[gcc r16-1323] ada: Do not build dispatch tables for generics

[Marc Poulhies]

https://gcc.gnu.org/g:31b7b7518e5842509e8fdbef6dc38e6a4ce28396

commit r16-1323-g31b7b7518e5842509e8fdbef6dc38e6a4ce28396
Author: Ronan Desplanques <desplanques@adacore.com>
Date:   Wed Mar 5 16:18:49 2025 +0100

    ada: Do not build dispatch tables for generics
    
    Before this patch, Build_Static_Dispatch_Tables was called on generic
    package bodies. While this has not been proved to cause any actual bug,
    it was clearly inappropriate and also useless, so this patch removes
    those calls.
    
    gcc/ada/ChangeLog:
    
            * sem_ch10.adb (Analyze_Compilation_Unit): Check for generic bodies.
            * exp_disp.adb (Build_Dispatch_Tables): Likewise.

Diff:
---
 gcc/ada/exp_disp.adb | 4 +++-
 gcc/ada/sem_ch10.adb | 8 +++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/exp_disp.adb b/gcc/ada/exp_disp.adb
index 458b32c1730e..080a2e1a6c16 100644
--- a/gcc/ada/exp_disp.adb
+++ b/gcc/ada/exp_disp.adb
@@ -413,7 +413,9 @@ package body Exp_Disp is
             if Nkind (D) = N_Package_Declaration then
                Build_Package_Dispatch_Tables (D);
 
-            elsif Nkind (D) = N_Package_Body then
+            elsif Nkind (D) = N_Package_Body
+              and then Ekind (Corresponding_Spec (D)) /= E_Generic_Package
+            then
                Build_Dispatch_Tables (Declarations (D));
 
             elsif Nkind (D) = N_Package_Body_Stub
diff --git a/gcc/ada/sem_ch10.adb b/gcc/ada/sem_ch10.adb
index 25bba9b60759..45aabadf21f8 100644
--- a/gcc/ada/sem_ch10.adb
+++ b/gcc/ada/sem_ch10.adb
@@ -1225,9 +1225,15 @@ package body Sem_Ch10 is
 
       if Expander_Active and then Tagged_Type_Expansion then
          case Nkind (Unit_Node) is
-            when N_Package_Declaration | N_Package_Body =>
+            when N_Package_Declaration =>
                Build_Static_Dispatch_Tables (Unit_Node);
 
+            when N_Package_Body =>
+               if Ekind (Corresponding_Spec (Unit_Node)) /= E_Generic_Package
+               then
+                  Build_Static_Dispatch_Tables (Unit_Node);
+               end if;
+
             when N_Package_Instantiation =>
                Build_Static_Dispatch_Tables (Instance_Spec (Unit_Node));