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[Ada] Deallocation of a class-wide object with unknown discriminants

Message ID 20111123133316.GA30993@adacore.com
State New
Headers show

Commit Message

Arnaud Charlet Nov. 23, 2011, 1:33 p.m. UTC 
This patch corrects the creation of equivalent class-wide types for records
with unknown discriminants. Equivalent class-wide types are used by the back
end to determine the size of an object. As a result it is now possible to
deallocate a class-wide object whose root base type has unknown discriminants.

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

2011-11-23  Hristian Kirtchev  <kirtchev@adacore.com>

	* exp_intr.adb (Expand_Unc_Deallocation): Ensure that the
	dereference has a proper type before the side effect removal
	mechanism kicks in.
	* sem_ch3.adb (Analyze_Subtype_Declaration): Handle a rare case
	where the base type of the subtype is a private itype created
	to act as the partial view of a constrained record type. This
	scenario manifests with equivalent class-wide types for records
	with unknown discriminants.
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Patch

Index: sem_ch3.adb
===================================================================
--- sem_ch3.adb	(revision 181662)
+++ sem_ch3.adb	(working copy)
@@ -4064,6 +4064,19 @@ 
 
       T := Process_Subtype (Subtype_Indication (N), N, Id, 'P');
 
+      --  Class-wide equivalent types of records with unknown discriminants
+      --  involve the generation of an itype which serves as the private view
+      --  of a constrained record subtype. In such cases the base type of the
+      --  current subtype we are processing is the private itype. Use the full
+      --  of the private itype when decorating various attributes.
+
+      if Is_Itype (T)
+        and then Is_Private_Type (T)
+        and then Present (Full_View (T))
+      then
+         T := Full_View (T);
+      end if;
+
       --  Inherit common attributes
 
       Set_Is_Generic_Type   (Id, Is_Generic_Type   (Base_Type (T)));
Index: exp_intr.adb
===================================================================
--- exp_intr.adb	(revision 181662)
+++ exp_intr.adb	(working copy)
@@ -1123,6 +1123,10 @@ 
                D_Type   : Entity_Id;
 
             begin
+               --  Perform minor decoration as it is needed by the side effect
+               --  removal mechanism.
+
+               Set_Etype  (Deref, Desig_T);
                Set_Parent (Deref, Free_Node);
                D_Subtyp := Make_Subtype_From_Expr (Deref, Desig_T);