1 files changed, 69 insertions, 0 deletions
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index dc73544..0ee80e4 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -30,8 +30,10 @@ along with GCC; see the file COPYING3.  If not see
 #include "timevar.h"
 #include "toplev.h"
 #include "diagnostic-core.h"
+#include "intl.h"
 #include "debug.h"
 #include "c-family/c-pragma.h"
+#include "params.h"
 
 /* The bindings for a particular name in a particular scope.  */
 
@@ -3917,6 +3919,73 @@ remove_hidden_names (tree fns)
   return fns;
 }
 
+/* Suggest alternatives for NAME, an IDENTIFIER_NODE for which name
+   lookup failed.  Search through all available namespaces and print out
+   possible candidates.  */
+
+void
+suggest_alternatives_for (tree name)
+{
+  VEC(tree,heap) *candidates = NULL;
+  VEC(tree,heap) *namespaces_to_search = NULL;
+  int max_to_search = PARAM_VALUE (CXX_MAX_NAMESPACES_FOR_DIAGNOSTIC_HELP);
+  int n_searched = 0;
+  char *spaces;
+  const char *str;
+  tree t;
+  unsigned ix;
+
+  VEC_safe_push (tree, heap, namespaces_to_search, global_namespace);
+
+  while (!VEC_empty (tree, namespaces_to_search)
+	 && n_searched < max_to_search)
+    {
+      tree scope = VEC_pop (tree, namespaces_to_search);
+      struct scope_binding binding = EMPTY_SCOPE_BINDING;
+      struct cp_binding_level *level = NAMESPACE_LEVEL (scope);
+
+      /* Look in this namespace.  */
+      qualified_lookup_using_namespace (name, scope, &binding, 0);
+
+      n_searched++;
+
+      if (binding.value)
+	VEC_safe_push (tree, heap, candidates, binding.value);
+
+      /* Add child namespaces.  */
+      for (t = level->namespaces; t; t = DECL_CHAIN (t))
+	VEC_safe_push (tree, heap, namespaces_to_search, t);
+    }
+
+  /* If we stopped before we could examine all namespaces, inform the
+     user.  Do this even if we don't have any candidates, since there
+     might be more candidates further down that we weren't able to
+     find.  */
+  if (n_searched >= max_to_search)
+    inform (input_location,
+	    "maximum limit of %d namespaces searched for %qE",
+	    max_to_search, name);
+
+  /* Nothing useful to report.  */
+  if (VEC_empty (tree, candidates))
+    return;
+
+  str = (VEC_length(tree, candidates) > 1
+	 ? _("suggested alternatives:")
+	 : _("suggested alternative:"));
+  spaces = NULL;
+
+  FOR_EACH_VEC_ELT (tree, candidates, ix, t)
+    {
+      inform (input_location, "%s %qE", (spaces ? spaces : str), t);
+      spaces = spaces ? spaces : get_spaces (str);
+    }
+
+  VEC_free (tree, heap, candidates);
+  VEC_free (tree, heap, namespaces_to_search);
+  free (spaces);
+}
+
 /* Unscoped lookup of a global: iterate over current namespaces,
    considering using-directives.  */