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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ W A R N --
-- --
-- B o d y --
-- --
-- $Revision$
-- --
-- Copyright (C) 1999-2001 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. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
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_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");
-- 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");
Current_Entity_List : Elist_Id := No_Elist;
-- This is a copy of the Defs list of the current branch of the current
-- conditional. It could be accessed by taking the top element of the
-- Conditional_Stack, and going to te Current_Branch entry of this
-- conditional, but we keep it precomputed for rapid access.
----------------------
-- Check_References --
----------------------
procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
E1 : Entity_Id;
UR : Node_Id;
PU : Node_Id;
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, or for entities in tasks or protected objects
-- that are themselves publicly visible.
----------------------------
-- 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
S : Entity_Id;
begin
-- Any entity in a generic package is considered to be publicly
-- referenceable, since it could be referenced in an instantiation
if Ekind (E) = E_Generic_Package then
return True;
end if;
-- Otherwise look up the scope stack
S := Scope (Ent);
loop
if Is_Package (S) then
return Is_Library_Level_Entity (S);
elsif Ekind (S) = E_Task_Type
or else Ekind (S) = E_Protected_Type
or else Ekind (S) = E_Entry
then
S := Scope (S);
else
return False;
end if;
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).
-- 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 Warning_Mode = Suppress
or else Errors_Detected /= 0
or else Unloaded_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 off
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 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 Not_Source_Assigned (E1) then
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;
goto Continue;
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.
UR := Unset_Reference (E1);
if Present (UR) then
-- For access types, the only time we complain is when
-- we have a dereference (of a null value)
if Is_Access_Type (Etype (E1)) then
PU := Parent (UR);
if (Nkind (PU) = N_Selected_Component
or else
Nkind (PU) = N_Explicit_Dereference
or else
Nkind (PU) = N_Indexed_Component)
and then
Prefix (PU) = UR
then
Error_Msg_N ("& may be null?", UR);
goto Continue;
end if;
-- For other than access type, go back to original node
-- to deal with case where original unset reference
-- has been rewritten during expansion.
else
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;
Error_Msg_N
("& may be referenced before it has a value?", UR);
goto Continue;
end if;
end if;
end if;
-- Then check for unreferenced variables
if Check_Unreferenced
-- Check entity is flagged as not referenced and that
-- warnings are not suppressed for this entity
and then not Referenced (E1)
and then not Warnings_Off (E1)
-- Warnings are placed on objects, types, subprograms,
-- labels, and enumeration literals.
and then (Is_Object (E1)
or else
Is_Type (E1)
or else
Ekind (E1) = E_Label
or else
Ekind (E1) = E_Named_Integer
or else
Ekind (E1) = E_Named_Real
or else
Is_Overloadable (E1))
-- We only place warnings for the main unit
and then In_Extended_Main_Source_Unit (E1)
-- 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 (in the case
-- where there is a separate spec, it is the spec formals
-- that are of interest).
and then (not Is_Formal (E1)
or else
Ekind (Scope (E1)) /= E_Subprogram_Body)
-- Consider private type referenced if full view is
-- referenced.
and then not (Is_Private_Type (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)))
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;
end if;
end if;
-- Recurse into nested package or block
<<Continue>>
if (Ekind (E1) = E_Package
and then Nkind (Parent (E1)) = N_Package_Specification)
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;
-- 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 Not_Source_Assigned (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
-- 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!
-- If the entity is an out_parameter, it is ok to read its
-- its discriminants (that was true in Ada83) so suppress
-- the message in that case as well.
if Ekind (E) = E_Out_Parameter
and then Nkind (Parent (N)) = N_Selected_Component
and then Ekind (Entity (Selector_Name (Parent (N))))
= E_Discriminant
then
return;
end if;
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;
if Nkind (N) = N_Identifier then
Set_Unset_Reference (E, N);
else
Set_Unset_Reference (E, Selector_Name (N));
end if;
end;
end if;
end;
when N_Indexed_Component | N_Selected_Component | N_Slice =>
Check_Unset_Reference (Prefix (N));
return;
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;
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.
---------------------------
-- 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 No_Run_Time_Mode, we remove the bodies of non-
-- inlined subprograms, which may lead to spurious
-- warnings, clearly undesirable.
elsif No_Run_Time
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);
-- 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) 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
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;
----------------------------------
-- 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 =>
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;
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 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
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;
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 Warn_On_Known_Condition;
end Sem_Warn;