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Re: [PATCH] accept all C integer types in function parameters referenced by alloc_align (PR 88363)


On Mon, Dec 10, 2018 at 04:30:11PM -0700, Martin Sebor wrote:
> Some of my testing exposed a minor problem in GCC 9's validation
> of the type of function parameters referred to by attribute
> positional arguments.  Whereas GCC 8 accepts all C integer types,
> including enumerated types, such as:
> 
>   enum AllocAlign { Align16 = 16, Align32 = 32 };
> 
>   __attribute__ ((alloc_align (1))) void*
>   alloc (size_t, enum AllocAlign)
> 
> GCC 9 only accepts signed and unsigned integer types.  This change
> (introduced by myself) was unintentional, and a fix for it is in
> the attached trivial patch.  I plan to commit it without approval
> in the next day or so unless any concerns or suggestions come up.

There is nothing obvious about this, so please don't commit it without
approval.  GCC 8 and older used to accept
even float or void * or struct arguments and just ignored them.
I think we need to discuss what types we want to allow without warnings and
what we should warn.
As I wrote in the PR, I believe e.g. using alloc_align/alloc_size with
bool/_Bool is just a clear bug, you can store 0 or 1 in there, but e.g.
alignment 0 doesn't make sense.
Enums are on the border line, I'll defer to C/C++ maintainers whether we
want to include that or not.

	Jakub


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