];
+}
test/cases/const_slice_child.zig
@@ -21,7 +21,7 @@ fn foo(args: [][]const u8) {
 }
 
 fn bar(argc: usize) {
-    const args = %%debug.global_allocator.alloc([]u8, argc);
+    const args = %%debug.global_allocator.alloc([]const u8, argc);
     for (args) |_, i| {
         const ptr = argv[i];
         args[i] = ptr[0...strlen(ptr)];