[multiple changes]

2017-09-06  Yannick Moy  <moy@adacore.com>

	* sem_res.adb (Resolve): Update message for function call as statement.

2017-09-06  Ed Schonberg  <schonberg@adacore.com>

	* sem_ch6.adb (Check_Returns): Clean up warnings coming from
	generated bodies for renamings that are completions, when renamed
	procedure is No_Return.
	* sem_ch8.adb (Analyze_Subprogram_Renaming): Implement legality
	rule in 6.5.1 (7/2): if a renaming is a completion of a subprogram
	with No_Return, the renamed entity must be No_Return as well.

From-SVN: r251768

gcc/ada/ChangeLog

+2017-09-06  Yannick Moy  <moy@adacore.com>
+
+	* sem_res.adb (Resolve): Update message for function call as statement.
+
+2017-09-06  Ed Schonberg  <schonberg@adacore.com>
+
+	* sem_ch6.adb (Check_Returns): Clean up warnings coming from
+	generated bodies for renamings that are completions, when renamed
+	procedure is No_Return.
+	* sem_ch8.adb (Analyze_Subprogram_Renaming): Implement legality
+	rule in 6.5.1 (7/2): if a renaming is a completion of a subprogram
+	with No_Return, the renamed entity must be No_Return as well.
+
 2017-09-06  Hristian Kirtchev  <kirtchev@adacore.com>
 
 	* exp_ch5.adb, freeze.adb, exp_ch4.adb, exp_ch6.adb, lib-xref.adb:

gcc/ada/sem_ch6.adb

@@ -6693,7 +6693,11 @@ package body Sem_Ch6 is
                   Error_Msg_N
                     ("implied return after this statement "
                      & "would have raised Program_Error", Last_Stm);
-               else
+
+               --  In normal compilation mode, do not warn on a generated
+               --  call (e.g. in the body of a renaming as completion).
+
+               elsif Comes_From_Source (Last_Stm) then
                   Error_Msg_N
                     ("implied return after this statement "
                      & "will raise Program_Error??", Last_Stm);

gcc/ada/sem_ch8.adb

@@ -2946,6 +2946,14 @@ package body Sem_Ch8 is
          Check_Fully_Conformant (New_S, Rename_Spec);
          Set_Public_Status (New_S);
 
+         if No_Return (Rename_Spec)
+            and then not No_Return (Entity (Nam))
+         then
+            Error_Msg_N ("renaming completes a No_Return procedure", N);
+            Error_Msg_N
+              ("\renamed procedure must be nonreturning (RM 6.5.1 (7/2))", N);
+         end if;
+
          --  The specification does not introduce new formals, but only
          --  repeats the formals of the original subprogram declaration.
          --  For cross-reference purposes, and for refactoring tools, we

gcc/ada/sem_res.adb

@@ -2533,8 +2533,11 @@ package body Sem_Res is
                  and then Ekind (Entity (Name (N))) = E_Function
                then
                   Error_Msg_NE
-                    ("cannot use function & in a procedure call",
+                    ("cannot use call to function & as a statement",
                      Name (N), Entity (Name (N)));
+                  Error_Msg_N
+                    ("\return value of a function call cannot be ignored",
+                     Name (N));
 
                --  Otherwise give general message (not clear what cases this
                --  covers, but no harm in providing for them).