Disable -Wreturn-type by default in all languages other from C++.

2017-11-15  Martin Liska  <mliska@suse.cz>

	* tree-cfg.c (pass_warn_function_return::execute):
	Compare warn_return_type for greater than zero.
2017-11-15  Martin Liska  <mliska@suse.cz>

	* options.c (gfc_post_options):
	Do not set default value of warn_return_type.
	* trans-decl.c (gfc_trans_deferred_vars):
	Compare warn_return_type for greater than zero.
	(generate_local_decl): Likewise
	(gfc_generate_function_code): Likewise.

From-SVN: r254764

gcc/ChangeLog

+2017-11-15  Martin Liska  <mliska@suse.cz>
+
+	* tree-cfg.c (pass_warn_function_return::execute):
+	Compare warn_return_type for greater than zero.
+
 2017-11-15  Sebastian Peryt  <sebastian.peryt@intel.com>
 
 	PR target/82941

gcc/fortran/ChangeLog

+2017-11-15  Martin Liska  <mliska@suse.cz>
+
+	* options.c (gfc_post_options):
+	Do not set default value of warn_return_type.
+	* trans-decl.c (gfc_trans_deferred_vars):
+	Compare warn_return_type for greater than zero.
+	(generate_local_decl): Likewise
+	(gfc_generate_function_code): Likewise.
+
 2017-11-13  Fritz Reese <fritzoreese@gmail.com>
 
 	PR fortran/78240

gcc/fortran/options.c

@@ -435,9 +435,6 @@ gfc_post_options (const char **pfilename)
     gfc_fatal_error ("Maximum subrecord length cannot exceed %d",
 		     MAX_SUBRECORD_LENGTH);
 
-  if (warn_return_type == -1)
-    warn_return_type = 0;
-
   gfc_cpp_post_options ();
 
   if (gfc_option.allow_std & GFC_STD_F2008)

gcc/fortran/trans-decl.c

@@ -4198,7 +4198,7 @@ gfc_trans_deferred_vars (gfc_symbol * proc_sym, gfc_wrapped_block * block)
 		  break;
 	    }
 	  /* TODO: move to the appropriate place in resolve.c.  */
-	  if (warn_return_type && el == NULL)
+	  if (warn_return_type > 0 && el == NULL)
 	    gfc_warning (OPT_Wreturn_type,
 			 "Return value of function %qs at %L not set",
 			 proc_sym->name, &proc_sym->declared_at);
@@ -5619,7 +5619,7 @@ generate_local_decl (gfc_symbol * sym)
   else if (sym->attr.flavor == FL_PROCEDURE)
     {
       /* TODO: move to the appropriate place in resolve.c.  */
-      if (warn_return_type
+      if (warn_return_type > 0
 	  && sym->attr.function
 	  && sym->result
 	  && sym != sym->result
@@ -6494,11 +6494,11 @@ gfc_generate_function_code (gfc_namespace * ns)
       if (result == NULL_TREE || artificial_result_decl)
 	{
 	  /* TODO: move to the appropriate place in resolve.c.  */
-	  if (warn_return_type && sym == sym->result)
+	  if (warn_return_type > 0 && sym == sym->result)
 	    gfc_warning (OPT_Wreturn_type,
 			 "Return value of function %qs at %L not set",
 			 sym->name, &sym->declared_at);
-	  if (warn_return_type)
+	  if (warn_return_type > 0)
 	    TREE_NO_WARNING(sym->backend_decl) = 1;
 	}
       if (result != NULL_TREE)

gcc/tree-cfg.c

@@ -9071,7 +9071,7 @@ pass_warn_function_return::execute (function *fun)
 
   /* If we see "return;" in some basic block, then we do reach the end
      without returning a value.  */
-  else if (warn_return_type
+  else if (warn_return_type > 0
 	   && !TREE_NO_WARNING (fun->decl)
 	   && EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (fun)->preds) > 0
 	   && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (fun->decl))))