https://gcc.gnu.org/g:a74dff4d9d0b26e91d02acb81e9ed2e34d0d38e9

commit r15-683-ga74dff4d9d0b26e91d02acb81e9ed2e34d0d38e9
Author: Gary Dismukes <dismu...@adacore.com>
Date:   Tue Mar 26 22:36:02 2024 +0000

    ada: Error on instantiation of generic containing legal container aggregate
    
    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. Also, add error
            check for an attempt to use "[]" for an aggregate of a record type
            that does not specify an Aggregate aspect.
            (Resolve_Record_Aggregate): Remove error check for record
            aggregates with "[]" (now done by Resolve_Aggregate).

Diff:
---
 gcc/ada/sem_aggr.adb | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/gcc/ada/sem_aggr.adb b/gcc/ada/sem_aggr.adb
index 6e40e5c25649..60738550ec1f 100644
--- a/gcc/ada/sem_aggr.adb
+++ b/gcc/ada/sem_aggr.adb
@@ -1198,6 +1198,14 @@ package body Sem_Aggr is
 
          Resolve_Container_Aggregate (N, Typ);
 
+      --  Check for an attempt to use "[]" for an aggregate of a record type
+      --  after handling the case where the type has an Aggregate aspect,
+      --  because the aspect can be specified for record types, but if it
+      --  wasn't specified, then this is an error.
+
+      elsif Is_Record_Type (Typ) and then Is_Homogeneous_Aggregate (N) then
+         Error_Msg_N ("record aggregate must use (), not '[']", N);
+
       elsif Is_Array_Type (Typ) then
 
          --  First a special test, for the case of a positional aggregate of
@@ -5518,15 +5526,6 @@ package body Sem_Aggr is
          return;
       end if;
 
-      --  A record aggregate can only use parentheses
-
-      if Nkind (N) = N_Aggregate
-        and then Is_Homogeneous_Aggregate (N)
-      then
-         Error_Msg_N ("record aggregate must use (), not '[']", N);
-         return;
-      end if;
-
       --  STEP 2: Verify aggregate structure
 
       Step_2 : declare

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