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[Ada] Revert too late setting of Ekind on discriminants

Message ID 20200710094420.GA35375@adacore.com
State New
Headers show
Series [Ada] Revert too late setting of Ekind on discriminants | expand

Commit Message

Pierre-Marie de Rodat July 10, 2020, 9:44 a.m. UTC 
A recent patch enforced an existing comment in Is_Effectively_Volatile
with an assertion. To satisfy this assertion, it also set the Ekind on
discriminants earlier. However, a subtle prevention of cascaded errors
in routine Enter_Name relies on the Ekind of discriminants being set
late.

This patch reverts change to setting Ekind for discriminants and instead
detects effective volatility of a discriminant by directly looking at
its type.

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

gcc/ada/

	* sem_ch3.adb (Process_Discriminants): Revert recent change to
	location of Set_Ekind; detect effectively volatile discriminants
	by their type only.
diff mbox series

Patch

diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -19977,7 +19977,6 @@  package body Sem_Ch3 is
          end if;
 
          Set_Etype (Defining_Identifier (Discr), Discr_Type);
-         Set_Ekind (Defining_Identifier (Discr), E_Discriminant);
 
          --  If a discriminant specification includes the assignment compound
          --  delimiter followed by an expression, the expression is the default
@@ -20131,10 +20130,13 @@  package body Sem_Ch3 is
 
          --  A discriminant cannot be effectively volatile (SPARK RM 7.1.3(4)).
          --  This check is relevant only when SPARK_Mode is on as it is not a
-         --  standard Ada legality rule.
+         --  standard Ada legality rule. The only way for a discriminant to be
+         --  effectively volatile is to have an effectively volatile type, so
+         --  we check this directly, because the Ekind of Discr might not be
+         --  set yet (to help preventing cascaded errors on derived types).
 
          if SPARK_Mode = On
-           and then Is_Effectively_Volatile (Defining_Identifier (Discr))
+           and then Is_Effectively_Volatile (Discr_Type)
          then
             Error_Msg_N ("discriminant cannot be volatile", Discr);
          end if;
@@ -20176,6 +20178,7 @@  package body Sem_Ch3 is
       Discr_Number := Uint_1;
       while Present (Discr) loop
          Id := Defining_Identifier (Discr);
+         Set_Ekind (Id, E_Discriminant);
          Init_Component_Location (Id);
          Init_Esize (Id);
          Set_Discriminant_Number (Id, Discr_Number);