Fix ICE with spelling hints within explicit namespace aliases (PR c++/79298)

gcc/cp/ChangeLog:
	PR c++/79298
	* name-lookup.c (suggest_alternative_in_explicit_scope): Resolve
	any namespace aliases.

gcc/testsuite/ChangeLog:
	PR c++/79298
	* g++.dg/spellcheck-pr79298.C: New test case.

From-SVN: r245072

gcc/cp/ChangeLog

+2017-01-31  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c++/79298
+	* name-lookup.c (suggest_alternative_in_explicit_scope): Resolve
+	any namespace aliases.
+
 2017-01-31  Nathan Sidwell  <nathan@acm.org>
 
 	PR c++/79290

gcc/cp/name-lookup.c

@@ -4545,6 +4545,9 @@ bool
 suggest_alternative_in_explicit_scope (location_t location, tree name,
 				       tree scope)
 {
+  /* Resolve any namespace aliases.  */
+  scope = ORIGINAL_NAMESPACE (scope);
+
   cp_binding_level *level = NAMESPACE_LEVEL (scope);
 
   best_match <tree, tree> bm (name);

gcc/testsuite/ChangeLog

 2017-01-31  David Malcolm  <dmalcolm@redhat.com>
 
+	PR c++/79298
+	* g++.dg/spellcheck-pr79298.C: New test case.
+
+2017-01-31  David Malcolm  <dmalcolm@redhat.com>
+
 	PR preprocessor/79210
 	* gcc.dg/format/pr79210.c: New test case.
 	* gcc.dg/plugin/diagnostic-test-string-literals-2.c (test_pr79210):

gcc/testsuite/g++.dg/spellcheck-pr79298.C

+// Ensure that we can offer suggestions for misspellings via a
+// namespace alias.
+
+namespace N { int x; int color; }
+namespace M = N; 
+namespace O = M; 
+
+int foo () 
+{
+  return M::y; // { dg-error ".y. is not a member of .M." }
+}
+
+int bar () 
+{
+  return O::colour; // { dg-error ".colour. is not a member of .O." }
+  // { dg-message "suggested alternative: .color." "" { target *-*-* } .-1 }
+}