[gcc r15-9816] ada: Error on subtype with static predicate used in case_expression

[Eric Botcazou]

https://gcc.gnu.org/g:a35f642d231baa62d6b28e5e5aaf3cc30425552c

commit r15-9816-ga35f642d231baa62d6b28e5e5aaf3cc30425552c
Author: Gary Dismukes <dismukes@adacore.com>
Date:   Sat Mar 22 00:01:52 2025 +0000

    ada: Error on subtype with static predicate used in case_expression
    
    The compiler improperly flags an error on the use of a subtype with a
    static predicate as a choice in a case expression alternative, complaining
    that the subtype has a nonstatic predicate. The fix for this is to add
    a test for the subtype not having a static predicate.
    
    gcc/ada/ChangeLog:
    
            * einfo.ads: Revise comment about Dynamic_Predicate flag to make it
            more accurate.
            * sem_case.adb (Check_Choices): Test "not Has_Static_Predicate_Aspect"
            as additional guard for error about use of subtype with nonstatic
            predicate as a case choice. Improve related error message.

Diff:
---
 gcc/ada/einfo.ads    | 2 +-
 gcc/ada/sem_case.adb | 8 +++++---
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/gcc/ada/einfo.ads b/gcc/ada/einfo.ads
index f154e7f0d763..7c05e532aea7 100644
--- a/gcc/ada/einfo.ads
+++ b/gcc/ada/einfo.ads
@@ -1623,7 +1623,7 @@ package Einfo is
 
 --    Has_Dynamic_Predicate_Aspect
 --       Defined in all types and subtypes. Set if a Dynamic_Predicate aspect
---       was explicitly applied to the type. Generally we treat predicates as
+--       was applied to the type or subtype. Generally we treat predicates as
 --       static if possible, regardless of whether they are specified using
 --       Predicate, Static_Predicate, or Dynamic_Predicate. And if a predicate
 --       can be treated as static (i.e. its expression is predicate-static),
diff --git a/gcc/ada/sem_case.adb b/gcc/ada/sem_case.adb
index 3399a41343e8..c81b56337f6a 100644
--- a/gcc/ada/sem_case.adb
+++ b/gcc/ada/sem_case.adb
@@ -3684,13 +3684,15 @@ package body Sem_Case is
                            --  Use of nonstatic predicate is an error
 
                            if not Is_Discrete_Type (E)
-                             or else not Has_Static_Predicate (E)
+                             or else (not Has_Static_Predicate (E)
+                                        and then
+                                      not Has_Static_Predicate_Aspect (E))
                              or else Has_Dynamic_Predicate_Aspect (E)
                              or else Has_Ghost_Predicate_Aspect (E)
                            then
                               Bad_Predicated_Subtype_Use
-                                ("cannot use subtype& with non-static "
-                                 & "predicate as case alternative",
+                                ("cannot use subtype& with nonstatic "
+                                 & "predicate as choice in case alternative",
                                  Choice, E, Suggest_Static => True);
 
                            --  Static predicate case. The bounds are those of