[gcc r14-10868] ada: Fix internal error on concatenation of discriminant-dependent component

[Eric Botcazou via Gcc-cvs]

https://gcc.gnu.org/g:4f563063f93af3ecad5ee8e8a0c61c1753087dac

commit r14-10868-g4f563063f93af3ecad5ee8e8a0c61c1753087dac
Author: Eric Botcazou <ebotca...@adacore.com>
Date:   Fri Aug 16 16:03:30 2024 +0200

    ada: Fix internal error on concatenation of discriminant-dependent component
    
    This only occurs with optimization enabled, but the expanded code is always
    wrong because it reuses the formal parameter of an initialization procedure
    associated with a discriminant (a discriminal in GNAT parlance) outside of
    the initialization procedure.
    
    gcc/ada/
    
            * checks.adb (Selected_Length_Checks.Get_E_Length): For a
            component of a record with discriminants and if the expression is
            a selected component, try to build an actual subtype from its
            prefix instead of from the discriminal.

Diff:
---
 gcc/ada/checks.adb | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/checks.adb b/gcc/ada/checks.adb
index c81482a7b059..9c3c2fdd66c9 100644
--- a/gcc/ada/checks.adb
+++ b/gcc/ada/checks.adb
@@ -9800,7 +9800,15 @@ package body Checks is
          if Ekind (Scope (E)) = E_Record_Type
            and then Has_Discriminants (Scope (E))
          then
-            N := Build_Discriminal_Subtype_Of_Component (E);
+            --  If the expression is a selected component, in other words,
+            --  has a prefix, then build an actual subtype from the prefix.
+            --  Otherwise, build an actual subtype from the discriminal.
+
+            if Nkind (Expr) = N_Selected_Component then
+               N := Build_Actual_Subtype_Of_Component (E, Expr);
+            else
+               N := Build_Discriminal_Subtype_Of_Component (E);
+            end if;
 
             if Present (N) then
                Insert_Action (Expr, N);