------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ W A R N --
-- --
-- B o d y --
-- --
-- Copyright (C) 1999-2006, 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 Alloc;
with Atree; use Atree;
with Einfo; use Einfo;
with Errout; use Errout;
with Exp_Code; use Exp_Code;
with Fname; use Fname;
with Lib; use Lib;
with Namet; use Namet;
with Nlists; use Nlists;
with Opt; use Opt;
with Sem; use Sem;
with Sem_Ch8; use Sem_Ch8;
with Sem_Eval; use Sem_Eval;
with Sem_Util; use Sem_Util;
with Sinfo; use Sinfo;
with Sinput; use Sinput;
with Snames; use Snames;
with Stand; use Stand;
with Stringt; use Stringt;
with Table;
with Uintp; use Uintp;
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");
-----------------------
-- 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_Code_Statement --
--------------------------
procedure Check_Code_Statement (N : Node_Id) is
begin
-- If volatile, nothing to worry about
if Is_Asm_Volatile (N) then
return;
end if;
-- Warn if no input or no output
Setup_Asm_Inputs (N);
if No (Asm_Input_Value) then
Error_Msg_F
("?code statement with no inputs should usually be Volatile", N);
return;
end if;
Setup_Asm_Outputs (N);
if No (Asm_Output_Variable) then
Error_Msg_F
("?code statement with no outputs should usually be Volatile", N);
return;
end if;
-- Check multiple code statements in a row
if Is_List_Member (N)
and then Present (Prev (N))
and then Nkind (Prev (N)) = N_Code_Statement
then
Error_Msg_F
("?code statements in sequence should usually be Volatile", N);
Error_Msg_F
("\?(suggest using template with multiple instructions)", N);
end if;
end Check_Code_Statement;
----------------------
-- 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);
-- Similarly, the generic formals of a generic subprogram
-- are not accessible.
when N_Generic_Subprogram_Declaration =>
if Is_List_Member (Prev)
and then List_Containing (Prev) =
Generic_Formal_Declarations (P)
then
return False;
else
P := Parent (P);
end if;
-- 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 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
if Referenced (E1) then
Output_Reference_Error
("variable& is read but never assigned?");
else
Output_Reference_Error
("variable& is never read and never assigned?");
end if;
-- 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
-- A special case, if this variable is volatile and not
-- imported, it is not helpful to tell the programmer
-- to mark the variable as constant, since this would be
-- illegal by virtue of RM C.6(13).
if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
and then not Is_Imported (E1)
then
Error_Msg_N
("& is not modified, volatile has no effect?", E1);
else
Error_Msg_N
("& is not modified, could be declared constant?", E1);
end if;
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_Subprogram_Body
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 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
Access_Type_Case : 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 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.
-------------
-- Process --
-------------
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;
------------
-- Ref_In --
------------
function Ref_In (Nod : Node_Id) return Boolean is
function Traverse is new Traverse_Func (Process);
begin
return Traverse (Nod) = Abandon;
end Ref_In;
-- Start of processing for Access_Type_Case
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 Access_Type_Case;
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 (skip the check if this
-- is explicitly marked by a pragma Unreferenced).
if not Referenced (Lunit)
and then not Has_Pragma_Unreferenced (Lunit)
then
-- Suppress warnings in internal units if not in -gnatg mode
-- (these would be junk warnings for an application 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!)
-- This may be transitive: the unit in the with_clause may
-- itself be a renaming, in which case both it and the main
-- unit rename the same ultimate package.
elsif Present (Renamed_Entity (Munite))
and then
(Renamed_Entity (Munite) = Lunit
or else Renamed_Entity (Munite) = Renamed_Entity (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 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
if Limited_Present (Item) then
Ent := First_Entity (Limited_View (Lunit));
else
Ent := First_Entity (Lunit);
end if;
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
-- quit 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_Obsolescent_Entity_Warnings --
----------------------------------------
procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
P : constant Node_Id := Parent (N);
S : Entity_Id;
begin
S := Current_Scope;
-- Do not output message if we are the scope of standard. This means
-- we have a reference from a context clause from when it is originally
-- processed, and that's too early to tell whether it is an obsolescent
-- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
-- sure that we have a later call when the scope is available. This test
-- also eliminates all messages for use clauses, which is fine (we do
-- not want messages for use clauses, since they are always redundant
-- with respect to the associated with clause).
if S = Standard_Standard then
return;
end if;
-- Do not output message if we are in scope of an obsolescent package
-- or subprogram.
loop
if Is_Obsolescent (S) then
return;
end if;
S := Scope (S);
exit when S = Standard_Standard;
end loop;
-- Here we will output the message
Error_Msg_Sloc := Sloc (E);
-- Case of with clause
if Nkind (P) = N_With_Clause then
if Ekind (E) = E_Package then
Error_Msg_NE
("?with of obsolescent package& declared#", N, E);
elsif Ekind (E) = E_Procedure then
Error_Msg_NE
("?with of obsolescent procedure& declared#", N, E);
else
Error_Msg_NE
("?with of obsolescent function& declared#", N, E);
end if;
-- If we do not have a with clause, then ignore any reference to an
-- obsolescent package name. We only want to give the one warning of
-- withing the package, not one each time it is used to qualify.
elsif Ekind (E) = E_Package then
return;
-- Procedure call statement
elsif Nkind (P) = N_Procedure_Call_Statement then
Error_Msg_NE
("?call to obsolescent procedure& declared#", N, E);
-- Function call
elsif Nkind (P) = N_Function_Call then
Error_Msg_NE
("?call to obsolescent function& declared#", N, E);
-- Reference to obsolescent type
elsif Is_Type (E) then
Error_Msg_NE
("?reference to obsolescent type& declared#", N, E);
-- Reference to obsolescent component
elsif Ekind (E) = E_Component
or else Ekind (E) = E_Discriminant
then
Error_Msg_NE
("?reference to obsolescent component& declared#", N, E);
-- Reference to obsolescent variable
elsif Ekind (E) = E_Variable then
Error_Msg_NE
("?reference to obsolescent variable& declared#", N, E);
-- Reference to obsolescent constant
elsif Ekind (E) = E_Constant
or else Ekind (E) in Named_Kind
then
Error_Msg_NE
("?reference to obsolescent constant& declared#", N, E);
-- Reference to obsolescent enumeration literal
elsif Ekind (E) = E_Enumeration_Literal then
Error_Msg_NE
("?reference to obsolescent enumeration literal& declared#", N, E);
-- Generic message for any other case we missed
else
Error_Msg_NE
("?reference to obsolescent entity& declared#", N, E);
end if;
-- Output additional warning if present
declare
W : constant Node_Id := Obsolescent_Warning (E);
begin
if Present (W) then
-- This is a warning continuation to start on a new line
Name_Buffer (1) := '\';
Name_Buffer (2) := '\';
Name_Buffer (3) := '?';
Name_Len := 3;
-- Add characters to message, and output message. Note that
-- we quote every character of the message since we don't
-- want to process any insertions.
for J in 1 .. String_Length (Strval (W)) loop
Add_Char_To_Name_Buffer (''');
Add_Char_To_Name_Buffer
(Get_Character (Get_String_Char (Strval (W), J)));
end loop;
Error_Msg_N (Name_Buffer (1 .. Name_Len), N);
end if;
end;
end Output_Obsolescent_Entity_Warnings;
----------------------------------
-- 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 message for aliased or renamed variables,
-- since there may be other entities that read the
-- same memory location.
and then not Is_Aliased (E)
and then No (Renamed_Object (E))
then
Error_Msg_N
("variable & is assigned but never read?", E);
Set_Last_Assignment (E, Empty);
end if;
-- Normal case of neither assigned nor read
else
-- We suppress the message for limited controlled types,
-- to catch the common design pattern (known as RAII, or
-- Resource Acquisition Is Initialization) which uses
-- such types solely for their initialization and
-- finalization semantics.
if Is_Controlled (Etype (E))
and then Is_Limited_Type (Etype (E))
then
null;
-- Normal case where we want to give message
else
-- Distinguish renamed case in message
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;
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;
------------------------
-- Set_Warning_Switch --
------------------------
function Set_Warning_Switch (C : Character) return Boolean is
begin
case C is
when 'a' =>
Check_Unreferenced := True;
Check_Unreferenced_Formals := True;
Check_Withs := True;
Constant_Condition_Warnings := True;
Implementation_Unit_Warnings := True;
Ineffective_Inline_Warnings := True;
Warn_On_Ada_2005_Compatibility := True;
Warn_On_Assumed_Low_Bound := True;
Warn_On_Bad_Fixed_Value := True;
Warn_On_Constant := True;
Warn_On_Export_Import := True;
Warn_On_Modified_Unread := True;
Warn_On_No_Value_Assigned := True;
Warn_On_Obsolescent_Feature := True;
Warn_On_Questionable_Missing_Parens := True;
Warn_On_Redundant_Constructs := True;
Warn_On_Unchecked_Conversion := True;
Warn_On_Unrecognized_Pragma := True;
when 'A' =>
Check_Unreferenced := False;
Check_Unreferenced_Formals := False;
Check_Withs := False;
Constant_Condition_Warnings := False;
Elab_Warnings := False;
Implementation_Unit_Warnings := False;
Ineffective_Inline_Warnings := False;
Warn_On_Ada_2005_Compatibility := False;
Warn_On_Bad_Fixed_Value := False;
Warn_On_Constant := False;
Warn_On_Deleted_Code := False;
Warn_On_Dereference := False;
Warn_On_Export_Import := False;
Warn_On_Hiding := False;
Warn_On_Modified_Unread := False;
Warn_On_No_Value_Assigned := False;
Warn_On_Obsolescent_Feature := False;
Warn_On_Questionable_Missing_Parens := True;
Warn_On_Redundant_Constructs := False;
Warn_On_Unchecked_Conversion := False;
Warn_On_Unrecognized_Pragma := False;
when 'b' =>
Warn_On_Bad_Fixed_Value := True;
when 'B' =>
Warn_On_Bad_Fixed_Value := False;
when 'c' =>
Constant_Condition_Warnings := True;
when 'C' =>
Constant_Condition_Warnings := False;
when 'd' =>
Warn_On_Dereference := True;
when 'D' =>
Warn_On_Dereference := False;
when 'e' =>
Warning_Mode := Treat_As_Error;
when 'f' =>
Check_Unreferenced_Formals := True;
when 'F' =>
Check_Unreferenced_Formals := False;
when 'g' =>
Warn_On_Unrecognized_Pragma := True;
when 'G' =>
Warn_On_Unrecognized_Pragma := False;
when 'h' =>
Warn_On_Hiding := True;
when 'H' =>
Warn_On_Hiding := False;
when 'i' =>
Implementation_Unit_Warnings := True;
when 'I' =>
Implementation_Unit_Warnings := False;
when 'j' =>
Warn_On_Obsolescent_Feature := True;
when 'J' =>
Warn_On_Obsolescent_Feature := False;
when 'k' =>
Warn_On_Constant := True;
when 'K' =>
Warn_On_Constant := False;
when 'l' =>
Elab_Warnings := True;
when 'L' =>
Elab_Warnings := False;
when 'm' =>
Warn_On_Modified_Unread := True;
when 'M' =>
Warn_On_Modified_Unread := False;
when 'n' =>
Warning_Mode := Normal;
when 'o' =>
Address_Clause_Overlay_Warnings := True;
when 'O' =>
Address_Clause_Overlay_Warnings := False;
when 'p' =>
Ineffective_Inline_Warnings := True;
when 'P' =>
Ineffective_Inline_Warnings := False;
when 'q' =>
Warn_On_Questionable_Missing_Parens := True;
when 'Q' =>
Warn_On_Questionable_Missing_Parens := False;
when 'r' =>
Warn_On_Redundant_Constructs := True;
when 'R' =>
Warn_On_Redundant_Constructs := False;
when 's' =>
Warning_Mode := Suppress;
when 't' =>
Warn_On_Deleted_Code := True;
when 'T' =>
Warn_On_Deleted_Code := False;
when 'u' =>
Check_Unreferenced := True;
Check_Withs := True;
Check_Unreferenced_Formals := True;
when 'U' =>
Check_Unreferenced := False;
Check_Withs := False;
Check_Unreferenced_Formals := False;
when 'v' =>
Warn_On_No_Value_Assigned := True;
when 'V' =>
Warn_On_No_Value_Assigned := False;
when 'w' =>
Warn_On_Assumed_Low_Bound := True;
when 'W' =>
Warn_On_Assumed_Low_Bound := False;
when 'x' =>
Warn_On_Export_Import := True;
when 'X' =>
Warn_On_Export_Import := False;
when 'y' =>
Warn_On_Ada_2005_Compatibility := True;
when 'Y' =>
Warn_On_Ada_2005_Compatibility := False;
when 'z' =>
Warn_On_Unchecked_Conversion := True;
when 'Z' =>
Warn_On_Unchecked_Conversion := False;
when others =>
return False;
end case;
return True;
end Set_Warning_Switch;
-----------------------------
-- Warn_On_Known_Condition --
-----------------------------
procedure Warn_On_Known_Condition (C : Node_Id) is
P : Node_Id;
procedure Track (N : Node_Id; Loc : Node_Id);
-- Adds continuation warning(s) pointing to reason (assignment or test)
-- for the operand of the conditional having a known value (or at least
-- enough is known about the value to issue the warning). N is the node
-- which is judged to have a known value. Loc is the warning location.
-----------
-- Track --
-----------
procedure Track (N : Node_Id; Loc : Node_Id) is
Nod : constant Node_Id := Original_Node (N);
begin
if Nkind (Nod) in N_Op_Compare then
Track (Left_Opnd (Nod), Loc);
Track (Right_Opnd (Nod), Loc);
elsif Is_Entity_Name (Nod)
and then Is_Object (Entity (Nod))
then
declare
CV : constant Node_Id := Current_Value (Entity (Nod));
begin
if Present (CV) then
Error_Msg_Sloc := Sloc (CV);
if Nkind (CV) not in N_Subexpr then
Error_Msg_N ("\\?(see test #)", Loc);
elsif Nkind (Parent (CV)) =
N_Case_Statement_Alternative
then
Error_Msg_N ("\\?(see case alternative #)", Loc);
else
Error_Msg_N ("\\?(see assignment #)", Loc);
end if;
end if;
end;
end if;
end Track;
-- Start of processing for Warn_On_Known_Condition
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
-- the original expression is an inequality, it has been expanded
-- into a negation, and the value of the original expression is the
-- negation of the equality. If the expression is an entity that
-- appears within a negation, it is clearer to flag the negation
-- itself, and report on its constant value.
if not Operand_Has_Warnings_Suppressed (C) then
declare
True_Branch : Boolean := Entity (C) = Standard_True;
Cond : Node_Id := C;
begin
if Present (Parent (C))
and then Nkind (Parent (C)) = N_Op_Not
then
True_Branch := not True_Branch;
Cond := Parent (C);
end if;
if True_Branch then
if Is_Entity_Name (Original_Node (C))
and then Nkind (Cond) /= N_Op_Not
then
Error_Msg_NE
("object & is always True?", Cond, Original_Node (C));
Track (Original_Node (C), Cond);
else
Error_Msg_N ("condition is always True?", Cond);
Track (Cond, Cond);
end if;
else
Error_Msg_N ("condition is always False?", Cond);
Track (Cond, Cond);
end if;
end;
end if;
end if;
end Warn_On_Known_Condition;
------------------------------
-- Warn_On_Suspicious_Index --
------------------------------
procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
Low_Bound : Uint;
-- Set to lower bound for a suspicious type
Ent : Entity_Id;
-- Entity for array reference
Typ : Entity_Id;
-- Array type
function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
-- Tests to see if Typ is a type for which we may have a suspicious
-- index, namely an unconstrained array type, whose lower bound is
-- either zero or one. If so, True is returned, and Low_Bound is set
-- to this lower bound. If not, False is returned, and Low_Bound is
-- undefined on return.
--
-- For now, we limite this to standard string types, so any other
-- unconstrained types return False. We may change our minds on this
-- later on, but strings seem the most important case.
procedure Test_Suspicious_Index;
-- Test if index is of suspicious type and if so, generate warning
------------------------
-- Is_Suspicious_Type --
------------------------
function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
LB : Node_Id;
begin
if Is_Array_Type (Typ)
and then not Is_Constrained (Typ)
and then Number_Dimensions (Typ) = 1
and then not Warnings_Off (Typ)
and then (Root_Type (Typ) = Standard_String
or else
Root_Type (Typ) = Standard_Wide_String
or else
Root_Type (Typ) = Standard_Wide_Wide_String)
then
LB := Type_Low_Bound (Etype (First_Index (Typ)));
if Compile_Time_Known_Value (LB) then
Low_Bound := Expr_Value (LB);
return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
end if;
end if;
return False;
end Is_Suspicious_Type;
---------------------------
-- Test_Suspicious_Index --
---------------------------
procedure Test_Suspicious_Index is
function Length_Reference (N : Node_Id) return Boolean;
-- Check if node N is of the form Name'Length
procedure Warn1;
-- Generate first warning line
----------------------
-- Length_Reference --
----------------------
function Length_Reference (N : Node_Id) return Boolean is
R : constant Node_Id := Original_Node (N);
begin
return
Nkind (R) = N_Attribute_Reference
and then Attribute_Name (R) = Name_Length
and then Is_Entity_Name (Prefix (R))
and then Entity (Prefix (R)) = Ent;
end Length_Reference;
-----------
-- Warn1 --
-----------
procedure Warn1 is
begin
Error_Msg_Uint_1 := Low_Bound;
Error_Msg_FE ("?index for& may assume lower bound of^", X, Ent);
end Warn1;
-- Start of processing for Test_Suspicious_Index
begin
-- Nothing to do if subscript does not come from source (we don't
-- want to give garbage warnings on compiler expanded code, e.g. the
-- loops generated for slice assignments. Sucb junk warnings would
-- be placed on source constructs with no subscript in sight!)
if not Comes_From_Source (Original_Node (X)) then
return;
end if;
-- Case where subscript is a constant integer
if Nkind (X) = N_Integer_Literal then
Warn1;
-- Case where original form of subscript is an integer literal
if Nkind (Original_Node (X)) = N_Integer_Literal then
if Intval (X) = Low_Bound then
Error_Msg_FE
("\suggested replacement: `&''First`", X, Ent);
else
Error_Msg_Uint_1 := Intval (X) - Low_Bound;
Error_Msg_FE
("\suggested replacement: `&''First + ^`", X, Ent);
end if;
-- Case where original form of subscript is more complex
else
-- Build string X'First - 1 + expression where the expression
-- is the original subscript. If the expression starts with "1
-- + ", then the "- 1 + 1" is elided.
Error_Msg_String (1 .. 13) := "'First - 1 + ";
Error_Msg_Strlen := 13;
declare
Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
Tref : constant Source_Buffer_Ptr :=
Source_Text (Get_Source_File_Index (Sref));
-- Tref (Sref) is used to scan the subscript
Pctr : Natural;
-- Paretheses counter when scanning subscript
begin
-- Tref (Sref) points to start of subscript
-- Elide - 1 if subscript starts with 1 +
if Tref (Sref .. Sref + 2) = "1 +" then
Error_Msg_Strlen := Error_Msg_Strlen - 6;
Sref := Sref + 2;
elsif Tref (Sref .. Sref + 1) = "1+" then
Error_Msg_Strlen := Error_Msg_Strlen - 6;
Sref := Sref + 1;
end if;
-- Now we will copy the subscript to the string buffer
Pctr := 0;
loop
-- Count parens, exit if terminating right paren. Note
-- check to ignore paren appearing as character literal.
if Tref (Sref + 1) = '''
and then
Tref (Sref - 1) = '''
then
null;
else
if Tref (Sref) = '(' then
Pctr := Pctr + 1;
elsif Tref (Sref) = ')' then
exit when Pctr = 0;
Pctr := Pctr - 1;
end if;
end if;
-- Done if terminating double dot (slice case)
exit when Pctr = 0
and then (Tref (Sref .. Sref + 1) = ".."
or else
Tref (Sref .. Sref + 2) = " ..");
-- Quit if we have hit EOF character, something wrong
if Tref (Sref) = EOF then
return;
end if;
-- String literals are too much of a pain to handle
if Tref (Sref) = '"' or else Tref (Sref) = '%' then
return;
end if;
-- If we have a 'Range reference, then this is a case
-- where we cannot easily give a replacement. Don't try!
if Tref (Sref .. Sref + 4) = "range"
and then Tref (Sref - 1) < 'A'
and then Tref (Sref + 5) < 'A'
then
return;
end if;
-- Else store next character
Error_Msg_Strlen := Error_Msg_Strlen + 1;
Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
Sref := Sref + 1;
-- If we get more than 40 characters then the expression
-- is too long to copy, or something has gone wrong. In
-- either case, just skip the attempt at a suggested fix.
if Error_Msg_Strlen > 40 then
return;
end if;
end loop;
end;
-- Replacement subscript is now in string buffer
Error_Msg_FE
("\suggested replacement: `&~`", Original_Node (X), Ent);
end if;
-- Case where subscript is of the form X'Length
elsif Length_Reference (X) then
Warn1;
Error_Msg_Node_2 := Ent;
Error_Msg_FE
("\suggest replacement of `&''Length` by `&''Last`",
X, Ent);
-- Case where subscript is of the form X'Length - expression
elsif Nkind (X) = N_Op_Subtract
and then Length_Reference (Left_Opnd (X))
then
Warn1;
Error_Msg_Node_2 := Ent;
Error_Msg_FE
("\suggest replacement of `&''Length` by `&''Last`",
Left_Opnd (X), Ent);
end if;
end Test_Suspicious_Index;
-- Start of processing for Warn_On_Suspicious_Index
begin
-- Only process if warnings activated
if Warn_On_Assumed_Low_Bound then
-- Test if array is simple entity name
if Is_Entity_Name (Name) then
-- Test if array is parameter of unconstrained string type
Ent := Entity (Name);
Typ := Etype (Ent);
if Is_Formal (Ent)
and then Is_Suspicious_Type (Typ)
and then not Low_Bound_Known (Ent)
then
Test_Suspicious_Index;
end if;
end if;
end if;
end Warn_On_Suspicious_Index;
--------------------------------
-- Warn_On_Useless_Assignment --
--------------------------------
procedure Warn_On_Useless_Assignment
(Ent : Entity_Id;
Loc : Source_Ptr := No_Location)
is
P : Node_Id;
X : Node_Id;
function Check_Ref (N : Node_Id) return Traverse_Result;
-- Used to instantiate Traverse_Func. Returns Abandon if
-- a reference to the entity in question is found.
function Test_No_Refs is new Traverse_Func (Check_Ref);
---------------
-- Check_Ref --
---------------
function Check_Ref (N : Node_Id) return Traverse_Result is
begin
-- Check reference to our identifier. We use name equality here
-- because the exception handlers have not yet been analyzed. This
-- is not quite right, but it really does not matter that we fail
-- to output the warning in some obscure cases of name clashes.
if Nkind (N) = N_Identifier
and then Chars (N) = Chars (Ent)
then
return Abandon;
else
return OK;
end if;
end Check_Ref;
-- Start of processing for Warn_On_Useless_Assignment
begin
-- Check if this is a case we want to warn on, a variable with
-- the last assignment field set, with warnings enabled, and
-- which is not imported or exported.
if Ekind (Ent) = E_Variable
and then Present (Last_Assignment (Ent))
and then not Warnings_Off (Ent)
and then not Has_Pragma_Unreferenced (Ent)
and then not Is_Imported (Ent)
and then not Is_Exported (Ent)
then
-- Before we issue the message, check covering exception handlers.
-- Search up tree for enclosing statement sequences and handlers
P := Parent (Last_Assignment (Ent));
while Present (P) loop
-- Something is really wrong if we don't find a handled
-- statement sequence, so just suppress the warning.
if No (P) then
Set_Last_Assignment (Ent, Empty);
return;
-- When we hit a package/subprogram body, issue warning and exit
elsif Nkind (P) = N_Subprogram_Body
or else Nkind (P) = N_Package_Body
then
if Loc = No_Location then
Error_Msg_NE
("?useless assignment to&, value never referenced",
Last_Assignment (Ent), Ent);
else
Error_Msg_Sloc := Loc;
Error_Msg_NE
("?useless assignment to&, value overwritten #",
Last_Assignment (Ent), Ent);
end if;
Set_Last_Assignment (Ent, Empty);
return;
-- Enclosing handled sequence of statements
elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
-- Check exception handlers present
if Present (Exception_Handlers (P)) then
-- If we are not at the top level, we regard an inner
-- exception handler as a decisive indicator that we should
-- not generate the warning, since the variable in question
-- may be acceessed after an exception in the outer block.
if Nkind (Parent (P)) /= N_Subprogram_Body
and then Nkind (Parent (P)) /= N_Package_Body
then
Set_Last_Assignment (Ent, Empty);
return;
-- Otherwise we are at the outer level. An exception
-- handler is significant only if it references the
-- variable in question.
else
X := First (Exception_Handlers (P));
while Present (X) loop
if Test_No_Refs (X) = Abandon then
Set_Last_Assignment (Ent, Empty);
return;
end if;
X := Next (X);
end loop;
end if;
end if;
end if;
P := Parent (P);
end loop;
end if;
end Warn_On_Useless_Assignment;
---------------------------------
-- Warn_On_Useless_Assignments --
---------------------------------
procedure Warn_On_Useless_Assignments (E : Entity_Id) is
Ent : Entity_Id;
begin
if Warn_On_Modified_Unread
and then In_Extended_Main_Source_Unit (E)
then
Ent := First_Entity (E);
while Present (Ent) loop
Warn_On_Useless_Assignment (Ent);
Next_Entity (Ent);
end loop;
end if;
end Warn_On_Useless_Assignments;
end Sem_Warn;