[gcc r13-7872] ada: Fix small fallout of previous change

[Eric Botcazou]

https://gcc.gnu.org/g:5cc6e7886b7f6cf31e25257268eec3336433fd5f

commit r13-7872-g5cc6e7886b7f6cf31e25257268eec3336433fd5f
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Wed Apr 5 23:53:18 2023 +0200

    ada: Fix small fallout of previous change
    
    It may lead to an infinite recursion if no interpretation exists.
    
    gcc/ada/
    
            * sem_res.adb (Try_User_Defined_Literal): Restrict previous change
            to non-leaf nodes.

Diff:
---
 gcc/ada/sem_res.adb | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/gcc/ada/sem_res.adb b/gcc/ada/sem_res.adb
index 615d9d81a84..4d0c1b4b17e 100644
--- a/gcc/ada/sem_res.adb
+++ b/gcc/ada/sem_res.adb
@@ -13219,15 +13219,17 @@ package body Sem_Res is
          --  Both operands must have the same type as the context
          --  (ignoring for now fixed-point and exponentiation ops).
 
-         if Covers (Typ, Etype (Right_Opnd (N)))
-           or else Has_Applicable_User_Defined_Literal (Right_Opnd (N), Typ)
+         if Has_Applicable_User_Defined_Literal (Right_Opnd (N), Typ)
+           or else (Nkind (Left_Opnd (N)) in N_Op
+                     and then Covers (Typ, Etype (Right_Opnd (N))))
          then
             Resolve (Left_Opnd (N), Typ);
             Analyze_And_Resolve (N, Typ);
             return True;
 
-         elsif Covers (Typ, Etype (Left_Opnd (N)))
-           or else Has_Applicable_User_Defined_Literal (Left_Opnd (N), Typ)
+         elsif Has_Applicable_User_Defined_Literal (Left_Opnd (N), Typ)
+           or else (Nkind (Right_Opnd (N)) in N_Op
+                     and then Covers (Typ, Etype (Left_Opnd (N))))
          then
             Resolve (Right_Opnd (N), Typ);
             Analyze_And_Resolve (N, Typ);