| author |  Matthew Lugg <mlugg@mlugg.co.uk> 2026-03-06 16:30:56+00:00 |
| committer | Matthew Lugg <mlugg@mlugg.co.uk> 2026-03-10 10:38:51+00:00 |
| log | f92b998f9fe985d554d6078bb2bb11d094d94b91 |
| tree | 62b942e26572bd859e2253bb1c3ed180835d8c37 |
| parent | 1293f080fdfc74966b541b44f0a907561df3d617 |
| signature |  Commit is signed but in an unrecognized format. |
behavior: disable some tests under the C backend targeting MSVC
The bugs here actually exist on master branch too, but they are being
caught by the new static assertions which check type size and alignment.
It turns out that MSVC's struct/union "pack" pragma and its "align"
declspec interact in undocumented ways which are extremely problematic
for generated code. Solving this will require changing how the C backend
lowers various types; the disabled tests are all tagged unions, but
there are also issues with structs with underaligned fields which the
behavior tests just happen to not currently be triggering.2 files changed, 3 insertions(+), 0 deletions(-)
test/behavior/align.zig+1
| ... | ... | @@ -18,6 +18,7 @@ test "global variable alignment" { |
| 18 | 18 | test "large alignment of local constant" { |
| 19 | 19 | if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; |
| 20 | 20 | if (builtin.zig_backend == .stage2_spirv) return error.SkipZigTest; // flaky |
| 21 | if (builtin.zig_backend == .stage2_c and builtin.target.abi == .msvc) return error.SkipZigTest; | |
| 21 | 22 | |
| 22 | 23 | const x: f32 align(128) = 12.34; |
| 23 | 24 | try std.testing.expect(@intFromPtr(&x) % 128 == 0); |
test/behavior/union.zig+2
| ... | ... | @@ -148,6 +148,7 @@ const err = @as(anyerror!Agg, Agg{ |
| 148 | 148 | const array = [_]Value{ v1, v2, v1, v2 }; |
| 149 | 149 | |
| 150 | 150 | test "unions embedded in aggregate types" { |
| 151 | if (builtin.zig_backend == .stage2_c and builtin.target.abi == .msvc) return error.SkipZigTest; | |
| 151 | 152 | switch (array[1]) { |
| 152 | 153 | Value.Array => |arr| try expect(arr[4] == 3), |
| 153 | 154 | else => unreachable, |
| ... | ... | @@ -2022,6 +2023,7 @@ test "runtime union init, most-aligned field != largest" { |
| 2022 | 2023 | if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO |
| 2023 | 2024 | if (builtin.zig_backend == .stage2_spirv) return error.SkipZigTest; |
| 2024 | 2025 | if (builtin.zig_backend == .stage2_riscv64) return error.SkipZigTest; |
| 2026 | if (builtin.zig_backend == .stage2_c and builtin.target.abi == .msvc) return error.SkipZigTest; | |
| 2025 | 2027 | |
| 2026 | 2028 | const U = union(enum) { |
| 2027 | 2029 | x: u128, |