[COMMITTED] ada: Rework comment in Expand_Ctrl_Function_Call

[COMMITTED] ada: Rework comment in Expand_Ctrl_Function_Call

[Marc Poulhiès]

From: Eric Botcazou <ebotcazou@adacore.com>

This expands on the reason for properly guarding the transformation.

gcc/ada/

	* exp_ch6.adb (Expand_Ctrl_Function_Call): Rework last comment.

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

---
 gcc/ada/exp_ch6.adb | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/exp_ch6.adb b/gcc/ada/exp_ch6.adb
index 195e34a3479..8e4c9035b22 100644
--- a/gcc/ada/exp_ch6.adb
+++ b/gcc/ada/exp_ch6.adb
@@ -5477,7 +5477,12 @@ package body Exp_Ch6 is
 
       Set_Analyzed (N);
 
-      --  Apply the transformation, unless it was already applied manually
+      --  Apply the transformation unless it was already applied earlier. This
+      --  may happen because Remove_Side_Effects can be called during semantic
+      --  analysis, for example from Build_Actual_Subtype_Of_Component. It is
+      --  crucial to avoid creating a reference of reference here, because it
+      --  would not be subsequently recognized by the Is_Finalizable_Transient
+      --  and Requires_Cleanup_Actions predicates.
 
       if Nkind (Par) /= N_Reference then
          Remove_Side_Effects (N);
-- 
2.43.0