[Ada] Fix PR ada/121968

[Eric Botcazou]

This is a small regression present on the mainline and 15 branch: the compiler 
aborts on a use clause present in the formal part of a generic unit because of 
an oversight in the new inference code for generic actual parameters.  The fix 
also adds an unrelated missing test to Analyze_Dimension_Array_Aggregate.

Tested on x86-64/Linux, applied on the mainline and 15 branch.


2025-09-22  Eric Botcazou  <ebotca...@adacore.com>

        PR ada/121968
        * sem_ch12.adb (Associations.Find_Assoc): Add guard for clauses.
        * sem_dim.adb (Analyze_Dimension_Array_Aggregate): Add test for
        N_Iterated_Component_Association nodes.

-- 
Eric Botcazou
diff --git a/sem_ch12.adb b/sem_ch12.adb
index 0f1746f1ac5..f1f37509a7e 100644
--- a/sem_ch12.adb
+++ b/sem_ch12.adb
@@ -2067,9 +2067,15 @@ package body Sem_Ch12 is
       is
       begin
          for Index in Match.Assocs'Range loop
-            if Defining_Entity (Match.Assocs (Index).An_Formal) = F then
-               return Index;
-            end if;
+            declare
+               An_F : constant Node_Id := Match.Assocs (Index).An_Formal;
+            begin
+               if Nkind (An_F) not in N_Use_Package_Clause | N_Use_Type_Clause
+                 and then Defining_Entity (An_F) = F
+               then
+                  return Index;
+               end if;
+            end;
          end loop;
 
          raise Program_Error; -- it must be present
diff --git a/sem_dim.adb b/sem_dim.adb
index 139ed661f90..822c1284d53 100644
--- a/sem_dim.adb
+++ b/sem_dim.adb
@@ -1273,7 +1273,9 @@ package body Sem_Dim is
 
          --  Get the expression from the component
 
-         if Nkind (Comp) = N_Component_Association then
+         if Nkind (Comp) in N_Component_Association
+                          | N_Iterated_Component_Association
+         then
             Expr := Expression (Comp);
          else
             Expr := Comp;