------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- S E M _ W A R N -- -- -- -- B o d y -- -- -- -- Copyright (C) 1999-2007, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 2, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- -- Boston, MA 02110-1301, USA. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ with Alloc; with Atree; use Atree; with Debug; use Debug; 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_Infinite_Loop_Warning -- --------------------------------- -- The case we look for is a while loop which tests a local variable, where -- there is no obvious direct or possible indirect update of the variable -- within the body of the loop. procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is Iter : constant Node_Id := Iteration_Scheme (Loop_Statement); Ref : Node_Id := Empty; -- Reference in iteration scheme to variable that may not be modified -- in loop, indicating a possible infinite loop. Var : Entity_Id := Empty; -- Corresponding entity (entity of Ref) procedure Find_Var (N : Node_Id); -- Inspect condition to see if it depends on a single entity -- reference. If so, Ref is set to point to the reference node, -- and Var is set to the referenced Entity. function Has_Indirection (T : Entity_Id) return Boolean; -- If the controlling variable is an access type, or is a record type -- with access components, assume that it is changed indirectly and -- suppress the warning. As a concession to low-level programming, in -- particular within Declib, we also suppress warnings on a record -- type that contains components of type Address or Short_Address. function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean; -- Given an entity name, see if the name appears to have something to -- do with I/O or network stuff, and if so, return True. Used to kill -- some false positives on a heuristic basis that such functions will -- likely have some strange side effect dependencies. A rather funny -- kludge, but warning messages are in the heuristics business. function Test_Ref (N : Node_Id) return Traverse_Result; -- Test for reference to variable in question. Returns Abandon if -- matching reference found. function Find_Ref is new Traverse_Func (Test_Ref); -- Function to traverse body of procedure. Returns Abandon if matching -- reference found. -------------- -- Find_Var -- -------------- procedure Find_Var (N : Node_Id) is begin -- Condition is a direct variable reference if Is_Entity_Name (N) then Ref := N; Var := Entity (Ref); -- Case of condition is a comparison with compile time known value elsif Nkind (N) in N_Op_Compare then if Compile_Time_Known_Value (Right_Opnd (N)) then Find_Var (Left_Opnd (N)); elsif Compile_Time_Known_Value (Left_Opnd (N)) then Find_Var (Right_Opnd (N)); -- Ignore any other comparison else return; end if; -- If condition is a negation, check its operand elsif Nkind (N) = N_Op_Not then Find_Var (Right_Opnd (N)); -- Case of condition is function call elsif Nkind (N) = N_Function_Call then -- Forget it if function name is not entity, who knows what -- we might be calling? if not Is_Entity_Name (Name (N)) then return; -- Forget it if warnings are suppressed on function entity elsif Warnings_Off (Entity (Name (N))) then return; -- Forget it if function name is suspicious. A strange test -- but warning generation is in the heuristics business! elsif Is_Suspicious_Function_Name (Entity (Name (N))) then return; end if; -- OK, see if we have one argument declare PA : constant List_Id := Parameter_Associations (N); begin -- One argument, so check the argument if Present (PA) and then List_Length (PA) = 1 then if Nkind (First (PA)) = N_Parameter_Association then Find_Var (Explicit_Actual_Parameter (First (PA))); else Find_Var (First (PA)); end if; -- Not one argument else return; end if; end; -- Any other kind of node is not something we warn for else return; end if; end Find_Var; --------------------- -- Has_Indirection -- --------------------- function Has_Indirection (T : Entity_Id) return Boolean is Comp : Entity_Id; Rec : Entity_Id; begin if Is_Access_Type (T) then return True; elsif Is_Private_Type (T) and then Present (Full_View (T)) and then Is_Access_Type (Full_View (T)) then return True; elsif Is_Record_Type (T) then Rec := T; elsif Is_Private_Type (T) and then Present (Full_View (T)) and then Is_Record_Type (Full_View (T)) then Rec := Full_View (T); else return False; end if; Comp := First_Component (Rec); while Present (Comp) loop if Is_Access_Type (Etype (Comp)) or else Is_Descendent_Of_Address (Etype (Comp)) then return True; end if; Next_Component (Comp); end loop; return False; end Has_Indirection; --------------------------------- -- Is_Suspicious_Function_Name -- --------------------------------- function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is S : Entity_Id; function Substring_Present (S : String) return Boolean; -- Returns True if name buffer has given string delimited by non- -- alphabetic characters or by end of string. S is lower case. ----------------------- -- Substring_Present -- ----------------------- function Substring_Present (S : String) return Boolean is Len : constant Natural := S'Length; begin for J in 1 .. Name_Len - (Len - 1) loop if Name_Buffer (J .. J + (Len - 1)) = S and then (J = 1 or else Name_Buffer (J - 1) not in 'a' .. 'z') and then (J + Len > Name_Len or else Name_Buffer (J + Len) not in 'a' .. 'z') then return True; end if; end loop; return False; end Substring_Present; -- Start of processing for Is_Suspicious_Function_Name begin S := E; while Present (S) and then S /= Standard_Standard loop Get_Name_String (Chars (S)); if Substring_Present ("io") or else Substring_Present ("file") or else Substring_Present ("network") then return True; else S := Scope (S); end if; end loop; return False; end Is_Suspicious_Function_Name; -------------- -- Test_Ref -- -------------- function Test_Ref (N : Node_Id) return Traverse_Result is begin -- Waste of time to look at iteration scheme if N = Iter then return Skip; -- Direct reference to variable in question elsif Is_Entity_Name (N) and then Present (Entity (N)) and then Entity (N) = Var then -- If this is an Lvalue, then definitely abandon, since -- this could be a direct modification of the variable. if May_Be_Lvalue (N) then return Abandon; end if; -- If we appear in the context of a procedure call, then also -- abandon, since there may be issues of non-visible side -- effects going on in the call. declare P : Node_Id; begin P := N; loop P := Parent (P); exit when P = Loop_Statement; if Nkind (P) = N_Procedure_Call_Statement then return Abandon; end if; end loop; end; -- Reference to variable renaming variable in question elsif Is_Entity_Name (N) and then Present (Entity (N)) and then Ekind (Entity (N)) = E_Variable and then Present (Renamed_Object (Entity (N))) and then Is_Entity_Name (Renamed_Object (Entity (N))) and then Entity (Renamed_Object (Entity (N))) = Var and then May_Be_Lvalue (N) then return Abandon; -- Call to subprogram elsif Nkind (N) = N_Procedure_Call_Statement or else Nkind (N) = N_Function_Call then -- If subprogram is within the scope of the entity we are -- dealing with as the loop variable, then it could modify -- this parameter, so we abandon in this case. In the case -- of a subprogram that is not an entity we also abandon. if not Is_Entity_Name (Name (N)) or else Scope_Within (Entity (Name (N)), Scope (Var)) then return Abandon; end if; end if; -- All OK, continue scan return OK; end Test_Ref; -- Start of processing for Check_Infinite_Loop_Warning begin -- We need a while iteration with no condition actions. Conditions -- actions just make things too complicated to get the warning right. if No (Iter) or else No (Condition (Iter)) or else Present (Condition_Actions (Iter)) or else Debug_Flag_Dot_W then return; end if; -- Initial conditions met, see if condition is of right form Find_Var (Condition (Iter)); -- Nothing to do if local variable from source not found if No (Var) or else Ekind (Var) /= E_Variable or else Is_Library_Level_Entity (Var) or else not Comes_From_Source (Var) then return; -- Nothing to do if there is some indirection involved (assume that the -- designated variable might be modified in some way we don't see). elsif Has_Indirection (Etype (Var)) then return; -- Same sort of thing for volatile variable, might be modified by -- some other task or by the operating system in some way. elsif Is_Volatile (Var) then return; end if; -- Filter out case of original statement sequence starting with delay. -- We assume this is a multi-tasking program and that the condition -- is affected by other threads (some kind of busy wait). declare Fstm : constant Node_Id := Original_Node (First (Statements (Loop_Statement))); begin if Nkind (Fstm) = N_Delay_Relative_Statement or else Nkind (Fstm) = N_Delay_Until_Statement then return; end if; end; -- We have a variable reference of the right form, now we scan the loop -- body to see if it looks like it might not be modified if Find_Ref (Loop_Statement) = OK then Error_Msg_NE ("variable& is not modified in loop body?", Ref, Var); Error_Msg_N ("\possible infinite loop", Ref); end if; end Check_Infinite_Loop_Warning; ---------------------- -- 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. We also -- ignore objects whose type or base type has warnings suppressed. if Comes_From_Source (E1) and then not Warnings_Off (E1) and then not Warnings_Off (Etype (E1)) and then not Warnings_Off (Base_Type (Etype (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 Has_Pragma_Unreferenced_Objects (Etype (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) -- No warning on a return object, because these are often -- created with a single expression and an implicit return. -- If the object is a variable there will be a warning -- indicating that it could be declared constant. and then not (Ekind (E1) = E_Constant and then Is_Return_Object (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; -- 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. <> 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 dereferences 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) and then not Is_Return_Object (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 types for which a valid -- pragma Unreferenced_Objects has been given, otherwise -- we go ahead and give the message. if not Has_Pragma_Unreferenced_Objects (Etype (E)) then -- 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_Dot_Warning_Switch -- ---------------------------- function Set_Dot_Warning_Switch (C : Character) return Boolean is begin case C is when 'c' => Warn_On_Unrepped_Components := True; when 'C' => Warn_On_Unrepped_Components := False; when 'r' => Warn_On_Object_Renames_Function := True; when 'R' => Warn_On_Object_Renames_Function := False; when 'x' => Warn_On_Non_Local_Exception := True; when 'X' => Warn_On_Non_Local_Exception := False; when others => return False; end case; return True; end Set_Dot_Warning_Switch; ------------------------ -- 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_Non_Local_Exception := True; Warn_On_Obsolescent_Feature := True; Warn_On_Questionable_Missing_Parens := True; Warn_On_Redundant_Constructs := True; Warn_On_Object_Renames_Function := True; Warn_On_Unchecked_Conversion := True; Warn_On_Unrecognized_Pragma := True; Warn_On_Unrepped_Components := 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_Non_Local_Exception := False; Warn_On_Obsolescent_Feature := False; Warn_On_Questionable_Missing_Parens := False; Warn_On_Redundant_Constructs := False; Warn_On_Object_Renames_Function := False; Warn_On_Unchecked_Conversion := False; Warn_On_Unrecognized_Pragma := False; Warn_On_Unrepped_Components := 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 not Is_Return_Object (Ent) 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;