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gcc/gcc/ada/sem_ch11.adb
Javier Miranda 8909e1edc6 sem_ch11.adb (Analyze_Exception_Handlers): Add barrier to avoid the use of entity Exception_Occurrence if... 
2007-04-20  Javier Miranda  <miranda@adacore.com>
	    Hristian Kirtchev  <kirtchev@adacore.com>
	    Gary Dismukes  <dismukes@adacore.com>

	* sem_ch11.adb (Analyze_Exception_Handlers): Add barrier to avoid the
	use of entity Exception_Occurrence if it is not available in the
	target run-time.

	* sem_ch9.adb (Analyze_Protected_Type, Analyze_Task_Type): When
	concurrent types are declared within an Ada 2005 generic, build their
	corresponding record types since they are needed for overriding-related
	semantic checks.
	(Analyze_Protected_Type): Rearrange and simplify code for testing that a
	protected type does not implement a task interface or a nonlimited
	interface.
	(Analyze_Task_Type): Rearrange and simplify code for testing that a task
	type does not implement a protected interface or a nonlimited interface.
	(Single_Task_Declaration, Single_Protected_Declaration): use original
	entity for variable declaration, to ensure that debugging information
	is correcty generated.
	(Analyze_Protected_Type, Analyze_Task_Type): Do not call expander
	routines if the expander is not active.
	(Analyze_Task_Body): Mark all handlers to stop optimization of local
	raise, since special things happen for task exception handlers.

	* sem_disp.adb (Check_Controlling_Formals): Add type retrieval for
	concurrent types declared within a generic.
	(Check_Dispatching_Operation): Do not emit warning about late interface
	operations in the context of an instance.
	(Check_Dispatching_Call): Remove restriction against calling a
	dispatching operation with a limited controlling result.
	(Check_Dispatching_Operation): Replace calls to Fill_DT_Entry and
	Register_Interface_DT_Entry by calls to Register_Primitive.
	(Check_Dispatching_Formals): Handle properly a function with a
	controlling access result.

From-SVN: r125448
2007-06-06 12:42:51 +02:00

567 lines
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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ C H 1 1 --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2007, 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 2, 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 COPYING. If not, write --
-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, USA. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Atree; use Atree;
with Checks; use Checks;
with Einfo; use Einfo;
with Errout; use Errout;
with Lib; use Lib;
with Lib.Xref; use Lib.Xref;
with Namet; use Namet;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
with Restrict; use Restrict;
with Rident; use Rident;
with Rtsfind; use Rtsfind;
with Sem; use Sem;
with Sem_Ch5; use Sem_Ch5;
with Sem_Ch8; use Sem_Ch8;
with Sem_Res; use Sem_Res;
with Sem_Util; use Sem_Util;
with Sem_Warn; use Sem_Warn;
with Sinfo; use Sinfo;
with Stand; use Stand;
with Uintp; use Uintp;
package body Sem_Ch11 is
-----------------------------------
-- Analyze_Exception_Declaration --
-----------------------------------
procedure Analyze_Exception_Declaration (N : Node_Id) is
Id : constant Entity_Id := Defining_Identifier (N);
PF : constant Boolean := Is_Pure (Current_Scope);
begin
Generate_Definition (Id);
Enter_Name (Id);
Set_Ekind (Id, E_Exception);
Set_Exception_Code (Id, Uint_0);
Set_Etype (Id, Standard_Exception_Type);
Set_Is_Statically_Allocated (Id);
Set_Is_Pure (Id, PF);
end Analyze_Exception_Declaration;
--------------------------------
-- Analyze_Exception_Handlers --
--------------------------------
procedure Analyze_Exception_Handlers (L : List_Id) is
Handler : Node_Id;
Choice : Entity_Id;
Id : Node_Id;
H_Scope : Entity_Id := Empty;
procedure Check_Duplication (Id : Node_Id);
-- Iterate through the identifiers in each handler to find duplicates
function Others_Present return Boolean;
-- Returns True if others handler is present
-----------------------
-- Check_Duplication --
-----------------------
procedure Check_Duplication (Id : Node_Id) is
Handler : Node_Id;
Id1 : Node_Id;
Id_Entity : Entity_Id := Entity (Id);
begin
if Present (Renamed_Entity (Id_Entity)) then
Id_Entity := Renamed_Entity (Id_Entity);
end if;
Handler := First_Non_Pragma (L);
while Present (Handler) loop
Id1 := First (Exception_Choices (Handler));
while Present (Id1) loop
-- Only check against the exception choices which precede
-- Id in the handler, since the ones that follow Id have not
-- been analyzed yet and will be checked in a subsequent call.
if Id = Id1 then
return;
elsif Nkind (Id1) /= N_Others_Choice
and then
(Id_Entity = Entity (Id1)
or else (Id_Entity = Renamed_Entity (Entity (Id1))))
then
if Handler /= Parent (Id) then
Error_Msg_Sloc := Sloc (Id1);
Error_Msg_NE
("exception choice duplicates &#", Id, Id1);
else
if Ada_Version = Ada_83
and then Comes_From_Source (Id)
then
Error_Msg_N
("(Ada 83): duplicate exception choice&", Id);
end if;
end if;
end if;
Next_Non_Pragma (Id1);
end loop;
Next (Handler);
end loop;
end Check_Duplication;
--------------------
-- Others_Present --
--------------------
function Others_Present return Boolean is
H : Node_Id;
begin
H := First (L);
while Present (H) loop
if Nkind (H) /= N_Pragma
and then Nkind (First (Exception_Choices (H))) = N_Others_Choice
then
return True;
end if;
Next (H);
end loop;
return False;
end Others_Present;
-- Start processing for Analyze_Exception_Handlers
begin
Handler := First (L);
Check_Restriction (No_Exceptions, Handler);
Check_Restriction (No_Exception_Handlers, Handler);
-- Kill current remembered values, since we don't know where we were
-- when the exception was raised.
Kill_Current_Values;
-- Loop through handlers (which can include pragmas)
while Present (Handler) loop
-- If pragma just analyze it
if Nkind (Handler) = N_Pragma then
Analyze (Handler);
-- Otherwise we have a real exception handler
else
-- Deal with choice parameter. The exception handler is a
-- declarative part for the choice parameter, so it constitutes a
-- scope for visibility purposes. We create an entity to denote
-- the whole exception part, and use it as the scope of all the
-- choices, which may even have the same name without conflict.
-- This scope plays no other role in expansion or or code
-- generation.
Choice := Choice_Parameter (Handler);
if Present (Choice) then
Set_Local_Raise_Not_OK (Handler);
if Comes_From_Source (Choice) then
Check_Restriction (No_Exception_Propagation, Choice);
end if;
if No (H_Scope) then
H_Scope :=
New_Internal_Entity
(E_Block, Current_Scope, Sloc (Choice), 'E');
end if;
Push_Scope (H_Scope);
Set_Etype (H_Scope, Standard_Void_Type);
-- Set the Finalization Chain entity to Error means that it
-- should not be used at that level but the parent one should
-- be used instead.
-- ??? this usage needs documenting in Einfo/Exp_Ch7 ???
-- ??? using Error for this non-error condition is nasty ???
Set_Finalization_Chain_Entity (H_Scope, Error);
Enter_Name (Choice);
Set_Ekind (Choice, E_Variable);
if RTE_Available (RE_Exception_Occurrence) then
Set_Etype (Choice, RTE (RE_Exception_Occurrence));
end if;
Generate_Definition (Choice);
-- Set source assigned flag, since in effect this field is
-- always assigned an initial value by the exception.
Set_Never_Set_In_Source (Choice, False);
end if;
Id := First (Exception_Choices (Handler));
while Present (Id) loop
if Nkind (Id) = N_Others_Choice then
if Present (Next (Id))
or else Present (Next (Handler))
or else Present (Prev (Id))
then
Error_Msg_N ("OTHERS must appear alone and last", Id);
end if;
else
Analyze (Id);
-- In most cases the choice has already been analyzed in
-- Analyze_Handled_Statement_Sequence, in order to expand
-- local handlers. This advance analysis does not take into
-- account the case in which a choice has the same name as
-- the choice parameter of the handler, which may hide an
-- outer exception. This pathological case appears in ACATS
-- B80001_3.adb, and requires an explicit check to verify
-- that the id is not hidden.
if not Is_Entity_Name (Id)
or else Ekind (Entity (Id)) /= E_Exception
or else
(Nkind (Id) = N_Identifier
and then Chars (Id) = Chars (Choice))
then
Error_Msg_N ("exception name expected", Id);
else
if Present (Renamed_Entity (Entity (Id))) then
if Entity (Id) = Standard_Numeric_Error then
Check_Restriction (No_Obsolescent_Features, Id);
if Warn_On_Obsolescent_Feature then
Error_Msg_N
("Numeric_Error is an " &
"obsolescent feature ('R'M 'J.6(1))?", Id);
Error_Msg_N
("\use Constraint_Error instead?", Id);
end if;
end if;
end if;
Check_Duplication (Id);
-- Check for exception declared within generic formal
-- package (which is illegal, see RM 11.2(8))
declare
Ent : Entity_Id := Entity (Id);
Scop : Entity_Id;
begin
if Present (Renamed_Entity (Ent)) then
Ent := Renamed_Entity (Ent);
end if;
Scop := Scope (Ent);
while Scop /= Standard_Standard
and then Ekind (Scop) = E_Package
loop
if Nkind (Declaration_Node (Scop)) =
N_Package_Specification
and then
Nkind (Original_Node (Parent
(Declaration_Node (Scop)))) =
N_Formal_Package_Declaration
then
Error_Msg_NE
("exception& is declared in " &
"generic formal package", Id, Ent);
Error_Msg_N
("\and therefore cannot appear in " &
"handler ('R'M 11.2(8))", Id);
exit;
-- If the exception is declared in an inner
-- instance, nothing else to check.
elsif Is_Generic_Instance (Scop) then
exit;
end if;
Scop := Scope (Scop);
end loop;
end;
end if;
end if;
Next (Id);
end loop;
-- Check for redundant handler (has only raise statement) and is
-- either an others handler, or is a specific handler when no
-- others handler is present.
if Warn_On_Redundant_Constructs
and then List_Length (Statements (Handler)) = 1
and then Nkind (First (Statements (Handler))) = N_Raise_Statement
and then No (Name (First (Statements (Handler))))
and then (not Others_Present
or else Nkind (First (Exception_Choices (Handler))) =
N_Others_Choice)
then
Error_Msg_N
("useless handler contains only a reraise statement?",
Handler);
end if;
-- Now analyze the statements of this handler
Analyze_Statements (Statements (Handler));
-- If a choice was present, we created a special scope for it,
-- so this is where we pop that special scope to get rid of it.
if Present (Choice) then
End_Scope;
end if;
end if;
Next (Handler);
end loop;
end Analyze_Exception_Handlers;
--------------------------------
-- Analyze_Handled_Statements --
--------------------------------
procedure Analyze_Handled_Statements (N : Node_Id) is
Handlers : constant List_Id := Exception_Handlers (N);
Handler : Node_Id;
Choice : Node_Id;
begin
if Present (Handlers) then
Kill_All_Checks;
end if;
-- We are now going to analyze the statements and then the exception
-- handlers. We certainly need to do things in this order to get the
-- proper sequential semantics for various warnings.
-- However, there is a glitch. When we process raise statements, an
-- optimization is to look for local handlers and specialize the code
-- in this case.
-- In order to detect if a handler is matching, we must have at least
-- analyzed the choices in the proper scope so that proper visibility
-- analysis is performed. Hence we analyze just the choices first,
-- before we analyze the statement sequence.
Handler := First_Non_Pragma (Handlers);
while Present (Handler) loop
Choice := First_Non_Pragma (Exception_Choices (Handler));
while Present (Choice) loop
Analyze (Choice);
Next_Non_Pragma (Choice);
end loop;
Next_Non_Pragma (Handler);
end loop;
-- Analyze statements in sequence
Analyze_Statements (Statements (N));
-- If the current scope is a subprogram, then this is the right place to
-- check for hanging useless assignments from the statement sequence of
-- the subprogram body.
if Is_Subprogram (Current_Scope) then
Warn_On_Useless_Assignments (Current_Scope);
end if;
-- Deal with handlers or AT END proc
if Present (Handlers) then
Analyze_Exception_Handlers (Handlers);
elsif Present (At_End_Proc (N)) then
Analyze (At_End_Proc (N));
end if;
end Analyze_Handled_Statements;
-----------------------------
-- Analyze_Raise_Statement --
-----------------------------
procedure Analyze_Raise_Statement (N : Node_Id) is
Exception_Id : constant Node_Id := Name (N);
Exception_Name : Entity_Id := Empty;
P : Node_Id;
Nkind_P : Node_Kind;
begin
Check_Unreachable_Code (N);
-- Check exception restrictions on the original source
if Comes_From_Source (N) then
Check_Restriction (No_Exceptions, N);
end if;
-- Check for useless assignment to OUT or IN OUT scalar immediately
-- preceding the raise. Right now we only look at assignment statements,
-- we could do more.
if Is_List_Member (N) then
declare
P : Node_Id;
L : Node_Id;
begin
P := Prev (N);
if Present (P)
and then Nkind (P) = N_Assignment_Statement
then
L := Name (P);
if Is_Scalar_Type (Etype (L))
and then Is_Entity_Name (L)
and then Is_Formal (Entity (L))
then
Error_Msg_N
("?assignment to pass-by-copy formal may have no effect",
P);
Error_Msg_N
("\?RAISE statement may result in abnormal return" &
" ('R'M 6.4.1(17))", P);
end if;
end if;
end;
end if;
-- Reraise statement
if No (Exception_Id) then
P := Parent (N);
Nkind_P := Nkind (P);
while Nkind_P /= N_Exception_Handler
and then Nkind_P /= N_Subprogram_Body
and then Nkind_P /= N_Package_Body
and then Nkind_P /= N_Task_Body
and then Nkind_P /= N_Entry_Body
loop
P := Parent (P);
Nkind_P := Nkind (P);
end loop;
if Nkind (P) /= N_Exception_Handler then
Error_Msg_N
("reraise statement must appear directly in a handler", N);
-- If a handler has a reraise, it cannot be the target of a local
-- raise (goto optimization is impossible), and if the no exception
-- propagation restriction is set, this is a violation.
else
Set_Local_Raise_Not_OK (P);
Check_Restriction (No_Exception_Propagation, N);
end if;
-- Normal case with exception id present
else
Analyze (Exception_Id);
if Is_Entity_Name (Exception_Id) then
Exception_Name := Entity (Exception_Id);
end if;
if No (Exception_Name)
or else Ekind (Exception_Name) /= E_Exception
then
Error_Msg_N
("exception name expected in raise statement", Exception_Id);
end if;
if Present (Expression (N)) then
Analyze_And_Resolve (Expression (N), Standard_String);
end if;
end if;
end Analyze_Raise_Statement;
-----------------------------
-- Analyze_Raise_xxx_Error --
-----------------------------
-- Normally, the Etype is already set (when this node is used within
-- an expression, since it is copied from the node which it rewrites).
-- If this node is used in a statement context, then we set the type
-- Standard_Void_Type. This is used both by Gigi and by the front end
-- to distinguish the statement use and the subexpression use.
-- The only other required processing is to take care of the Condition
-- field if one is present.
procedure Analyze_Raise_xxx_Error (N : Node_Id) is
begin
if No (Etype (N)) then
Set_Etype (N, Standard_Void_Type);
end if;
if Present (Condition (N)) then
Analyze_And_Resolve (Condition (N), Standard_Boolean);
end if;
-- Deal with static cases in obvious manner
if Nkind (Condition (N)) = N_Identifier then
if Entity (Condition (N)) = Standard_True then
Set_Condition (N, Empty);
elsif Entity (Condition (N)) = Standard_False then
Rewrite (N, Make_Null_Statement (Sloc (N)));
end if;
end if;
end Analyze_Raise_xxx_Error;
-----------------------------
-- Analyze_Subprogram_Info --
-----------------------------
procedure Analyze_Subprogram_Info (N : Node_Id) is
begin
Set_Etype (N, RTE (RE_Code_Loc));
end Analyze_Subprogram_Info;
end Sem_Ch11;
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