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add implicit cast from enum tag type of union to const ptr to the union

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closes #654
This commit is contained in:
Andrew Kelley 2017-12-08 17:49:14 -05:00
parent 3577a80bb6
commit 756a218e27
2 changed files with 48 additions and 0 deletions
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34
src/ir.cpp
View File

@ -7492,6 +7492,19 @@ static ImplicitCastMatchResult ir_types_match_with_implicit_cast(IrAnalyze *ira,
}
}
// implicit enum to &const union which has the enum as the tag type
if (actual_type->id == TypeTableEntryIdEnum && expected_type->id == TypeTableEntryIdPointer) {
TypeTableEntry *union_type = expected_type->data.pointer.child_type;
if (union_type->data.unionation.decl_node->data.container_decl.auto_enum ||
union_type->data.unionation.decl_node->data.container_decl.init_arg_expr != nullptr)
{
type_ensure_zero_bits_known(ira->codegen, union_type);
if (union_type->data.unionation.tag_type == actual_type) {
return ImplicitCastMatchResultYes;
}
}
}
// implicit undefined literal to anything
if (actual_type->id == TypeTableEntryIdUndefLit) {
return ImplicitCastMatchResultYes;
@ -9079,6 +9092,27 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
}
}
// explicit enum to &const union which has the enum as the tag type
if (actual_type->id == TypeTableEntryIdEnum && wanted_type->id == TypeTableEntryIdPointer) {
TypeTableEntry *union_type = wanted_type->data.pointer.child_type;
if (union_type->data.unionation.decl_node->data.container_decl.auto_enum ||
union_type->data.unionation.decl_node->data.container_decl.init_arg_expr != nullptr)
{
type_ensure_zero_bits_known(ira->codegen, union_type);
if (union_type->data.unionation.tag_type == actual_type) {
IrInstruction *cast1 = ir_analyze_cast(ira, source_instr, union_type, value);
if (type_is_invalid(cast1->value.type))
return ira->codegen->invalid_instruction;
IrInstruction *cast2 = ir_analyze_cast(ira, source_instr, wanted_type, cast1);
if (type_is_invalid(cast2->value.type))
return ira->codegen->invalid_instruction;
return cast2;
}
}
}
// explicit cast from undefined to anything
if (actual_type->id == TypeTableEntryIdUndefLit) {
return ir_analyze_undefined_to_anything(ira, source_instr, value, wanted_type);

14
test/cases/union.zig
View File

@ -206,3 +206,17 @@ test "implicit cast union to its tag type" {
fn giveMeLetterB(x: Letter2) {
assert(x == Value2.B);
}
test "implicit cast from @EnumTagType(TheUnion) to &const TheUnion" {
assertIsTheUnion2Item1(TheUnion2.Item1);
}
const TheUnion2 = union(enum) {
Item1,
Item2: i32,
};
fn assertIsTheUnion2Item1(value: &const TheUnion2) {
assert(*value == TheUnion2.Item1);
}