[COMMITTED] ada: Leave detection of missing return in functions to GNATprove

[COMMITTED] ada: Leave detection of missing return in functions to GNATprove

[Marc Poulhiès]

From: Piotr Trojanek <trojanek@adacore.com>

GNAT has a heuristic to warn about missing return statements in
functions. This warning was escalated to errors when operating in
GNATprove mode and SPARK_Mode was On. However, this heuristic was
imprecise and caused spurious errors. Also, it was applied after the
Push_Scope/End_Scope, so for functions acting as compilation units it
was using the wrong SPARK_Mode.

It is better to simply leave this detection to GNATprove.

gcc/ada/

	* sem_ch6.adb (Check_Statement_Sequence): Only warn about missing return
	statements and let GNATprove emit a check when needed.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/sem_ch6.adb | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/gcc/ada/sem_ch6.adb b/gcc/ada/sem_ch6.adb
index 62ca985bf87..4e64833b3f7 100644
--- a/gcc/ada/sem_ch6.adb
+++ b/gcc/ada/sem_ch6.adb
@@ -7315,18 +7315,11 @@ package body Sem_Ch6 is
             --  already, so the Assert_False is for the assertions off case.
 
             if not Raise_Exception_Call and then not Assert_False then
-
-               --  In GNATprove mode, it is an error to have a missing return
-
-               Error_Msg_Warn := SPARK_Mode /= On;
-
-               --  Issue error message or warning
-
                Error_Msg_N
-                 ("RETURN statement missing following this statement<<!",
+                 ("RETURN statement missing following this statement??!",
                   Last_Stm);
                Error_Msg_N
-                 ("\Program_Error [<<!", Last_Stm);
+                 ("\Program_Error [??!", Last_Stm);
             end if;
 
             --  Note: we set Err even though we have not issued a warning
-- 
2.40.0