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c8fb36b36c
Introduced a new AIR instruction: `tag_name`. Reasons to do this instead of lowering it in Sema to a switch, function call, array lookup, or if-else tower: * Sema is a bottleneck; do less work in Sema whenever possible. * If any optimization passes run, and the operand to becomes comptime-known, then it could change to have a comptime result value instead of lowering to a function or array or something which would then have to be garbage-collected. * Backends may want to choose to use a function and a switch branch, or they may want to use a different strategy. Codegen for `@tagName` is implemented for the LLVM backend but not any others yet. Introduced some new `Type` tags: * `const_slice_u8_sentinel_0` * `manyptr_const_u8_sentinel_0` The motivation for this was to make typeof() on the tag_name AIR instruction non-allocating. A bunch more enum tests are passing now.
50 lines
1.2 KiB
Zig
50 lines
1.2 KiB
Zig
const std = @import("std");
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const expect = std.testing.expect;
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const mem = std.mem;
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const Tag = std.meta.Tag;
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test "@tagName" {
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try expect(mem.eql(u8, testEnumTagNameBare(BareNumber.Three), "Three"));
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comptime try expect(mem.eql(u8, testEnumTagNameBare(BareNumber.Three), "Three"));
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}
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fn testEnumTagNameBare(n: anytype) []const u8 {
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return @tagName(n);
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}
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const BareNumber = enum { One, Two, Three };
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test "@tagName non-exhaustive enum" {
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try expect(mem.eql(u8, testEnumTagNameBare(NonExhaustive.B), "B"));
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comptime try expect(mem.eql(u8, testEnumTagNameBare(NonExhaustive.B), "B"));
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}
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const NonExhaustive = enum(u8) { A, B, _ };
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test "@tagName is null-terminated" {
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const S = struct {
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fn doTheTest(n: BareNumber) !void {
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try expect(@tagName(n)[3] == 0);
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}
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};
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try S.doTheTest(.Two);
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try comptime S.doTheTest(.Two);
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}
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test "tag name with assigned enum values" {
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const LocalFoo = enum(u8) {
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A = 1,
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B = 0,
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};
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var b = LocalFoo.B;
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try expect(mem.eql(u8, @tagName(b), "B"));
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}
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const Bar = enum { A, B, C, D };
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test "enum literal casting to optional" {
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var bar: ?Bar = undefined;
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bar = .B;
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try expect(bar.? == Bar.B);
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}
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