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|
------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- G H O S T --
-- --
-- B o d y --
-- --
-- Copyright (C) 2014-2015, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Alloc; use Alloc;
with Aspects; use Aspects;
with Atree; use Atree;
with Einfo; use Einfo;
with Elists; use Elists;
with Errout; use Errout;
with Lib; use Lib;
with Namet; use Namet;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
with Sem; use Sem;
with Sem_Aux; use Sem_Aux;
with Sem_Disp; use Sem_Disp;
with Sem_Eval; use Sem_Eval;
with Sem_Prag; use Sem_Prag;
with Sem_Res; use Sem_Res;
with Sem_Util; use Sem_Util;
with Sinfo; use Sinfo;
with Snames; use Snames;
with Table;
package body Ghost is
-- The following table contains the N_Compilation_Unit node for a unit that
-- is either subject to pragma Ghost with policy Ignore or contains ignored
-- Ghost code. The table is used in the removal of ignored Ghost code from
-- units.
package Ignored_Ghost_Units is new Table.Table (
Table_Component_Type => Node_Id,
Table_Index_Type => Int,
Table_Low_Bound => 0,
Table_Initial => Alloc.Ignored_Ghost_Units_Initial,
Table_Increment => Alloc.Ignored_Ghost_Units_Increment,
Table_Name => "Ignored_Ghost_Units");
-----------------------
-- Local Subprograms --
-----------------------
function Ghost_Entity (N : Node_Id) return Entity_Id;
-- Subsidiary to Check_Ghost_Context and Set_Ghost_Mode. Find the entity of
-- a reference to a Ghost entity. Return Empty if there is no such entity.
function Is_Subject_To_Ghost (N : Node_Id) return Boolean;
-- Subsidiary to routines Is_OK_xxx and Set_Ghost_Mode. Determine whether
-- declaration or body N is subject to aspect or pragma Ghost. Use this
-- routine in cases where [source] pragma Ghost has not been analyzed yet,
-- but the context needs to establish the "ghostness" of N.
procedure Propagate_Ignored_Ghost_Code (N : Node_Id);
-- Subsidiary to routines Mark_xxx_As_Ghost and Set_Ghost_Mode_From_xxx.
-- Signal all enclosing scopes that they now contain ignored Ghost code.
-- Add the compilation unit containing N to table Ignored_Ghost_Units for
-- post processing.
----------------------------
-- Add_Ignored_Ghost_Unit --
----------------------------
procedure Add_Ignored_Ghost_Unit (Unit : Node_Id) is
begin
pragma Assert (Nkind (Unit) = N_Compilation_Unit);
-- Avoid duplicates in the table as pruning the same unit more than once
-- is wasteful. Since ignored Ghost code tends to be grouped up, check
-- the contents of the table in reverse.
for Index in reverse Ignored_Ghost_Units.First ..
Ignored_Ghost_Units.Last
loop
-- If the unit is already present in the table, do not add it again
if Unit = Ignored_Ghost_Units.Table (Index) then
return;
end if;
end loop;
-- If we get here, then this is the first time the unit is being added
Ignored_Ghost_Units.Append (Unit);
end Add_Ignored_Ghost_Unit;
----------------------------
-- Check_Ghost_Completion --
----------------------------
procedure Check_Ghost_Completion
(Partial_View : Entity_Id;
Full_View : Entity_Id)
is
Policy : constant Name_Id := Policy_In_Effect (Name_Ghost);
begin
-- The Ghost policy in effect at the point of declaration and at the
-- point of completion must match (SPARK RM 6.9(14)).
if Is_Checked_Ghost_Entity (Partial_View)
and then Policy = Name_Ignore
then
Error_Msg_Sloc := Sloc (Full_View);
Error_Msg_N ("incompatible ghost policies in effect", Partial_View);
Error_Msg_N ("\& declared with ghost policy `Check`", Partial_View);
Error_Msg_N ("\& completed # with ghost policy `Ignore`",
Partial_View);
elsif Is_Ignored_Ghost_Entity (Partial_View)
and then Policy = Name_Check
then
Error_Msg_Sloc := Sloc (Full_View);
Error_Msg_N ("incompatible ghost policies in effect", Partial_View);
Error_Msg_N ("\& declared with ghost policy `Ignore`", Partial_View);
Error_Msg_N ("\& completed # with ghost policy `Check`",
Partial_View);
end if;
end Check_Ghost_Completion;
-------------------------
-- Check_Ghost_Context --
-------------------------
procedure Check_Ghost_Context (Ghost_Id : Entity_Id; Ghost_Ref : Node_Id) is
procedure Check_Ghost_Policy (Id : Entity_Id; Err_N : Node_Id);
-- Verify that the Ghost policy at the point of declaration of entity Id
-- matches the policy at the point of reference. If this is not the case
-- emit an error at Err_N.
function Is_OK_Ghost_Context (Context : Node_Id) return Boolean;
-- Determine whether node Context denotes a Ghost-friendly context where
-- a Ghost entity can safely reside (SPARK RM 6.9(10)).
-------------------------
-- Is_OK_Ghost_Context --
-------------------------
function Is_OK_Ghost_Context (Context : Node_Id) return Boolean is
function Is_OK_Declaration (Decl : Node_Id) return Boolean;
-- Determine whether node Decl is a suitable context for a reference
-- to a Ghost entity. To qualify as such, Decl must either
-- 1) Be subject to pragma Ghost
-- 2) Rename a Ghost entity
function Is_OK_Pragma (Prag : Node_Id) return Boolean;
-- Determine whether node Prag is a suitable context for a reference
-- to a Ghost entity. To qualify as such, Prag must either
-- 1) Be an assertion expression pragma
-- 2) Denote pragma Global, Depends, Initializes, Refined_Global,
-- Refined_Depends or Refined_State
-- 3) Specify an aspect of a Ghost entity
-- 4) Contain a reference to a Ghost entity
function Is_OK_Statement (Stmt : Node_Id) return Boolean;
-- Determine whether node Stmt is a suitable context for a reference
-- to a Ghost entity. To qualify as such, Stmt must either
-- 1) Denote a call to a Ghost procedure
-- 2) Denote an assignment statement whose target is Ghost
-----------------------
-- Is_OK_Declaration --
-----------------------
function Is_OK_Declaration (Decl : Node_Id) return Boolean is
function Is_Ghost_Renaming (Ren_Decl : Node_Id) return Boolean;
-- Determine whether node Ren_Decl denotes a renaming declaration
-- with a Ghost name.
-----------------------
-- Is_Ghost_Renaming --
-----------------------
function Is_Ghost_Renaming (Ren_Decl : Node_Id) return Boolean is
Nam_Id : Entity_Id;
begin
if Is_Renaming_Declaration (Ren_Decl) then
Nam_Id := Ghost_Entity (Name (Ren_Decl));
return Present (Nam_Id) and then Is_Ghost_Entity (Nam_Id);
end if;
return False;
end Is_Ghost_Renaming;
-- Local variables
Subp_Decl : Node_Id;
Subp_Id : Entity_Id;
-- Start of processing for Is_OK_Declaration
begin
if Is_Declaration (Decl) then
-- A renaming declaration is Ghost when it renames a Ghost
-- entity.
if Is_Ghost_Renaming (Decl) then
return True;
-- The declaration may not have been analyzed yet, determine
-- whether it is subject to pragma Ghost.
elsif Is_Subject_To_Ghost (Decl) then
return True;
end if;
-- Special cases
-- A reference to a Ghost entity may appear as the default
-- expression of a formal parameter of a subprogram body. This
-- context must be treated as suitable because the relation
-- between the spec and the body has not been established and
-- the body is not marked as Ghost yet. The real check was
-- performed on the spec.
elsif Nkind (Decl) = N_Parameter_Specification
and then Nkind (Parent (Parent (Decl))) = N_Subprogram_Body
then
return True;
-- References to Ghost entities may be relocated in internally
-- generated bodies.
elsif Nkind (Decl) = N_Subprogram_Body
and then not Comes_From_Source (Decl)
then
Subp_Id := Corresponding_Spec (Decl);
if Present (Subp_Id) then
-- The context is the internally built _Postconditions
-- procedure, which is OK because the real check was done
-- before expansion activities.
if Chars (Subp_Id) = Name_uPostconditions then
return True;
else
Subp_Decl :=
Original_Node (Unit_Declaration_Node (Subp_Id));
-- The original context is an expression function that
-- has been split into a spec and a body. The context is
-- OK as long as the initial declaration is Ghost.
if Nkind (Subp_Decl) = N_Expression_Function then
return Is_Subject_To_Ghost (Subp_Decl);
end if;
end if;
-- Otherwise this is either an internal body or an internal
-- completion. Both are OK because the real check was done
-- before expansion activities.
else
return True;
end if;
end if;
return False;
end Is_OK_Declaration;
------------------
-- Is_OK_Pragma --
------------------
function Is_OK_Pragma (Prag : Node_Id) return Boolean is
procedure Check_Policies (Prag_Nam : Name_Id);
-- Verify that the Ghost policy in effect is the same as the
-- assertion policy for pragma name Prag_Nam. Emit an error if
-- this is not the case.
--------------------
-- Check_Policies --
--------------------
procedure Check_Policies (Prag_Nam : Name_Id) is
AP : constant Name_Id := Check_Kind (Prag_Nam);
GP : constant Name_Id := Policy_In_Effect (Name_Ghost);
begin
-- If the Ghost policy in effect at the point of a Ghost entity
-- reference is Ignore, then the assertion policy of the pragma
-- must be Ignore (SPARK RM 6.9(18)).
if GP = Name_Ignore and then AP /= Name_Ignore then
Error_Msg_N
("incompatible ghost policies in effect",
Ghost_Ref);
Error_Msg_NE
("\ghost entity & has policy `Ignore`",
Ghost_Ref, Ghost_Id);
Error_Msg_Name_1 := AP;
Error_Msg_N
("\assertion expression has policy %", Ghost_Ref);
end if;
end Check_Policies;
-- Local variables
Arg : Node_Id;
Arg_Id : Entity_Id;
Prag_Id : Pragma_Id;
Prag_Nam : Name_Id;
-- Start of processing for Is_OK_Pragma
begin
if Nkind (Prag) = N_Pragma then
Prag_Id := Get_Pragma_Id (Prag);
Prag_Nam := Original_Aspect_Pragma_Name (Prag);
-- A pragma that applies to a Ghost construct or specifies an
-- aspect of a Ghost entity is a Ghost pragma (SPARK RM 6.9(3))
if Is_Ghost_Pragma (Prag) then
return True;
-- An assertion expression pragma is Ghost when it contains a
-- reference to a Ghost entity (SPARK RM 6.9(10)).
elsif Assertion_Expression_Pragma (Prag_Id) then
-- Ensure that the assertion policy and the Ghost policy are
-- compatible (SPARK RM 6.9(18)).
Check_Policies (Prag_Nam);
return True;
-- Several pragmas that may apply to a non-Ghost entity are
-- treated as Ghost when they contain a reference to a Ghost
-- entity (SPARK RM 6.9(11)).
elsif Nam_In (Prag_Nam, Name_Global,
Name_Depends,
Name_Initializes,
Name_Refined_Global,
Name_Refined_Depends,
Name_Refined_State)
then
return True;
-- Otherwise a normal pragma is Ghost when it encloses a Ghost
-- name (SPARK RM 6.9(3)).
else
Arg := First (Pragma_Argument_Associations (Prag));
while Present (Arg) loop
Arg_Id := Ghost_Entity (Get_Pragma_Arg (Arg));
if Present (Arg_Id) and then Is_Ghost_Entity (Arg_Id) then
return True;
end if;
Next (Arg);
end loop;
end if;
end if;
return False;
end Is_OK_Pragma;
---------------------
-- Is_OK_Statement --
---------------------
function Is_OK_Statement (Stmt : Node_Id) return Boolean is
Nam_Id : Entity_Id;
begin
-- An assignment statement or a procedure call is Ghost when the
-- name denotes a Ghost entity.
if Nkind_In (Stmt, N_Assignment_Statement,
N_Procedure_Call_Statement)
then
Nam_Id := Ghost_Entity (Name (Stmt));
return Present (Nam_Id) and then Is_Ghost_Entity (Nam_Id);
-- Special cases
-- An if statement is a suitable context for a Ghost entity if it
-- is the byproduct of assertion expression expansion. Note that
-- the assertion expression may not be related to a Ghost entity,
-- but it may still contain references to Ghost entities.
elsif Nkind (Stmt) = N_If_Statement
and then Nkind (Original_Node (Stmt)) = N_Pragma
and then Assertion_Expression_Pragma
(Get_Pragma_Id (Original_Node (Stmt)))
then
return True;
end if;
return False;
end Is_OK_Statement;
-- Local variables
Par : Node_Id;
-- Start of processing for Is_OK_Ghost_Context
begin
-- The context is Ghost when it appears within a Ghost package or
-- subprogram.
if Ghost_Mode > None then
return True;
-- Routine Expand_Record_Extension creates a parent subtype without
-- inserting it into the tree. There is no good way of recognizing
-- this special case as there is no parent. Try to approximate the
-- context.
elsif No (Parent (Context)) and then Is_Tagged_Type (Ghost_Id) then
return True;
-- Otherwise climb the parent chain looking for a suitable Ghost
-- context.
else
Par := Context;
while Present (Par) loop
if Is_Ignored_Ghost_Node (Par) then
return True;
-- A reference to a Ghost entity can appear within an aspect
-- specification (SPARK RM 6.9(10)).
elsif Nkind (Par) = N_Aspect_Specification then
return True;
elsif Is_OK_Declaration (Par) then
return True;
elsif Is_OK_Pragma (Par) then
return True;
elsif Is_OK_Statement (Par) then
return True;
-- Prevent the search from going too far
elsif Is_Body_Or_Package_Declaration (Par) then
exit;
end if;
Par := Parent (Par);
end loop;
-- The expansion of assertion expression pragmas and attribute Old
-- may cause a legal Ghost entity reference to become illegal due
-- to node relocation. Check the In_Assertion_Expr counter as last
-- resort to try and infer the original legal context.
if In_Assertion_Expr > 0 then
return True;
-- Otherwise the context is not suitable for a reference to a
-- Ghost entity.
else
return False;
end if;
end if;
end Is_OK_Ghost_Context;
------------------------
-- Check_Ghost_Policy --
------------------------
procedure Check_Ghost_Policy (Id : Entity_Id; Err_N : Node_Id) is
Policy : constant Name_Id := Policy_In_Effect (Name_Ghost);
begin
-- The Ghost policy in effect a the point of declaration and at the
-- point of use must match (SPARK RM 6.9(13)).
if Is_Checked_Ghost_Entity (Id) and then Policy = Name_Ignore then
Error_Msg_Sloc := Sloc (Err_N);
Error_Msg_N ("incompatible ghost policies in effect", Err_N);
Error_Msg_NE ("\& declared with ghost policy `Check`", Err_N, Id);
Error_Msg_NE ("\& used # with ghost policy `Ignore`", Err_N, Id);
elsif Is_Ignored_Ghost_Entity (Id) and then Policy = Name_Check then
Error_Msg_Sloc := Sloc (Err_N);
Error_Msg_N ("incompatible ghost policies in effect", Err_N);
Error_Msg_NE ("\& declared with ghost policy `Ignore`", Err_N, Id);
Error_Msg_NE ("\& used # with ghost policy `Check`", Err_N, Id);
end if;
end Check_Ghost_Policy;
-- Start of processing for Check_Ghost_Context
begin
-- Once it has been established that the reference to the Ghost entity
-- is within a suitable context, ensure that the policy at the point of
-- declaration and at the point of use match.
if Is_OK_Ghost_Context (Ghost_Ref) then
Check_Ghost_Policy (Ghost_Id, Ghost_Ref);
-- Otherwise the Ghost entity appears in a non-Ghost context and affects
-- its behavior or value (SPARK RM 6.9(11,12)).
else
Error_Msg_N ("ghost entity cannot appear in this context", Ghost_Ref);
end if;
end Check_Ghost_Context;
----------------------------
-- Check_Ghost_Overriding --
----------------------------
procedure Check_Ghost_Overriding
(Subp : Entity_Id;
Overridden_Subp : Entity_Id)
is
Deriv_Typ : Entity_Id;
Over_Subp : Entity_Id;
begin
if Present (Subp) and then Present (Overridden_Subp) then
Over_Subp := Ultimate_Alias (Overridden_Subp);
Deriv_Typ := Find_Dispatching_Type (Subp);
-- A Ghost primitive of a non-Ghost type extension cannot override an
-- inherited non-Ghost primitive (SPARK RM 6.9(8)).
if Is_Ghost_Entity (Subp)
and then Present (Deriv_Typ)
and then not Is_Ghost_Entity (Deriv_Typ)
and then not Is_Ghost_Entity (Over_Subp)
then
Error_Msg_N ("incompatible overriding in effect", Subp);
Error_Msg_Sloc := Sloc (Over_Subp);
Error_Msg_N ("\& declared # as non-ghost subprogram", Subp);
Error_Msg_Sloc := Sloc (Subp);
Error_Msg_N ("\overridden # with ghost subprogram", Subp);
end if;
-- A non-Ghost primitive of a type extension cannot override an
-- inherited Ghost primitive (SPARK RM 6.9(8)).
if not Is_Ghost_Entity (Subp)
and then Is_Ghost_Entity (Over_Subp)
then
Error_Msg_N ("incompatible overriding in effect", Subp);
Error_Msg_Sloc := Sloc (Over_Subp);
Error_Msg_N ("\& declared # as ghost subprogram", Subp);
Error_Msg_Sloc := Sloc (Subp);
Error_Msg_N ("\overridden # with non-ghost subprogram", Subp);
end if;
if Present (Deriv_Typ)
and then not Is_Ignored_Ghost_Entity (Deriv_Typ)
then
-- When a tagged type is either non-Ghost or checked Ghost and
-- one of its primitives overrides an inherited operation, the
-- overridden operation of the ancestor type must be ignored Ghost
-- if the primitive is ignored Ghost (SPARK RM 6.9(17)).
if Is_Ignored_Ghost_Entity (Subp) then
-- Both the parent subprogram and overriding subprogram are
-- ignored Ghost.
if Is_Ignored_Ghost_Entity (Over_Subp) then
null;
-- The parent subprogram carries policy Check
elsif Is_Checked_Ghost_Entity (Over_Subp) then
Error_Msg_N
("incompatible ghost policies in effect", Subp);
Error_Msg_Sloc := Sloc (Over_Subp);
Error_Msg_N
("\& declared # with ghost policy `Check`", Subp);
Error_Msg_Sloc := Sloc (Subp);
Error_Msg_N
("\overridden # with ghost policy `Ignore`", Subp);
-- The parent subprogram is non-Ghost
else
Error_Msg_N
("incompatible ghost policies in effect", Subp);
Error_Msg_Sloc := Sloc (Over_Subp);
Error_Msg_N ("\& declared # as non-ghost subprogram", Subp);
Error_Msg_Sloc := Sloc (Subp);
Error_Msg_N
("\overridden # with ghost policy `Ignore`", Subp);
end if;
-- When a tagged type is either non-Ghost or checked Ghost and
-- one of its primitives overrides an inherited operation, the
-- the primitive of the tagged type must be ignored Ghost if the
-- overridden operation is ignored Ghost (SPARK RM 6.9(17)).
elsif Is_Ignored_Ghost_Entity (Over_Subp) then
-- Both the parent subprogram and the overriding subprogram are
-- ignored Ghost.
if Is_Ignored_Ghost_Entity (Subp) then
null;
-- The overriding subprogram carries policy Check
elsif Is_Checked_Ghost_Entity (Subp) then
Error_Msg_N
("incompatible ghost policies in effect", Subp);
Error_Msg_Sloc := Sloc (Over_Subp);
Error_Msg_N
("\& declared # with ghost policy `Ignore`", Subp);
Error_Msg_Sloc := Sloc (Subp);
Error_Msg_N
("\overridden # with Ghost policy `Check`", Subp);
-- The overriding subprogram is non-Ghost
else
Error_Msg_N
("incompatible ghost policies in effect", Subp);
Error_Msg_Sloc := Sloc (Over_Subp);
Error_Msg_N
("\& declared # with ghost policy `Ignore`", Subp);
Error_Msg_Sloc := Sloc (Subp);
Error_Msg_N
("\overridden # with non-ghost subprogram", Subp);
end if;
end if;
end if;
end if;
end Check_Ghost_Overriding;
---------------------------
-- Check_Ghost_Primitive --
---------------------------
procedure Check_Ghost_Primitive (Prim : Entity_Id; Typ : Entity_Id) is
begin
-- The Ghost policy in effect at the point of declaration of a primitive
-- operation and a tagged type must match (SPARK RM 6.9(16)).
if Is_Tagged_Type (Typ) then
if Is_Checked_Ghost_Entity (Prim)
and then Is_Ignored_Ghost_Entity (Typ)
then
Error_Msg_N ("incompatible ghost policies in effect", Prim);
Error_Msg_Sloc := Sloc (Typ);
Error_Msg_NE
("\tagged type & declared # with ghost policy `Ignore`",
Prim, Typ);
Error_Msg_Sloc := Sloc (Prim);
Error_Msg_N
("\primitive subprogram & declared # with ghost policy `Check`",
Prim);
elsif Is_Ignored_Ghost_Entity (Prim)
and then Is_Checked_Ghost_Entity (Typ)
then
Error_Msg_N ("incompatible ghost policies in effect", Prim);
Error_Msg_Sloc := Sloc (Typ);
Error_Msg_NE
("\tagged type & declared # with ghost policy `Check`",
Prim, Typ);
Error_Msg_Sloc := Sloc (Prim);
Error_Msg_N
("\primitive subprogram & declared # with ghost policy `Ignore`",
Prim);
end if;
end if;
end Check_Ghost_Primitive;
----------------------------
-- Check_Ghost_Refinement --
----------------------------
procedure Check_Ghost_Refinement
(State : Node_Id;
State_Id : Entity_Id;
Constit : Node_Id;
Constit_Id : Entity_Id)
is
begin
if Is_Ghost_Entity (State_Id) then
if Is_Ghost_Entity (Constit_Id) then
-- The Ghost policy in effect at the point of abstract state
-- declaration and constituent must match (SPARK RM 6.9(15)).
if Is_Checked_Ghost_Entity (State_Id)
and then Is_Ignored_Ghost_Entity (Constit_Id)
then
Error_Msg_Sloc := Sloc (Constit);
SPARK_Msg_N ("incompatible ghost policies in effect", State);
SPARK_Msg_NE
("\abstract state & declared with ghost policy `Check`",
State, State_Id);
SPARK_Msg_NE
("\constituent & declared # with ghost policy `Ignore`",
State, Constit_Id);
elsif Is_Ignored_Ghost_Entity (State_Id)
and then Is_Checked_Ghost_Entity (Constit_Id)
then
Error_Msg_Sloc := Sloc (Constit);
SPARK_Msg_N ("incompatible ghost policies in effect", State);
SPARK_Msg_NE
("\abstract state & declared with ghost policy `Ignore`",
State, State_Id);
SPARK_Msg_NE
("\constituent & declared # with ghost policy `Check`",
State, Constit_Id);
end if;
-- A constituent of a Ghost abstract state must be a Ghost entity
-- (SPARK RM 7.2.2(12)).
else
SPARK_Msg_NE
("constituent of ghost state & must be ghost",
Constit, State_Id);
end if;
end if;
end Check_Ghost_Refinement;
------------------
-- Ghost_Entity --
------------------
function Ghost_Entity (N : Node_Id) return Entity_Id is
Ref : Node_Id;
begin
-- When the reference extracts a subcomponent, recover the related
-- object (SPARK RM 6.9(1)).
Ref := N;
while Nkind_In (Ref, N_Explicit_Dereference,
N_Indexed_Component,
N_Selected_Component,
N_Slice)
loop
Ref := Prefix (Ref);
end loop;
if Is_Entity_Name (Ref) then
return Entity (Ref);
else
return Empty;
end if;
end Ghost_Entity;
--------------------------------
-- Implements_Ghost_Interface --
--------------------------------
function Implements_Ghost_Interface (Typ : Entity_Id) return Boolean is
Iface_Elmt : Elmt_Id;
begin
-- Traverse the list of interfaces looking for a Ghost interface
if Is_Tagged_Type (Typ) and then Present (Interfaces (Typ)) then
Iface_Elmt := First_Elmt (Interfaces (Typ));
while Present (Iface_Elmt) loop
if Is_Ghost_Entity (Node (Iface_Elmt)) then
return True;
end if;
Next_Elmt (Iface_Elmt);
end loop;
end if;
return False;
end Implements_Ghost_Interface;
----------------
-- Initialize --
----------------
procedure Initialize is
begin
Ignored_Ghost_Units.Init;
end Initialize;
-------------------------
-- Is_Subject_To_Ghost --
-------------------------
function Is_Subject_To_Ghost (N : Node_Id) return Boolean is
function Enables_Ghostness (Arg : Node_Id) return Boolean;
-- Determine whether aspect or pragma argument Arg enables "ghostness"
-----------------------
-- Enables_Ghostness --
-----------------------
function Enables_Ghostness (Arg : Node_Id) return Boolean is
Expr : Node_Id;
begin
Expr := Arg;
if Nkind (Expr) = N_Pragma_Argument_Association then
Expr := Get_Pragma_Arg (Expr);
end if;
-- Determine whether the expression of the aspect or pragma is static
-- and denotes True.
if Present (Expr) then
Preanalyze_And_Resolve (Expr);
return
Is_OK_Static_Expression (Expr)
and then Is_True (Expr_Value (Expr));
-- Otherwise Ghost defaults to True
else
return True;
end if;
end Enables_Ghostness;
-- Local variables
Id : constant Entity_Id := Defining_Entity (N);
Asp : Node_Id;
Decl : Node_Id;
Prev_Id : Entity_Id;
-- Start of processing for Is_Subject_To_Ghost
begin
-- The related entity of the declaration has not been analyzed yet, do
-- not inspect its attributes.
if Ekind (Id) = E_Void then
null;
elsif Is_Ghost_Entity (Id) then
return True;
-- The completion of a type or a constant is not fully analyzed when the
-- reference to the Ghost entity is resolved. Because the completion is
-- not marked as Ghost yet, inspect the partial view.
elsif Is_Record_Type (Id)
or else Ekind (Id) = E_Constant
or else (Nkind (N) = N_Object_Declaration
and then Constant_Present (N))
then
Prev_Id := Incomplete_Or_Partial_View (Id);
if Present (Prev_Id) and then Is_Ghost_Entity (Prev_Id) then
return True;
end if;
end if;
-- Examine the aspect specifications (if any) looking for aspect Ghost
if Permits_Aspect_Specifications (N) then
Asp := First (Aspect_Specifications (N));
while Present (Asp) loop
if Chars (Identifier (Asp)) = Name_Ghost then
return Enables_Ghostness (Expression (Asp));
end if;
Next (Asp);
end loop;
end if;
Decl := Empty;
-- When the context is a [generic] package declaration, pragma Ghost
-- resides in the visible declarations.
if Nkind_In (N, N_Generic_Package_Declaration,
N_Package_Declaration)
then
Decl := First (Visible_Declarations (Specification (N)));
-- When the context is a package or a subprogram body, pragma Ghost
-- resides in the declarative part.
elsif Nkind_In (N, N_Package_Body, N_Subprogram_Body) then
Decl := First (Declarations (N));
-- Otherwise pragma Ghost appears in the declarations following N
elsif Is_List_Member (N) then
Decl := Next (N);
end if;
while Present (Decl) loop
if Nkind (Decl) = N_Pragma
and then Pragma_Name (Decl) = Name_Ghost
then
return
Enables_Ghostness (First (Pragma_Argument_Associations (Decl)));
-- A source construct ends the region where pragma Ghost may appear,
-- stop the traversal. Check the original node as source constructs
-- may be rewritten into something else by expansion.
elsif Comes_From_Source (Original_Node (Decl)) then
exit;
end if;
Next (Decl);
end loop;
return False;
end Is_Subject_To_Ghost;
----------
-- Lock --
----------
procedure Lock is
begin
Ignored_Ghost_Units.Locked := True;
Ignored_Ghost_Units.Release;
end Lock;
-----------------------------
-- Mark_Full_View_As_Ghost --
-----------------------------
procedure Mark_Full_View_As_Ghost
(Priv_Typ : Entity_Id;
Full_Typ : Entity_Id)
is
Full_Decl : constant Node_Id := Declaration_Node (Full_Typ);
begin
if Is_Checked_Ghost_Entity (Priv_Typ) then
Set_Is_Checked_Ghost_Entity (Full_Typ);
elsif Is_Ignored_Ghost_Entity (Priv_Typ) then
Set_Is_Ignored_Ghost_Entity (Full_Typ);
Set_Is_Ignored_Ghost_Node (Full_Decl);
Propagate_Ignored_Ghost_Code (Full_Decl);
end if;
end Mark_Full_View_As_Ghost;
--------------------------
-- Mark_Pragma_As_Ghost --
--------------------------
procedure Mark_Pragma_As_Ghost
(Prag : Node_Id;
Context_Id : Entity_Id)
is
begin
if Is_Checked_Ghost_Entity (Context_Id) then
Set_Is_Ghost_Pragma (Prag);
elsif Is_Ignored_Ghost_Entity (Context_Id) then
Set_Is_Ghost_Pragma (Prag);
Set_Is_Ignored_Ghost_Node (Prag);
Propagate_Ignored_Ghost_Code (Prag);
end if;
end Mark_Pragma_As_Ghost;
----------------------------
-- Mark_Renaming_As_Ghost --
----------------------------
procedure Mark_Renaming_As_Ghost
(Ren_Decl : Node_Id;
Nam_Id : Entity_Id)
is
Ren_Id : constant Entity_Id := Defining_Entity (Ren_Decl);
begin
if Is_Checked_Ghost_Entity (Nam_Id) then
Set_Is_Checked_Ghost_Entity (Ren_Id);
elsif Is_Ignored_Ghost_Entity (Nam_Id) then
Set_Is_Ignored_Ghost_Entity (Ren_Id);
Set_Is_Ignored_Ghost_Node (Ren_Decl);
Propagate_Ignored_Ghost_Code (Ren_Decl);
end if;
end Mark_Renaming_As_Ghost;
----------------------------------
-- Propagate_Ignored_Ghost_Code --
----------------------------------
procedure Propagate_Ignored_Ghost_Code (N : Node_Id) is
Nod : Node_Id;
Scop : Entity_Id;
begin
-- Traverse the parent chain looking for blocks, packages and
-- subprograms or their respective bodies.
Nod := Parent (N);
while Present (Nod) loop
Scop := Empty;
if Nkind (Nod) = N_Block_Statement then
Scop := Entity (Identifier (Nod));
elsif Nkind_In (Nod, N_Package_Body,
N_Package_Declaration,
N_Subprogram_Body,
N_Subprogram_Declaration)
then
Scop := Defining_Entity (Nod);
end if;
-- The current node denotes a scoping construct
if Present (Scop) then
-- Stop the traversal when the scope already contains ignored
-- Ghost code as all enclosing scopes have already been marked.
if Contains_Ignored_Ghost_Code (Scop) then
exit;
-- Otherwise mark this scope and keep climbing
else
Set_Contains_Ignored_Ghost_Code (Scop);
end if;
end if;
Nod := Parent (Nod);
end loop;
-- The unit containing the ignored Ghost code must be post processed
-- before invoking the back end.
Add_Ignored_Ghost_Unit (Cunit (Get_Code_Unit (N)));
end Propagate_Ignored_Ghost_Code;
-------------------------------
-- Remove_Ignored_Ghost_Code --
-------------------------------
procedure Remove_Ignored_Ghost_Code is
procedure Prune_Tree (Root : Node_Id);
-- Remove all code marked as ignored Ghost from the tree of denoted by
-- Root.
----------------
-- Prune_Tree --
----------------
procedure Prune_Tree (Root : Node_Id) is
procedure Prune (N : Node_Id);
-- Remove a given node from the tree by rewriting it into null
function Prune_Node (N : Node_Id) return Traverse_Result;
-- Determine whether node N denotes an ignored Ghost construct. If
-- this is the case, rewrite N as a null statement. See the body for
-- special cases.
-----------
-- Prune --
-----------
procedure Prune (N : Node_Id) is
begin
-- Destroy any aspects that may be associated with the node
if Permits_Aspect_Specifications (N) and then Has_Aspects (N) then
Remove_Aspects (N);
end if;
Rewrite (N, Make_Null_Statement (Sloc (N)));
end Prune;
----------------
-- Prune_Node --
----------------
function Prune_Node (N : Node_Id) return Traverse_Result is
Id : Entity_Id;
begin
-- The node is either declared as ignored Ghost or is a byproduct
-- of expansion. Destroy it and stop the traversal on this branch.
if Is_Ignored_Ghost_Node (N) then
Prune (N);
return Skip;
-- Scoping constructs such as blocks, packages, subprograms and
-- bodies offer some flexibility with respect to pruning.
elsif Nkind_In (N, N_Block_Statement,
N_Package_Body,
N_Package_Declaration,
N_Subprogram_Body,
N_Subprogram_Declaration)
then
if Nkind (N) = N_Block_Statement then
Id := Entity (Identifier (N));
else
Id := Defining_Entity (N);
end if;
-- The scoping construct contains both living and ignored Ghost
-- code, let the traversal prune all relevant nodes.
if Contains_Ignored_Ghost_Code (Id) then
return OK;
-- Otherwise the construct contains only living code and should
-- not be pruned.
else
return Skip;
end if;
-- Otherwise keep searching for ignored Ghost nodes
else
return OK;
end if;
end Prune_Node;
procedure Prune_Nodes is new Traverse_Proc (Prune_Node);
-- Start of processing for Prune_Tree
begin
Prune_Nodes (Root);
end Prune_Tree;
-- Start of processing for Remove_Ignored_Ghost_Code
begin
for Index in Ignored_Ghost_Units.First .. Ignored_Ghost_Units.Last loop
Prune_Tree (Unit (Ignored_Ghost_Units.Table (Index)));
end loop;
end Remove_Ignored_Ghost_Code;
--------------------
-- Set_Ghost_Mode --
--------------------
procedure Set_Ghost_Mode (N : Node_Id; Id : Entity_Id := Empty) is
procedure Set_From_Entity (Ent_Id : Entity_Id);
-- Set the value of global variable Ghost_Mode depending on the mode of
-- entity Ent_Id.
procedure Set_From_Policy;
-- Set the value of global variable Ghost_Mode depending on the current
-- Ghost policy in effect.
---------------------
-- Set_From_Entity --
---------------------
procedure Set_From_Entity (Ent_Id : Entity_Id) is
begin
Set_Ghost_Mode_From_Entity (Ent_Id);
if Is_Ignored_Ghost_Entity (Ent_Id) then
Set_Is_Ignored_Ghost_Node (N);
Propagate_Ignored_Ghost_Code (N);
end if;
end Set_From_Entity;
---------------------
-- Set_From_Policy --
---------------------
procedure Set_From_Policy is
Policy : constant Name_Id := Policy_In_Effect (Name_Ghost);
begin
if Policy = Name_Check then
Ghost_Mode := Check;
elsif Policy = Name_Ignore then
Ghost_Mode := Ignore;
Set_Is_Ignored_Ghost_Node (N);
Propagate_Ignored_Ghost_Code (N);
end if;
end Set_From_Policy;
-- Local variables
Nam_Id : Entity_Id;
-- Start of processing for Set_Ghost_Mode
begin
-- The input node denotes one of the many declaration kinds that may be
-- subject to pragma Ghost.
if Is_Declaration (N) then
if Is_Subject_To_Ghost (N) then
Set_From_Policy;
-- The declaration denotes the completion of a deferred constant,
-- pragma Ghost appears on the partial declaration.
elsif Nkind (N) = N_Object_Declaration
and then Constant_Present (N)
and then Present (Id)
then
Set_From_Entity (Id);
-- The declaration denotes the full view of a private type, pragma
-- Ghost appears on the partial declaration.
elsif Nkind (N) = N_Full_Type_Declaration
and then Is_Private_Type (Defining_Entity (N))
and then Present (Id)
then
Set_From_Entity (Id);
end if;
-- The input denotes an assignment or a procedure call. In this case
-- the Ghost mode is dictated by the name of the construct.
elsif Nkind_In (N, N_Assignment_Statement,
N_Procedure_Call_Statement)
then
Nam_Id := Ghost_Entity (Name (N));
if Present (Nam_Id) then
Set_From_Entity (Nam_Id);
end if;
-- The input denotes a package or subprogram body
elsif Nkind_In (N, N_Package_Body, N_Subprogram_Body) then
if (Present (Id) and then Is_Ghost_Entity (Id))
or else Is_Subject_To_Ghost (N)
then
Set_From_Policy;
end if;
-- The input denotes a pragma
elsif Nkind (N) = N_Pragma and then Is_Ghost_Pragma (N) then
if Is_Ignored_Ghost_Node (N) then
Ghost_Mode := Ignore;
else
Ghost_Mode := Check;
end if;
-- The input denotes a freeze node
elsif Nkind (N) = N_Freeze_Entity and then Present (Id) then
Set_From_Entity (Id);
end if;
end Set_Ghost_Mode;
--------------------------------
-- Set_Ghost_Mode_From_Entity --
--------------------------------
procedure Set_Ghost_Mode_From_Entity (Id : Entity_Id) is
begin
if Is_Checked_Ghost_Entity (Id) then
Ghost_Mode := Check;
elsif Is_Ignored_Ghost_Entity (Id) then
Ghost_Mode := Ignore;
end if;
end Set_Ghost_Mode_From_Entity;
-------------------------
-- Set_Is_Ghost_Entity --
-------------------------
procedure Set_Is_Ghost_Entity (Id : Entity_Id) is
Policy : constant Name_Id := Policy_In_Effect (Name_Ghost);
begin
if Policy = Name_Check then
Set_Is_Checked_Ghost_Entity (Id);
elsif Policy = Name_Ignore then
Set_Is_Ignored_Ghost_Entity (Id);
end if;
end Set_Is_Ghost_Entity;
end Ghost;
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