[COMMITED] ada: Accessibility error incorrectly flagged on call within Pre'Class expression

["Marc Poulhiès" <poulhies@adacore.com>]

From: Gary Dismukes <dismukes@adacore.com>

The compiler was wrongly reporting an error on a function call within
a Pre'Class expression when a formal of the aspect's subprogram was
passed to an aliased formal. This occurred due to the call appearing
with the return statement of the wrapper function created for the
precondition, but the accessibility error check should only be done
for return statements that appear in the source program.

gcc/ada/

	* sem_ch4.adb (Analyze_Call): Add test of Comes_From_Source on the
	enclosing subprogram's Entity_Id for determining whether to
	perform the compile-time accessibility check on actuals passed to
	aliased formals in a function call occurring within a return
	statement. That test excludes cases where the call occurs within
	the return statement of a Pre'Class wrapper function.

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

---
 gcc/ada/sem_ch4.adb | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/sem_ch4.adb b/gcc/ada/sem_ch4.adb
index ceaf66bd3e2..6824941fa34 100644
--- a/gcc/ada/sem_ch4.adb
+++ b/gcc/ada/sem_ch4.adb
@@ -1467,12 +1467,17 @@ package body Sem_Ch4 is
       end if;
 
       --  Check the accessibility level for actuals for explicitly aliased
-      --  formals.
+      --  formals when a function call appears within a return statement.
+      --  This is only checked if the enclosing subprogram Comes_From_Source,
+      --  to avoid issuing errors on calls occurring in wrapper subprograms
+      --  (for example, where the call is part of an expression of an aspect
+      --  associated with a wrapper, such as Pre'Class).
 
       if Nkind (N) = N_Function_Call
         and then Comes_From_Source (N)
         and then Present (Nam_Ent)
         and then In_Return_Value (N)
+        and then Comes_From_Source (Current_Subprogram)
       then
          declare
             Form : Node_Id;
-- 
2.34.1