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andrewrkandrewrk
committedDec 6, 2017
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
·
0.15.20.2.0
1 parent 63a2f9a commit 960914a

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5 files changed

+129
-8
lines changed

5 files changed

+129
-8
lines changed
 

‎src/analyze.cpp‎

Lines changed: 10 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -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

33203318
TypeUnionField *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

33323330
TypeUnionField *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];
@@ -3888,14 +3886,21 @@ 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);
38953892
case TypeTableEntryIdMaybe:
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

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -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

Lines changed: 79 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -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

8384+
static 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+
83738441
static 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

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -190,3 +190,10 @@ test "cast union to tag type of union" {
190190
fn testCastUnionToTagType(x: &const TheUnion) {
191191
assert(TheTag(*x) == TheTag.B);
192192
}
193+
194+
test "cast tag type of union to union" {
195+
var x: Value2 = Letter2.B;
196+
assert(Letter2(x) == Letter2.B);
197+
}
198+
const Letter2 = enum { A, B, C };
199+
const Value2 = union(Letter2) { A: i32, B, C, };

‎test/compile_errors.zig‎

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -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
}

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