[COMMITTED 23/30] ada: Error on instantiation of generic containing legal container aggregate

["Marc Poulhiès" <poulhies@adacore.com>]

From: Gary Dismukes <dismukes@adacore.com>

When a container aggregate for a predefined container type (such as
a Vector type) that has an iterated component association occurs within
a generic unit and that generic is instantiated, the compiler reports
a spurious error message "iterated component association can only appear
in an array aggregate" and the compilation aborts (because Unrecoverable_Error
is raised unconditionally after that error). The problem is that as part of
the instantiation process, for aggregates whose type has a partial view,
in Copy_Generic_Node the compiler switches the visibility so that the full
view of the type is available, and for a type whose full view is a record
type this leads to incorrectly trying to process the aggregate as a record
aggregate in Resolve_Aggregate (making a call to Resolve_Record_Aggregate).

Rather than trying to address this by changing what Copy_Generic_Node does,
this can be fixed by reordering and adjusting the code in Resolve_Aggregate,
so that we first test whether we need to resolve as a record aggregate
(if the aggregate is not homogeneous), followed by testing whether the
type has an Aggregate aspect and calling Resolve_Container_Aggregate.
As a bonus, we also remove the subsequent complex condition and redundant
code for handling null container aggregates.

gcc/ada/

	* sem_aggr.adb (Resolve_Aggregate): Move condition and call for
	Resolve_Record_Aggregate in front of code related to calling
	Resolve_Container_Aggregate (and add test that the aggregate
	is not homogeneous), and remove special-case testing and call
	to Resolve_Container_Aggregate for empty aggregates.

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

---
 gcc/ada/sem_aggr.adb | 22 +++++-----------------
 1 file changed, 5 insertions(+), 17 deletions(-)

diff --git a/gcc/ada/sem_aggr.adb b/gcc/ada/sem_aggr.adb
index 658b3a4634c..6e40e5c2564 100644
--- a/gcc/ada/sem_aggr.adb
+++ b/gcc/ada/sem_aggr.adb
@@ -1182,8 +1182,12 @@ package body Sem_Aggr is
       elsif Is_Array_Type (Typ) and then Null_Record_Present (N) then
          Error_Msg_N ("null record forbidden in array aggregate", N);
 
+      elsif Is_Record_Type (Typ)
+        and then not Is_Homogeneous_Aggregate (N)
+      then
+         Resolve_Record_Aggregate (N, Typ);
+
       elsif Has_Aspect (Typ, Aspect_Aggregate)
-        and then Ekind (Typ) /= E_Record_Type
         and then Ada_Version >= Ada_2022
       then
          --  Check for Ada 2022 and () aggregate.
@@ -1194,22 +1198,6 @@ package body Sem_Aggr is
 
          Resolve_Container_Aggregate (N, Typ);
 
-      --  Check Ada 2022 empty aggregate [] initializing a record type that has
-      --  aspect aggregate; the empty aggregate will be expanded into a call to
-      --  the empty function specified in the aspect aggregate.
-
-      elsif Has_Aspect (Typ, Aspect_Aggregate)
-        and then Ekind (Typ) = E_Record_Type
-        and then Is_Homogeneous_Aggregate (N)
-        and then Is_Empty_List (Expressions (N))
-        and then Is_Empty_List (Component_Associations (N))
-        and then Ada_Version >= Ada_2022
-      then
-         Resolve_Container_Aggregate (N, Typ);
-
-      elsif Is_Record_Type (Typ) then
-         Resolve_Record_Aggregate (N, Typ);
-
       elsif Is_Array_Type (Typ) then
 
          --  First a special test, for the case of a positional aggregate of
-- 
2.43.2