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value: fix bitcasting packed structs with u0 fields

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Closes #13942
This commit is contained in:
Veikka Tuominen 2022-12-22 12:45:51 +02:00
parent b7730c7478
commit 9c0f3163a8
2 changed files with 15 additions and 0 deletions
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2
src/value.zig
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@ -1378,6 +1378,7 @@ pub const Value = extern union {
var enum_buffer: Payload.U64 = undefined;
const int_val = val.enumToInt(ty, &enum_buffer);
if (abi_size == 0) return;
if (abi_size <= @sizeOf(u64)) {
const int: u64 = switch (int_val.tag()) {
.zero => 0,
@ -1571,6 +1572,7 @@ pub const Value = extern union {
const abi_size = @intCast(usize, ty.abiSize(target));
const bits = int_info.bits;
if (bits == 0) return Value.zero;
if (bits <= 64) switch (int_info.signedness) { // Fast path for integers <= u64
.signed => return Value.Tag.int_i64.create(arena, std.mem.readVarPackedInt(i64, buffer, bit_offset, bits, endian, .signed)),
.unsigned => return Value.Tag.int_u64.create(arena, std.mem.readVarPackedInt(u64, buffer, bit_offset, bits, endian, .unsigned)),

13
test/behavior/cast.zig
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@ -1505,3 +1505,16 @@ test "implicit cast from [:0]T to [*c]T" {
try expect(c.len == a.len);
try expect(c.ptr == a.ptr);
}
test "bitcast packed struct with u0" {
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
const S = packed struct(u2) { a: u0, b: u2 };
const s = @bitCast(S, @as(u2, 2));
try expect(s.a == 0);
try expect(s.b == 2);
const i = @bitCast(u2, s);
try expect(i == 2);
}