authorgravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2017-12-05 20:46:58-05:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2017-12-05 20:46:58-05:00
log960914a073c367883c9fdf54e900890a6aefc05f
tree4dca5efa7967f0ecca20bd0d852005008a1ec925
parent63a2f9a8b2251ffdc37d5f28dfbd3f6be1bd7908

add implicit cast from enum to union

when the enum is the tag type of the union and is comptime known to be of a void field of the union See #642

5 files changed, 129 insertions(+), 8 deletions(-)

src/analyze.cpp+10-5
......@@ -2244,12 +2244,10 @@ static void resolve_union_zero_bits(CodeGen *g, TypeTableEntry *union_type) {
22442244 TypeTableEntry *enum_type = analyze_type_expr(g, scope, enum_type_node);
22452245 if (type_is_invalid(enum_type)) {
22462246 union_type->data.unionation.is_invalid = true;
2247 union_type->data.unionation.embedded_in_current = false;
22482247 return;
22492248 }
22502249 if (enum_type->id != TypeTableEntryIdEnum) {
22512250 union_type->data.unionation.is_invalid = true;
2252 union_type->data.unionation.embedded_in_current = false;
22532251 add_node_error(g, enum_type_node,
22542252 buf_sprintf("expected enum tag type, found '%s'", buf_ptr(&enum_type->name)));
22552253 return;
......@@ -3319,7 +3317,7 @@ TypeStructField *find_struct_type_field(TypeTableEntry *type_entry, Buf *name) {
33193317
33203318TypeUnionField *find_union_type_field(TypeTableEntry *type_entry, Buf *name) {
33213319 assert(type_entry->id == TypeTableEntryIdUnion);
3322 assert(type_entry->data.unionation.complete);
3320 assert(type_entry->data.unionation.zero_bits_known);
33233321 for (uint32_t i = 0; i < type_entry->data.unionation.src_field_count; i += 1) {
33243322 TypeUnionField *field = &type_entry->data.unionation.fields[i];
33253323 if (buf_eql_buf(field->enum_field->name, name)) {
......@@ -3331,7 +3329,7 @@ TypeUnionField *find_union_type_field(TypeTableEntry *type_entry, Buf *name) {
33313329
33323330TypeUnionField *find_union_field_by_tag(TypeTableEntry *type_entry, const BigInt *tag) {
33333331 assert(type_entry->id == TypeTableEntryIdUnion);
3334 assert(type_entry->data.unionation.complete);
3332 assert(type_entry->data.unionation.zero_bits_known);
33353333 assert(type_entry->data.unionation.gen_tag_index != SIZE_MAX);
33363334 for (uint32_t i = 0; i < type_entry->data.unionation.src_field_count; i += 1) {
33373335 TypeUnionField *field = &type_entry->data.unionation.fields[i];
......@@ -3888,7 +3886,6 @@ bool handle_is_ptr(TypeTableEntry *type_entry) {
38883886 return false;
38893887 case TypeTableEntryIdArray:
38903888 case TypeTableEntryIdStruct:
3891 case TypeTableEntryIdUnion:
38923889 return type_has_bits(type_entry);
38933890 case TypeTableEntryIdErrorUnion:
38943891 return type_has_bits(type_entry->data.error.child_type);
......@@ -3896,6 +3893,14 @@ bool handle_is_ptr(TypeTableEntry *type_entry) {
38963893 return type_has_bits(type_entry->data.maybe.child_type) &&
38973894 type_entry->data.maybe.child_type->id != TypeTableEntryIdPointer &&
38983895 type_entry->data.maybe.child_type->id != TypeTableEntryIdFn;
3896 case TypeTableEntryIdUnion:
3897 assert(type_entry->data.unionation.complete);
3898 if (type_entry->data.unionation.gen_field_count == 0)
3899 return false;
3900 if (!type_has_bits(type_entry))
3901 return false;
3902 return true;
3903
38993904 }
39003905 zig_unreachable();
39013906}
src/codegen.cpp+2-3
......@@ -3946,8 +3946,6 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
39463946 case TypeTableEntryIdUnion:
39473947 {
39483948 LLVMTypeRef union_type_ref = type_entry->data.unionation.union_type_ref;
3949 ConstExprValue *payload_value = const_val->data.x_union.payload;
3950 assert(payload_value != nullptr);
39513949
39523950 if (type_entry->data.unionation.gen_field_count == 0) {
39533951 if (type_entry->data.unionation.gen_tag_index == SIZE_MAX) {
......@@ -3960,7 +3958,8 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
39603958
39613959 LLVMValueRef union_value_ref;
39623960 bool make_unnamed_struct;
3963 if (!type_has_bits(payload_value->type)) {
3961 ConstExprValue *payload_value = const_val->data.x_union.payload;
3962 if (payload_value == nullptr || !type_has_bits(payload_value->type)) {
39643963 if (type_entry->data.unionation.gen_tag_index == SIZE_MAX)
39653964 return LLVMGetUndef(type_entry->type_ref);
39663965
src/ir.cpp+79
......@@ -7468,6 +7468,17 @@ static ImplicitCastMatchResult ir_types_match_with_implicit_cast(IrAnalyze *ira,
74687468 }
74697469 }
74707470
7471 // implicit enum to union which has the enum as the tag type
7472 if (expected_type->id == TypeTableEntryIdUnion && actual_type->id == TypeTableEntryIdEnum &&
7473 (expected_type->data.unionation.decl_node->data.container_decl.auto_enum ||
7474 expected_type->data.unionation.decl_node->data.container_decl.init_arg_expr != nullptr))
7475 {
7476 type_ensure_zero_bits_known(ira->codegen, expected_type);
7477 if (expected_type->data.unionation.tag_type == actual_type) {
7478 return ImplicitCastMatchResultYes;
7479 }
7480 }
7481
74717482 // implicit undefined literal to anything
74727483 if (actual_type->id == TypeTableEntryIdUndefLit) {
74737484 return ImplicitCastMatchResultYes;
......@@ -8370,6 +8381,63 @@ static IrInstruction *ir_analyze_undefined_to_anything(IrAnalyze *ira, IrInstruc
83708381 return result;
83718382}
83728383
8384static IrInstruction *ir_analyze_enum_to_union(IrAnalyze *ira, IrInstruction *source_instr,
8385 IrInstruction *target, TypeTableEntry *wanted_type)
8386{
8387 assert(wanted_type->id == TypeTableEntryIdUnion);
8388 assert(target->value.type->id == TypeTableEntryIdEnum);
8389
8390 if (instr_is_comptime(target)) {
8391 ConstExprValue *val = ir_resolve_const(ira, target, UndefBad);
8392 if (!val)
8393 return ira->codegen->invalid_instruction;
8394 TypeUnionField *union_field = find_union_field_by_tag(wanted_type, &val->data.x_enum_tag);
8395 assert(union_field != nullptr);
8396 type_ensure_zero_bits_known(ira->codegen, union_field->type_entry);
8397 if (!union_field->type_entry->zero_bits) {
8398 AstNode *field_node = wanted_type->data.unionation.decl_node->data.container_decl.fields.at(
8399 union_field->enum_field->decl_index);
8400 ErrorMsg *msg = ir_add_error(ira, source_instr,
8401 buf_sprintf("cast to union '%s' must initialize '%s' field '%s'",
8402 buf_ptr(&wanted_type->name),
8403 buf_ptr(&union_field->type_entry->name),
8404 buf_ptr(union_field->name)));
8405 add_error_note(ira->codegen, msg, field_node,
8406 buf_sprintf("field '%s' declared here", buf_ptr(union_field->name)));
8407 return ira->codegen->invalid_instruction;
8408 }
8409 IrInstruction *result = ir_create_const(&ira->new_irb, source_instr->scope,
8410 source_instr->source_node, wanted_type);
8411 result->value.special = ConstValSpecialStatic;
8412 result->value.type = wanted_type;
8413 bigint_init_bigint(&result->value.data.x_union.tag, &val->data.x_enum_tag);
8414 return result;
8415 }
8416
8417 // if the union has all fields 0 bits, we can do it
8418 // and in fact it's a noop cast because the union value is just the enum value
8419 if (wanted_type->data.unionation.gen_field_count == 0) {
8420 IrInstruction *result = ir_build_cast(&ira->new_irb, target->scope, target->source_node, wanted_type, target, CastOpNoop);
8421 result->value.type = wanted_type;
8422 return result;
8423 }
8424
8425 ErrorMsg *msg = ir_add_error(ira, source_instr,
8426 buf_sprintf("runtime cast to union '%s' which has non-void fields",
8427 buf_ptr(&wanted_type->name)));
8428 for (uint32_t i = 0; i < wanted_type->data.unionation.src_field_count; i += 1) {
8429 TypeUnionField *union_field = &wanted_type->data.unionation.fields[i];
8430 if (type_has_bits(union_field->type_entry)) {
8431 AstNode *field_node = wanted_type->data.unionation.decl_node->data.container_decl.fields.at(i);
8432 add_error_note(ira->codegen, msg, field_node,
8433 buf_sprintf("field '%s' has type '%s'",
8434 buf_ptr(union_field->name),
8435 buf_ptr(&union_field->type_entry->name)));
8436 }
8437 }
8438 return ira->codegen->invalid_instruction;
8439}
8440
83738441static IrInstruction *ir_analyze_widen_or_shorten(IrAnalyze *ira, IrInstruction *source_instr,
83748442 IrInstruction *target, TypeTableEntry *wanted_type)
83758443{
......@@ -8919,6 +8987,17 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
89198987 }
89208988 }
89218989
8990 // explicit enum to union which has the enum as the tag type
8991 if (wanted_type->id == TypeTableEntryIdUnion && actual_type->id == TypeTableEntryIdEnum &&
8992 (wanted_type->data.unionation.decl_node->data.container_decl.auto_enum ||
8993 wanted_type->data.unionation.decl_node->data.container_decl.init_arg_expr != nullptr))
8994 {
8995 type_ensure_zero_bits_known(ira->codegen, wanted_type);
8996 if (wanted_type->data.unionation.tag_type == actual_type) {
8997 return ir_analyze_enum_to_union(ira, source_instr, value, wanted_type);
8998 }
8999 }
9000
89229001 // explicit cast from undefined to anything
89239002 if (actual_type->id == TypeTableEntryIdUndefLit) {
89249003 return ir_analyze_undefined_to_anything(ira, source_instr, value, wanted_type);
test/cases/union.zig+7
......@@ -190,3 +190,10 @@ test "cast union to tag type of union" {
190190fn testCastUnionToTagType(x: &const TheUnion) {
191191 assert(TheTag(*x) == TheTag.B);
192192}
193
194test "cast tag type of union to union" {
195 var x: Value2 = Letter2.B;
196 assert(Letter2(x) == Letter2.B);
197}
198const Letter2 = enum { A, B, C };
199const Value2 = union(Letter2) { A: i32, B, C, };
test/compile_errors.zig+31
......@@ -2696,4 +2696,35 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
26962696 ,
26972697 ".tmp_source.zig:6:16: error: enum 'Foo' has no tag matching integer value 0",
26982698 ".tmp_source.zig:1:13: note: 'Foo' declared here");
2699
2700 cases.add("comptime cast enum to union but field has payload",
2701 \\const Letter = enum { A, B, C };
2702 \\const Value = union(Letter) {
2703 \\ A: i32,
2704 \\ B,
2705 \\ C,
2706 \\};
2707 \\export fn entry() {
2708 \\ var x: Value = Letter.A;
2709 \\}
2710 ,
2711 ".tmp_source.zig:8:26: error: cast to union 'Value' must initialize 'i32' field 'A'",
2712 ".tmp_source.zig:3:5: note: field 'A' declared here");
2713
2714 cases.add("runtime cast to union which has non-void fields",
2715 \\const Letter = enum { A, B, C };
2716 \\const Value = union(Letter) {
2717 \\ A: i32,
2718 \\ B,
2719 \\ C,
2720 \\};
2721 \\export fn entry() {
2722 \\ foo(Letter.A);
2723 \\}
2724 \\fn foo(l: Letter) {
2725 \\ var x: Value = l;
2726 \\}
2727 ,
2728 ".tmp_source.zig:11:20: error: runtime cast to union 'Value' which has non-void fields",
2729 ".tmp_source.zig:3:5: note: field 'A' has type 'i32'");
26992730}