Hi!
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).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2023-01-19 Jakub Jelinek <ja...@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.
--- gcc/cp/cp-gimplify.cc.jj 2023-01-16 11:52:16.065734330 +0100
+++ gcc/cp/cp-gimplify.cc 2023-01-19 18:13:54.592661735 +0100
@@ -1010,6 +1010,16 @@ cp_fold_r (tree *stmt_p, int *walk_subtr
}
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;
}
--- gcc/testsuite/g++.dg/init/pr53932.C.jj 2023-01-19 18:22:24.837231192
+0100
+++ gcc/testsuite/g++.dg/init/pr53932.C 2023-01-19 18:20:51.776586408 +0100
@@ -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 ()
+{
+}
Jakub
