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[C] fix crash when checking for compatibility of structures [PR116726]

Message ID ef26cd4cb2660403ae5654f98bc0bf8d00c0cab3.camel@tugraz.at
State New
Headers show
Series [C] fix crash when checking for compatibility of structures [PR116726] | expand

Commit Message

Martin Uecker Sept. 17, 2024, 1:19 p.m. UTC 
Here is a fix for a mistake I made when recursively checking for
type compatibility.


Bootstrapped and regression tested on x86-64.


    c: fix crash when checking for compatibility of structures [PR116726]
    
    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/Changelog:
            * c/c-typeck.cc (tagged_types_tu_compatible_p): Restore value
            of the cache after recursing into comptypes_internal.
    
    gcc/testsuite/Changelog:
            * pr116726.c: New test.


.
diff mbox series

Patch

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 58b2724b39e..ba6d96d26b2 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -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));
diff --git a/gcc/testsuite/gcc.dg/pr116726.c b/gcc/testsuite/gcc.dg/pr116726.c
new file mode 100644
index 00000000000..bb25efca586
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr116726.c
@@ -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 *);