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8sa1-gcc/gcc/ada/sem_warn.adb
Arnaud Charlet 15ce9ca22b [multiple changes] 
2004-07-06  Vincent Celier  <celier@gnat.com>

	* vms_conv.ads: Minor reformatting.
	Alphabetical order for enumerated values of type Command_Type, to have
	the command in alphabetical order for the usage.

	* vms_conv.adb (Process_Argument): Set Keep_Temporary_Files to True for
	the special qualifier /KEEP_TEMPORARY_FILES (minimum 6 characters).

	* gnat_ugn.texi: Document new switch -dn for the GNAT driver.

	* makegpr.adb (Global_Archive_Exists): New global Boolean variable
	(Add_Archive_Path): Only add the global archive if there is one.
	(Build_Global_Archive): Set Global_Archive_Exists depending if there is
	or not any object file to put in the global archive, and don't build
	a global archive if there is none.
	(X_Switches): New table
	(Compile_Link_With_Gnatmake): Pass to gnatmake the -X switches stored
	in the X_Switches table, if any.
	(Initialize): Make sure the X_Switches table is empty
	(Scan_Arg): Record -X switches in table X_Switches

	* opt.ads (Keep_Temporary_Files): New Boolean flag, defaulted to False.

	* make.adb: Minor comment fix

	* gnatname.adb (Gnatname): When not on VMS, and gnatname has been
	invoked with directory information, add the directory in front of the
	path.

	* gnatchop.adb (Gnatchop): When not on VMS, and gnatchop has been
	invoked with directory information, add the directory in front of the
	path.

	* gnatcmd.adb (Delete_Temp_Config_Files): Only delete temporary files
	when Keep_Temporary_Files is False.
	(GNATCmd): When not on VMS, and the GNAT driver has been invoked with
	directory information, add the directory in front of the path.
	When not on VMS, handle new switch -dn before the command to set
	Keep_Temporary_Files to True.
	(Non_VMS_Usage): Use lower case for the non VMS usage: this is valid
	everywhere.

	* gnatlink.adb (Gnatlink): When not on VMS, and gnatlink has been
	invoked with directory information, add the directory in front of the
	path.

2004-07-06  Thomas Quinot  <quinot@act-europe.fr>

	* snames.ads, snames.adb (Name_Stub): New name for the distributed
	systems annex.

	* rtsfind.ads: New RTE TC_Object, for DSA/PolyORB.
	New RTEs RAS_Proxy_Type and RAS_Proxy_Type_Access, for DSA.

	* g-socket.adb (To_Timeval): Fix incorrect conversion of
	Selector_Duration to Timeval for the case of 0.0.

	* exp_util.ads (Evolve_Or_Else): Fix overenthusiastic copy/paste of
	documentation from Evolve_And_Then.

2004-07-06  Jose Ruiz  <ruiz@act-europe.fr>

	* s-taprop-tru64.adb, s-taprop-os2.adb,
	s-taprop-mingw.adb, s-taprop-posix.adb: Update comment.

2004-07-06  Robert Dewar  <dewar@gnat.com>

	* s-osinte-hpux.ads, s-osinte-freebsd.ads,
	s-osinte-lynxos.ads, s-taprop-lynxos.adb, s-osinte-tru64.ads,
	s-osinte-aix.ads, s-osinte-irix.ads, s-taprop-irix.adb,
	s-interr-sigaction.adb, s-taprop-irix-athread.adb,
	s-osinte-hpux-dce.adb, s-taprop-hpux-dce.adb,
	s-taprop-linux.adb, s-taprop-dummy.adb, s-taprop-solaris.adb,
	s-interr-vms.adb, s-osinte-vms.ads, s-taprop-vms.adb,
	s-osinte-vxworks.ads, s-osprim-vxworks.adb, a-numaux-x86.adb,
	a-except.adb, a-exexpr.adb, a-intsig.adb, a-tags.adb,
	a-tags.ads, bindgen.ads, checks.adb, checks.adb,
	csets.ads, einfo.ads, einfo.ads, elists.adb, exp_ch4.adb,
	exp_ch7.adb, exp_dist.adb, exp_util.adb, freeze.adb,
	g-dynhta.adb, gnatmem.adb, g-regexp.adb, inline.adb,
	i-os2thr.ads, osint.adb, prj.adb, scng.adb, sem_cat.adb,
	sem_ch10.adb, sem_ch12.adb, sem_ch4.adb, sem_ch7.adb,
	sem_ch8.adb, sem_disp.adb, sem_prag.adb, sem_res.adb,
	sem_type.adb, sem_type.ads, sem_warn.adb, s-ficobl.ads,
	s-finimp.adb, s-htable.adb, sinfo.ads, sinput-l.ads,
	s-interr.adb, s-interr.ads, sprint.adb, s-tarest.adb,
	s-tasini.ads, s-taskin.ads, s-taskin.ads, uname.adb,
	vms_data.ads: Minor reformatting,
	Fix bad box comment format.

	* gnat_rm.texi: Fix minor grammatical error

	* sem_attr.adb, exp_attr.adb: New attribute Has_Access_Values

	* sem_util.ads, sem_util.adb (Requires_Transient_Scope): Allow many
	more cases of discriminated records to be recognized as not needing a
	secondary stack.
	(Has_Access_Values): New function.

	* snames.h, snames.adb, snames.ads: New attribute Has_Access_Values

	* cstand.adb, layout.ads, layout.adb, sem_ch13.ads: Change name
	Set_Prim_Alignment to Set_Elem_Alignment (more accurate correspondence
	with LRM terminology).
	Change terminology in comments primitive type => elementary type.

2004-07-06  Ed Schonberg  <schonberg@gnat.com>

	PR ada/15602
	* sem_ch7.adb (Unit_Requires_Body): For a generic package, the formal
	parameters do not impose any requirements on the presence of a body.

2004-07-06  Ed Schonberg  <schonberg@gnat.com>

	PR ada/15593
	* sem_ch12.adb (Analyze_Package_Instantiation): If the generic is not a
	compilation unit and is in an open scope at the point of instantiation,
	assume that a body may be present later.

2004-07-06  Ed Schonberg  <schonberg@gnat.com>

	* sem_ch13.adb (Analyze_Attribute_Definition_Clause, case 'Size):
	Improve error message when specified size is not supported.

	* sem_ch6.adb (Maybe_Primitive_Operation): A library-level subprogram
	is never a primitive operation.

From-SVN: r84152
2004-07-06 15:57:33 +02:00

1651 lines
62 KiB
Ada
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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ W A R N --
-- --
-- B o d y --
-- --
-- Copyright (C) 1999-2004 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, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Alloc;
with Atree; use Atree;
with Einfo; use Einfo;
with Errout; use Errout;
with Fname; use Fname;
with Lib; use Lib;
with Nlists; use Nlists;
with Opt; use Opt;
with Sem; use Sem;
with Sem_Ch8; use Sem_Ch8;
with Sem_Util; use Sem_Util;
with Sinfo; use Sinfo;
with Sinput; use Sinput;
with Snames; use Snames;
with Stand; use Stand;
with Table;
package body Sem_Warn is
-- The following table collects Id's of entities that are potentially
-- unreferenced. See Check_Unset_Reference for further details.
package Unreferenced_Entities is new Table.Table (
Table_Component_Type => Entity_Id,
Table_Index_Type => Nat,
Table_Low_Bound => 1,
Table_Initial => Alloc.Unreferenced_Entities_Initial,
Table_Increment => Alloc.Unreferenced_Entities_Increment,
Table_Name => "Unreferenced_Entities");
------------------------------
-- Handling of Conditionals --
------------------------------
-- Note: this is work in progress, the data structures and general
-- approach are defined, but are not in use yet. ???
-- One entry is made in the following table for each branch of
-- a conditional, e.g. an if-then-elsif-else-endif structure
-- creates three entries in this table.
type Branch_Entry is record
Sloc : Source_Ptr;
-- Location for warnings associated with this branch
Defs : Elist_Id;
-- List of entities defined for the first time in this branch. On
-- exit from a conditional structure, any entity that is in the
-- list of all branches is removed (and the entity flagged as
-- defined by the conditional as a whole). Thus after processing
-- a conditional, Defs contains a list of entities defined in this
-- branch for the first time, but not defined at all in some other
-- branch of the same conditional. A value of No_Elist is used to
-- represent the initial empty list.
Next : Nat;
-- Index of next branch for this conditional, zero = last branch
end record;
package Branch_Table is new Table.Table (
Table_Component_Type => Branch_Entry,
Table_Index_Type => Nat,
Table_Low_Bound => 1,
Table_Initial => Alloc.Branches_Initial,
Table_Increment => Alloc.Branches_Increment,
Table_Name => "Branches");
-- The following table is used to represent conditionals, there is
-- one entry in this table for each conditional structure.
type Conditional_Entry is record
If_Stmt : Boolean;
-- True for IF statement, False for CASE statement
First_Branch : Nat;
-- Index in Branch table of first branch, zero = none yet
Current_Branch : Nat;
-- Index in Branch table of current branch, zero = none yet
end record;
package Conditional_Table is new Table.Table (
Table_Component_Type => Conditional_Entry,
Table_Index_Type => Nat,
Table_Low_Bound => 1,
Table_Initial => Alloc.Conditionals_Initial,
Table_Increment => Alloc.Conditionals_Increment,
Table_Name => "Conditionals");
-- The following table is a stack that keeps track of the current
-- conditional. The Last entry is the top of the stack. An Empty
-- entry represents the start of a compilation unit. Non-zero
-- entries in the stack are indexes into the conditional table.
package Conditional_Stack is new Table.Table (
Table_Component_Type => Nat,
Table_Index_Type => Nat,
Table_Low_Bound => 1,
Table_Initial => Alloc.Conditional_Stack_Initial,
Table_Increment => Alloc.Conditional_Stack_Increment,
Table_Name => "Conditional_Stack");
pragma Warnings (Off, Branch_Table);
pragma Warnings (Off, Conditional_Table);
pragma Warnings (Off, Conditional_Stack);
-- Not yet referenced, see note above ???
-----------------------
-- Local Subprograms --
-----------------------
function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean;
-- This returns true if the entity E is declared within a generic package.
-- The point of this is to detect variables which are not assigned within
-- the generic, but might be assigned outside the package for any given
-- instance. These are cases where we leave the warnings to be posted
-- for the instance, when we will know more.
function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean;
-- This function traverses the expression tree represented by the node
-- N and determines if any sub-operand is a reference to an entity for
-- which the Warnings_Off flag is set. True is returned if such an
-- entity is encountered, and False otherwise.
----------------------
-- Check_References --
----------------------
procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
E1 : Entity_Id;
UR : Node_Id;
function Missing_Subunits return Boolean;
-- We suppress warnings when there are missing subunits, because this
-- may generate too many false positives: entities in a parent may
-- only be referenced in one of the subunits. We make an exception
-- for subunits that contain no other stubs.
procedure Output_Reference_Error (M : String);
-- Used to output an error message. Deals with posting the error on
-- the body formal in the accept case.
function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
-- This is true if the entity in question is potentially referenceable
-- from another unit. This is true for entities in packages that are
-- at the library level.
----------------------
-- Missing_Subunits --
----------------------
function Missing_Subunits return Boolean is
D : Node_Id;
begin
if not Unloaded_Subunits then
-- Normal compilation, all subunits are present
return False;
elsif E /= Main_Unit_Entity then
-- No warnings on a stub that is not the main unit
return True;
elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
D := First (Declarations (Unit_Declaration_Node (E)));
while Present (D) loop
-- No warnings if the proper body contains nested stubs
if Nkind (D) in N_Body_Stub then
return True;
end if;
Next (D);
end loop;
return False;
else
-- Missing stubs elsewhere
return True;
end if;
end Missing_Subunits;
----------------------------
-- Output_Reference_Error --
----------------------------
procedure Output_Reference_Error (M : String) is
begin
-- Other than accept case, post error on defining identifier
if No (Anod) then
Error_Msg_N (M, E1);
-- Accept case, find body formal to post the message
else
declare
Parm : Node_Id;
Enod : Node_Id;
Defid : Entity_Id;
begin
Enod := Anod;
if Present (Parameter_Specifications (Anod)) then
Parm := First (Parameter_Specifications (Anod));
while Present (Parm) loop
Defid := Defining_Identifier (Parm);
if Chars (E1) = Chars (Defid) then
Enod := Defid;
exit;
end if;
Next (Parm);
end loop;
end if;
Error_Msg_NE (M, Enod, E1);
end;
end if;
end Output_Reference_Error;
----------------------------
-- Publicly_Referenceable --
----------------------------
function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
P : Node_Id;
Prev : Node_Id;
begin
-- Examine parents to look for a library level package spec
-- But if we find a body or block or other similar construct
-- along the way, we cannot be referenced.
Prev := Ent;
P := Parent (Ent);
loop
case Nkind (P) is
-- If we get to top of tree, then publicly referenceable
when N_Empty =>
return True;
-- If we reach a generic package declaration, then always
-- consider this referenceable, since any instantiation will
-- have access to the entities in the generic package. Note
-- that the package itself may not be instantiated, but then
-- we will get a warning for the package entity
-- Note that generic formal parameters are themselves not
-- publicly referenceable in an instance, and warnings on
-- them are useful.
when N_Generic_Package_Declaration =>
return
not Is_List_Member (Prev)
or else List_Containing (Prev)
/= Generic_Formal_Declarations (P);
-- if we reach a subprogram body, entity is not referenceable
-- unless it is the defining entity of the body. This will
-- happen, e.g. when a function is an attribute renaming that
-- is rewritten as a body.
when N_Subprogram_Body =>
if Ent /= Defining_Entity (P) then
return False;
else
P := Parent (P);
end if;
-- If we reach any other body, definitely not referenceable
when N_Package_Body |
N_Task_Body |
N_Entry_Body |
N_Protected_Body |
N_Block_Statement |
N_Subunit =>
return False;
-- For all other cases, keep looking up tree
when others =>
Prev := P;
P := Parent (P);
end case;
end loop;
end Publicly_Referenceable;
-- Start of processing for Check_References
begin
-- No messages if warnings are suppressed, or if we have detected
-- any real errors so far (this last check avoids junk messages
-- resulting from errors, e.g. a subunit that is not loaded).
if Warning_Mode = Suppress
or else Serious_Errors_Detected /= 0
then
return;
end if;
-- We also skip the messages if any subunits were not loaded (see
-- comment in Sem_Ch10 to understand how this is set, and why it is
-- necessary to suppress the warnings in this case).
if Missing_Subunits then
return;
end if;
-- Otherwise loop through entities, looking for suspicious stuff
E1 := First_Entity (E);
while Present (E1) loop
-- We only look at source entities with warning flag on
if Comes_From_Source (E1) and then not Warnings_Off (E1) then
-- We are interested in variables and out parameters, but we
-- exclude protected types, too complicated to worry about.
if Ekind (E1) = E_Variable
or else
(Ekind (E1) = E_Out_Parameter
and then not Is_Protected_Type (Current_Scope))
then
-- Post warning if this object not assigned. Note that we
-- do not consider the implicit initialization of an access
-- type to be the assignment of a value for this purpose.
if Ekind (E1) = E_Out_Parameter
and then Present (Spec_Entity (E1))
then
UR := Unset_Reference (Spec_Entity (E1));
else
UR := Unset_Reference (E1);
end if;
-- If the entity is an out parameter of the current subprogram
-- body, check the warning status of the parameter in the spec.
if Ekind (E1) = E_Out_Parameter
and then Present (Spec_Entity (E1))
and then Warnings_Off (Spec_Entity (E1))
then
null;
elsif Present (UR)
and then Is_Access_Type (Etype (E1))
then
-- For access types, the only time we made a UR
-- entry was for a dereference, and so we post
-- the appropriate warning here (note that the
-- dereference may not be explicit in the source,
-- for example in the case of a dispatching call
-- with an anonymous access controlling formal, or
-- of an assignment of a pointer involving a
-- discriminant check on the designated object).
Error_Msg_NE ("& may be null?", UR, E1);
goto Continue;
elsif Never_Set_In_Source (E1)
and then not Generic_Package_Spec_Entity (E1)
then
if Warn_On_No_Value_Assigned then
-- Do not output complaint about never being assigned a
-- value if a pragma Unreferenced applies to the variable
-- or if it is a parameter, to the corresponding spec.
if Has_Pragma_Unreferenced (E1)
or else (Is_Formal (E1)
and then Present (Spec_Entity (E1))
and then
Has_Pragma_Unreferenced (Spec_Entity (E1)))
then
null;
-- Pragma Unreferenced not set, so output message
else
Output_Reference_Error
("& is never assigned a value?");
-- Deal with special case where this variable is
-- hidden by a loop variable
if Ekind (E1) = E_Variable
and then Present (Hiding_Loop_Variable (E1))
then
Error_Msg_Sloc := Sloc (E1);
Error_Msg_N
("declaration hides &#?",
Hiding_Loop_Variable (E1));
Error_Msg_N
("for loop implicitly declares loop variable?",
Hiding_Loop_Variable (E1));
end if;
end if;
end if;
goto Continue;
-- Case of variable that could be a constant. Note that we
-- never signal such messages for generic package entities,
-- since a given instance could have modifications outside
-- the package.
elsif Warn_On_Constant
and then Ekind (E1) = E_Variable
and then Is_True_Constant (E1)
and then not Generic_Package_Spec_Entity (E1)
then
Error_Msg_N
("& is not modified, could be declared constant?", E1);
end if;
-- Check for unset reference, note that we exclude access
-- types from this check, since access types do always have
-- a null value, and that seems legitimate in this case.
if Warn_On_No_Value_Assigned and then Present (UR) then
-- For other than access type, go back to original node
-- to deal with case where original unset reference
-- has been rewritten during expansion.
UR := Original_Node (UR);
-- In some cases, the original node may be a type
-- conversion or qualification, and in this case
-- we want the object entity inside.
while Nkind (UR) = N_Type_Conversion
or else Nkind (UR) = N_Qualified_Expression
loop
UR := Expression (UR);
end loop;
-- Here we issue the warning, all checks completed
-- If the unset reference is prefix of a selected
-- component that comes from source, mention the
-- component as well. If the selected component comes
-- from expansion, all we know is that the entity is
-- not fully initialized at the point of the reference.
-- Locate an unintialized component to get a better
-- error message.
if Nkind (Parent (UR)) = N_Selected_Component then
Error_Msg_Node_2 := Selector_Name (Parent (UR));
if not Comes_From_Source (Parent (UR)) then
declare
Comp : Entity_Id;
begin
Comp := First_Entity (Etype (E1));
while Present (Comp) loop
if Ekind (Comp) = E_Component
and then Nkind (Parent (Comp)) =
N_Component_Declaration
and then No (Expression (Parent (Comp)))
then
Error_Msg_Node_2 := Comp;
exit;
end if;
Next_Entity (Comp);
end loop;
end;
end if;
Error_Msg_N
("`&.&` may be referenced before it has a value?",
UR);
else
Error_Msg_N
("& may be referenced before it has a value?",
UR);
end if;
goto Continue;
end if;
end if;
-- Then check for unreferenced entities. Note that we are only
-- interested in entities which do not have the Referenced flag
-- set. The Referenced_As_LHS flag is interesting only if the
-- Referenced flag is not set.
if not Referenced (E1)
-- Check that warnings on unreferenced entities are enabled
and then ((Check_Unreferenced and then not Is_Formal (E1))
or else
(Check_Unreferenced_Formals and then Is_Formal (E1))
or else
(Warn_On_Modified_Unread
and then Referenced_As_LHS (E1)))
-- Labels, and enumeration literals, and exceptions. The
-- warnings are also placed on local packages that cannot
-- be referenced from elsewhere, including those declared
-- within a package body.
and then (Is_Object (E1)
or else
Is_Type (E1)
or else
Ekind (E1) = E_Label
or else
Ekind (E1) = E_Exception
or else
Ekind (E1) = E_Named_Integer
or else
Ekind (E1) = E_Named_Real
or else
Is_Overloadable (E1)
or else
(Ekind (E1) = E_Package
and then
(Ekind (E) = E_Function
or else Ekind (E) = E_Package_Body
or else Ekind (E) = E_Procedure
or else Ekind (E) = E_Block)))
-- Exclude instantiations, since there is no reason why
-- every entity in an instantiation should be referenced.
and then Instantiation_Location (Sloc (E1)) = No_Location
-- Exclude formal parameters from bodies if the corresponding
-- spec entity has been referenced in the case where there is
-- a separate spec.
and then not (Is_Formal (E1)
and then
Ekind (Scope (E1)) = E_Subprogram_Body
and then
Present (Spec_Entity (E1))
and then
Referenced (Spec_Entity (E1)))
-- Consider private type referenced if full view is referenced
-- If there is not full view, this is a generic type on which
-- warnings are also useful.
and then
not (Is_Private_Type (E1)
and then
Present (Full_View (E1))
and then Referenced (Full_View (E1)))
-- Don't worry about full view, only about private type
and then not Has_Private_Declaration (E1)
-- Eliminate dispatching operations from consideration, we
-- cannot tell if these are referenced or not in any easy
-- manner (note this also catches Adjust/Finalize/Initialize)
and then not Is_Dispatching_Operation (E1)
-- Check entity that can be publicly referenced (we do not
-- give messages for such entities, since there could be
-- other units, not involved in this compilation, that
-- contain relevant references.
and then not Publicly_Referenceable (E1)
-- Class wide types are marked as source entities, but
-- they are not really source entities, and are always
-- created, so we do not care if they are not referenced.
and then Ekind (E1) /= E_Class_Wide_Type
-- Objects other than parameters of task types are allowed
-- to be non-referenced, since they start up tasks!
and then ((Ekind (E1) /= E_Variable
and then Ekind (E1) /= E_Constant
and then Ekind (E1) /= E_Component)
or else not Is_Task_Type (Etype (E1)))
-- For subunits, only place warnings on the main unit
-- itself, since parent units are not completely compiled
and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
or else
Get_Source_Unit (E1) = Main_Unit)
then
-- Suppress warnings in internal units if not in -gnatg
-- mode (these would be junk warnings for an applications
-- program, since they refer to problems in internal units)
if GNAT_Mode
or else not
Is_Internal_File_Name
(Unit_File_Name (Get_Source_Unit (E1)))
then
-- We do not immediately flag the error. This is because
-- we have not expanded generic bodies yet, and they may
-- have the missing reference. So instead we park the
-- entity on a list, for later processing. However, for
-- the accept case, post the error right here, since we
-- have the information now in this case.
if Present (Anod) then
Output_Reference_Error ("& is not referenced?");
else
Unreferenced_Entities.Increment_Last;
Unreferenced_Entities.Table
(Unreferenced_Entities.Last) := E1;
end if;
end if;
-- Generic units are referenced in the generic body,
-- but if they are not public and never instantiated
-- we want to force a warning on them. We treat them
-- as redundant constructs to minimize noise.
elsif Is_Generic_Subprogram (E1)
and then not Is_Instantiated (E1)
and then not Publicly_Referenceable (E1)
and then Instantiation_Depth (Sloc (E1)) = 0
and then Warn_On_Redundant_Constructs
then
Unreferenced_Entities.Increment_Last;
Unreferenced_Entities.Table (Unreferenced_Entities.Last) := E1;
-- Force warning on entity.
Set_Referenced (E1, False);
end if;
end if;
-- Recurse into nested package or block. Do not recurse into a
-- formal package, because the correponding body is not analyzed.
<<Continue>>
if ((Ekind (E1) = E_Package or else Ekind (E1) = E_Generic_Package)
and then Nkind (Parent (E1)) = N_Package_Specification
and then
Nkind (Original_Node (Unit_Declaration_Node (E1)))
/= N_Formal_Package_Declaration)
or else Ekind (E1) = E_Block
then
Check_References (E1);
end if;
Next_Entity (E1);
end loop;
end Check_References;
---------------------------
-- Check_Unset_Reference --
---------------------------
procedure Check_Unset_Reference (N : Node_Id) is
begin
-- Nothing to do if warnings suppressed
if Warning_Mode = Suppress then
return;
end if;
-- Ignore reference to non-scalar if not from source. Almost always
-- such references are bogus (e.g. calls to init procs to set
-- default discriminant values).
if not Comes_From_Source (N)
and then not Is_Scalar_Type (Etype (N))
then
return;
end if;
-- Otherwise see what kind of node we have. If the entity already
-- has an unset reference, it is not necessarily the earliest in
-- the text, because resolution of the prefix of selected components
-- is completed before the resolution of the selected component itself.
-- as a result, given (R /= null and then R.X > 0), the occurrences
-- of R are examined in right-to-left order. If there is already an
-- unset reference, we check whether N is earlier before proceeding.
case Nkind (N) is
when N_Identifier | N_Expanded_Name =>
declare
E : constant Entity_Id := Entity (N);
begin
if (Ekind (E) = E_Variable
or else Ekind (E) = E_Out_Parameter)
and then Never_Set_In_Source (E)
and then (No (Unset_Reference (E))
or else Earlier_In_Extended_Unit
(Sloc (N), Sloc (Unset_Reference (E))))
and then not Warnings_Off (E)
then
-- We may have an unset reference. The first test is
-- whether we are accessing a discriminant of a record
-- or a component with default initialization. Both of
-- these cases can be ignored, since the actual object
-- that is referenced is definitely initialized. Note
-- that this covers the case of reading discriminants
-- of an out parameter, which is OK even in Ada 83.
-- Note that we are only interested in a direct reference
-- to a record component here. If the reference is via an
-- access type, then the access object is being referenced,
-- not the record, and still deserves an unset reference.
if Nkind (Parent (N)) = N_Selected_Component
and not Is_Access_Type (Etype (N))
then
declare
ES : constant Entity_Id :=
Entity (Selector_Name (Parent (N)));
begin
if Ekind (ES) = E_Discriminant
or else Present (Expression (Declaration_Node (ES)))
then
return;
end if;
end;
end if;
-- Here we have a potential unset reference. But before we
-- get worried about it, we have to make sure that the
-- entity declaration is in the same procedure as the
-- reference, since if they are in separate procedures,
-- then we have no idea about sequential execution.
-- The tests in the loop below catch all such cases, but
-- do allow the reference to appear in a loop, block, or
-- package spec that is nested within the declaring scope.
-- As always, it is possible to construct cases where the
-- warning is wrong, that is why it is a warning!
declare
SR : Entity_Id;
SE : constant Entity_Id := Scope (E);
begin
SR := Current_Scope;
while SR /= SE loop
if SR = Standard_Standard
or else Is_Subprogram (SR)
or else Is_Concurrent_Body (SR)
or else Is_Concurrent_Type (SR)
then
return;
end if;
SR := Scope (SR);
end loop;
-- Case of reference has an access type. This is a
-- special case since access types are always set to
-- null so cannot be truly uninitialized, but we still
-- want to warn about cases of obvious null dereference.
if Is_Access_Type (Etype (N)) then
declare
P : Node_Id;
function Process
(N : Node_Id)
return Traverse_Result;
-- Process function for instantation of Traverse
-- below. Checks if N contains reference to E
-- other than a dereference.
function Ref_In (Nod : Node_Id) return Boolean;
-- Determines whether Nod contains a reference
-- to the entity E that is not a dereference.
function Process
(N : Node_Id)
return Traverse_Result
is
begin
if Is_Entity_Name (N)
and then Entity (N) = E
and then not Is_Dereferenced (N)
then
return Abandon;
else
return OK;
end if;
end Process;
function Ref_In (Nod : Node_Id) return Boolean is
function Traverse is new Traverse_Func (Process);
begin
return Traverse (Nod) = Abandon;
end Ref_In;
begin
-- Don't bother if we are inside an instance,
-- since the compilation of the generic template
-- is where the warning should be issued.
if In_Instance then
return;
end if;
-- Don't bother if this is not the main unit.
-- If we try to give this warning for with'ed
-- units, we get some false positives, since
-- we do not record references in other units.
if not In_Extended_Main_Source_Unit (E)
or else
not In_Extended_Main_Source_Unit (N)
then
return;
end if;
-- We are only interested in deferences
if not Is_Dereferenced (N) then
return;
end if;
-- One more check, don't bother with references
-- that are inside conditional statements or while
-- loops if the condition references the entity in
-- question. This avoids most false positives.
P := Parent (N);
loop
P := Parent (P);
exit when No (P);
if (Nkind (P) = N_If_Statement
or else
Nkind (P) = N_Elsif_Part)
and then Ref_In (Condition (P))
then
return;
elsif Nkind (P) = N_Loop_Statement
and then Present (Iteration_Scheme (P))
and then
Ref_In (Condition (Iteration_Scheme (P)))
then
return;
end if;
end loop;
end;
end if;
-- Here we definitely have a case for giving a warning
-- for a reference to an unset value. But we don't give
-- the warning now. Instead we set the Unset_Reference
-- field of the identifier involved. The reason for this
-- is that if we find the variable is never ever assigned
-- a value then that warning is more important and there
-- is no point in giving the reference warning.
-- If this is an identifier, set the field directly
if Nkind (N) = N_Identifier then
Set_Unset_Reference (E, N);
-- Otherwise it is an expanded name, so set the field
-- of the actual identifier for the reference.
else
Set_Unset_Reference (E, Selector_Name (N));
end if;
end;
end if;
end;
when N_Indexed_Component | N_Slice =>
Check_Unset_Reference (Prefix (N));
when N_Selected_Component =>
if Present (Entity (Selector_Name (N)))
and then Ekind (Entity (Selector_Name (N))) = E_Discriminant
then
-- A discriminant is always initialized
null;
else
Check_Unset_Reference (Prefix (N));
end if;
when N_Type_Conversion | N_Qualified_Expression =>
Check_Unset_Reference (Expression (N));
when others =>
null;
end case;
end Check_Unset_Reference;
------------------------
-- Check_Unused_Withs --
------------------------
procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
Cnode : Node_Id;
Item : Node_Id;
Lunit : Node_Id;
Ent : Entity_Id;
Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
-- This is needed for checking the special renaming case
procedure Check_One_Unit (Unit : Unit_Number_Type);
-- Subsidiary procedure, performs checks for specified unit
--------------------
-- Check_One_Unit --
--------------------
procedure Check_One_Unit (Unit : Unit_Number_Type) is
Is_Visible_Renaming : Boolean := False;
Pack : Entity_Id;
procedure Check_Inner_Package (Pack : Entity_Id);
-- Pack is a package local to a unit in a with_clause. Both the
-- unit and Pack are referenced. If none of the entities in Pack
-- are referenced, then the only occurrence of Pack is in a use
-- clause or a pragma, and a warning is worthwhile as well.
function Check_System_Aux return Boolean;
-- Before giving a warning on a with_clause for System, check
-- whether a system extension is present.
function Find_Package_Renaming
(P : Entity_Id;
L : Entity_Id) return Entity_Id;
-- The only reference to a context unit may be in a renaming
-- declaration. If this renaming declares a visible entity, do
-- not warn that the context clause could be moved to the body,
-- because the renaming may be intented to re-export the unit.
-------------------------
-- Check_Inner_Package --
-------------------------
procedure Check_Inner_Package (Pack : Entity_Id) is
E : Entity_Id;
Un : constant Node_Id := Sinfo.Unit (Cnode);
function Check_Use_Clause (N : Node_Id) return Traverse_Result;
-- If N is a use_clause for Pack, emit warning.
procedure Check_Use_Clauses is new
Traverse_Proc (Check_Use_Clause);
----------------------
-- Check_Use_Clause --
----------------------
function Check_Use_Clause (N : Node_Id) return Traverse_Result is
Nam : Node_Id;
begin
if Nkind (N) = N_Use_Package_Clause then
Nam := First (Names (N));
while Present (Nam) loop
if Entity (Nam) = Pack then
Error_Msg_Qual_Level := 1;
Error_Msg_NE
("no entities of package& are referenced?",
Nam, Pack);
Error_Msg_Qual_Level := 0;
end if;
Next (Nam);
end loop;
end if;
return OK;
end Check_Use_Clause;
-- Start of processing for Check_Inner_Package
begin
E := First_Entity (Pack);
while Present (E) loop
if Referenced (E) then
return;
end if;
Next_Entity (E);
end loop;
-- No entities of the package are referenced. Check whether
-- the reference to the package itself is a use clause, and
-- if so place a warning on it.
Check_Use_Clauses (Un);
end Check_Inner_Package;
----------------------
-- Check_System_Aux --
----------------------
function Check_System_Aux return Boolean is
Ent : Entity_Id;
begin
if Chars (Lunit) = Name_System
and then Scope (Lunit) = Standard_Standard
and then Present_System_Aux
then
Ent := First_Entity (System_Aux_Id);
while Present (Ent) loop
if Referenced (Ent) then
return True;
end if;
Next_Entity (Ent);
end loop;
end if;
return False;
end Check_System_Aux;
---------------------------
-- Find_Package_Renaming --
---------------------------
function Find_Package_Renaming
(P : Entity_Id;
L : Entity_Id) return Entity_Id
is
E1 : Entity_Id;
R : Entity_Id;
begin
Is_Visible_Renaming := False;
E1 := First_Entity (P);
while Present (E1) loop
if Ekind (E1) = E_Package
and then Renamed_Object (E1) = L
then
Is_Visible_Renaming := not Is_Hidden (E1);
return E1;
elsif Ekind (E1) = E_Package
and then No (Renamed_Object (E1))
and then not Is_Generic_Instance (E1)
then
R := Find_Package_Renaming (E1, L);
if Present (R) then
Is_Visible_Renaming := not Is_Hidden (R);
return R;
end if;
end if;
Next_Entity (E1);
end loop;
return Empty;
end Find_Package_Renaming;
-- Start of processing for Check_One_Unit
begin
Cnode := Cunit (Unit);
-- Only do check in units that are part of the extended main
-- unit. This is actually a necessary restriction, because in
-- the case of subprogram acting as its own specification,
-- there can be with's in subunits that we will not see.
if not In_Extended_Main_Source_Unit (Cnode) then
return;
-- In configurable run time mode, we remove the bodies of
-- non-inlined subprograms, which may lead to spurious warnings,
-- which are clearly undesirable.
elsif Configurable_Run_Time_Mode
and then Is_Predefined_File_Name (Unit_File_Name (Unit))
then
return;
end if;
-- Loop through context items in this unit
Item := First (Context_Items (Cnode));
while Present (Item) loop
if Nkind (Item) = N_With_Clause
and then not Implicit_With (Item)
and then In_Extended_Main_Source_Unit (Item)
then
Lunit := Entity (Name (Item));
-- Check if this unit is referenced
if not Referenced (Lunit) then
-- Suppress warnings in internal units if not in -gnatg
-- mode (these would be junk warnings for an applications
-- program, since they refer to problems in internal units)
if GNAT_Mode
or else not Is_Internal_File_Name (Unit_File_Name (Unit))
then
-- Here we definitely have a non-referenced unit. If
-- it is the special call for a spec unit, then just
-- set the flag to be read later.
if Unit = Spec_Unit then
Set_Unreferenced_In_Spec (Item);
-- Otherwise simple unreferenced message
else
Error_Msg_N
("unit& is not referenced?", Name (Item));
end if;
end if;
-- If main unit is a renaming of this unit, then we consider
-- the with to be OK (obviously it is needed in this case!)
elsif Present (Renamed_Entity (Munite))
and then Renamed_Entity (Munite) = Lunit
then
null;
-- If this unit is referenced, and it is a package, we
-- do another test, to see if any of the entities in the
-- package are referenced. If none of the entities are
-- referenced, we still post a warning. This occurs if
-- the only use of the package is in a use clause, or
-- in a package renaming declaration.
elsif Ekind (Lunit) = E_Package then
-- If Is_Instantiated is set, it means that the package
-- is implicitly instantiated (this is the case of a
-- parent instance or an actual for a generic package
-- formal), and this counts as a reference.
if Is_Instantiated (Lunit) then
null;
-- If no entities in package, and there is a pragma
-- Elaborate_Body present, then assume that this with
-- is done for purposes of this elaboration.
elsif No (First_Entity (Lunit))
and then Has_Pragma_Elaborate_Body (Lunit)
then
null;
-- Otherwise see if any entities have been referenced
else
Ent := First_Entity (Lunit);
loop
-- No more entities, and we did not find one
-- that was referenced. Means we have a definite
-- case of a with none of whose entities was
-- referenced.
if No (Ent) then
-- If in spec, just set the flag
if Unit = Spec_Unit then
Set_No_Entities_Ref_In_Spec (Item);
elsif Check_System_Aux then
null;
-- Else give the warning
else
Error_Msg_N
("no entities of & are referenced?",
Name (Item));
-- Look for renamings of this package, and
-- flag them as well. If the original package
-- has warnings off, we suppress the warning
-- on the renaming as well.
Pack := Find_Package_Renaming (Munite, Lunit);
if Present (Pack)
and then not Warnings_Off (Lunit)
then
Error_Msg_NE
("no entities of & are referenced?",
Unit_Declaration_Node (Pack),
Pack);
end if;
end if;
exit;
-- Case of next entity is referenced
elsif Referenced (Ent)
or else Referenced_As_LHS (Ent)
then
-- This means that the with is indeed fine, in
-- that it is definitely needed somewhere, and
-- we can quite worrying about this one.
-- Except for one little detail, if either of
-- the flags was set during spec processing,
-- this is where we complain that the with
-- could be moved from the spec. If the spec
-- contains a visible renaming of the package,
-- inhibit warning to move with_clause to body.
if Ekind (Munite) = E_Package_Body then
Pack :=
Find_Package_Renaming
(Spec_Entity (Munite), Lunit);
end if;
if Unreferenced_In_Spec (Item) then
Error_Msg_N
("unit& is not referenced in spec?",
Name (Item));
elsif No_Entities_Ref_In_Spec (Item) then
Error_Msg_N
("no entities of & are referenced in spec?",
Name (Item));
else
if Ekind (Ent) = E_Package then
Check_Inner_Package (Ent);
end if;
exit;
end if;
if not Is_Visible_Renaming then
Error_Msg_N
("\with clause might be moved to body?",
Name (Item));
end if;
exit;
-- Move to next entity to continue search
else
Next_Entity (Ent);
end if;
end loop;
end if;
-- For a generic package, the only interesting kind of
-- reference is an instantiation, since entities cannot
-- be referenced directly.
elsif Is_Generic_Unit (Lunit) then
-- Unit was never instantiated, set flag for case of spec
-- call, or give warning for normal call.
if not Is_Instantiated (Lunit) then
if Unit = Spec_Unit then
Set_Unreferenced_In_Spec (Item);
else
Error_Msg_N
("unit& is never instantiated?", Name (Item));
end if;
-- If unit was indeed instantiated, make sure that
-- flag is not set showing it was uninstantiated in
-- the spec, and if so, give warning.
elsif Unreferenced_In_Spec (Item) then
Error_Msg_N
("unit& is not instantiated in spec?", Name (Item));
Error_Msg_N
("\with clause can be moved to body?", Name (Item));
end if;
end if;
end if;
Next (Item);
end loop;
end Check_One_Unit;
-- Start of processing for Check_Unused_Withs
begin
if not Opt.Check_Withs
or else Operating_Mode = Check_Syntax
then
return;
end if;
-- Flag any unused with clauses, but skip this step if we are
-- compiling a subunit on its own, since we do not have enough
-- information to determine whether with's are used. We will get
-- the relevant warnings when we compile the parent. This is the
-- normal style of GNAT compilation in any case.
if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
return;
end if;
-- Process specified units
if Spec_Unit = No_Unit then
-- For main call, check all units
for Unit in Main_Unit .. Last_Unit loop
Check_One_Unit (Unit);
end loop;
else
-- For call for spec, check only the spec
Check_One_Unit (Spec_Unit);
end if;
end Check_Unused_Withs;
---------------------------------
-- Generic_Package_Spec_Entity --
---------------------------------
function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
S : Entity_Id;
begin
if Is_Package_Body_Entity (E) then
return False;
else
S := Scope (E);
loop
if S = Standard_Standard then
return False;
elsif Ekind (S) = E_Generic_Package then
return True;
elsif Ekind (S) = E_Package then
S := Scope (S);
else
return False;
end if;
end loop;
end if;
end Generic_Package_Spec_Entity;
-------------------------------------
-- Operand_Has_Warnings_Suppressed --
-------------------------------------
function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
function Check_For_Warnings (N : Node_Id) return Traverse_Result;
-- Function used to check one node to see if it is or was originally
-- a reference to an entity for which Warnings are off. If so, Abandon
-- is returned, otherwise OK_Orig is returned to continue the traversal
-- of the original expression.
function Traverse is new Traverse_Func (Check_For_Warnings);
-- Function used to traverse tree looking for warnings
------------------------
-- Check_For_Warnings --
------------------------
function Check_For_Warnings (N : Node_Id) return Traverse_Result is
R : constant Node_Id := Original_Node (N);
begin
if Nkind (R) in N_Has_Entity
and then Present (Entity (R))
and then Warnings_Off (Entity (R))
then
return Abandon;
else
return OK_Orig;
end if;
end Check_For_Warnings;
-- Start of processing for Operand_Has_Warnings_Suppressed
begin
return Traverse (N) = Abandon;
-- If any exception occurs, then something has gone wrong, and this is
-- only a minor aesthetic issue anyway, so just say we did not find what
-- we are looking for, rather than blow up.
exception
when others =>
return False;
end Operand_Has_Warnings_Suppressed;
----------------------------------
-- Output_Unreferenced_Messages --
----------------------------------
procedure Output_Unreferenced_Messages is
E : Entity_Id;
begin
for J in Unreferenced_Entities.First ..
Unreferenced_Entities.Last
loop
E := Unreferenced_Entities.Table (J);
if not Referenced (E) and then not Warnings_Off (E) then
case Ekind (E) is
when E_Variable =>
-- Case of variable that is assigned but not read. We
-- suppress the message if the variable is volatile,
-- has an address clause, or is imported.
if Referenced_As_LHS (E)
and then No (Address_Clause (E))
and then not Is_Volatile (E)
then
if Warn_On_Modified_Unread
and then not Is_Imported (E)
-- Suppress the message for aliased, renamed
-- and access variables since there may be
-- other entities that read the memory location.
and then not Is_Aliased (E)
and then No (Renamed_Object (E))
and then not (Is_Access_Type (Etype (E))
or else
-- Case of private access type, must examine the
-- full view due to visibility issues.
(Is_Private_Type (Etype (E))
and then
Is_Access_Type
(Full_View (Etype (E)))))
then
Error_Msg_N
("variable & is assigned but never read?", E);
end if;
-- Normal case of neither assigned nor read
else
if Present (Renamed_Object (E))
and then Comes_From_Source (Renamed_Object (E))
then
Error_Msg_N
("renamed variable & is not referenced?", E);
else
Error_Msg_N
("variable & is not referenced?", E);
end if;
end if;
when E_Constant =>
if Present (Renamed_Object (E))
and then Comes_From_Source (Renamed_Object (E))
then
Error_Msg_N ("renamed constant & is not referenced?", E);
else
Error_Msg_N ("constant & is not referenced?", E);
end if;
when E_In_Parameter |
E_Out_Parameter |
E_In_Out_Parameter =>
-- Do not emit message for formals of a renaming, because
-- they are never referenced explicitly.
if Nkind (Original_Node (Unit_Declaration_Node (Scope (E))))
/= N_Subprogram_Renaming_Declaration
then
Error_Msg_N ("formal parameter & is not referenced?", E);
end if;
when E_Named_Integer |
E_Named_Real =>
Error_Msg_N ("named number & is not referenced?", E);
when E_Enumeration_Literal =>
Error_Msg_N ("literal & is not referenced?", E);
when E_Function =>
Error_Msg_N ("function & is not referenced?", E);
when E_Procedure =>
Error_Msg_N ("procedure & is not referenced?", E);
when E_Generic_Procedure =>
Error_Msg_N
("generic procedure & is never instantiated?", E);
when E_Generic_Function =>
Error_Msg_N ("generic function & is never instantiated?", E);
when Type_Kind =>
Error_Msg_N ("type & is not referenced?", E);
when others =>
Error_Msg_N ("& is not referenced?", E);
end case;
Set_Warnings_Off (E);
end if;
end loop;
end Output_Unreferenced_Messages;
-----------------------------
-- Warn_On_Known_Condition --
-----------------------------
procedure Warn_On_Known_Condition (C : Node_Id) is
P : Node_Id;
begin
-- Argument replacement in an inlined body can make conditions
-- static. Do not emit warnings in this case.
if In_Inlined_Body then
return;
end if;
if Constant_Condition_Warnings
and then Nkind (C) = N_Identifier
and then
(Entity (C) = Standard_False or else Entity (C) = Standard_True)
and then Comes_From_Source (Original_Node (C))
and then not In_Instance
then
-- See if this is in a statement or a declaration
P := Parent (C);
loop
-- If tree is not attached, do not issue warning (this is very
-- peculiar, and probably arises from some other error condition)
if No (P) then
return;
-- If we are in a declaration, then no warning, since in practice
-- conditionals in declarations are used for intended tests which
-- may be known at compile time, e.g. things like
-- x : constant Integer := 2 + (Word'Size = 32);
-- And a warning is annoying in such cases
elsif Nkind (P) in N_Declaration
or else
Nkind (P) in N_Later_Decl_Item
then
return;
-- Don't warn in assert pragma, since presumably tests in such
-- a context are very definitely intended, and might well be
-- known at compile time. Note that we have to test the original
-- node, since assert pragmas get rewritten at analysis time.
elsif Nkind (Original_Node (P)) = N_Pragma
and then Chars (Original_Node (P)) = Name_Assert
then
return;
end if;
exit when Is_Statement (P);
P := Parent (P);
end loop;
-- Here we issue the warning unless some sub-operand has warnings
-- set off, in which case we suppress the warning for the node.
if not Operand_Has_Warnings_Suppressed (C) then
if Entity (C) = Standard_True then
Error_Msg_N ("condition is always True?", C);
else
Error_Msg_N ("condition is always False?", C);
end if;
end if;
end if;
end Warn_On_Known_Condition;
end Sem_Warn;
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