ada: Confusing "modified by call, but value overwritten" warning

The patch fixes an issue in the compiler whereby not referencing a local
variable used in multiple procedure calls as an "out" actual in between
calls would lead to a warning despite "-gnatw.o" not being present.
Additionally, this meant that using pragma Unreferenced on such variables
would not be able to silence such warnings.

gcc/ada/ChangeLog:

	* sem_warn.adb
	(Warn_On_Useless_Assignment): Disable out value "overwritten" warning
	when we are not warning on unread out parameters (e.g. "-gnatw.o").

diff --git a/gcc/ada/sem_warn.adb b/gcc/ada/sem_warn.adb
index 35ef616647234d1492e6cd90d3665302efc7566e..1bc97a851039e482a1672a29c2c37bbd162e40a6 100644 (file)
--- a/gcc/ada/sem_warn.adb
+++ b/gcc/ada/sem_warn.adb
@@ -4670,9 +4670,11 @@ package body Sem_Warn is
                      if Nkind (Parent (LA)) in N_Procedure_Call_Statement
                                              | N_Parameter_Association
                      then
-                        Error_Msg_NE
-                          ("?m?& modified by call, but value overwritten #!",
-                           LA, Ent);
+                        if Warn_On_All_Unread_Out_Parameters then
+                           Error_Msg_NE
+                            ("?m?& modified by call, but value overwritten #!",
+                             LA, Ent);
+                        end if;
                      else
                         Error_Msg_NE -- CODEFIX
                           ("?m?useless assignment to&, value overwritten #!",