re PR c++/45330 (Suggest likely nested-name-specifiers for undeclared identifiers.)

gcc/
	PR c++/45330
	* params.def (CXX_MAX_NAMESPACES_FOR_DIAGNOSTIC_HELP): New parameter.
	* doc/invoke.texi (cxx-max-namespaces-for-diagnostic-help): Document.

gcc/cp/
	PR c++/45330
	* cp-tree.h (suggest_alternatives_for, location_of): Declare.
	* error.c (dump_expr): Handle TYPE_DECL.
	(location_of): Unstaticize.
	* name-lookup.c (suggest_alternatives_for): New function.
	* lex.c (unqualified_name_lookup_error): Call it.

gcc/testsuite/
	PR c++/45330
	* g++.dg/pr45330.C: New test.
	* g++.dg/ext/builtin3.C: Adjust.
	* g++.dg/lookup/error1.C: Adjust.
	* g++.dg/lookup/koenig5.C: Adjust.
	* g++.dg/overload/koenig1.C: Adjust.
	* g++.dg/parse/decl-specifier-1.C: Adjust.
	* g++.dg/template/static10.C: Adjust.
	* g++.old-deja/g++.mike/ns5.C: Adjust.
	* g++.old-deja/g++.mike/ns7.C: Adjust.
	* g++.old-deja/g++.ns/koenig5.C: Adjust.
	* g++.old-deja/g++.ns/koenig9.C: Adjust.
	* g++.old-deja/g++.other/lineno5.C: Adjust.

From-SVN: r167536

5 files changed, 86 insertions, 3 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index ef506d1..2bbd7e4 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,12 @@
+2010-12-07  Nathan Froyd  <froydnj@codesourcery.com>
+
+	PR c++/45330
+	* cp-tree.h (suggest_alternatives_for, location_of): Declare.
+	* error.c (dump_expr): Handle TYPE_DECL.
+	(location_of): Unstaticize.
+	* name-lookup.c (suggest_alternatives_for): New function.
+	* lex.c (unqualified_name_lookup_error): Call it.
+
 2010-12-06  Nicola Pero  <nicola.pero@meta-innovation.com>
 
 	* call.c: Include c-family/c-objc.h.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 59342e3..aba8dfd 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4907,6 +4907,7 @@ extern void print_instantiation_context		(void);
 extern void maybe_warn_variadic_templates       (void);
 extern void maybe_warn_cpp0x			(cpp0x_warn_str str);
 extern bool pedwarn_cxx98                       (location_t, int, const char *, ...) ATTRIBUTE_GCC_DIAG(3,4);
+extern location_t location_of                   (tree);
 
 /* in except.c */
 extern void init_exception_processing		(void);
@@ -5639,6 +5640,9 @@ extern tree cxx_omp_clause_dtor			(tree, tree);
 extern void cxx_omp_finish_clause		(tree);
 extern bool cxx_omp_privatize_by_reference	(const_tree);
 
+/* in name-lookup.c */
+extern void suggest_alternatives_for (tree);
+
 /* -- end of C++ */
 
 #endif /* ! GCC_CP_TREE_H */
diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index ed168c4..4fb47dc 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -98,7 +98,6 @@ static void cp_print_error_function (diagnostic_context *, diagnostic_info *);
 
 static bool cp_printer (pretty_printer *, text_info *, const char *,
 			int, bool, bool, bool);
-static location_t location_of (tree);
 
 void
 init_error (void)
@@ -1700,6 +1699,7 @@ dump_expr (tree t, int flags)
     case NAMESPACE_DECL:
     case LABEL_DECL:
     case OVERLOAD:
+    case TYPE_DECL:
     case IDENTIFIER_NODE:
       dump_decl (t, (flags & ~TFF_DECL_SPECIFIERS) | TFF_NO_FUNCTION_ARGUMENTS);
       break;
@@ -2487,7 +2487,7 @@ lang_decl_name (tree decl, int v, bool translate)
 
 /* Return the location of a tree passed to %+ formats.  */
 
-static location_t
+location_t
 location_of (tree t)
 {
   if (TREE_CODE (t) == PARM_DECL && DECL_CONTEXT (t))
diff --git a/gcc/cp/lex.c b/gcc/cp/lex.c
index 684803f..5a2ae41 100644
--- a/gcc/cp/lex.c
+++ b/gcc/cp/lex.c
@@ -450,7 +450,10 @@ unqualified_name_lookup_error (tree name)
   else
     {
       if (!objc_diagnose_private_ivar (name))
-        error ("%qD was not declared in this scope", name);
+	{
+	  error ("%qD was not declared in this scope", name);
+	  suggest_alternatives_for (name);
+	}
       /* Prevent repeated error messages by creating a VAR_DECL with
 	 this NAME in the innermost block scope.  */
       if (current_function_decl)
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 3d19c08..4cf1380 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -29,8 +29,10 @@ along with GCC; see the file COPYING3.  If not see
 #include "name-lookup.h"
 #include "timevar.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.  */
 
@@ -3916,6 +3918,71 @@ 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;
+  tree t;
+  unsigned ix;
+  location_t name_location;
+
+  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);
+    }
+
+  name_location = location_of (name);
+
+  /* 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
+      && !VEC_empty (tree, namespaces_to_search))
+    inform (name_location,
+	    "maximum limit of %d namespaces searched for %qE",
+	    max_to_search, name);
+
+  VEC_free (tree, heap, namespaces_to_search);
+
+  /* Nothing useful to report.  */
+  if (VEC_empty (tree, candidates))
+    return;
+
+  inform_n (name_location, VEC_length (tree, candidates),
+	    "suggested alternative:",
+	    "suggested alternatives:");
+
+  FOR_EACH_VEC_ELT (tree, candidates, ix, t)
+    inform (location_of (t), "  %qE", t);
+
+  VEC_free (tree, heap, candidates);
+}
+
 /* Unscoped lookup of a global: iterate over current namespaces,
    considering using-directives.  */