JustinStitt wrote:
> Adding attributes to types as type sugar (not part of the canonical type) is
> generally problematic: non-canonical types are not reliably preserved
> throughout the compiler, particularly in cases involving templates.
I see, here's an example that currently breaks my attribute (without any
special handling):
```c++
typedef int __attribute__((wraps)) wrapping_int;
template <typename T>
void foo(T a) {
++a; // this will throw a sanitizer error because the generic method
// created for this templated type is generic
}
int main(void) {
wrapping_int A = INT_MAX;
foo(A);
}
```
>
> Can we use a type qualifier here?
FWICT, qualifiers are extremely sparse with only a handful existing at all.
```
Type.h +142:
/// The collection of all-type qualifiers we support.
/// Clang supports five independent qualifiers:
/// * C99: const, volatile, and restrict
/// * MS: __unaligned
/// * Embedded C (TR18037): address spaces
/// * Objective C: the GC attributes (none, weak, or strong)
```
Most if not all type qualifiers are strongly associated with how the storage
memory of a type is handled. For the behavior needed out of `wraps`, I was
thinking this kind of thing is typically done via an attribute. Something like
[noderef](https://clang.llvm.org/docs/AttributeReference.html#noderef) is
similar. You apply it to types which then adjusts Clang's handling of variables
of that type.
If it comes down to it, we can make this attribute only available for C under
``__attribute__(())`` or I can try to add support for templates to be made
aware of specific type attributes.
https://github.com/llvm/llvm-project/pull/86618
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