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Commit f4c16c58 by Yannick Moy Committed by Pierre-Marie de Rodat
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[Ada] Refine pointer support in SPARK 

Refine the implementation of pointer support for SPARK analysis.

There is no impact on compilation.

2019-07-03  Yannick Moy  <moy@adacore.com>

gcc/ada/

	* sem_spark.adb (Get_Observed_Or_Borrowed_Expr): New function to
	return go through traversal function call.
	(Check_Type): Consistently use underlying type.
	(Get_Perm): Adapt for case of elaboration code where variables
	are not declared in the environment. Remove incorrect handling
	of borrow and observe.

From-SVN: r272981
parent abc856cf
Showing with 69 additions and 51 deletions
gcc/ada/ChangeLog
2019-07-03 Yannick Moy <moy@adacore.com>
* sem_spark.adb (Get_Observed_Or_Borrowed_Expr): New function to
return go through traversal function call.
(Check_Type): Consistently use underlying type.
(Get_Perm): Adapt for case of elaboration code where variables
are not declared in the environment. Remove incorrect handling
of borrow and observe.
2019-07-03 Hristian Kirtchev <kirtchev@adacore.com>
* inline.adb (Build_Return_Object_Formal): New routine.
......
gcc/ada/sem_spark.adb
......@@ -650,6 +650,12 @@ package body Sem_SPARK is
-- Check that type Typ is either not deep, or that it is an observing or
-- owning type according to SPARK RM 3.10
function Get_Observed_Or_Borrowed_Expr (Expr : Node_Id) return Node_Id;
pragma Precondition (Is_Path_Expression (Expr));
-- Return the expression being borrowed/observed when borrowing or
-- observing Expr. If Expr is a call to a traversal function, this is
-- the first actual, otherwise it is Expr.
function Get_Perm (N : Node_Or_Entity_Id) return Perm_Kind;
-- The function that takes a name as input and returns a permission
-- associated with it.
......@@ -999,15 +1005,9 @@ package body Sem_SPARK is
Expr : Node_Id;
Is_Decl : Boolean)
is
Borrowed : Node_Id;
Borrowed : constant Node_Id := Get_Observed_Or_Borrowed_Expr (Expr);
begin
if Is_Traversal_Function_Call (Expr) then
Borrowed := First_Actual (Expr);
else
Borrowed := Expr;
end if;
-- SPARK RM 3.10(8): If the type of the target is an anonymous
-- access-to-variable type (an owning access type), the source shall
-- be an owning access object [..] whose root object is the target
......@@ -1038,14 +1038,9 @@ package body Sem_SPARK is
Expr : Node_Id;
Is_Decl : Boolean)
is
Observed : Node_Id;
begin
if Is_Traversal_Function_Call (Expr) then
Observed := First_Actual (Expr);
else
Observed := Expr;
end if;
Observed : constant Node_Id := Get_Observed_Or_Borrowed_Expr (Expr);
begin
-- ??? We are currently using the same restriction for observers
-- as for borrowers. To be seen if the SPARK RM current rule really
-- allows more uses.
......@@ -1131,6 +1126,7 @@ package body Sem_SPARK is
-- name that is in the Unrestricted state, and whose root
-- object is the target object itself.
Check_Expression (Expr, Observe);
Handle_Observe (Target_Root, Expr, Is_Decl);
else
......@@ -1156,6 +1152,7 @@ package body Sem_SPARK is
end if;
end if;
Check_Expression (Expr, Borrow);
Handle_Borrow (Target_Root, Expr, Is_Decl);
end if;
......@@ -2973,46 +2970,52 @@ package body Sem_SPARK is
----------------
procedure Check_Type (Typ : Entity_Id) is
Check_Typ : constant Entity_Id := Underlying_Type (Typ);
begin
case Type_Kind'(Ekind (Underlying_Type (Typ))) is
case Type_Kind'(Ekind (Check_Typ)) is
when Access_Kind =>
case Access_Kind'(Ekind (Typ)) is
case Access_Kind'(Ekind (Underlying_Type (Check_Typ))) is
when E_Access_Type
| E_Anonymous_Access_Type
=>
null;
when E_Access_Subtype =>
Check_Type (Base_Type (Typ));
Check_Type (Base_Type (Check_Typ));
when E_Access_Attribute_Type =>
Error_Msg_N ("access attribute not allowed in SPARK", Typ);
Error_Msg_N ("access attribute not allowed in SPARK",
Check_Typ);
when E_Allocator_Type =>
Error_Msg_N ("missing type resolution", Typ);
Error_Msg_N ("missing type resolution", Check_Typ);
when E_General_Access_Type =>
Error_Msg_NE
("general access type & not allowed in SPARK", Typ, Typ);
("general access type & not allowed in SPARK",
Check_Typ, Check_Typ);
when Access_Subprogram_Kind =>
Error_Msg_NE
("access to subprogram type & not allowed in SPARK",
Typ, Typ);
Check_Typ, Check_Typ);
end case;
when E_Array_Type
| E_Array_Subtype
=>
Check_Type (Component_Type (Typ));
Check_Type (Component_Type (Check_Typ));
when Record_Kind =>
if Is_Deep (Typ)
and then (Is_Tagged_Type (Typ) or else Is_Class_Wide_Type (Typ))
if Is_Deep (Check_Typ)
and then (Is_Tagged_Type (Check_Typ)
or else Is_Class_Wide_Type (Check_Typ))
then
Error_Msg_NE
("tagged type & cannot be owning in SPARK", Typ, Typ);
("tagged type & cannot be owning in SPARK",
Check_Typ, Check_Typ);
else
declare
Comp : Entity_Id;
begin
Comp := First_Component_Or_Discriminant (Typ);
Comp := First_Component_Or_Discriminant (Check_Typ);
while Present (Comp) loop
Check_Type (Etype (Comp));
Next_Component_Or_Discriminant (Comp);
......@@ -3041,6 +3044,19 @@ package body Sem_SPARK is
end case;
end Check_Type;
-----------------------------------
-- Get_Observed_Or_Borrowed_Expr --
-----------------------------------
function Get_Observed_Or_Borrowed_Expr (Expr : Node_Id) return Node_Id is
begin
if Is_Traversal_Function_Call (Expr) then
return First_Actual (Expr);
else
return Expr;
end if;
end Get_Observed_Or_Borrowed_Expr;
--------------
-- Get_Perm --
--------------
......@@ -4067,7 +4083,7 @@ package body Sem_SPARK is
Expr_Type : constant Entity_Id := Etype (Expr);
Root : Entity_Id := Get_Root_Object (Expr);
Perm : Perm_Kind;
Perm : Perm_Kind_Option;
-- Start of processing for Process_Path
......@@ -4085,14 +4101,23 @@ package body Sem_SPARK is
Root := Unique_Entity (Root);
-- The root object should have been declared and entered into the
-- current permission environment.
-- Except during elaboration, the root object should have been declared
-- and entered into the current permission environment.
if Get (Current_Perm_Env, Root) = null then
if not Inside_Elaboration
and then Get (Current_Perm_Env, Root) = null
then
Illegal_Global_Usage (Expr);
end if;
Perm := Get_Perm (Expr);
-- During elaboration, only the validity of operations is checked, no
-- need to compute the permission of Expr.
if Inside_Elaboration then
Perm := None;
else
Perm := Get_Perm (Expr);
end if;
-- Check permissions
......@@ -4265,27 +4290,11 @@ package body Sem_SPARK is
Set_Perm_Prefixes_Assign (Expr);
end;
when Borrow =>
-- Set permission NO for the path and its extensions
declare
Tree : constant Perm_Tree_Access :=
Set_Perm_Prefixes (Expr, No_Access);
begin
Set_Perm_Extensions (Tree, No_Access);
end;
when Observe =>
-- Set permission R for the path and its extensions
-- Borrowing and observing of paths is handled by the variables
-- Current_Borrowers and Current_Observers.
declare
Tree : constant Perm_Tree_Access :=
Set_Perm_Prefixes (Expr, Read_Only);
begin
Set_Perm_Extensions (Tree, Read_Only);
end;
when Borrow | Observe =>
null;
end case;
end Process_Path;
......
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