c++: Don't strip USING_DECLs when updating local bindings [PR116748]

Currently update_binding strips USING_DECLs too eagerly, leading to ICEs
in pop_local_decl as it can't find the decl it's popping in the binding
list.  Let's rather try to keep the original USING_DECL around.

This also means that using59.C can point to the location of the
using-decl rather than the underlying object directly; this is in the
direction required to fix PR c++/106851 (though more work is needed to
emit properly helpful diagnostics here).

	PR c++/116748

gcc/cp/ChangeLog:

	* name-lookup.cc (update_binding): Maintain USING_DECLs in the
	binding slots.

gcc/testsuite/ChangeLog:

	* g++.dg/lookup/using59.C: Update location.
	* g++.dg/lookup/using69.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
Reviewed-by: Jason Merrill <jason@redhat.com>

diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
index eb365b259d928b8e6a365d7263a9d0dccc86135d..a2f94e0f363ef72e4d7b0d02f82a33ec8a641f0f 100644 (file)
--- a/gcc/cp/name-lookup.cc
+++ b/gcc/cp/name-lookup.cc
@@ -3005,6 +3005,8 @@ update_binding (cp_binding_level *level, cxx_binding *binding, tree *slot,
 
   if (old == error_mark_node)
     old = NULL_TREE;
+
+  tree old_bval = old;
   old = strip_using_decl (old);
 
   if (DECL_IMPLICIT_TYPEDEF_P (decl))
@@ -3021,7 +3023,7 @@ update_binding (cp_binding_level *level, cxx_binding *binding, tree *slot,
          gcc_checking_assert (!to_type);
          hide_type = hiding;
          to_type = decl;
-         to_val = old;
+         to_val = old_bval;
        }
       else
        hide_value = hiding;
@@ -3034,7 +3036,7 @@ update_binding (cp_binding_level *level, cxx_binding *binding, tree *slot,
       /* OLD is an implicit typedef.  Move it to to_type.  */
       gcc_checking_assert (!to_type);
 
-      to_type = old;
+      to_type = old_bval;
       hide_type = hide_value;
       old = NULL_TREE;
       hide_value = false;
@@ -3093,7 +3095,7 @@ update_binding (cp_binding_level *level, cxx_binding *binding, tree *slot,
        {
          if (same_type_p (TREE_TYPE (old), TREE_TYPE (decl)))
            /* Two type decls to the same type.  Do nothing.  */
-           return old;
+           return old_bval;
          else
            goto conflict;
        }
@@ -3106,7 +3108,7 @@ update_binding (cp_binding_level *level, cxx_binding *binding, tree *slot,
 
          /* The new one must be an alias at this point.  */
          gcc_assert (DECL_NAMESPACE_ALIAS (decl));
-         return old;
+         return old_bval;
        }
       else if (TREE_CODE (old) == VAR_DECL)
        {
@@ -3121,7 +3123,7 @@ update_binding (cp_binding_level *level, cxx_binding *binding, tree *slot,
       else
        {
        conflict:
-         diagnose_name_conflict (decl, old);
+         diagnose_name_conflict (decl, old_bval);
          to_val = NULL_TREE;
        }
     }

diff --git a/gcc/testsuite/g++.dg/lookup/using59.C b/gcc/testsuite/g++.dg/lookup/using59.C
index 3c3a73c28d59ea34eb9fcadbb8ba81aac97e580c..b7ec325d2348268218dc3ba32e18d579cf51829d 100644 (file)
--- a/gcc/testsuite/g++.dg/lookup/using59.C
+++ b/gcc/testsuite/g++.dg/lookup/using59.C
@@ -1,10 +1,10 @@
 
 namespace Y
 {
-  extern int I; //  { dg-message "previous declaration" }
+  extern int I;
 }
 
-using Y::I;
+using Y::I; // { dg-message "previous declaration" }
 extern int I; // { dg-error "conflicts with a previous" }
 
 extern int J;

diff --git a/gcc/testsuite/g++.dg/lookup/using69.C b/gcc/testsuite/g++.dg/lookup/using69.C
new file mode 100644 (file)
index 0000000..7d52b73
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/using69.C
@@ -0,0 +1,10 @@
+// PR c++/116748
+
+namespace ns {
+  struct empty;
+}
+
+void foo() {
+  using ns::empty;
+  int empty;
+}