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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
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andrewrk committed Dec 6, 2017
1 parent 63a2f9a commit 960914a073c367883c9fdf54e900890a6aefc05f
Showing with 129 additions and 8 deletions.
  1. +10 −5 src/analyze.cpp
  2. +2 −3 src/codegen.cpp
  3. +79 −0 src/ir.cpp
  4. +7 −0 test/cases/union.zig
  5. +31 −0 test/compile_errors.zig
View
@@ -2244,12 +2244,10 @@ static void resolve_union_zero_bits(CodeGen *g, TypeTableEntry *union_type) {
TypeTableEntry *enum_type = analyze_type_expr(g, scope, enum_type_node);
if (type_is_invalid(enum_type)) {
union_type->data.unionation.is_invalid = true;
union_type->data.unionation.embedded_in_current = false;
return;
}
if (enum_type->id != TypeTableEntryIdEnum) {
union_type->data.unionation.is_invalid = true;
union_type->data.unionation.embedded_in_current = false;
add_node_error(g, enum_type_node,
buf_sprintf("expected enum tag type, found '%s'", buf_ptr(&enum_type->name)));
return;
@@ -3319,7 +3317,7 @@ TypeStructField *find_struct_type_field(TypeTableEntry *type_entry, Buf *name) {
TypeUnionField *find_union_type_field(TypeTableEntry *type_entry, Buf *name) {
assert(type_entry->id == TypeTableEntryIdUnion);
assert(type_entry->data.unionation.complete);
assert(type_entry->data.unionation.zero_bits_known);
for (uint32_t i = 0; i < type_entry->data.unionation.src_field_count; i += 1) {
TypeUnionField *field = &type_entry->data.unionation.fields[i];
if (buf_eql_buf(field->enum_field->name, name)) {
@@ -3331,7 +3329,7 @@ TypeUnionField *find_union_type_field(TypeTableEntry *type_entry, Buf *name) {
TypeUnionField *find_union_field_by_tag(TypeTableEntry *type_entry, const BigInt *tag) {
assert(type_entry->id == TypeTableEntryIdUnion);
assert(type_entry->data.unionation.complete);
assert(type_entry->data.unionation.zero_bits_known);
assert(type_entry->data.unionation.gen_tag_index != SIZE_MAX);
for (uint32_t i = 0; i < type_entry->data.unionation.src_field_count; i += 1) {
TypeUnionField *field = &type_entry->data.unionation.fields[i];
@@ -3888,14 +3886,21 @@ bool handle_is_ptr(TypeTableEntry *type_entry) {
return false;
case TypeTableEntryIdArray:
case TypeTableEntryIdStruct:
case TypeTableEntryIdUnion:
return type_has_bits(type_entry);
case TypeTableEntryIdErrorUnion:
return type_has_bits(type_entry->data.error.child_type);
case TypeTableEntryIdMaybe:
return type_has_bits(type_entry->data.maybe.child_type) &&
type_entry->data.maybe.child_type->id != TypeTableEntryIdPointer &&
type_entry->data.maybe.child_type->id != TypeTableEntryIdFn;
case TypeTableEntryIdUnion:
assert(type_entry->data.unionation.complete);
if (type_entry->data.unionation.gen_field_count == 0)
return false;
if (!type_has_bits(type_entry))
return false;
return true;
}
zig_unreachable();
}
View
@@ -3946,8 +3946,6 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
case TypeTableEntryIdUnion:
{
LLVMTypeRef union_type_ref = type_entry->data.unionation.union_type_ref;
ConstExprValue *payload_value = const_val->data.x_union.payload;
assert(payload_value != nullptr);
if (type_entry->data.unionation.gen_field_count == 0) {
if (type_entry->data.unionation.gen_tag_index == SIZE_MAX) {
@@ -3960,7 +3958,8 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
LLVMValueRef union_value_ref;
bool make_unnamed_struct;
if (!type_has_bits(payload_value->type)) {
ConstExprValue *payload_value = const_val->data.x_union.payload;
if (payload_value == nullptr || !type_has_bits(payload_value->type)) {
if (type_entry->data.unionation.gen_tag_index == SIZE_MAX)
return LLVMGetUndef(type_entry->type_ref);
View
@@ -7468,6 +7468,17 @@ static ImplicitCastMatchResult ir_types_match_with_implicit_cast(IrAnalyze *ira,
}
}
// implicit enum to union which has the enum as the tag type
if (expected_type->id == TypeTableEntryIdUnion && actual_type->id == TypeTableEntryIdEnum &&
(expected_type->data.unionation.decl_node->data.container_decl.auto_enum ||
expected_type->data.unionation.decl_node->data.container_decl.init_arg_expr != nullptr))
{
type_ensure_zero_bits_known(ira->codegen, expected_type);
if (expected_type->data.unionation.tag_type == actual_type) {
return ImplicitCastMatchResultYes;
}
}
// implicit undefined literal to anything
if (actual_type->id == TypeTableEntryIdUndefLit) {
return ImplicitCastMatchResultYes;
@@ -8370,6 +8381,63 @@ static IrInstruction *ir_analyze_undefined_to_anything(IrAnalyze *ira, IrInstruc
return result;
}
static IrInstruction *ir_analyze_enum_to_union(IrAnalyze *ira, IrInstruction *source_instr,
IrInstruction *target, TypeTableEntry *wanted_type)
{
assert(wanted_type->id == TypeTableEntryIdUnion);
assert(target->value.type->id == TypeTableEntryIdEnum);
if (instr_is_comptime(target)) {
ConstExprValue *val = ir_resolve_const(ira, target, UndefBad);
if (!val)
return ira->codegen->invalid_instruction;
TypeUnionField *union_field = find_union_field_by_tag(wanted_type, &val->data.x_enum_tag);
assert(union_field != nullptr);
type_ensure_zero_bits_known(ira->codegen, union_field->type_entry);
if (!union_field->type_entry->zero_bits) {
AstNode *field_node = wanted_type->data.unionation.decl_node->data.container_decl.fields.at(
union_field->enum_field->decl_index);
ErrorMsg *msg = ir_add_error(ira, source_instr,
buf_sprintf("cast to union '%s' must initialize '%s' field '%s'",
buf_ptr(&wanted_type->name),
buf_ptr(&union_field->type_entry->name),
buf_ptr(union_field->name)));
add_error_note(ira->codegen, msg, field_node,
buf_sprintf("field '%s' declared here", buf_ptr(union_field->name)));
return ira->codegen->invalid_instruction;
}
IrInstruction *result = ir_create_const(&ira->new_irb, source_instr->scope,
source_instr->source_node, wanted_type);
result->value.special = ConstValSpecialStatic;
result->value.type = wanted_type;
bigint_init_bigint(&result->value.data.x_union.tag, &val->data.x_enum_tag);
return result;
}
// if the union has all fields 0 bits, we can do it
// and in fact it's a noop cast because the union value is just the enum value
if (wanted_type->data.unionation.gen_field_count == 0) {
IrInstruction *result = ir_build_cast(&ira->new_irb, target->scope, target->source_node, wanted_type, target, CastOpNoop);
result->value.type = wanted_type;
return result;
}
ErrorMsg *msg = ir_add_error(ira, source_instr,
buf_sprintf("runtime cast to union '%s' which has non-void fields",
buf_ptr(&wanted_type->name)));
for (uint32_t i = 0; i < wanted_type->data.unionation.src_field_count; i += 1) {
TypeUnionField *union_field = &wanted_type->data.unionation.fields[i];
if (type_has_bits(union_field->type_entry)) {
AstNode *field_node = wanted_type->data.unionation.decl_node->data.container_decl.fields.at(i);
add_error_note(ira->codegen, msg, field_node,
buf_sprintf("field '%s' has type '%s'",
buf_ptr(union_field->name),
buf_ptr(&union_field->type_entry->name)));
}
}
return ira->codegen->invalid_instruction;
}
static IrInstruction *ir_analyze_widen_or_shorten(IrAnalyze *ira, IrInstruction *source_instr,
IrInstruction *target, TypeTableEntry *wanted_type)
{
@@ -8919,6 +8987,17 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
}
}
// explicit enum to union which has the enum as the tag type
if (wanted_type->id == TypeTableEntryIdUnion && actual_type->id == TypeTableEntryIdEnum &&
(wanted_type->data.unionation.decl_node->data.container_decl.auto_enum ||
wanted_type->data.unionation.decl_node->data.container_decl.init_arg_expr != nullptr))
{
type_ensure_zero_bits_known(ira->codegen, wanted_type);
if (wanted_type->data.unionation.tag_type == actual_type) {
return ir_analyze_enum_to_union(ira, source_instr, value, wanted_type);
}
}
// explicit cast from undefined to anything
if (actual_type->id == TypeTableEntryIdUndefLit) {
return ir_analyze_undefined_to_anything(ira, source_instr, value, wanted_type);
View
@@ -190,3 +190,10 @@ test "cast union to tag type of union" {
fn testCastUnionToTagType(x: &const TheUnion) {
assert(TheTag(*x) == TheTag.B);
}
test "cast tag type of union to union" {
var x: Value2 = Letter2.B;
assert(Letter2(x) == Letter2.B);
}
const Letter2 = enum { A, B, C };
const Value2 = union(Letter2) { A: i32, B, C, };
View
@@ -2696,4 +2696,35 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
,
".tmp_source.zig:6:16: error: enum 'Foo' has no tag matching integer value 0",
".tmp_source.zig:1:13: note: 'Foo' declared here");
cases.add("comptime cast enum to union but field has payload",
\\const Letter = enum { A, B, C };
\\const Value = union(Letter) {
\\ A: i32,
\\ B,
\\ C,
\\};
\\export fn entry() {
\\ var x: Value = Letter.A;
\\}
,
".tmp_source.zig:8:26: error: cast to union 'Value' must initialize 'i32' field 'A'",
".tmp_source.zig:3:5: note: field 'A' declared here");
cases.add("runtime cast to union which has non-void fields",
\\const Letter = enum { A, B, C };
\\const Value = union(Letter) {
\\ A: i32,
\\ B,
\\ C,
\\};
\\export fn entry() {
\\ foo(Letter.A);
\\}
\\fn foo(l: Letter) {
\\ var x: Value = l;
\\}
,
".tmp_source.zig:11:20: error: runtime cast to union 'Value' which has non-void fields",
".tmp_source.zig:3:5: note: field 'A' has type 'i32'");
}

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