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Sema: fix invalid coercion *[n:x]T -> *[m]T for n != m

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The change in `Sema.coerceExtra` is just to avoid an unhelpful error
message, covered by the added test case.

Resolves: #22373
This commit is contained in:
mlugg 2025-01-01 11:30:33 +00:00 committed by Matthew Lugg
parent d02c2c76fc
commit 5333d2443a
2 changed files with 73 additions and 1 deletions
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4
src/Sema.zig
View File

@ -29736,6 +29736,7 @@ fn coerceExtra(
// Coercions where the source is a single pointer to an array.
src_array_ptr: {
if (!inst_ty.isSinglePointer(zcu)) break :src_array_ptr;
if (dest_info.flags.size == .One) break :src_array_ptr; // `*[n]T` -> `*T` isn't valid
if (!sema.checkPtrAttributes(dest_ty, inst_ty, &in_memory_result)) break :pointer;
const array_ty = inst_ty.childType(zcu);
if (array_ty.zigTypeTag(zcu) != .array) break :src_array_ptr;
@ -29791,7 +29792,7 @@ fn coerceExtra(
// *[N]T to [*]T
return sema.coerceCompatiblePtrs(block, dest_ty, inst, inst_src);
},
.One => {},
.One => unreachable, // early exit at top of block
}
}
@ -31259,6 +31260,7 @@ fn coerceInMemoryAllowedPtrs(
// As a special case, we also allow coercing `*[n:s]T` to `*[n]T`, akin to dropping the sentinel from a slice.
// `*[n:s]T` cannot coerce in memory to `*[n]T` since they have different sizes.
if (src_child.zigTypeTag(zcu) == .array and dest_child.zigTypeTag(zcu) == .array and
src_child.arrayLen(zcu) == dest_child.arrayLen(zcu) and
src_child.sentinel(zcu) != null and dest_child.sentinel(zcu) == null and
.ok == try sema.coerceInMemoryAllowed(block, dest_child.childType(zcu), src_child.childType(zcu), !dest_info.flags.is_const, target, dest_src, src_src, null))
{

70
test/cases/compile_errors/coerce_array_to_different_size.zig Normal file
View File

@ -0,0 +1,70 @@
export fn bigger(a: *const [10]u32) void {
const b: *const [20]u32 = a;
_ = b;
}
comptime {
const a: *const [10]u32 = &@splat(0);
const b: *const [20]u32 = a;
_ = b;
}
export fn biggerSentinel(a: *const [10:0]u32) void {
const b: *const [20]u32 = a;
_ = b;
}
comptime {
const a: *const [10:0]u32 = &@splat(0);
const b: *const [20]u32 = a;
_ = b;
}
export fn smaller(a: *const [10]u32) void {
const b: *const [5]u32 = a;
_ = b;
}
comptime {
const a: *const [10]u32 = &@splat(0);
const b: *const [5]u32 = a;
_ = b;
}
export fn smallerSentinel(a: *const [10:0]u32) void {
const b: *const [5]u32 = a;
_ = b;
}
comptime {
const a: *const [10:0]u32 = &@splat(0);
const b: *const [5]u32 = a;
_ = b;
}
// error
//
// :2:31: error: expected type '*const [20]u32', found '*const [10]u32'
// :2:31: note: pointer type child '[10]u32' cannot cast into pointer type child '[20]u32'
// :2:31: note: array of length 10 cannot cast into an array of length 20
// :8:31: error: expected type '*const [20]u32', found '*const [10]u32'
// :8:31: note: pointer type child '[10]u32' cannot cast into pointer type child '[20]u32'
// :8:31: note: array of length 10 cannot cast into an array of length 20
// :13:31: error: expected type '*const [20]u32', found '*const [10:0]u32'
// :13:31: note: pointer type child '[10:0]u32' cannot cast into pointer type child '[20]u32'
// :13:31: note: array of length 10 cannot cast into an array of length 20
// :19:31: error: expected type '*const [20]u32', found '*const [10:0]u32'
// :19:31: note: pointer type child '[10:0]u32' cannot cast into pointer type child '[20]u32'
// :19:31: note: array of length 10 cannot cast into an array of length 20
// :24:30: error: expected type '*const [5]u32', found '*const [10]u32'
// :24:30: note: pointer type child '[10]u32' cannot cast into pointer type child '[5]u32'
// :24:30: note: array of length 10 cannot cast into an array of length 5
// :30:30: error: expected type '*const [5]u32', found '*const [10]u32'
// :30:30: note: pointer type child '[10]u32' cannot cast into pointer type child '[5]u32'
// :30:30: note: array of length 10 cannot cast into an array of length 5
// :35:30: error: expected type '*const [5]u32', found '*const [10:0]u32'
// :35:30: note: pointer type child '[10:0]u32' cannot cast into pointer type child '[5]u32'
// :35:30: note: array of length 10 cannot cast into an array of length 5
// :41:30: error: expected type '*const [5]u32', found '*const [10:0]u32'
// :41:30: note: pointer type child '[10:0]u32' cannot cast into pointer type child '[5]u32'
// :41:30: note: array of length 10 cannot cast into an array of length 5