1 files changed, 32 insertions, 4 deletions

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 9e84a1b1f2e..e574c271194 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -1195,19 +1195,41 @@ pushdecl_maybe_friend_1 (tree x, bool is_friend)
 		  nowarn = true;
 		}
 
-	      if (warn_shadow && !nowarn)
+	      if ((warn_shadow
+		   || warn_shadow_local
+		   || warn_shadow_compatible_local)
+		  && !nowarn)
 		{
 		  bool warned;
+		  enum opt_code warning_code;
+		  /* If '-Wshadow=compatible-local' is specified without other
+		     -Wshadow= flags, we will warn only when the type of the
+		     shadowing variable (i.e. x) can be converted to that of
+		     the shadowed parameter (oldlocal). The reason why we only
+		     check if x's type can be converted to oldlocal's type
+		     (but not the other way around) is because when users
+		     accidentally shadow a parameter, more than often they
+		     would use the variable thinking (mistakenly) it's still
+		     the parameter. It would be rare that users would use the
+		     variable in the place that expects the parameter but
+		     thinking it's a new decl.  */
+		  if (warn_shadow)
+		    warning_code = OPT_Wshadow;
+		  else if (can_convert (TREE_TYPE (oldlocal), TREE_TYPE (x),
+					tf_none))
+		    warning_code = OPT_Wshadow_compatible_local;
+		  else
+		    warning_code = OPT_Wshadow_local;
 
 		  if (TREE_CODE (oldlocal) == PARM_DECL)
-		    warned = warning_at (input_location, OPT_Wshadow,
+		    warned = warning_at (input_location, warning_code,
 				"declaration of %q#D shadows a parameter", x);
 		  else if (is_capture_proxy (oldlocal))
-		    warned = warning_at (input_location, OPT_Wshadow,
+		    warned = warning_at (input_location, warning_code,
 				"declaration of %qD shadows a lambda capture",
 				x);
 		  else
-		    warned = warning_at (input_location, OPT_Wshadow,
+		    warned = warning_at (input_location, warning_code,
 				"declaration of %qD shadows a previous local",
 				x);
 
@@ -3399,6 +3421,12 @@ do_class_using_decl (tree scope, tree name)
 	      return NULL_TREE;
 	    }
 	}
+      else if (name == ctor_identifier
+	       && BINFO_INHERITANCE_CHAIN (BINFO_INHERITANCE_CHAIN (binfo)))
+	{
+	  error ("cannot inherit constructors from indirect base %qT", scope);
+	  return NULL_TREE;
+	}
       else if (!name_dependent_p)
 	{
 	  decl = lookup_member (binfo, name, 0, false, tf_warning_or_error);