[C PATCH] Fix ICE related to incomplete structures in C23 [PR114930, PR115502].

[Richard Biener]

> Am 18.06.2024 um 17:20 schrieb Martin Uecker <uecker@tugraz.at>:
> 
> 
> As discussed this replaces the use of check_qualified_type with
> a simple check for qualifiers as suggested by Jakub in
> c_update_type_canonical.

Note a canonical type should always be unqualified (for classical qualifiers, not address space or atomic qualification)

Richard 

> Martin
> 
> 
> Bootstrapped and regression tested on x86_64.
> 
> 
>    C23: Fix ICE related to incomplete structures [PR114930,PR115502].
> 
>    The fix for PR114574 needs to be further revised because check_qualified_type
>    makes decision based on TYPE_NAME which can be incorrect for C when there
>    are TYPE_DECLS involved.
> 
>    gcc/c/:
>            * c-decl.c (c_update_type_canonical): Do not use check_qualified_type.
> 
>    gcc/testsuite/:
>            * gcc.dg/pr114930.c: New test.
>            * gcc.dg/pr115502.c: New test.
> 
> diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
> index 01326570e2b..610061a07f8 100644
> --- a/gcc/c/c-decl.cc
> +++ b/gcc/c/c-decl.cc
> @@ -9374,7 +9374,7 @@ c_update_type_canonical (tree t)
>      if (TYPE_QUALS (x) == TYPE_QUALS (t))
>        TYPE_CANONICAL (x) = TYPE_CANONICAL (t);
>      else if (TYPE_CANONICAL (t) != t
> -           || check_qualified_type (x, t, TYPE_QUALS (x)))
> +           || TYPE_QUALS (x) != TYPE_QUALS (TYPE_CANONICAL (t)))
>        TYPE_CANONICAL (x)
>          = build_qualified_type (TYPE_CANONICAL (t), TYPE_QUALS (x));
>      else
> diff --git a/gcc/testsuite/gcc.dg/pr114930.c b/gcc/testsuite/gcc.dg/pr114930.c
> new file mode 100644
> index 00000000000..5e982fb8929
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr114930.c
> @@ -0,0 +1,9 @@
> +/* { dg-do compile }
> + * { dg-options "-std=c23 -flto" } */
> +
> +typedef struct WebPPicture WebPPicture;
> +typedef int (*WebPProgressHook)(const WebPPicture *);
> +WebPProgressHook progress_hook;
> +struct WebPPicture {
> +} WebPGetColorPalette(const struct WebPPicture *);
> +
> diff --git a/gcc/testsuite/gcc.dg/pr115502.c b/gcc/testsuite/gcc.dg/pr115502.c
> new file mode 100644
> index 00000000000..02b52622c5a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr115502.c
> @@ -0,0 +1,9 @@
> +/* { dg-do compile }
> + * { dg-options "-std=c23 -flto" } */
> +
> +typedef struct _OSet OSet;
> +typedef OSet AvlTree;
> +void vgPlain_OSetGen_Lookup(const OSet *);
> +struct _OSet {};
> +void vgPlain_OSetGen_Lookup(const AvlTree *);
> +
>