1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 2014-2016, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Alloc
; use Alloc
;
27 with Aspects
; use Aspects
;
28 with Atree
; use Atree
;
29 with Einfo
; use Einfo
;
30 with Elists
; use Elists
;
31 with Errout
; use Errout
;
33 with Namet
; use Namet
;
34 with Nlists
; use Nlists
;
35 with Nmake
; use Nmake
;
38 with Sem_Aux
; use Sem_Aux
;
39 with Sem_Disp
; use Sem_Disp
;
40 with Sem_Eval
; use Sem_Eval
;
41 with Sem_Prag
; use Sem_Prag
;
42 with Sem_Res
; use Sem_Res
;
43 with Sem_Util
; use Sem_Util
;
44 with Sinfo
; use Sinfo
;
45 with Snames
; use Snames
;
50 -- The following table contains the N_Compilation_Unit node for a unit that
51 -- is either subject to pragma Ghost with policy Ignore or contains ignored
52 -- Ghost code. The table is used in the removal of ignored Ghost code from
55 package Ignored_Ghost_Units
is new Table
.Table
(
56 Table_Component_Type
=> Node_Id
,
57 Table_Index_Type
=> Int
,
59 Table_Initial
=> Alloc
.Ignored_Ghost_Units_Initial
,
60 Table_Increment
=> Alloc
.Ignored_Ghost_Units_Increment
,
61 Table_Name
=> "Ignored_Ghost_Units");
63 -----------------------
64 -- Local Subprograms --
65 -----------------------
67 function Ghost_Entity
(N
: Node_Id
) return Entity_Id
;
68 -- Subsidiary to Check_Ghost_Context and Set_Ghost_Mode. Find the entity of
69 -- a reference to a Ghost entity. Return Empty if there is no such entity.
71 function Is_Subject_To_Ghost
(N
: Node_Id
) return Boolean;
72 -- Subsidiary to routines Is_OK_xxx and Set_Ghost_Mode. Determine whether
73 -- declaration or body N is subject to aspect or pragma Ghost. Use this
74 -- routine in cases where [source] pragma Ghost has not been analyzed yet,
75 -- but the context needs to establish the "ghostness" of N.
77 procedure Propagate_Ignored_Ghost_Code
(N
: Node_Id
);
78 -- Subsidiary to routines Mark_xxx_As_Ghost and Set_Ghost_Mode_From_xxx.
79 -- Signal all enclosing scopes that they now contain ignored Ghost code.
80 -- Add the compilation unit containing N to table Ignored_Ghost_Units for
83 ----------------------------
84 -- Add_Ignored_Ghost_Unit --
85 ----------------------------
87 procedure Add_Ignored_Ghost_Unit
(Unit
: Node_Id
) is
89 pragma Assert
(Nkind
(Unit
) = N_Compilation_Unit
);
91 -- Avoid duplicates in the table as pruning the same unit more than once
92 -- is wasteful. Since ignored Ghost code tends to be grouped up, check
93 -- the contents of the table in reverse.
95 for Index
in reverse Ignored_Ghost_Units
.First
..
96 Ignored_Ghost_Units
.Last
98 -- If the unit is already present in the table, do not add it again
100 if Unit
= Ignored_Ghost_Units
.Table
(Index
) then
105 -- If we get here, then this is the first time the unit is being added
107 Ignored_Ghost_Units
.Append
(Unit
);
108 end Add_Ignored_Ghost_Unit
;
110 ----------------------------
111 -- Check_Ghost_Completion --
112 ----------------------------
114 procedure Check_Ghost_Completion
115 (Partial_View
: Entity_Id
;
116 Full_View
: Entity_Id
)
118 Policy
: constant Name_Id
:= Policy_In_Effect
(Name_Ghost
);
121 -- The Ghost policy in effect at the point of declaration and at the
122 -- point of completion must match (SPARK RM 6.9(14)).
124 if Is_Checked_Ghost_Entity
(Partial_View
)
125 and then Policy
= Name_Ignore
127 Error_Msg_Sloc
:= Sloc
(Full_View
);
129 Error_Msg_N
("incompatible ghost policies in effect", Partial_View
);
130 Error_Msg_N
("\& declared with ghost policy `Check`", Partial_View
);
131 Error_Msg_N
("\& completed # with ghost policy `Ignore`",
134 elsif Is_Ignored_Ghost_Entity
(Partial_View
)
135 and then Policy
= Name_Check
137 Error_Msg_Sloc
:= Sloc
(Full_View
);
139 Error_Msg_N
("incompatible ghost policies in effect", Partial_View
);
140 Error_Msg_N
("\& declared with ghost policy `Ignore`", Partial_View
);
141 Error_Msg_N
("\& completed # with ghost policy `Check`",
144 end Check_Ghost_Completion
;
146 -------------------------
147 -- Check_Ghost_Context --
148 -------------------------
150 procedure Check_Ghost_Context
(Ghost_Id
: Entity_Id
; Ghost_Ref
: Node_Id
) is
151 procedure Check_Ghost_Policy
(Id
: Entity_Id
; Err_N
: Node_Id
);
152 -- Verify that the Ghost policy at the point of declaration of entity Id
153 -- matches the policy at the point of reference. If this is not the case
154 -- emit an error at Err_N.
156 function Is_OK_Ghost_Context
(Context
: Node_Id
) return Boolean;
157 -- Determine whether node Context denotes a Ghost-friendly context where
158 -- a Ghost entity can safely reside (SPARK RM 6.9(10)).
160 -------------------------
161 -- Is_OK_Ghost_Context --
162 -------------------------
164 function Is_OK_Ghost_Context
(Context
: Node_Id
) return Boolean is
165 function Is_OK_Declaration
(Decl
: Node_Id
) return Boolean;
166 -- Determine whether node Decl is a suitable context for a reference
167 -- to a Ghost entity. To qualify as such, Decl must either
168 -- 1) Be subject to pragma Ghost
169 -- 2) Rename a Ghost entity
171 function Is_OK_Pragma
(Prag
: Node_Id
) return Boolean;
172 -- Determine whether node Prag is a suitable context for a reference
173 -- to a Ghost entity. To qualify as such, Prag must either
174 -- 1) Be an assertion expression pragma
175 -- 2) Denote pragma Global, Depends, Initializes, Refined_Global,
176 -- Refined_Depends or Refined_State
177 -- 3) Specify an aspect of a Ghost entity
178 -- 4) Contain a reference to a Ghost entity
180 function Is_OK_Statement
(Stmt
: Node_Id
) return Boolean;
181 -- Determine whether node Stmt is a suitable context for a reference
182 -- to a Ghost entity. To qualify as such, Stmt must either
183 -- 1) Denote a call to a Ghost procedure
184 -- 2) Denote an assignment statement whose target is Ghost
186 -----------------------
187 -- Is_OK_Declaration --
188 -----------------------
190 function Is_OK_Declaration
(Decl
: Node_Id
) return Boolean is
191 function In_Subprogram_Body_Profile
(N
: Node_Id
) return Boolean;
192 -- Determine whether node N appears in the profile of a subprogram
195 function Is_Ghost_Renaming
(Ren_Decl
: Node_Id
) return Boolean;
196 -- Determine whether node Ren_Decl denotes a renaming declaration
197 -- with a Ghost name.
199 --------------------------------
200 -- In_Subprogram_Body_Profile --
201 --------------------------------
203 function In_Subprogram_Body_Profile
(N
: Node_Id
) return Boolean is
204 Spec
: constant Node_Id
:= Parent
(N
);
207 -- The node appears in a parameter specification in which case
208 -- it is either the parameter type or the default expression or
209 -- the node appears as the result definition of a function.
212 (Nkind
(N
) = N_Parameter_Specification
214 (Nkind
(Spec
) = N_Function_Specification
215 and then N
= Result_Definition
(Spec
)))
216 and then Nkind
(Parent
(Spec
)) = N_Subprogram_Body
;
217 end In_Subprogram_Body_Profile
;
219 -----------------------
220 -- Is_Ghost_Renaming --
221 -----------------------
223 function Is_Ghost_Renaming
(Ren_Decl
: Node_Id
) return Boolean is
227 if Is_Renaming_Declaration
(Ren_Decl
) then
228 Nam_Id
:= Ghost_Entity
(Name
(Ren_Decl
));
230 return Present
(Nam_Id
) and then Is_Ghost_Entity
(Nam_Id
);
234 end Is_Ghost_Renaming
;
241 -- Start of processing for Is_OK_Declaration
244 if Is_Declaration
(Decl
) then
246 -- A renaming declaration is Ghost when it renames a Ghost
249 if Is_Ghost_Renaming
(Decl
) then
252 -- The declaration may not have been analyzed yet, determine
253 -- whether it is subject to pragma Ghost.
255 elsif Is_Subject_To_Ghost
(Decl
) then
261 -- A reference to a Ghost entity may appear within the profile of
262 -- a subprogram body. This context is treated as suitable because
263 -- it duplicates the context of the corresponding spec. The real
264 -- check was already performed during the analysis of the spec.
266 elsif In_Subprogram_Body_Profile
(Decl
) then
269 -- A reference to a Ghost entity may appear within an expression
270 -- function which is still being analyzed. This context is treated
271 -- as suitable because it is not yet known whether the expression
272 -- function is an initial declaration or a completion. The real
273 -- check is performed when the expression function is expanded.
275 elsif Nkind
(Decl
) = N_Expression_Function
276 and then not Analyzed
(Decl
)
280 -- References to Ghost entities may be relocated in internally
283 elsif Nkind
(Decl
) = N_Subprogram_Body
284 and then not Comes_From_Source
(Decl
)
286 Subp_Id
:= Corresponding_Spec
(Decl
);
288 if Present
(Subp_Id
) then
290 -- The context is the internally built _Postconditions
291 -- procedure, which is OK because the real check was done
292 -- before expansion activities.
294 if Chars
(Subp_Id
) = Name_uPostconditions
then
299 Original_Node
(Unit_Declaration_Node
(Subp_Id
));
301 -- The original context is an expression function that
302 -- has been split into a spec and a body. The context is
303 -- OK as long as the initial declaration is Ghost.
305 if Nkind
(Subp_Decl
) = N_Expression_Function
then
306 return Is_Subject_To_Ghost
(Subp_Decl
);
310 -- Otherwise this is either an internal body or an internal
311 -- completion. Both are OK because the real check was done
312 -- before expansion activities.
320 end Is_OK_Declaration
;
326 function Is_OK_Pragma
(Prag
: Node_Id
) return Boolean is
327 procedure Check_Policies
(Prag_Nam
: Name_Id
);
328 -- Verify that the Ghost policy in effect is the same as the
329 -- assertion policy for pragma name Prag_Nam. Emit an error if
330 -- this is not the case.
336 procedure Check_Policies
(Prag_Nam
: Name_Id
) is
337 AP
: constant Name_Id
:= Check_Kind
(Prag_Nam
);
338 GP
: constant Name_Id
:= Policy_In_Effect
(Name_Ghost
);
341 -- If the Ghost policy in effect at the point of a Ghost entity
342 -- reference is Ignore, then the assertion policy of the pragma
343 -- must be Ignore (SPARK RM 6.9(18)).
345 if GP
= Name_Ignore
and then AP
/= Name_Ignore
then
347 ("incompatible ghost policies in effect",
350 ("\ghost entity & has policy `Ignore`",
351 Ghost_Ref
, Ghost_Id
);
353 Error_Msg_Name_1
:= AP
;
355 ("\assertion expression has policy %", Ghost_Ref
);
366 -- Start of processing for Is_OK_Pragma
369 if Nkind
(Prag
) = N_Pragma
then
370 Prag_Id
:= Get_Pragma_Id
(Prag
);
371 Prag_Nam
:= Original_Aspect_Pragma_Name
(Prag
);
373 -- A pragma that applies to a Ghost construct or specifies an
374 -- aspect of a Ghost entity is a Ghost pragma (SPARK RM 6.9(3))
376 if Is_Ghost_Pragma
(Prag
) then
379 -- An assertion expression pragma is Ghost when it contains a
380 -- reference to a Ghost entity (SPARK RM 6.9(10)).
382 elsif Assertion_Expression_Pragma
(Prag_Id
) then
384 -- Ensure that the assertion policy and the Ghost policy are
385 -- compatible (SPARK RM 6.9(18)).
387 Check_Policies
(Prag_Nam
);
390 -- Several pragmas that may apply to a non-Ghost entity are
391 -- treated as Ghost when they contain a reference to a Ghost
392 -- entity (SPARK RM 6.9(11)).
394 elsif Nam_In
(Prag_Nam
, Name_Global
,
398 Name_Refined_Depends
,
403 -- Otherwise a normal pragma is Ghost when it encloses a Ghost
404 -- name (SPARK RM 6.9(3)).
407 Arg
:= First
(Pragma_Argument_Associations
(Prag
));
408 while Present
(Arg
) loop
409 Arg_Id
:= Ghost_Entity
(Get_Pragma_Arg
(Arg
));
411 if Present
(Arg_Id
) and then Is_Ghost_Entity
(Arg_Id
) then
423 ---------------------
424 -- Is_OK_Statement --
425 ---------------------
427 function Is_OK_Statement
(Stmt
: Node_Id
) return Boolean is
431 -- An assignment statement or a procedure call is Ghost when the
432 -- name denotes a Ghost entity.
434 if Nkind_In
(Stmt
, N_Assignment_Statement
,
435 N_Procedure_Call_Statement
)
437 Nam_Id
:= Ghost_Entity
(Name
(Stmt
));
439 return Present
(Nam_Id
) and then Is_Ghost_Entity
(Nam_Id
);
443 -- An if statement is a suitable context for a Ghost entity if it
444 -- is the byproduct of assertion expression expansion. Note that
445 -- the assertion expression may not be related to a Ghost entity,
446 -- but it may still contain references to Ghost entities.
448 elsif Nkind
(Stmt
) = N_If_Statement
449 and then Nkind
(Original_Node
(Stmt
)) = N_Pragma
450 and then Assertion_Expression_Pragma
451 (Get_Pragma_Id
(Original_Node
(Stmt
)))
463 -- Start of processing for Is_OK_Ghost_Context
466 -- The context is Ghost when it appears within a Ghost package or
469 if Ghost_Mode
> None
then
472 -- Routine Expand_Record_Extension creates a parent subtype without
473 -- inserting it into the tree. There is no good way of recognizing
474 -- this special case as there is no parent. Try to approximate the
477 elsif No
(Parent
(Context
)) and then Is_Tagged_Type
(Ghost_Id
) then
480 -- Otherwise climb the parent chain looking for a suitable Ghost
485 while Present
(Par
) loop
486 if Is_Ignored_Ghost_Node
(Par
) then
489 -- A reference to a Ghost entity can appear within an aspect
490 -- specification (SPARK RM 6.9(10)).
492 elsif Nkind
(Par
) = N_Aspect_Specification
then
495 elsif Is_OK_Declaration
(Par
) then
498 elsif Is_OK_Pragma
(Par
) then
501 elsif Is_OK_Statement
(Par
) then
504 -- Prevent the search from going too far
506 elsif Is_Body_Or_Package_Declaration
(Par
) then
513 -- The expansion of assertion expression pragmas and attribute Old
514 -- may cause a legal Ghost entity reference to become illegal due
515 -- to node relocation. Check the In_Assertion_Expr counter as last
516 -- resort to try and infer the original legal context.
518 if In_Assertion_Expr
> 0 then
521 -- Otherwise the context is not suitable for a reference to a
528 end Is_OK_Ghost_Context
;
530 ------------------------
531 -- Check_Ghost_Policy --
532 ------------------------
534 procedure Check_Ghost_Policy
(Id
: Entity_Id
; Err_N
: Node_Id
) is
535 Policy
: constant Name_Id
:= Policy_In_Effect
(Name_Ghost
);
538 -- The Ghost policy in effect a the point of declaration and at the
539 -- point of use must match (SPARK RM 6.9(13)).
541 if Is_Checked_Ghost_Entity
(Id
) and then Policy
= Name_Ignore
then
542 Error_Msg_Sloc
:= Sloc
(Err_N
);
544 Error_Msg_N
("incompatible ghost policies in effect", Err_N
);
545 Error_Msg_NE
("\& declared with ghost policy `Check`", Err_N
, Id
);
546 Error_Msg_NE
("\& used # with ghost policy `Ignore`", Err_N
, Id
);
548 elsif Is_Ignored_Ghost_Entity
(Id
) and then Policy
= Name_Check
then
549 Error_Msg_Sloc
:= Sloc
(Err_N
);
551 Error_Msg_N
("incompatible ghost policies in effect", Err_N
);
552 Error_Msg_NE
("\& declared with ghost policy `Ignore`", Err_N
, Id
);
553 Error_Msg_NE
("\& used # with ghost policy `Check`", Err_N
, Id
);
555 end Check_Ghost_Policy
;
557 -- Start of processing for Check_Ghost_Context
560 -- Once it has been established that the reference to the Ghost entity
561 -- is within a suitable context, ensure that the policy at the point of
562 -- declaration and at the point of use match.
564 if Is_OK_Ghost_Context
(Ghost_Ref
) then
565 Check_Ghost_Policy
(Ghost_Id
, Ghost_Ref
);
567 -- Otherwise the Ghost entity appears in a non-Ghost context and affects
568 -- its behavior or value (SPARK RM 6.9(11,12)).
571 Error_Msg_N
("ghost entity cannot appear in this context", Ghost_Ref
);
573 end Check_Ghost_Context
;
575 ----------------------------
576 -- Check_Ghost_Overriding --
577 ----------------------------
579 procedure Check_Ghost_Overriding
581 Overridden_Subp
: Entity_Id
)
583 Deriv_Typ
: Entity_Id
;
584 Over_Subp
: Entity_Id
;
587 if Present
(Subp
) and then Present
(Overridden_Subp
) then
588 Over_Subp
:= Ultimate_Alias
(Overridden_Subp
);
589 Deriv_Typ
:= Find_Dispatching_Type
(Subp
);
591 -- A Ghost primitive of a non-Ghost type extension cannot override an
592 -- inherited non-Ghost primitive (SPARK RM 6.9(8)).
594 if Is_Ghost_Entity
(Subp
)
595 and then Present
(Deriv_Typ
)
596 and then not Is_Ghost_Entity
(Deriv_Typ
)
597 and then not Is_Ghost_Entity
(Over_Subp
)
599 Error_Msg_N
("incompatible overriding in effect", Subp
);
601 Error_Msg_Sloc
:= Sloc
(Over_Subp
);
602 Error_Msg_N
("\& declared # as non-ghost subprogram", Subp
);
604 Error_Msg_Sloc
:= Sloc
(Subp
);
605 Error_Msg_N
("\overridden # with ghost subprogram", Subp
);
608 -- A non-Ghost primitive of a type extension cannot override an
609 -- inherited Ghost primitive (SPARK RM 6.9(8)).
611 if not Is_Ghost_Entity
(Subp
)
612 and then Is_Ghost_Entity
(Over_Subp
)
614 Error_Msg_N
("incompatible overriding in effect", Subp
);
616 Error_Msg_Sloc
:= Sloc
(Over_Subp
);
617 Error_Msg_N
("\& declared # as ghost subprogram", Subp
);
619 Error_Msg_Sloc
:= Sloc
(Subp
);
620 Error_Msg_N
("\overridden # with non-ghost subprogram", Subp
);
623 if Present
(Deriv_Typ
)
624 and then not Is_Ignored_Ghost_Entity
(Deriv_Typ
)
626 -- When a tagged type is either non-Ghost or checked Ghost and
627 -- one of its primitives overrides an inherited operation, the
628 -- overridden operation of the ancestor type must be ignored Ghost
629 -- if the primitive is ignored Ghost (SPARK RM 6.9(17)).
631 if Is_Ignored_Ghost_Entity
(Subp
) then
633 -- Both the parent subprogram and overriding subprogram are
636 if Is_Ignored_Ghost_Entity
(Over_Subp
) then
639 -- The parent subprogram carries policy Check
641 elsif Is_Checked_Ghost_Entity
(Over_Subp
) then
643 ("incompatible ghost policies in effect", Subp
);
645 Error_Msg_Sloc
:= Sloc
(Over_Subp
);
647 ("\& declared # with ghost policy `Check`", Subp
);
649 Error_Msg_Sloc
:= Sloc
(Subp
);
651 ("\overridden # with ghost policy `Ignore`", Subp
);
653 -- The parent subprogram is non-Ghost
657 ("incompatible ghost policies in effect", Subp
);
659 Error_Msg_Sloc
:= Sloc
(Over_Subp
);
660 Error_Msg_N
("\& declared # as non-ghost subprogram", Subp
);
662 Error_Msg_Sloc
:= Sloc
(Subp
);
664 ("\overridden # with ghost policy `Ignore`", Subp
);
667 -- When a tagged type is either non-Ghost or checked Ghost and
668 -- one of its primitives overrides an inherited operation, the
669 -- the primitive of the tagged type must be ignored Ghost if the
670 -- overridden operation is ignored Ghost (SPARK RM 6.9(17)).
672 elsif Is_Ignored_Ghost_Entity
(Over_Subp
) then
674 -- Both the parent subprogram and the overriding subprogram are
677 if Is_Ignored_Ghost_Entity
(Subp
) then
680 -- The overriding subprogram carries policy Check
682 elsif Is_Checked_Ghost_Entity
(Subp
) then
684 ("incompatible ghost policies in effect", Subp
);
686 Error_Msg_Sloc
:= Sloc
(Over_Subp
);
688 ("\& declared # with ghost policy `Ignore`", Subp
);
690 Error_Msg_Sloc
:= Sloc
(Subp
);
692 ("\overridden # with Ghost policy `Check`", Subp
);
694 -- The overriding subprogram is non-Ghost
698 ("incompatible ghost policies in effect", Subp
);
700 Error_Msg_Sloc
:= Sloc
(Over_Subp
);
702 ("\& declared # with ghost policy `Ignore`", Subp
);
704 Error_Msg_Sloc
:= Sloc
(Subp
);
706 ("\overridden # with non-ghost subprogram", Subp
);
711 end Check_Ghost_Overriding
;
713 ---------------------------
714 -- Check_Ghost_Primitive --
715 ---------------------------
717 procedure Check_Ghost_Primitive
(Prim
: Entity_Id
; Typ
: Entity_Id
) is
719 -- The Ghost policy in effect at the point of declaration of a primitive
720 -- operation and a tagged type must match (SPARK RM 6.9(16)).
722 if Is_Tagged_Type
(Typ
) then
723 if Is_Checked_Ghost_Entity
(Prim
)
724 and then Is_Ignored_Ghost_Entity
(Typ
)
726 Error_Msg_N
("incompatible ghost policies in effect", Prim
);
728 Error_Msg_Sloc
:= Sloc
(Typ
);
730 ("\tagged type & declared # with ghost policy `Ignore`",
733 Error_Msg_Sloc
:= Sloc
(Prim
);
735 ("\primitive subprogram & declared # with ghost policy `Check`",
738 elsif Is_Ignored_Ghost_Entity
(Prim
)
739 and then Is_Checked_Ghost_Entity
(Typ
)
741 Error_Msg_N
("incompatible ghost policies in effect", Prim
);
743 Error_Msg_Sloc
:= Sloc
(Typ
);
745 ("\tagged type & declared # with ghost policy `Check`",
748 Error_Msg_Sloc
:= Sloc
(Prim
);
750 ("\primitive subprogram & declared # with ghost policy `Ignore`",
754 end Check_Ghost_Primitive
;
756 ----------------------------
757 -- Check_Ghost_Refinement --
758 ----------------------------
760 procedure Check_Ghost_Refinement
762 State_Id
: Entity_Id
;
764 Constit_Id
: Entity_Id
)
767 if Is_Ghost_Entity
(State_Id
) then
768 if Is_Ghost_Entity
(Constit_Id
) then
770 -- The Ghost policy in effect at the point of abstract state
771 -- declaration and constituent must match (SPARK RM 6.9(15)).
773 if Is_Checked_Ghost_Entity
(State_Id
)
774 and then Is_Ignored_Ghost_Entity
(Constit_Id
)
776 Error_Msg_Sloc
:= Sloc
(Constit
);
777 SPARK_Msg_N
("incompatible ghost policies in effect", State
);
780 ("\abstract state & declared with ghost policy `Check`",
783 ("\constituent & declared # with ghost policy `Ignore`",
786 elsif Is_Ignored_Ghost_Entity
(State_Id
)
787 and then Is_Checked_Ghost_Entity
(Constit_Id
)
789 Error_Msg_Sloc
:= Sloc
(Constit
);
790 SPARK_Msg_N
("incompatible ghost policies in effect", State
);
793 ("\abstract state & declared with ghost policy `Ignore`",
796 ("\constituent & declared # with ghost policy `Check`",
800 -- A constituent of a Ghost abstract state must be a Ghost entity
801 -- (SPARK RM 7.2.2(12)).
805 ("constituent of ghost state & must be ghost",
809 end Check_Ghost_Refinement
;
815 function Ghost_Entity
(N
: Node_Id
) return Entity_Id
is
819 -- When the reference extracts a subcomponent, recover the related
820 -- object (SPARK RM 6.9(1)).
823 while Nkind_In
(Ref
, N_Explicit_Dereference
,
825 N_Selected_Component
,
831 if Is_Entity_Name
(Ref
) then
838 --------------------------------
839 -- Implements_Ghost_Interface --
840 --------------------------------
842 function Implements_Ghost_Interface
(Typ
: Entity_Id
) return Boolean is
843 Iface_Elmt
: Elmt_Id
;
846 -- Traverse the list of interfaces looking for a Ghost interface
848 if Is_Tagged_Type
(Typ
) and then Present
(Interfaces
(Typ
)) then
849 Iface_Elmt
:= First_Elmt
(Interfaces
(Typ
));
850 while Present
(Iface_Elmt
) loop
851 if Is_Ghost_Entity
(Node
(Iface_Elmt
)) then
855 Next_Elmt
(Iface_Elmt
);
860 end Implements_Ghost_Interface
;
866 procedure Initialize
is
868 Ignored_Ghost_Units
.Init
;
871 -------------------------
872 -- Is_Subject_To_Ghost --
873 -------------------------
875 function Is_Subject_To_Ghost
(N
: Node_Id
) return Boolean is
876 function Enables_Ghostness
(Arg
: Node_Id
) return Boolean;
877 -- Determine whether aspect or pragma argument Arg enables "ghostness"
879 -----------------------
880 -- Enables_Ghostness --
881 -----------------------
883 function Enables_Ghostness
(Arg
: Node_Id
) return Boolean is
889 if Nkind
(Expr
) = N_Pragma_Argument_Association
then
890 Expr
:= Get_Pragma_Arg
(Expr
);
893 -- Determine whether the expression of the aspect or pragma is static
896 if Present
(Expr
) then
897 Preanalyze_And_Resolve
(Expr
);
900 Is_OK_Static_Expression
(Expr
)
901 and then Is_True
(Expr_Value
(Expr
));
903 -- Otherwise Ghost defaults to True
908 end Enables_Ghostness
;
912 Id
: constant Entity_Id
:= Defining_Entity
(N
);
917 -- Start of processing for Is_Subject_To_Ghost
920 -- The related entity of the declaration has not been analyzed yet, do
921 -- not inspect its attributes.
923 if Ekind
(Id
) = E_Void
then
926 elsif Is_Ghost_Entity
(Id
) then
929 -- The completion of a type or a constant is not fully analyzed when the
930 -- reference to the Ghost entity is resolved. Because the completion is
931 -- not marked as Ghost yet, inspect the partial view.
933 elsif Is_Record_Type
(Id
)
934 or else Ekind
(Id
) = E_Constant
935 or else (Nkind
(N
) = N_Object_Declaration
936 and then Constant_Present
(N
))
938 Prev_Id
:= Incomplete_Or_Partial_View
(Id
);
940 if Present
(Prev_Id
) and then Is_Ghost_Entity
(Prev_Id
) then
945 -- Examine the aspect specifications (if any) looking for aspect Ghost
947 if Permits_Aspect_Specifications
(N
) then
948 Asp
:= First
(Aspect_Specifications
(N
));
949 while Present
(Asp
) loop
950 if Chars
(Identifier
(Asp
)) = Name_Ghost
then
951 return Enables_Ghostness
(Expression
(Asp
));
960 -- When the context is a [generic] package declaration, pragma Ghost
961 -- resides in the visible declarations.
963 if Nkind_In
(N
, N_Generic_Package_Declaration
,
964 N_Package_Declaration
)
966 Decl
:= First
(Visible_Declarations
(Specification
(N
)));
968 -- When the context is a package or a subprogram body, pragma Ghost
969 -- resides in the declarative part.
971 elsif Nkind_In
(N
, N_Package_Body
, N_Subprogram_Body
) then
972 Decl
:= First
(Declarations
(N
));
974 -- Otherwise pragma Ghost appears in the declarations following N
976 elsif Is_List_Member
(N
) then
980 while Present
(Decl
) loop
981 if Nkind
(Decl
) = N_Pragma
982 and then Pragma_Name
(Decl
) = Name_Ghost
985 Enables_Ghostness
(First
(Pragma_Argument_Associations
(Decl
)));
987 -- A source construct ends the region where pragma Ghost may appear,
988 -- stop the traversal. Check the original node as source constructs
989 -- may be rewritten into something else by expansion.
991 elsif Comes_From_Source
(Original_Node
(Decl
)) then
999 end Is_Subject_To_Ghost
;
1007 Ignored_Ghost_Units
.Locked
:= True;
1008 Ignored_Ghost_Units
.Release
;
1011 -----------------------------
1012 -- Mark_Full_View_As_Ghost --
1013 -----------------------------
1015 procedure Mark_Full_View_As_Ghost
1016 (Priv_Typ
: Entity_Id
;
1017 Full_Typ
: Entity_Id
)
1019 Full_Decl
: constant Node_Id
:= Declaration_Node
(Full_Typ
);
1022 if Is_Checked_Ghost_Entity
(Priv_Typ
) then
1023 Set_Is_Checked_Ghost_Entity
(Full_Typ
);
1025 elsif Is_Ignored_Ghost_Entity
(Priv_Typ
) then
1026 Set_Is_Ignored_Ghost_Entity
(Full_Typ
);
1027 Set_Is_Ignored_Ghost_Node
(Full_Decl
);
1028 Propagate_Ignored_Ghost_Code
(Full_Decl
);
1030 end Mark_Full_View_As_Ghost
;
1032 --------------------------
1033 -- Mark_Pragma_As_Ghost --
1034 --------------------------
1036 procedure Mark_Pragma_As_Ghost
1038 Context_Id
: Entity_Id
)
1041 if Is_Checked_Ghost_Entity
(Context_Id
) then
1042 Set_Is_Ghost_Pragma
(Prag
);
1044 elsif Is_Ignored_Ghost_Entity
(Context_Id
) then
1045 Set_Is_Ghost_Pragma
(Prag
);
1046 Set_Is_Ignored_Ghost_Node
(Prag
);
1047 Propagate_Ignored_Ghost_Code
(Prag
);
1049 end Mark_Pragma_As_Ghost
;
1051 ----------------------------
1052 -- Mark_Renaming_As_Ghost --
1053 ----------------------------
1055 procedure Mark_Renaming_As_Ghost
1056 (Ren_Decl
: Node_Id
;
1059 Ren_Id
: constant Entity_Id
:= Defining_Entity
(Ren_Decl
);
1062 if Is_Checked_Ghost_Entity
(Nam_Id
) then
1063 Set_Is_Checked_Ghost_Entity
(Ren_Id
);
1065 elsif Is_Ignored_Ghost_Entity
(Nam_Id
) then
1066 Set_Is_Ignored_Ghost_Entity
(Ren_Id
);
1067 Set_Is_Ignored_Ghost_Node
(Ren_Decl
);
1068 Propagate_Ignored_Ghost_Code
(Ren_Decl
);
1070 end Mark_Renaming_As_Ghost
;
1072 ----------------------------------
1073 -- Propagate_Ignored_Ghost_Code --
1074 ----------------------------------
1076 procedure Propagate_Ignored_Ghost_Code
(N
: Node_Id
) is
1081 -- Traverse the parent chain looking for blocks, packages and
1082 -- subprograms or their respective bodies.
1085 while Present
(Nod
) loop
1088 if Nkind
(Nod
) = N_Block_Statement
then
1089 Scop
:= Entity
(Identifier
(Nod
));
1091 elsif Nkind_In
(Nod
, N_Package_Body
,
1092 N_Package_Declaration
,
1094 N_Subprogram_Declaration
)
1096 Scop
:= Defining_Entity
(Nod
);
1099 -- The current node denotes a scoping construct
1101 if Present
(Scop
) then
1103 -- Stop the traversal when the scope already contains ignored
1104 -- Ghost code as all enclosing scopes have already been marked.
1106 if Contains_Ignored_Ghost_Code
(Scop
) then
1109 -- Otherwise mark this scope and keep climbing
1112 Set_Contains_Ignored_Ghost_Code
(Scop
);
1116 Nod
:= Parent
(Nod
);
1119 -- The unit containing the ignored Ghost code must be post processed
1120 -- before invoking the back end.
1122 Add_Ignored_Ghost_Unit
(Cunit
(Get_Code_Unit
(N
)));
1123 end Propagate_Ignored_Ghost_Code
;
1125 -------------------------------
1126 -- Remove_Ignored_Ghost_Code --
1127 -------------------------------
1129 procedure Remove_Ignored_Ghost_Code
is
1130 procedure Prune_Tree
(Root
: Node_Id
);
1131 -- Remove all code marked as ignored Ghost from the tree of denoted by
1138 procedure Prune_Tree
(Root
: Node_Id
) is
1139 procedure Prune
(N
: Node_Id
);
1140 -- Remove a given node from the tree by rewriting it into null
1142 function Prune_Node
(N
: Node_Id
) return Traverse_Result
;
1143 -- Determine whether node N denotes an ignored Ghost construct. If
1144 -- this is the case, rewrite N as a null statement. See the body for
1151 procedure Prune
(N
: Node_Id
) is
1153 -- Destroy any aspects that may be associated with the node
1155 if Permits_Aspect_Specifications
(N
) and then Has_Aspects
(N
) then
1159 Rewrite
(N
, Make_Null_Statement
(Sloc
(N
)));
1166 function Prune_Node
(N
: Node_Id
) return Traverse_Result
is
1170 -- The node is either declared as ignored Ghost or is a byproduct
1171 -- of expansion. Destroy it and stop the traversal on this branch.
1173 if Is_Ignored_Ghost_Node
(N
) then
1177 -- A freeze node for an ignored ghost entity must be pruned as
1178 -- well, to prevent meaningless references in the back end.
1180 elsif Nkind
(N
) = N_Freeze_Entity
1181 and then Is_Ignored_Ghost_Entity
(Entity
(N
))
1186 -- Scoping constructs such as blocks, packages, subprograms and
1187 -- bodies offer some flexibility with respect to pruning.
1189 elsif Nkind_In
(N
, N_Block_Statement
,
1191 N_Package_Declaration
,
1193 N_Subprogram_Declaration
)
1195 if Nkind
(N
) = N_Block_Statement
then
1196 Id
:= Entity
(Identifier
(N
));
1198 Id
:= Defining_Entity
(N
);
1201 -- The scoping construct contains both living and ignored Ghost
1202 -- code, let the traversal prune all relevant nodes.
1204 if Contains_Ignored_Ghost_Code
(Id
) then
1207 -- Otherwise the construct contains only living code and should
1214 -- Otherwise keep searching for ignored Ghost nodes
1221 procedure Prune_Nodes
is new Traverse_Proc
(Prune_Node
);
1223 -- Start of processing for Prune_Tree
1229 -- Start of processing for Remove_Ignored_Ghost_Code
1232 for Index
in Ignored_Ghost_Units
.First
.. Ignored_Ghost_Units
.Last
loop
1233 Prune_Tree
(Unit
(Ignored_Ghost_Units
.Table
(Index
)));
1235 end Remove_Ignored_Ghost_Code
;
1237 --------------------
1238 -- Set_Ghost_Mode --
1239 --------------------
1241 procedure Set_Ghost_Mode
(N
: Node_Id
; Id
: Entity_Id
:= Empty
) is
1242 procedure Set_From_Entity
(Ent_Id
: Entity_Id
);
1243 -- Set the value of global variable Ghost_Mode depending on the mode of
1246 procedure Set_From_Policy
;
1247 -- Set the value of global variable Ghost_Mode depending on the current
1248 -- Ghost policy in effect.
1250 ---------------------
1251 -- Set_From_Entity --
1252 ---------------------
1254 procedure Set_From_Entity
(Ent_Id
: Entity_Id
) is
1256 Set_Ghost_Mode_From_Entity
(Ent_Id
);
1258 if Is_Ignored_Ghost_Entity
(Ent_Id
) then
1259 Set_Is_Ignored_Ghost_Node
(N
);
1260 Propagate_Ignored_Ghost_Code
(N
);
1262 end Set_From_Entity
;
1264 ---------------------
1265 -- Set_From_Policy --
1266 ---------------------
1268 procedure Set_From_Policy
is
1269 Policy
: constant Name_Id
:= Policy_In_Effect
(Name_Ghost
);
1272 if Policy
= Name_Check
then
1273 Ghost_Mode
:= Check
;
1275 elsif Policy
= Name_Ignore
then
1276 Ghost_Mode
:= Ignore
;
1278 Set_Is_Ignored_Ghost_Node
(N
);
1279 Propagate_Ignored_Ghost_Code
(N
);
1281 end Set_From_Policy
;
1287 -- Start of processing for Set_Ghost_Mode
1290 -- The input node denotes one of the many declaration kinds that may be
1291 -- subject to pragma Ghost.
1293 if Is_Declaration
(N
) then
1294 if Is_Subject_To_Ghost
(N
) then
1297 -- The declaration denotes the completion of a deferred constant,
1298 -- pragma Ghost appears on the partial declaration.
1300 elsif Nkind
(N
) = N_Object_Declaration
1301 and then Constant_Present
(N
)
1302 and then Present
(Id
)
1304 Set_From_Entity
(Id
);
1306 -- The declaration denotes the full view of a private type, pragma
1307 -- Ghost appears on the partial declaration.
1309 elsif Nkind
(N
) = N_Full_Type_Declaration
1310 and then Is_Private_Type
(Defining_Entity
(N
))
1311 and then Present
(Id
)
1313 Set_From_Entity
(Id
);
1316 -- The input denotes an assignment or a procedure call. In this case
1317 -- the Ghost mode is dictated by the name of the construct.
1319 elsif Nkind_In
(N
, N_Assignment_Statement
,
1320 N_Procedure_Call_Statement
)
1322 Nam_Id
:= Ghost_Entity
(Name
(N
));
1324 if Present
(Nam_Id
) then
1325 Set_From_Entity
(Nam_Id
);
1328 -- The input denotes a package or subprogram body
1330 elsif Nkind_In
(N
, N_Package_Body
, N_Subprogram_Body
) then
1331 if (Present
(Id
) and then Is_Ghost_Entity
(Id
))
1332 or else Is_Subject_To_Ghost
(N
)
1337 -- The input denotes a pragma
1339 elsif Nkind
(N
) = N_Pragma
and then Is_Ghost_Pragma
(N
) then
1340 if Is_Ignored_Ghost_Node
(N
) then
1341 Ghost_Mode
:= Ignore
;
1343 Ghost_Mode
:= Check
;
1346 -- The input denotes a freeze node
1348 elsif Nkind
(N
) = N_Freeze_Entity
and then Present
(Id
) then
1349 Set_From_Entity
(Id
);
1353 --------------------------------
1354 -- Set_Ghost_Mode_From_Entity --
1355 --------------------------------
1357 procedure Set_Ghost_Mode_From_Entity
(Id
: Entity_Id
) is
1359 if Is_Checked_Ghost_Entity
(Id
) then
1360 Ghost_Mode
:= Check
;
1361 elsif Is_Ignored_Ghost_Entity
(Id
) then
1362 Ghost_Mode
:= Ignore
;
1364 end Set_Ghost_Mode_From_Entity
;
1366 -------------------------
1367 -- Set_Is_Ghost_Entity --
1368 -------------------------
1370 procedure Set_Is_Ghost_Entity
(Id
: Entity_Id
) is
1371 Policy
: constant Name_Id
:= Policy_In_Effect
(Name_Ghost
);
1373 if Policy
= Name_Check
then
1374 Set_Is_Checked_Ghost_Entity
(Id
);
1375 elsif Policy
= Name_Ignore
then
1376 Set_Is_Ignored_Ghost_Entity
(Id
);
1378 end Set_Is_Ghost_Entity
;