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c: fix crash when checking for compatibility of structures [PR116726]

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When checking for compatibility of structure or union types in
tagged_types_tu_compatible_p, restore the old value of the pointer to
the top of the temporary cache after recursively calling comptypes_internal
when looping over the members of a structure of union.  While the next
iteration of the loop overwrites the pointer, I missed the fact that it can
be accessed again when types of function arguments are compared as part
of recursive type checking and the function is entered again.

	PR c/116726

gcc/c/ChangeLog:

	* c-typeck.cc (tagged_types_tu_compatible_p): Restore value
	of the cache after recursing into comptypes_internal.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr116726.c: New test.
This commit is contained in:
Martin Uecker 2024-09-17 11:37:29 +02:00 • committed by Martin Uecker
parent 1f70503232
commit 9227a64495
2 changed files with 22 additions and 1 deletions
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5
gcc/c/c-typeck.cc
View file

@ -1686,8 +1686,11 @@ tagged_types_tu_compatible_p (const_tree t1, const_tree t2,
data->anon_field = !DECL_NAME (s1);
data->pointedto = false;
const struct tagged_tu_seen_cache *cache = data->cache;
data->cache = &entry;
if (!comptypes_internal (TREE_TYPE (s1), TREE_TYPE (s2), data))
bool ret = comptypes_internal (TREE_TYPE (s1), TREE_TYPE (s2), data);
data->cache = cache;
if (!ret)
return false;
tree st1 = TYPE_SIZE (TREE_TYPE (s1));

18
gcc/testsuite/gcc.dg/pr116726.c Normal file
View file

@ -0,0 +1,18 @@
/* { dg-do compile } */
/* { dg-options "-std=c23" } */
struct s1 {
int f1;
};
struct s2 {
int f2;
};
struct s1 f(struct s2 *);
struct s1 {
int f1;
};
struct s2 {
int f2;
};
struct s1 f(struct s2 *);