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tagName: return a null-terminated slice

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This commit is contained in:
Daniele Cocca 2021-04-27 23:57:28 +01:00 committed by Daniele Cocca
parent 1184b1d560
commit 00e1c0082c
4 changed files with 28 additions and 13 deletions
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8
doc/langref.html.in
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@ -2986,7 +2986,7 @@ test "@typeInfo" {
try expect(mem.eql(u8, @typeInfo(Small).Enum.fields[1].name, "two"));
}
// @tagName gives a []const u8 representation of an enum value:
// @tagName gives a [:0]const u8 representation of an enum value:
test "@tagName" {
try expect(mem.eql(u8, @tagName(Small.three), "three"));
}
@ -3233,7 +3233,7 @@ test "union method" {
{#code_end#}
<p>
{#link|@tagName#} can be used to return a {#link|comptime#}
{#syntax#}[]const u8{#endsyntax#} value representing the field name:
{#syntax#}[:0]const u8{#endsyntax#} value representing the field name:
</p>
{#code_begin|test#}
const std = @import("std");
@ -8494,9 +8494,9 @@ fn doTheTest() !void {
{#header_close#}
{#header_open|@tagName#}
<pre>{#syntax#}@tagName(value: anytype) []const u8{#endsyntax#}</pre>
<pre>{#syntax#}@tagName(value: anytype) [:0]const u8{#endsyntax#}</pre>
<p>
Converts an enum value or union value to a slice of bytes representing the name.</p><p>If the enum is non-exhaustive and the tag value does not map to a name, it invokes safety-checked {#link|Undefined Behavior#}.
Converts an enum value or union value to a string literal representing the name.</p><p>If the enum is non-exhaustive and the tag value does not map to a name, it invokes safety-checked {#link|Undefined Behavior#}.
</p>
{#header_close#}

21
src/stage1/ir.cpp
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@ -16898,8 +16898,9 @@ static IrInstGen *ir_analyze_instruction_enum_tag_name(IrAnalyze *ira, IrInstSrc
if (target_type->id == ZigTypeIdEnumLiteral) {
IrInstGen *result = ir_const(ira, &instruction->base.base, nullptr);
Buf *field_name = target->value->data.x_enum_literal;
ZigValue *array_val = create_const_str_lit(ira->codegen, field_name)->data.x_ptr.data.ref.pointee;
init_const_slice(ira->codegen, result->value, array_val, 0, buf_len(field_name), true);
result->value = create_sentineled_str_lit(
ira->codegen, field_name,
ira->codegen->intern.for_zero_byte());
return result;
}
@ -16918,9 +16919,10 @@ static IrInstGen *ir_analyze_instruction_enum_tag_name(IrAnalyze *ira, IrInstSrc
if (can_fold_enum_type(target_type)) {
TypeEnumField *only_field = &target_type->data.enumeration.fields[0];
ZigValue *array_val = create_const_str_lit(ira->codegen, only_field->name)->data.x_ptr.data.ref.pointee;
IrInstGen *result = ir_const(ira, &instruction->base.base, nullptr);
init_const_slice(ira->codegen, result->value, array_val, 0, buf_len(only_field->name), true);
result->value = create_sentineled_str_lit(
ira->codegen, only_field->name,
ira->codegen->intern.for_zero_byte());
return result;
}
@ -16936,16 +16938,17 @@ static IrInstGen *ir_analyze_instruction_enum_tag_name(IrAnalyze *ira, IrInstSrc
buf_sprintf("no tag by value %s", buf_ptr(int_buf)));
return ira->codegen->invalid_inst_gen;
}
ZigValue *array_val = create_const_str_lit(ira->codegen, field->name)->data.x_ptr.data.ref.pointee;
IrInstGen *result = ir_const(ira, &instruction->base.base, nullptr);
init_const_slice(ira->codegen, result->value, array_val, 0, buf_len(field->name), true);
result->value = create_sentineled_str_lit(
ira->codegen, field->name,
ira->codegen->intern.for_zero_byte());
return result;
}
ZigType *u8_ptr_type = get_pointer_to_type_extra(
ZigType *u8_ptr_type = get_pointer_to_type_extra2(
ira->codegen, ira->codegen->builtin_types.entry_u8,
true, false, PtrLenUnknown,
0, 0, 0, false);
true, false, PtrLenUnknown, 0, 0, 0, false,
VECTOR_INDEX_NONE, nullptr, ira->codegen->intern.for_zero_byte());
ZigType *result_type = get_slice_type(ira->codegen, u8_ptr_type);
return ir_build_tag_name_gen(ira, &instruction->base.base, target, result_type);
}

1
test/behavior.zig
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@ -51,6 +51,7 @@ comptime {
_ = @import("behavior/bugs/3384.zig");
_ = @import("behavior/bugs/3586.zig");
_ = @import("behavior/bugs/3742.zig");
_ = @import("behavior/bugs/3779.zig");
_ = @import("behavior/bugs/4328.zig");
_ = @import("behavior/bugs/4560.zig");
_ = @import("behavior/bugs/4769_a.zig");

11
test/behavior/bugs/3779.zig Normal file
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@ -0,0 +1,11 @@
const std = @import("std");
const TestEnum = enum { TestEnumValue };
const tag_name = @tagName(TestEnum.TestEnumValue);
const ptr_tag_name: [*:0]const u8 = tag_name;
test "@tagName() returns a string literal" {
try std.testing.expectEqual([:0]const u8, @TypeOf(tag_name));
try std.testing.expectEqualStrings("TestEnumValue", tag_name);
try std.testing.expectEqualStrings("TestEnumValue", ptr_tag_name[0..tag_name.len]);
}