[gcc r12-1499] [Ada] Implementation of AI12-0152: legality rules for Raise_Expression

[gcc r12-1499] [Ada] Implementation of AI12-0152: legality rules for Raise_Expression

[Pierre-Marie de Rodat]

https://gcc.gnu.org/g:a2d2310d80ae992306f97764a850c56e70a1a8e3

commit r12-1499-ga2d2310d80ae992306f97764a850c56e70a1a8e3
Author: Ed Schonberg <schonberg@adacore.com>
Date:   Thu Feb 18 11:09:36 2021 -0500

    [Ada] Implementation of AI12-0152: legality rules for Raise_Expression
    
    gcc/ada/
    
            * sem_res.adb (Resolve_Raise_Expression): Apply Ada_2020 rules
            concerning the need for parentheses around Raise_Expressions in
            various contexts.

Diff:
---
 gcc/ada/sem_res.adb | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/gcc/ada/sem_res.adb b/gcc/ada/sem_res.adb
index a57038528ad..e043085fbb9 100644
--- a/gcc/ada/sem_res.adb
+++ b/gcc/ada/sem_res.adb
@@ -10532,8 +10532,57 @@ package body Sem_Res is
       if Typ = Raise_Type then
          Error_Msg_N ("cannot find unique type for raise expression", N);
          Set_Etype (N, Any_Type);
+
       else
          Set_Etype (N, Typ);
+
+         --  Apply check for required parentheses in the enclosing
+         --  context of raise_expressions (RM 11.3 (2)), including default
+         --  expressions in contexts that can include aspect specifications,
+         --  and ancestor parts of extension aggregates.
+
+         declare
+            Par : Node_Id := Parent (N);
+            Parentheses_Found : Boolean := Paren_Count (N) > 0;
+
+         begin
+            while Present (Par)
+              and then Nkind (Par) in N_Has_Etype
+            loop
+               if Paren_Count (Par) > 0 then
+                  Parentheses_Found := True;
+               end if;
+
+               if Nkind (Par) = N_Extension_Aggregate
+                 and then N = Ancestor_Part (Par)
+               then
+                  exit;
+               end if;
+
+               Par := Parent (Par);
+            end loop;
+
+            if not Parentheses_Found
+              and then Comes_From_Source (Par)
+              and then
+                ((Nkind (Par) in N_Modular_Type_Definition
+                               | N_Floating_Point_Definition
+                               | N_Ordinary_Fixed_Point_Definition
+                               | N_Decimal_Fixed_Point_Definition
+                               | N_Extension_Aggregate
+                               | N_Discriminant_Specification
+                               | N_Parameter_Specification
+                               | N_Formal_Object_Declaration)
+
+                  or else (Nkind (Par) = N_Object_Declaration
+                    and then
+                      Nkind (Parent (Par)) /= N_Extended_Return_Statement))
+            then
+               Error_Msg_N
+                 ("raise_expression must be parenthesized in this context",
+                   N);
+            end if;
+         end;
       end if;
    end Resolve_Raise_Expression;