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authorJakub Jelinek <jakub@redhat.com>2023-01-19 23:27:34 +0100
committerJakub Jelinek <jakub@redhat.com>2023-02-10 14:24:08 +0100
commitd4eca31c521f54a3066f9940fbf09e28b53eff8c (patch)
treeb452d94909c4b46439aeff8fe0885d155c98109f
parent629907bff87e238d45afe609716880e8acf9e541 (diff)
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c++: Fix up handling of references to anon union members in initializers [PR53932]
For anonymous union members we create artificial VAR_DECLs which have DECL_VALUE_EXPR for the actual COMPONENT_REF. That works just fine inside of functions (including global dynamic constructors), because during gimplification such VAR_DECLs are gimplified as their DECL_VALUE_EXPR. This is also done during regimplification. But references to these artificial vars in DECL_INITIAL expressions aren't ever replaced by the DECL_VALUE_EXPRs, so we end up either with link failures like on the testcase below, or worse ICEs with LTO. The following patch fixes those during cp_fully_fold_init where we already walk all the trees (!data->genericize means that function rather than cp_fold_function). 2023-01-19 Jakub Jelinek <jakub@redhat.com> PR c++/53932 * cp-gimplify.cc (cp_fold_r): During cp_fully_fold_init replace DECL_ANON_UNION_VAR_P VAR_DECLs with their corresponding DECL_VALUE_EXPR. * g++.dg/init/pr53932.C: New test. (cherry picked from commit 9b9a989adc042b304572fd6d4ade46b47be6ccb8)
-rw-r--r--gcc/cp/cp-gimplify.cc10
-rw-r--r--gcc/testsuite/g++.dg/init/pr53932.C25
2 files changed, 35 insertions, 0 deletions
diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index e4c2644..426b373 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -1004,6 +1004,16 @@ cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_)
*stmt_p = stmt = cxx_constant_value (stmt);
break;
+ case VAR_DECL:
+ /* In initializers replace anon union artificial VAR_DECLs
+ with their DECL_VALUE_EXPRs, as nothing will do it later. */
+ if (DECL_ANON_UNION_VAR_P (stmt) && !data->genericize)
+ {
+ *stmt_p = stmt = unshare_expr (DECL_VALUE_EXPR (stmt));
+ break;
+ }
+ break;
+
default:
break;
}
diff --git a/gcc/testsuite/g++.dg/init/pr53932.C b/gcc/testsuite/g++.dg/init/pr53932.C
new file mode 100644
index 0000000..3b129e7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/pr53932.C
@@ -0,0 +1,25 @@
+// PR c++/53932
+// { dg-do link }
+
+static union { int i; };
+int &r = i;
+int s = i;
+int *t = &i;
+
+void
+foo (int **p, int *q)
+{
+ static int &u = i;
+ static int v = i;
+ static int *w = &i;
+ int &x = i;
+ int y = i;
+ int *z = &i;
+ *p = &i;
+ *q = i;
+}
+
+int
+main ()
+{
+}