https://gcc.gnu.org/g:cb71c251d846032cfb31e86c8e4d678c58a90ecc
commit r15-597-gcb71c251d846032cfb31e86c8e4d678c58a90ecc
Author: Bob Duff <d...@adacore.com>
Date: Tue Mar 5 18:35:25 2024 -0500
ada: Fix Constraint_Error on mutable assignment
For an assignment statement "X := Y;", where X is a formal parameter
of a "late overriding" subprogram (i.e. it has no spec, and the body
is overriding), and the subtype of X is an unconstrained record with
defaulted discriminants, if the actual parameter passed to X is
unconstrained, then X is unconstrained. This patch fixes a bug
where X was incorrectly considered constrained, so that if Y's
discriminants are different from X, Constraint_Error was raised.
The bug was caused by the fact that an extra "constrained" formal
parameter was missing in both caller and callee.
gcc/ada/
* sem_disp.adb (Check_Dispatching_Operation): Call
Create_Extra_Formals, so that the caller will have an extra
"constrained" parameter, which will be checked on assignment in
the callee, and will be passed in by the caller.
Diff:
---
gcc/ada/sem_disp.adb | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/gcc/ada/sem_disp.adb b/gcc/ada/sem_disp.adb
index 525a9f7f0a1a..fd521a09bc0f 100644
--- a/gcc/ada/sem_disp.adb
+++ b/gcc/ada/sem_disp.adb
@@ -1514,10 +1514,10 @@ package body Sem_Disp is
Subp);
else
-
-- The subprogram body declares a primitive operation.
-- We must update its dispatching information here. The
-- information is taken from the overridden subprogram.
+ -- Such a late-overriding body also needs extra formals.
-- We must also generate a cross-reference entry because
-- references to other primitives were already created
-- when type was frozen.
@@ -1527,6 +1527,7 @@ package body Sem_Disp is
if Present (DTC_Entity (Old_Subp)) then
Set_DTC_Entity (Subp, DTC_Entity (Old_Subp));
Set_DT_Position_Value (Subp, DT_Position (Old_Subp));
+ Create_Extra_Formals (Subp);
if not Restriction_Active (No_Dispatching_Calls) then
if Building_Static_DT (Tagged_Type) then
