| author |  glowsquid <sachabarsayuracko@gmail.com> 2026-04-10 23:31:21+02:00 |
| committer |  Matthew Lugg <mlugg@mlugg.co.uk> 2026-04-10 23:31:21+02:00 |
| log | 8111d3d63cf3662b5aecbd0ddd10567e025694a7 |
| tree | db471a1d98be6cba54a04cf2db414ee679bc036c |
| parent | 2c6e5006ed3adb02f3bc7b364b2bbc688271d9f7 |
fix comptime @ptrcasting from a larger type to a smaller one (#31774)
closes #30180
Note from mlugg: this fix is very much a hack, but it definitely won't break anything and it demonstrably fixes one case, so I'm merging it for now with the expectation that I'll be replacing the broken code soon.
Reviewed-on: https://codeberg.org/ziglang/zig/pulls/31774
Reviewed-by: mlugg <mlugg@noreply.codeberg.org>
Co-authored-by: glowsquid <sachabarsayuracko@gmail.com>
Co-committed-by: glowsquid <sachabarsayuracko@gmail.com>2 files changed, 19 insertions(+), 1 deletions(-)
src- test
- behavior
src/Sema/comptime_ptr_access.zig+11-1
| ... | @@ -498,8 +498,18 @@ fn loadComptimePtrInner( | ... | @@ -498,8 +498,18 @@ fn loadComptimePtrInner( |
| 498 | return .{ .success = cur_val }; | 498 | return .{ .success = cur_val }; |
| 499 | } | 499 | } |
| 500 | 500 | ||
| 501 | var bitcast_src_val = try cur_val.intern(sema.pt, sema.arena); | ||
| 502 | |||
| 503 | if (host_bits != 0) { | ||
| 504 | const src_bit_size = bitcast_src_val.typeOf(zcu).bitSize(zcu); | ||
| 505 | if (src_bit_size > host_bits) { | ||
| 506 | const truncate_ty = try pt.intType(.unsigned, @intCast(host_bits)); | ||
| 507 | bitcast_src_val = try pt.getCoerced(bitcast_src_val, truncate_ty); | ||
| 508 | } | ||
| 509 | } | ||
| 510 | |||
| 501 | const result_val = try sema.bitCastVal( | 511 | const result_val = try sema.bitCastVal( |
| 502 | try cur_val.intern(sema.pt, sema.arena), | 512 | bitcast_src_val, |
| 503 | load_ty, | 513 | load_ty, |
| 504 | cur_offset, | 514 | cur_offset, |
| 505 | host_bits, | 515 | host_bits, |
test/behavior/ptrcast.zig+8
| ... | @@ -562,3 +562,11 @@ test "@ptrCast array pointer removing sentinel" { | ... | @@ -562,3 +562,11 @@ test "@ptrCast array pointer removing sentinel" { |
| 562 | comptime assert(out[2] == 3); | 562 | comptime assert(out[2] == 3); |
| 563 | comptime assert(out[3] == 4); | 563 | comptime assert(out[3] == 4); |
| 564 | } | 564 | } |
| 565 | |||
| 566 | test "@ptrcast larger type to smaller one" { | ||
| 567 | const T = packed struct { x: u17 }; | ||
| 568 | const a: u32 = 0; | ||
| 569 | const b: *const T = @ptrCast(&a); | ||
| 570 | const c = b.x; | ||
| 571 | _ = c; | ||
| 572 | } |