[COMMITTED] ada: Compiler hangs on invalid postcondition

[COMMITTED] ada: Compiler hangs on invalid postcondition

[Marc Poulhiès]

From: Steve Baird <baird@adacore.com>

In some cases involving an illegal reference to F'Result in
the postcondition for a function not named F, the compiler would
hang instead of correctly diagnosing the error.

gcc/ada/

	* sem_attr.adb (Denote_Same_Function): Handle the case where
	Has_Homonym (Pref_Id) returns True but Homonym (Pref_Id) returns
	an empty result.

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

---
 gcc/ada/sem_attr.adb | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/sem_attr.adb b/gcc/ada/sem_attr.adb
index e00addd0152..d03761b1e30 100644
--- a/gcc/ada/sem_attr.adb
+++ b/gcc/ada/sem_attr.adb
@@ -5921,7 +5921,9 @@ package body Sem_Attr is
             --  When a qualified name is used for the prefix, homonyms may come
             --  before the current function in the homonym chain.
 
-            elsif Has_Homonym (Pref_Id) then
+            elsif Has_Homonym (Pref_Id)
+              and then Present (Homonym (Pref_Id))
+            then
                return Denote_Same_Function (Homonym (Pref_Id), Spec_Id);
             end if;
 
-- 
2.40.0