[gcc r12-6470] [Ada] Accept square brackets for expression functions

[Pierre-Marie de Rodat]

https://gcc.gnu.org/g:805655c137088519751e4ca18df722355a512d88

commit r12-6470-g805655c137088519751e4ca18df722355a512d88
Author: Etienne Servais <servais@adacore.com>
Date:   Mon Jan 3 14:41:58 2022 +0100

    [Ada] Accept square brackets for expression functions
    
    gcc/ada/
    
            * par-ch6.adb (Scan_Body_Or_Expression_Function): Accept left
            bracket as token to open an expression function.

Diff:
---
 gcc/ada/par-ch6.adb | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/par-ch6.adb b/gcc/ada/par-ch6.adb
index 1b3cf94af5c..d972eadbda5 100644
--- a/gcc/ada/par-ch6.adb
+++ b/gcc/ada/par-ch6.adb
@@ -841,7 +841,14 @@ package body Ch6 is
             begin
                --  Expression_Function case
 
-               if Token = Tok_Left_Paren
+               --  If likely an aggregate, check we are in Ada 2022 mode
+
+               if Token = Tok_Left_Bracket then
+                  Error_Msg_Ada_2022_Feature
+                    ("!aggregates as expression function", Token_Ptr);
+               end if;
+
+               if Token in Tok_Left_Paren | Tok_Left_Bracket
                  or else Likely_Expression_Function
                then
                   --  Check expression function allowed here