[COMMITTED] ada: ICE on BIP call in class-wide function return within instance

["Marc Poulhiès" <poulhies@adacore.com>]

From: Gary Dismukes <dismukes@adacore.com>

The compiler blows up (such as with a Storage_Error or Assert_Failure)
on a call to a limited build-in-place function occurring in the return
for a function with a limited class-wide result. Such a function
should include extra formals for a task master and activation chain
(because it's possible for a limited class-wide type to have values
with task parts), but when the enclosing function occurs within an
instantiation and the result subtype comes from a formal type, the
extra formals were missing for the enclosing function. As a result,
the attempt to retrieve the task master formal for passing along to
a BIP call in the return failed when calling Build_In_Place_Formal to
loop through the formals. When determining the need for the formals in
Create_Extra_Formals, Needs_BIP_Actual_Task_Actuals was returning False,
because Might_Have_Tasks incorrectly returned False due to the test
of Is_Limited_Record flag on the class-wide generic actual subtype's
Etype being False. Is_Limited_Record was not being properly inherited
by the class-wide type in the case of private extensions, because
Make_Class_Wide_Type was called in Analyze_Private_Extension_Declaration
before certain flags (such as Is_Limited_Record and Is_Controlled_Active)
are inherited later in Build_Derived_Record_Type (which will also call
Make_Class_Wide_Type). This is corrected by removing the early call
to Make_Class_Wide_Type.

gcc/ada/

	* exp_ch6.adb (Might_Have_Tasks): Remove unneeded Etype call from
	call to Is_Limited_Record, since that flag is now properly
	inherited by class-wide types.
	* sem_ch3.adb (Analyze_Private_Extension_Declaration): Remove call
	to Make_Class_Wide_Type, which is done too early, and will later
	be done in Build_Derived_Record_Type after flags such as
	Is_Limited_Record and Is_Controlled_Active have been set on the
	derived type.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/exp_ch6.adb | 2 +-
 gcc/ada/sem_ch3.adb | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/gcc/ada/exp_ch6.adb b/gcc/ada/exp_ch6.adb
index 28b746ba2c4..fce10d5e946 100644
--- a/gcc/ada/exp_ch6.adb
+++ b/gcc/ada/exp_ch6.adb
@@ -9326,7 +9326,7 @@ package body Exp_Ch6 is
         and then not No_Run_Time_Mode
         and then (Has_Task (Typ)
                     or else (Is_Class_Wide_Type (Typ)
-                               and then Is_Limited_Record (Etype (Typ))
+                               and then Is_Limited_Record (Typ)
                                and then not Has_Aspect
                                  (Etype (Typ), Aspect_No_Task_Parts)));
    end Might_Have_Tasks;
diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
index 50ccb390363..a0783195b8b 100644
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -5376,7 +5376,6 @@ package body Sem_Ch3 is
       Set_Convention       (T, Convention     (Parent_Type));
       Set_First_Rep_Item   (T, First_Rep_Item (Parent_Type));
       Set_Is_First_Subtype (T);
-      Make_Class_Wide_Type (T);
 
       --  Set the SPARK mode from the current context
 
-- 
2.40.0