Commit a9785fe8eef564011b4266e8a1b9aa15b7e37189 | zig

Closes #14474

3 files changed, 20 insertions(+), 1 deletions(-)

doc/langref.html.in+9

...	...	@@ -8799,6 +8799,15 @@ pub const PrefetchOptions = struct {
8799	8799	{#link\|Optional Pointers#} are allowed. Casting an optional pointer which is {#link\|null#}
8800	8800	to a non-optional pointer invokes safety-checked {#link\|Undefined Behavior#}.
8801	8801	</p>
	8802	<p>
	8803	{#syntax#}@ptrCast{#endsyntax#} cannot be used for:
	8804	</p>
	8805	<ul>
	8806	<li>Removing {#syntax#}const{#endsyntax#} or {#syntax#}volatile{#endsyntax#} qualifier. TODO add a {#syntax#}@qualCast{#endsyntax#} builtin.</li>
	8807	<li>Changing pointer address space, use {#link\|@addrSpaceCast#}</li>
	8808	<li>Increasing pointer alignment, use {#link\|@alignCast#}</li>
	8809	<li>Casting a non-slice pointer to a slice, use slicing syntax {#syntax#}ptr[start..end]{#endsyntax#}</li>
	8810	</ul>
8802	8811	{#header_close#}
8803	8812
8804	8813	{#header_open\|@ptrToInt#}

src/Sema.zig+10-1

...	...	@@ -19535,7 +19535,14 @@ fn zirPtrCast(sema: Sema, block: Block, inst: Zir.Inst.Index) CompileError!Air
19535	19535	return sema.fail(block, src, "cast discards volatile qualifier", .{});
19536	19536	}
19537	19537	if (operand_info.@"addrspace" != dest_info.@"addrspace") {
19538		return sema.fail(block, src, "cast changes pointer address space", .{});
	19538	const msg = msg: {
	19539	const msg = try sema.errMsg(block, src, "cast changes pointer address space", .{});
	19540	errdefer msg.destroy(sema.gpa);
	19541
	19542	try sema.errNote(block, src, msg, "consider using '@addrSpaceCast'", .{});
	19543	break :msg msg;
	19544	};
	19545	return sema.failWithOwnedErrorMsg(msg);
19539	19546	}
19540	19547
19541	19548	const dest_is_slice = dest_ty.isSlice();
...	...	@@ -19590,6 +19597,8 @@ fn zirPtrCast(sema: Sema, block: Block, inst: Zir.Inst.Index) CompileError!Air
19590	19597	try sema.errNote(block, dest_ty_src, msg, "'{}' has alignment '{d}'", .{
19591	19598	dest_ty.fmt(sema.mod), dest_align,
19592	19599	});
	19600
	19601	try sema.errNote(block, src, msg, "consider using '@alignCast'", .{});
19593	19602	break :msg msg;
19594	19603	};
19595	19604	return sema.failWithOwnedErrorMsg(msg);

test/cases/compile_errors/increase_pointer_alignment_in_ptrCast.zig+1

...	...	@@ -11,3 +11,4 @@ export fn entry() u32 {
11	11	// :3:17: error: cast increases pointer alignment
12	12	// :3:32: note: '*u8' has alignment '1'
13	13	// :3:26: note: '*u32' has alignment '4'
	14	// :3:17: note: consider using '@alignCast'