[Bug target/79671] [7 Regression] mapnik miscompilation on armv7hl since r235622

[bernd.edlinger at hotmail dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79671

--- Comment #98 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
I realized that my latest patch triggers a pre-existing
bug in the libstdc++ testsuite => PR80287

So the following patch would be needed on top of it:

Index: gcc/cp/class.c
===================================================================
--- gcc/cp/class.c      (revision 246605)
+++ gcc/cp/class.c      (working copy)
@@ -2060,12 +2060,14 @@
 static void
 fixup_may_alias (tree klass)
 {
-  tree t;
+  tree t, v;

   for (t = TYPE_POINTER_TO (klass); t; t = TYPE_NEXT_PTR_TO (t))
-    TYPE_REF_CAN_ALIAS_ALL (t) = true;
+    for (v = TYPE_MAIN_VARIANT (t); v; v = TYPE_NEXT_VARIANT (v))
+      TYPE_REF_CAN_ALIAS_ALL (v) = true;
   for (t = TYPE_REFERENCE_TO (klass); t; t = TYPE_NEXT_REF_TO (t))
-    TYPE_REF_CAN_ALIAS_ALL (t) = true;
+    for (v = TYPE_MAIN_VARIANT (t); v; v = TYPE_NEXT_VARIANT (v))
+      TYPE_REF_CAN_ALIAS_ALL (v) = true;
 }

 /* Early variant fixups: we apply attributes at the beginning of the class