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

Message ID 20210616084355.GA94726@adacore.com
State New
Headers show
Series [Ada] Implementation of AI12-0152: legality rules for Raise_Expression | expand

Commit Message

Pierre-Marie de Rodat June 16, 2021, 8:43 a.m. UTC 
This patch implements the legality rules specified in RM 11.3 (2) for
the placement of Raise_Expressions. In Ada2020 aspect specifications can
appear in several new declarative contexts, and the keyword "with" can
be part of a Raise_Expression or the start of a list of aspect
specifications.  To prevent ambiguities a Raise_Expression in such
contexts must appear within parentheses, or be part of a larger
parenthesized expression.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* sem_res.adb (Resolve_Raise_Expression): Apply Ada_2020 rules
	concerning the need for parentheses around Raise_Expressions in
	various contexts.
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Patch

diff --git a/gcc/ada/sem_res.adb b/gcc/ada/sem_res.adb
--- 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;