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translate-c: fix function pointer casting + alignCast and constCast at the same time #24546

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translate-c: fix function pointer casting + alignCast and constCast at the same time #24546

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fd023fe
translate-c: fix function pointers casting
paokitore Jul 21, 2025
c63a69a
translate-c: allow constCast and alignCast at the same time
paokitore Jul 21, 2025
9737749
fix formatting
paokitore Aug 3, 2025
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39 changes: 23 additions & 16 deletions src/translate_c.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -4030,24 +4030,26 @@ fn transCPtrCast(
const src_child_type = src_ty.getPointeeType();
const dst_type_node = try transType(c, scope, ty, loc);

if (!src_ty.isArrayType() and ((src_child_type.isConstQualified() and
!child_type.isConstQualified()) or
(src_child_type.isVolatileQualified() and
!child_type.isVolatileQualified())))
// Implicit downcasting from higher to lower alignment values is forbidden,
// use @alignCast to side-step this problem
const rhs = if (qualTypeCanon(child_type).isVoidType())
// void has 1-byte alignment, so @alignCast is not needed
expr
else if (typeIsOpaque(c, qualTypeCanon(child_type), loc))
// For opaque types a ptrCast is enough
expr
else blk: {
break :blk try Tag.align_cast.create(c.arena, expr);
};

if (!src_ty.isArrayType() and
(((src_child_type.isConstQualified() or qualTypeIsFunction(src_child_type)) and
!child_type.isConstQualified()) or
(src_child_type.isVolatileQualified() and
!child_type.isVolatileQualified())))
{
return removeCVQualifiers(c, dst_type_node, expr);
return removeCVQualifiers(c, dst_type_node, rhs);
} else {
// Implicit downcasting from higher to lower alignment values is forbidden,
// use @alignCast to side-step this problem
const rhs = if (qualTypeCanon(child_type).isVoidType())
// void has 1-byte alignment, so @alignCast is not needed
expr
else if (typeIsOpaque(c, qualTypeCanon(child_type), loc))
// For opaque types a ptrCast is enough
expr
else blk: {
break :blk try Tag.align_cast.create(c.arena, expr);
};
return Tag.as.create(c.arena, .{
.lhs = dst_type_node,
.rhs = try Tag.ptr_cast.create(c.arena, rhs),
Expand Down Expand Up @@ -4342,6 +4344,11 @@ fn qualTypeIsBoolean(qt: clang.QualType) bool {
return qualTypeCanon(qt).isBooleanType();
}

fn qualTypeIsFunction(qt: clang.QualType) bool {
const type_class = qualTypeCanon(qt).getTypeClass();
return type_class == .FunctionProto or type_class == .FunctionNoProto;
}

fn qualTypeIntBitWidth(c: *Context, qt: clang.QualType) !u32 {
const ty = qt.getTypePtr();

Expand Down
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