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[Ada] Spurious error on variable in private child package body

Message ID 20160427130549.GA78923@adacore.com
State New
Headers show

Commit Message

Arnaud Charlet April 27, 2016, 1:05 p.m. UTC
This patch modifies the contract freezing mechanism to suppress freezing when
the trigger is the body of an instantiated package. This effectively prevents
a spurious attempt to freeze because a) the body instantiation pass does not
have all semantic information and b) freezing has already taken place.

------------
-- Source --
------------

--  gp.ads

generic
   type T is private;

package GP with
   SPARK_Mode => On,
   Elaborate_Body,
   Abstract_State => (State,
                      (Atomic_State with External))
is
end GP;

--  gp.adb

package body GP with
   SPARK_Mode => On,
   Refined_State => (State        => GG1,
                     Atomic_State => GG2)
is
   GG1 : T;
   GG2 : T with Volatile;
end GP;

--  base.ads

package Base with
   SPARK_Mode => On
is
end Base;

--  base-a.ads

package Base.A with
   SPARK_Mode => On,
   Elaborate_Body,
   Abstract_State => (State,
                      (Atomic_State with External))
is
end Base.A;

--  base-a.adb

with Base.A.B;

package body Base.A with
   SPARK_Mode => On,
   Refined_State => (State        => Base.A.B.State,
                     Atomic_State => Base.A.B.Atomic_State)
is
end Base.A;

--  base-a-b.ads

private package Base.A.B with
   SPARK_Mode => On,
   Elaborate_Body,
   Abstract_State =>
     ((State        with           Part_Of => Base.A.State),
      (Atomic_State with External, Part_Of => Base.A.Atomic_State))
is
end Base.A.B;

--  base-a-b.adb

with GP; pragma Elaborate_All (GP);

package body Base.A.B with
   SPARK_Mode => On,
   Refined_State =>
     (State        => (G1, P.State),
      Atomic_State => P.Atomic_State)
is
   G1 : Boolean := False;

   package P is new GP (T => Boolean);
end Base.A.B;

-----------------
-- Compilation --
-----------------

$ gcc -c base-a-b.adb

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

2016-04-27  Hristian Kirtchev  <kirtchev@adacore.com>

	* sem_ch7.adb (Analyze_Package_Body_Helper): The body of an
	instantiated package should not cause freezing of previous contracts.
diff mbox

Patch

Index: sem_ch7.adb
===================================================================
--- sem_ch7.adb	(revision 235481)
+++ sem_ch7.adb	(working copy)
@@ -544,35 +544,6 @@ 
    --  Start of processing for Analyze_Package_Body_Helper
 
    begin
-      --  A [generic] package body "freezes" the contract of the nearest
-      --  enclosing package body and all other contracts encountered in the
-      --  same declarative part up to and excluding the package body:
-
-      --    package body Nearest_Enclosing_Package
-      --      with Refined_State => (State => Constit)
-      --    is
-      --       Constit : ...;
-
-      --       package body Freezes_Enclosing_Package_Body
-      --         with Refined_State => (State_2 => Constit_2)
-      --       is
-      --          Constit_2 : ...;
-
-      --          procedure Proc
-      --            with Refined_Depends => (Input => (Constit, Constit_2)) ...
-
-      --  This ensures that any annotations referenced by the contract of a
-      --  [generic] subprogram body declared within the current package body
-      --  are available. This form of "freezing" is decoupled from the usual
-      --  Freeze_xxx mechanism because it must also work in the context of
-      --  generics where normal freezing is disabled.
-
-      --  Only bodies coming from source should cause this type of "freezing"
-
-      if Comes_From_Source (N) then
-         Analyze_Previous_Contracts (N);
-      end if;
-
       --  Find corresponding package specification, and establish the current
       --  scope. The visible defining entity for the package is the defining
       --  occurrence in the spec. On exit from the package body, all body
@@ -628,6 +599,42 @@ 
          end if;
       end if;
 
+      --  A [generic] package body "freezes" the contract of the nearest
+      --  enclosing package body and all other contracts encountered in the
+      --  same declarative part up to and excluding the package body:
+
+      --    package body Nearest_Enclosing_Package
+      --      with Refined_State => (State => Constit)
+      --    is
+      --       Constit : ...;
+
+      --       package body Freezes_Enclosing_Package_Body
+      --         with Refined_State => (State_2 => Constit_2)
+      --       is
+      --          Constit_2 : ...;
+
+      --          procedure Proc
+      --            with Refined_Depends => (Input => (Constit, Constit_2)) ...
+
+      --  This ensures that any annotations referenced by the contract of a
+      --  [generic] subprogram body declared within the current package body
+      --  are available. This form of "freezing" is decoupled from the usual
+      --  Freeze_xxx mechanism because it must also work in the context of
+      --  generics where normal freezing is disabled.
+
+      --  Only bodies coming from source should cause this type of "freezing".
+      --  Instantiated generic bodies are excluded because their processing is
+      --  performed in a separate compilation pass which lacks enough semantic
+      --  information with respect to contract analysis. It is safe to suppress
+      --  the "freezing" of contracts in this case because this action already
+      --  took place at the end of the enclosing declarative part.
+
+      if Comes_From_Source (N)
+        and then not Is_Generic_Instance (Spec_Id)
+      then
+         Analyze_Previous_Contracts (N);
+      end if;
+
       --  A package body is Ghost when the corresponding spec is Ghost. Set
       --  the mode now to ensure that any nodes generated during analysis and
       --  expansion are properly flagged as ignored Ghost.