| author |  Andrew Kelley <andrew@ziglang.org> 2025-09-07 17:28:01-07:00 |
| committer | Andrew Kelley <andrew@ziglang.org> 2025-09-07 17:29:36-07:00 |
| log | 6673b476855931137119ae92e91fdcb2822e9c4f |
| tree | 397a6f1077f0eda6c194fcea91da0d2ca19e8651 |
| parent | 426d65d700012b27ffa652258554032f171ad77d |
frontend: vectors and arrays no longer support in-memory coercion
closes #251723 files changed, 9 insertions(+), 45 deletions(-)
doc- src
doc/langref.html.in+8
| ... | @@ -1969,6 +1969,14 @@ or | ... | @@ -1969,6 +1969,14 @@ or |
| 1969 | </p> | 1969 | </p> |
| 1970 | {#see_also|@splat|@shuffle|@select|@reduce#} | 1970 | {#see_also|@splat|@shuffle|@select|@reduce#} |
| 1971 | 1971 | ||
| 1972 | {#header_open|Relationship with Arrays#} | ||
| 1973 | <p>Vectors and {#link|Arrays#} each have a well-defined <strong>bit layout</strong> | ||
| 1974 | and therefore support {#link|@bitCast#} between each other. {#link|Type Coercion#} implicitly peforms | ||
| 1975 | {#syntax#}@bitCast{#endsyntax#}.</p> | ||
| 1976 | <p>Arrays have well-defined byte layout, but vectors do not, making {#link|@ptrCast#} between | ||
| 1977 | them {#link|Illegal Behavior#}.</p> | ||
| 1978 | {#header_close#} | ||
| 1979 | |||
| 1972 | {#header_open|Destructuring Vectors#} | 1980 | {#header_open|Destructuring Vectors#} |
| 1973 | <p> | 1981 | <p> |
| 1974 | Vectors can be destructured: | 1982 | Vectors can be destructured: |
doc/langref/test_vector.zig+1-1
| ... | @@ -17,7 +17,7 @@ test "Basic vector usage" { | ... | @@ -17,7 +17,7 @@ test "Basic vector usage" { |
| 17 | } | 17 | } |
| 18 | 18 | ||
| 19 | test "Conversion between vectors, arrays, and slices" { | 19 | test "Conversion between vectors, arrays, and slices" { |
| 20 | // Vectors and fixed-length arrays can be automatically assigned back and forth | 20 | // Vectors can be coerced to arrays, and vice versa. |
| 21 | const arr1: [4]f32 = [_]f32{ 1.1, 3.2, 4.5, 5.6 }; | 21 | const arr1: [4]f32 = [_]f32{ 1.1, 3.2, 4.5, 5.6 }; |
| 22 | const vec: @Vector(4, f32) = arr1; | 22 | const vec: @Vector(4, f32) = arr1; |
| 23 | const arr2: [4]f32 = vec; | 23 | const arr2: [4]f32 = vec; |
src/Sema.zig-44
| ... | @@ -29649,50 +29649,6 @@ pub fn coerceInMemoryAllowed( | ... | @@ -29649,50 +29649,6 @@ pub fn coerceInMemoryAllowed( |
| 29649 | return .ok; | 29649 | return .ok; |
| 29650 | } | 29650 | } |
| 29651 | 29651 | ||
| 29652 | // Arrays <-> Vectors | ||
| 29653 | if ((dest_tag == .vector and src_tag == .array) or | ||
| 29654 | (dest_tag == .array and src_tag == .vector)) | ||
| 29655 | { | ||
| 29656 | const dest_len = dest_ty.arrayLen(zcu); | ||
| 29657 | const src_len = src_ty.arrayLen(zcu); | ||
| 29658 | if (dest_len != src_len) { | ||
| 29659 | return .{ .array_len = .{ | ||
| 29660 | .actual = src_len, | ||
| 29661 | .wanted = dest_len, | ||
| 29662 | } }; | ||
| 29663 | } | ||
| 29664 | |||
| 29665 | const dest_elem_ty = dest_ty.childType(zcu); | ||
| 29666 | const src_elem_ty = src_ty.childType(zcu); | ||
| 29667 | const child = try sema.coerceInMemoryAllowed(block, dest_elem_ty, src_elem_ty, dest_is_mut, target, dest_src, src_src, null); | ||
| 29668 | if (child != .ok) { | ||
| 29669 | return .{ .array_elem = .{ | ||
| 29670 | .child = try child.dupe(sema.arena), | ||
| 29671 | .actual = src_elem_ty, | ||
| 29672 | .wanted = dest_elem_ty, | ||
| 29673 | } }; | ||
| 29674 | } | ||
| 29675 | |||
| 29676 | if (dest_tag == .array) { | ||
| 29677 | const dest_info = dest_ty.arrayInfo(zcu); | ||
| 29678 | if (dest_info.sentinel != null) { | ||
| 29679 | return .{ .array_sentinel = .{ | ||
| 29680 | .actual = Value.@"unreachable", | ||
| 29681 | .wanted = dest_info.sentinel.?, | ||
| 29682 | .ty = dest_info.elem_type, | ||
| 29683 | } }; | ||
| 29684 | } | ||
| 29685 | } | ||
| 29686 | |||
| 29687 | // The memory layout of @Vector(N, iM) is the same as the integer type i(N*M), | ||
| 29688 | // that is to say, the padding bits are not in the same place as the array [N]iM. | ||
| 29689 | // If there's no padding, the bitcast is possible. | ||
| 29690 | const elem_bit_size = dest_elem_ty.bitSize(zcu); | ||
| 29691 | const elem_abi_byte_size = dest_elem_ty.abiSize(zcu); | ||
| 29692 | if (elem_abi_byte_size * 8 == elem_bit_size) | ||
| 29693 | return .ok; | ||
| 29694 | } | ||
| 29695 | |||
| 29696 | // Optionals | 29652 | // Optionals |
| 29697 | if (dest_tag == .optional and src_tag == .optional) { | 29653 | if (dest_tag == .optional and src_tag == .optional) { |
| 29698 | if ((maybe_dest_ptr_ty != null) != (maybe_src_ptr_ty != null)) { | 29654 | if ((maybe_dest_ptr_ty != null) != (maybe_src_ptr_ty != null)) { |