This PR points out to a GC problem: when we freed a duplicate typedef, we were
leaving its type in the variants list, with its TYPE_NAME still pointing to the
now-freed TYPE_DECL, leading to a crash. I was lucky to discover that the
exact same problem was fixed in November for the C++ FE, so I could just follow
suit here. And because that change didn't add a new testcase, I'm putting the
new test into c-c++-common/.
Bootstrapped/regtested on x86_64-linux, ok for trunk/5?
2016-03-21 Marek Polacek <pola...@redhat.com>
PR c/70297
* c-decl.c (merge_decls): When combining typedefs, remove the new
type from the variants list.
* c-c++-common/pr70297.c: New test.
diff --git gcc/c/c-decl.c gcc/c/c-decl.c
index bab4715..98d7f2a 100644
--- gcc/c/c-decl.c
+++ gcc/c/c-decl.c
@@ -2358,6 +2358,26 @@ merge_decls (tree newdecl, tree olddecl, tree newtype,
tree oldtype)
DECL_ATTRIBUTES (newdecl)
= targetm.merge_decl_attributes (olddecl, newdecl);
+ /* For typedefs use the old type, as the new type's DECL_NAME points
+ at newdecl, which will be ggc_freed. */
+ if (TREE_CODE (newdecl) == TYPE_DECL)
+ {
+ newtype = oldtype;
+
+ /* And remove the new type from the variants list. */
+ if (TYPE_NAME (TREE_TYPE (newdecl)) == newdecl)
+ {
+ tree remove = TREE_TYPE (newdecl);
+ for (tree t = TYPE_MAIN_VARIANT (remove); ;
+ t = TYPE_NEXT_VARIANT (t))
+ if (TYPE_NEXT_VARIANT (t) == remove)
+ {
+ TYPE_NEXT_VARIANT (t) = TYPE_NEXT_VARIANT (remove);
+ break;
+ }
+ }
+ }
+
/* Merge the data types specified in the two decls. */
TREE_TYPE (newdecl)
= TREE_TYPE (olddecl)
diff --git gcc/testsuite/c-c++-common/pr70297.c
gcc/testsuite/c-c++-common/pr70297.c
index e69de29..bc078c8 100644
--- gcc/testsuite/c-c++-common/pr70297.c
+++ gcc/testsuite/c-c++-common/pr70297.c
@@ -0,0 +1,10 @@
+/* PR c/70297 */
+/* { dg-do compile } */
+/* { dg-options "-g" } */
+
+typedef unsigned int uint32_t;
+typedef uint32_t T;
+typedef uint32_t T __attribute__((aligned(4)));
+struct S {
+ T *t;
+};
Marek
