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------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- S E M _ W A R N -- -- -- -- B o d y -- -- -- -- Copyright (C) 1999-2011, 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 3, 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 COPYING3. If not, go to -- -- http://www.gnu.org/licenses for a complete copy of the license. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ with Atree; use Atree; with 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 Par_SCO; use Par_SCO; with Rtsfind; use Rtsfind; with Sem; use Sem; with Sem_Ch8; use Sem_Ch8; with Sem_Aux; use Sem_Aux; 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 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. -- ??? Check_Unset_Reference has zero information about this table. 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"); -- The following table collects potential warnings for IN OUT parameters -- that are referenced but not modified. These warnings are processed when -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings. -- The reason that we defer output of these messages is that we want to -- detect the case where the relevant procedure is used as a generic actual -- in an instantiation, since we suppress the warnings in this case. The -- flag Used_As_Generic_Actual will be set in this case, but only at the -- point of usage. Similarly, we suppress the message if the address of the -- procedure is taken, where the flag Address_Taken may be set later. package In_Out_Warnings is new Table.Table ( Table_Component_Type => Entity_Id, Table_Index_Type => Nat, Table_Low_Bound => 1, Table_Initial => Alloc.In_Out_Warnings_Initial, Table_Increment => Alloc.In_Out_Warnings_Increment, Table_Name => "In_Out_Warnings"); -------------------------------------------------------- -- Handling of Warnings Off, Unmodified, Unreferenced -- -------------------------------------------------------- -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and -- Has_Pragma_Unreferenced, as noted in the specs in Einfo. -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary -- warnings off pragma) mode, i.e. to avoid false negatives, the code -- must follow some important rules. -- Call these functions as late as possible, after completing all other -- tests, just before the warnings is given. For example, don't write: -- if not Has_Warnings_Off (E) -- and then some-other-predicate-on-E then .. -- Instead the following is preferred -- if some-other-predicate-on-E -- and then Has_Warnings_Off (E) -- This way if some-other-predicate is false, we avoid a false indication -- that a Warnings (Off,E) pragma was useful in preventing a warning. -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record -- that the Warnings (Off) could have been Unreferenced or Unmodified. In -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off, -- and so a subsequent test is not needed anyway (though it is harmless). ----------------------- -- 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 Goto_Spec_Entity (E : Entity_Id) return Entity_Id; -- If E is a parameter entity for a subprogram body, then this function -- returns the corresponding spec entity, if not, E is returned unchanged. function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean; -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal, -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is -- a body formal, the setting of the flag in the corresponding spec is -- also checked (and True returned if either flag is True). function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean; -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal, -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is -- a body formal, the setting of the flag in the corresponding spec is -- also checked (and True returned if either flag is True). function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean; -- Tests Never_Set_In_Source status for entity E. If E is not a formal, -- this is simply the setting of the flag Never_Set_In_Source. If E is -- a body formal, the setting of the flag in the corresponding spec is -- also checked (and False returned if either flag is False). 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. function Referenced_Check_Spec (E : Entity_Id) return Boolean; -- Tests Referenced status for entity E. If E is not a formal, this is -- simply the setting of the flag Referenced. If E is a body formal, the -- setting of the flag in the corresponding spec is also checked (and True -- returned if either flag is True). function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean; -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this -- is simply the setting of the flag Referenced_As_LHS. If E is a body -- formal, the setting of the flag in the corresponding spec is also -- checked (and True returned if either flag is True). function Referenced_As_Out_Parameter_Check_Spec (E : Entity_Id) return Boolean; -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E -- is a body formal, the setting of the flag in the corresponding spec is -- also checked (and True returned if either flag is True). procedure Warn_On_Unreferenced_Entity (Spec_E : Entity_Id; Body_E : Entity_Id := Empty); -- Output warnings for unreferenced entity E. For the case of an entry -- formal, Body_E is the corresponding body entity for a particular -- accept statement, and the message is posted on Body_E. In all other -- cases, Body_E is ignored and must be Empty. function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean; -- Returns True if Warnings_Off is set for the entity E or (in the case -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity. -------------------------- -- 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; 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 Expression : Node_Id := Empty; -- Set to WHILE or EXIT WHEN condition to be tested Ref : Node_Id := Empty; -- Reference in Expression to variable that might not be modified -- in loop, indicating a possible infinite loop. Var : Entity_Id := Empty; -- Corresponding entity (entity of Ref) Function_Call_Found : Boolean := False; -- True if Find_Var found a function call in the condition 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. Used in instantiation of No_Ref_Found. function No_Ref_Found 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 Function_Call_Found := True; -- 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 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; -- Forget it if warnings are suppressed on function entity elsif Has_Warnings_Off (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 the expression we are testing if N = Expression 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; -- Abandon if at procedure call, or something strange is -- going on (perhaps a node with no parent that should -- have one but does not?) As always, for a warning we -- prefer to just abandon the warning than get into the -- business of complaining about the tree structure here! if No (P) or else 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. The check for no entity being -- present is a defense against previous errors. if not Is_Entity_Name (Name (N)) or else No (Entity (Name (N))) or else Scope_Within (Entity (Name (N)), Scope (Var)) then return Abandon; end if; -- If any of the arguments are of type access to subprogram, then -- we may have funny side effects, so no warning in this case. declare Actual : Node_Id; begin Actual := First_Actual (N); while Present (Actual) loop if Is_Access_Subprogram_Type (Etype (Actual)) then return Abandon; else Next_Actual (Actual); end if; end loop; end; -- Declaration of the variable in question elsif Nkind (N) = N_Object_Declaration and then Defining_Identifier (N) = Var then return Abandon; end if; -- All OK, continue scan return OK; end Test_Ref; -- Start of processing for Check_Infinite_Loop_Warning begin -- Skip processing if debug flag gnatd.w is set if Debug_Flag_Dot_W then return; end if; -- Deal with Iteration scheme present declare Iter : constant Node_Id := Iteration_Scheme (Loop_Statement); begin if Present (Iter) then -- While iteration if Present (Condition (Iter)) then -- Skip processing for while iteration with conditions actions, -- since they make it too complicated to get the warning right. if Present (Condition_Actions (Iter)) then return; end if; -- Capture WHILE condition Expression := Condition (Iter); -- For iteration, do not process, since loop will always terminate elsif Present (Loop_Parameter_Specification (Iter)) then return; end if; end if; end; -- Check chain of EXIT statements, we only process loops that have a -- single exit condition (either a single EXIT WHEN statement, or a -- WHILE loop not containing any EXIT WHEN statements). declare Ident : constant Node_Id := Identifier (Loop_Statement); Exit_Stmt : Node_Id; begin -- If we don't have a proper chain set, ignore call entirely. This -- happens because of previous errors. if No (Entity (Ident)) or else Ekind (Entity (Ident)) /= E_Loop then return; end if; -- Otherwise prepare to scan list of EXIT statements Exit_Stmt := First_Exit_Statement (Entity (Ident)); while Present (Exit_Stmt) loop -- Check for EXIT WHEN if Present (Condition (Exit_Stmt)) then -- Quit processing if EXIT WHEN in WHILE loop, or more than -- one EXIT WHEN statement present in the loop. if Present (Expression) then return; -- Otherwise capture condition from EXIT WHEN statement else Expression := Condition (Exit_Stmt); end if; end if; Exit_Stmt := Next_Exit_Statement (Exit_Stmt); end loop; end; -- Return if no condition to test if No (Expression) then return; end if; -- Initial conditions met, see if condition is of right form Find_Var (Expression); -- Nothing to do if local variable from source not found. If it's a -- renaming, it is probably renaming something too complicated to deal -- with here. if No (Var) or else Ekind (Var) /= E_Variable or else Is_Library_Level_Entity (Var) or else not Comes_From_Source (Var) or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration 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). -- However, if no function call was found, then we don't care about -- indirections, because the condition must be something like "while X -- /= null loop", so we don't care if X.all is modified in the loop. elsif Function_Call_Found and then 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 No_Ref_Found (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_Low_Bound_Tested -- ---------------------------- procedure Check_Low_Bound_Tested (Expr : Node_Id) is begin if Comes_From_Source (Expr) then declare L : constant Node_Id := Left_Opnd (Expr); R : constant Node_Id := Right_Opnd (Expr); begin if Nkind (L) = N_Attribute_Reference and then Attribute_Name (L) = Name_First and then Is_Entity_Name (Prefix (L)) and then Is_Formal (Entity (Prefix (L))) then Set_Low_Bound_Tested (Entity (Prefix (L))); end if; if Nkind (R) = N_Attribute_Reference and then Attribute_Name (R) = Name_First and then Is_Entity_Name (Prefix (R)) and then Is_Formal (Entity (Prefix (R))) then Set_Low_Bound_Tested (Entity (Prefix (R))); end if; end; end if; end Check_Low_Bound_Tested; ---------------------- -- Check_References -- ---------------------- procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is E1 : Entity_Id; E1T : Entity_Id; UR : Node_Id; function Body_Formal (E : Entity_Id; Accept_Statement : Node_Id) return Entity_Id; -- For an entry formal entity from an entry declaration, find the -- corresponding body formal from the given accept statement. 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. function Warnings_Off_E1 return Boolean; -- Return True if Warnings_Off is set for E1, or for its Etype (E1T), -- or for the base type of E1T. ----------------- -- Body_Formal -- ----------------- function Body_Formal (E : Entity_Id; Accept_Statement : Node_Id) return Entity_Id is Body_Param : Node_Id; Body_E : Entity_Id; begin -- Loop to find matching parameter in accept statement Body_Param := First (Parameter_Specifications (Accept_Statement)); while Present (Body_Param) loop Body_E := Defining_Identifier (Body_Param); if Chars (Body_E) = Chars (E) then return Body_E; end if; Next (Body_Param); end loop; -- Should never fall through, should always find a match raise Program_Error; end Body_Formal; ---------------------- -- 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 -- Never issue messages for internal names, nor for renamings if Is_Internal_Name (Chars (E1)) or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration then return; end if; -- Don't output message for IN OUT formal unless we have the warning -- flag specifically set. It is a bit odd to distinguish IN OUT -- formals from other cases. This distinction is historical in -- nature. Warnings for IN OUT formals were added fairly late. if Ekind (E1) = E_In_Out_Parameter and then not Check_Unreferenced_Formals then return; end if; -- 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 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1); end if; end Output_Reference_Error; ---------------------------- -- Publicly_Referenceable -- ---------------------------- function Publicly_Referenceable (Ent : Entity_Id) return Boolean is P : Node_Id; Prev : Node_Id; begin -- A formal parameter is never referenceable outside the body of its -- subprogram or entry. if Is_Formal (Ent) then return False; end if; -- 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; --------------------- -- Warnings_Off_E1 -- --------------------- function Warnings_Off_E1 return Boolean is begin return Has_Warnings_Off (E1T) or else Has_Warnings_Off (Base_Type (E1T)) or else Warnings_Off_Check_Spec (E1); end Warnings_Off_E1; -- 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 E1T := Etype (E1); -- We are only interested in source entities. We also don't issue -- warnings within instances, since the proper place for such -- warnings is on the template when it is compiled. if Comes_From_Source (E1) and then Instantiation_Location (Sloc (E1)) = No_Location then -- We are interested in variables and out/in-out parameters, but -- we exclude protected types, too complicated to worry about. if Ekind (E1) = E_Variable or else (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter) and then not Is_Protected_Type (Current_Scope)) then -- Case of an unassigned variable -- First gather any Unset_Reference indication for E1. In the -- case of a parameter, it is the Spec_Entity that is relevant. 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; -- Special processing for access types if Present (UR) and then Is_Access_Type (E1T) 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). if not Warnings_Off_E1 then Error_Msg_NE ("?& may be null!", UR, E1); 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 Has_Initial_Value (E1)) and then Never_Set_In_Source_Check_Spec (E1) and then not Address_Taken (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); -- Another special case, Exception_Occurrence, this catches -- the case of exception choice (and a bit more too, but not -- worth doing more investigation here). elsif Is_RTE (E1T, RE_Exception_Occurrence) then null; -- Here we give the warning if referenced and no pragma -- Unreferenced or Unmodified is present. else -- Variable case if Ekind (E1) = E_Variable then if Referenced_Check_Spec (E1) and then not Has_Pragma_Unreferenced_Check_Spec (E1) and then not Has_Pragma_Unmodified_Check_Spec (E1) then if not Warnings_Off_E1 then Error_Msg_N -- CODEFIX ("?& is not modified, " & "could be declared constant!", E1); end if; end if; end if; end if; -- Other cases of a variable or parameter never set in source elsif Never_Set_In_Source_Check_Spec (E1) -- No warning if warning for this case turned off and then Warn_On_No_Value_Assigned -- No warning if address taken somewhere and then not Address_Taken (E1) -- No warning if explicit initial value and then not Has_Initial_Value (E1) -- No warning for generic package spec entities, since we -- might set them in a child unit or something like that and then not Generic_Package_Spec_Entity (E1) -- No warning if fully initialized type, except that for -- this purpose we do not consider access types to qualify -- as fully initialized types (relying on an access type -- variable being null when it is never set is a bit odd!) -- Also we generate warning for an out parameter that is -- never referenced, since again it seems odd to rely on -- default initialization to set an out parameter value. and then (Is_Access_Type (E1T) or else Ekind (E1) = E_Out_Parameter or else not Is_Fully_Initialized_Type (E1T)) then -- Do not output complaint about never being assigned a -- value if a pragma Unmodified applies to the variable -- we are examining, or if it is a parameter, if there is -- a pragma Unreferenced for the corresponding spec, or -- if the type is marked as having unreferenced objects. -- The last is a little peculiar, but better too few than -- too many warnings in this situation. if Has_Pragma_Unreferenced_Objects (E1T) or else Has_Pragma_Unmodified_Check_Spec (E1) then null; -- IN OUT parameter case where parameter is referenced. We -- separate this out, since this is the case where we delay -- output of the warning until more information is available -- (about use in an instantiation or address being taken). elsif Ekind (E1) = E_In_Out_Parameter and then Referenced_Check_Spec (E1) then -- Suppress warning if private type, and the procedure -- has a separate declaration in a different unit. This -- is the case where the client of a package sees only -- the private type, and it may be quite reasonable -- for the logical view to be IN OUT, even if the -- implementation ends up using access types or some -- other method to achieve the local effect of a -- modification. On the other hand if the spec and body -- are in the same unit, we are in the package body and -- there we have less excuse for a junk IN OUT parameter. if Has_Private_Declaration (E1T) and then Present (Spec_Entity (E1)) and then not In_Same_Source_Unit (E1, Spec_Entity (E1)) then null; -- Suppress warning for any parameter of a dispatching -- operation, since it is quite reasonable to have an -- operation that is overridden, and for some subclasses -- needs the formal to be IN OUT and for others happens -- not to assign it. elsif Is_Dispatching_Operation (Scope (Goto_Spec_Entity (E1))) then null; -- Suppress warning if composite type contains any access -- component, since the logical effect of modifying a -- parameter may be achieved by modifying a referenced -- object. elsif Is_Composite_Type (E1T) and then Has_Access_Values (E1T) then null; -- Suppress warning on formals of an entry body. All -- references are attached to the formal in the entry -- declaration, which are marked Is_Entry_Formal. elsif Ekind (Scope (E1)) = E_Entry and then not Is_Entry_Formal (E1) then null; -- OK, looks like warning for an IN OUT parameter that -- could be IN makes sense, but we delay the output of -- the warning, pending possibly finding out later on -- that the associated subprogram is used as a generic -- actual, or its address/access is taken. In these two -- cases, we suppress the warning because the context may -- force use of IN OUT, even if in this particular case -- the formal is not modified. else In_Out_Warnings.Append (E1); end if; -- Other cases of formals elsif Is_Formal (E1) then if not Is_Trivial_Subprogram (Scope (E1)) then if Referenced_Check_Spec (E1) then if not Has_Pragma_Unmodified_Check_Spec (E1) and then not Warnings_Off_E1 then Output_Reference_Error ("?formal parameter& is read but " & "never assigned!"); end if; elsif not Has_Pragma_Unreferenced_Check_Spec (E1) and then not Warnings_Off_E1 then Output_Reference_Error ("?formal parameter& is not referenced!"); end if; end if; -- Case of variable else if Referenced (E1) then if not Has_Unmodified (E1) and then not Warnings_Off_E1 then Output_Reference_Error ("?variable& is read but never assigned!"); end if; elsif not Has_Unreferenced (E1) and then not Warnings_Off_E1 then Output_Reference_Error -- CODEFIX ("?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)) and then not Warnings_Off_E1 then Error_Msg_N ("?for loop implicitly declares loop variable!", Hiding_Loop_Variable (E1)); Error_Msg_Sloc := Sloc (E1); Error_Msg_N ("\?declaration hides & declared#!", Hiding_Loop_Variable (E1)); end if; end if; goto Continue; end if; -- Check for unset reference 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. -- In some cases, the original node may be a type conversion -- or qualification, and in this case we want the object -- entity inside. UR := Original_Node (UR); 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 we have a return statement, this was a case of an OUT -- parameter not being set at the time of the return. (Note: -- it can't be N_Extended_Return_Statement, because those -- are only for functions, and functions do not allow OUT -- parameters.) if not Is_Trivial_Subprogram (Scope (E1)) then if Nkind (UR) = N_Simple_Return_Statement and then not Has_Pragma_Unmodified_Check_Spec (E1) then if not Warnings_Off_E1 then Error_Msg_NE ("?OUT parameter& not set before return", UR, E1); end if; -- If the unset reference is a selected component -- prefix 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 a random -- uninitialized component to get a better message. elsif 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 (E1T); 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; -- Issue proper warning. This is a case of referencing -- a variable before it has been explicitly assigned. -- For access types, UR was only set for dereferences, -- so the issue is that the value may be null. if not Is_Trivial_Subprogram (Scope (E1)) then if not Warnings_Off_E1 then if Is_Access_Type (Etype (Parent (UR))) then Error_Msg_N ("?`&.&` may be null!", UR); else Error_Msg_N ("?`&.&` may be referenced before " & "it has a value!", UR); end if; end if; end if; -- All other cases of unset reference active elsif not Warnings_Off_E1 then Error_Msg_N ("?& may be referenced before it has a value!", UR); end if; end if; goto Continue; end if; end if; -- Then check for unreferenced entities. Note that we are only -- interested in entities whose Referenced flag is not set. if not Referenced_Check_Spec (E1) -- If Referenced_As_LHS is set, then that's still interesting -- (potential "assigned but never read" case), but not if we -- have pragma Unreferenced, which cancels this warning. and then (not Referenced_As_LHS_Check_Spec (E1) or else not Has_Unreferenced (E1)) -- Check that warnings on unreferenced entities are enabled and then ((Check_Unreferenced and then not Is_Formal (E1)) -- Case of warning on unreferenced formal or else (Check_Unreferenced_Formals and then Is_Formal (E1)) -- Case of warning on unread variables modified by an -- assignment, or an OUT parameter if it is the only one. or else (Warn_On_Modified_Unread and then Referenced_As_LHS_Check_Spec (E1)) -- Case of warning on any unread OUT parameter (note -- such indications are only set if the appropriate -- warning options were set, so no need to recheck here.) or else Referenced_As_Out_Parameter_Check_Spec (E1)) -- All other entities, including 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) -- Package case, if the main unit is a package spec -- or generic package spec, then there may be a -- corresponding body that references this package -- in some other file. Otherwise we can be sure -- that there is no other reference. or else (Ekind (E1) = E_Package and then not Is_Package_Or_Generic_Package (Cunit_Entity (Current_Sem_Unit)))) -- 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 (E1T)) -- 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 case of an -- accept statement we want to output messages now, since -- we know we already have all information at hand, and we -- also want to have separate warnings for each accept -- statement for the same entry. if Present (Anod) then pragma Assert (Is_Formal (E1)); -- The unreferenced entity is E1, but post the warning -- on the body entity for this accept statement. if not Warnings_Off_E1 then Warn_On_Unreferenced_Entity (E1, Body_Formal (E1, Accept_Statement => Anod)); end if; elsif not Warnings_Off_E1 then Unreferenced_Entities.Append (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 if not Warnings_Off_E1 then Unreferenced_Entities.Append (E1); -- Force warning on entity Set_Referenced (E1, False); end if; end if; end if; -- Recurse into nested package or block. Do not recurse into a formal -- package, because the corresponding body is not analyzed. <<Continue>> if (Is_Package_Or_Generic_Package (E1) 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 Typ : constant Entity_Id := Etype (N); function Is_OK_Fully_Initialized return Boolean; -- This function returns true if the given node N is fully initialized -- so that the reference is safe as far as this routine is concerned. -- Safe generally means that the type of N is a fully initialized type. -- The one special case is that for access types, which are always fully -- initialized, we don't consider a dereference OK since it will surely -- be dereferencing a null value, which won't do. function Prefix_Has_Dereference (Pref : Node_Id) return Boolean; -- Used to test indexed or selected component or slice to see if the -- evaluation of the prefix depends on a dereference, and if so, returns -- True, in which case we always check the prefix, even if we know that -- the referenced component is initialized. Pref is the prefix to test. ----------------------------- -- Is_OK_Fully_Initialized -- ----------------------------- function Is_OK_Fully_Initialized return Boolean is begin if Is_Access_Type (Typ) and then Is_Dereferenced (N) then return False; else return Is_Fully_Initialized_Type (Typ); end if; end Is_OK_Fully_Initialized; ---------------------------- -- Prefix_Has_Dereference -- ---------------------------- function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is begin -- If prefix is of an access type, it certainly needs a dereference if Is_Access_Type (Etype (Pref)) then return True; -- If prefix is explicit dereference, that's a dereference for sure elsif Nkind (Pref) = N_Explicit_Dereference then return True; -- If prefix is itself a component reference or slice check prefix elsif Nkind (Pref) = N_Slice or else Nkind (Pref) = N_Indexed_Component or else Nkind (Pref) = N_Selected_Component then return Prefix_Has_Dereference (Prefix (Pref)); -- All other cases do not involve a dereference else return False; end if; end Prefix_Has_Dereference; -- Start of processing for Check_Unset_Reference begin -- Nothing to do if warnings suppressed if Warning_Mode = Suppress then return; end if; -- Ignore reference unless it comes from source. Almost always if we -- have a reference from generated code, it is bogus (e.g. calls to init -- procs to set default discriminant values). if not Comes_From_Source (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 -- For identifier or expanded name, examine the entity involved 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_Check_Spec (E) and then not Has_Initial_Value (E) and then (No (Unset_Reference (E)) or else Earlier_In_Extended_Unit (Sloc (N), Sloc (Unset_Reference (E)))) and then not Has_Pragma_Unmodified_Check_Spec (E) and then not Warnings_Off_Check_Spec (E) then -- We may have an unset reference. The first test is whether -- this is an access to 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 through 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 (Typ) then declare ES : constant Entity_Id := Entity (Selector_Name (Parent (N))); begin if Ekind (ES) = E_Discriminant or else (Present (Declaration_Node (ES)) and then Present (Expression (Declaration_Node (ES)))) then return; end if; end; end if; -- Exclude fully initialized types if Is_OK_Fully_Initialized then return; 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! Potential_Unset_Reference : declare SR : Entity_Id; SE : constant Entity_Id := Scope (E); function Within_Postcondition return Boolean; -- Returns True iff N is within a Postcondition or -- Ensures component in a Test_Case. -------------------------- -- Within_Postcondition -- -------------------------- function Within_Postcondition return Boolean is Nod, P : Node_Id; begin Nod := Parent (N); while Present (Nod) loop if Nkind (Nod) = N_Pragma and then Pragma_Name (Nod) = Name_Postcondition then return True; elsif Present (Parent (Nod)) then P := Parent (Nod); if Nkind (P) = N_Pragma and then Pragma_Name (P) = Name_Test_Case and then Nod = Get_Ensures_From_Test_Case_Pragma (P) then return True; end if; end if; Nod := Parent (Nod); end loop; return False; end Within_Postcondition; -- Start of processing for Potential_Unset_Reference begin SR := Current_Scope; while SR /= SE loop if SR = Standard_Standard or else Is_Subprogram (SR) or else Is_Concurrent_Body (SR) or else Is_Concurrent_Type (SR) then return; end if; SR := Scope (SR); end loop; -- Case of reference has an access type. This is a -- special case since access types are always set to null -- so cannot be truly uninitialized, but we still want to -- warn about cases of obvious null dereference. if Is_Access_Type (Typ) then Access_Type_Case : declare P : Node_Id; function Process (N : Node_Id) return Traverse_Result; -- Process function for instantiation of Traverse -- below. Checks if N contains reference to E other -- than a dereference. function Ref_In (Nod : Node_Id) return Boolean; -- Determines whether Nod contains a reference to -- the entity E that is not a dereference. ------------- -- 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; -- One more check, don't bother if we are within a -- postcondition, since the expression occurs in a -- place unrelated to the actual test. if not Within_Postcondition then -- 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 set Unset_Reference -- in 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 if; end Potential_Unset_Reference; end if; end; -- Indexed component or slice when N_Indexed_Component | N_Slice => -- If prefix does not involve dereferencing an access type, then -- we know we are OK if the component type is fully initialized, -- since the component will have been set as part of the default -- initialization. if not Prefix_Has_Dereference (Prefix (N)) and then Is_OK_Fully_Initialized then return; -- Look at prefix in access type case, or if the component is not -- fully initialized. else Check_Unset_Reference (Prefix (N)); end if; -- Record component when N_Selected_Component => declare Pref : constant Node_Id := Prefix (N); Ent : constant Entity_Id := Entity (Selector_Name (N)); begin -- If prefix involves dereferencing an access type, always -- check the prefix, since the issue then is whether this -- access value is null. if Prefix_Has_Dereference (Pref) then null; -- Always go to prefix if no selector entity is set. Can this -- happen in the normal case? Not clear, but it definitely can -- happen in error cases. elsif No (Ent) then null; -- For a record component, check some cases where we have -- reasonable cause to consider that the component is known to -- be or probably is initialized. In this case, we don't care -- if the prefix itself was explicitly initialized. -- Discriminants are always considered initialized elsif Ekind (Ent) = E_Discriminant then return; -- An explicitly initialized component is certainly initialized elsif Nkind (Parent (Ent)) = N_Component_Declaration and then Present (Expression (Parent (Ent))) then return; -- A fully initialized component is initialized elsif Is_OK_Fully_Initialized then return; end if; -- If none of those cases apply, check the record type prefix Check_Unset_Reference (Pref); end; -- For type conversions or qualifications examine the expression when N_Type_Conversion | N_Qualified_Expression => Check_Unset_Reference (Expression (N)); -- For explicit dereference, always check prefix, which will generate -- an unset reference (since this is a case of dereferencing null). when N_Explicit_Dereference => Check_Unset_Reference (Prefix (N)); -- All other cases are not cases of an unset reference 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 intended to re-export the unit. function Has_Visible_Entities (P : Entity_Id) return Boolean; -- This function determines if a package has any visible entities. -- True is returned if there is at least one declared visible entity, -- otherwise False is returned (e.g. case of only pragmas present). ------------------------- -- 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 -- CODEFIX ("?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_Check_Spec (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_Check_Spec (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; -------------------------- -- Has_Visible_Entities -- -------------------------- function Has_Visible_Entities (P : Entity_Id) return Boolean is E : Entity_Id; begin -- If unit in context is not a package, it is a subprogram that -- is not called or a generic unit that is not instantiated -- in the current unit, and warning is appropriate. if Ekind (P) /= E_Package then return True; end if; -- If unit comes from a limited_with clause, look for declaration -- of shadow entities. if Present (Limited_View (P)) then E := First_Entity (Limited_View (P)); else E := First_Entity (P); end if; while Present (E) and then E /= First_Private_Entity (P) loop if Comes_From_Source (E) or else Present (Limited_View (P)) then return True; end if; Next_Entity (E); end loop; return False; end Has_Visible_Entities; -- 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_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, but skip this -- if no visible entities, because that is most likely a -- case where warning would be false positive (e.g. a -- package with only a linker options pragma and nothing -- else or a pragma elaborate with a body library task). elsif Has_Visible_Entities (Entity (Name (Item))) then Error_Msg_N -- CODEFIX ("?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. This check is skipped for packages that are -- renamed in a spec, since the entities in such a package are -- visible to clients via the renaming. elsif Ekind (Lunit) = E_Package and then not Renamed_In_Spec (Lunit) 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 if not Has_Unreferenced (Entity (Name (Item))) then Error_Msg_N -- CODEFIX ("?no entities of & are referenced!", Name (Item)); end if; -- 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 Has_Warnings_Off (Lunit) and then not Has_Unreferenced (Pack) then Error_Msg_NE -- CODEFIX ("?no entities of & are referenced!", Unit_Declaration_Node (Pack), Pack); end if; end if; exit; -- Case of entity being referenced. The reference may -- come from a limited_with_clause, in which case the -- limited view of the entity carries the flag. elsif Referenced_Check_Spec (Ent) or else Referenced_As_LHS_Check_Spec (Ent) or else Referenced_As_Out_Parameter_Check_Spec (Ent) or else (From_With_Type (Ent) and then Is_Incomplete_Type (Ent) and then Present (Non_Limited_View (Ent)) and then Referenced (Non_Limited_View (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); else Pack := Empty; end if; -- If a renaming is present in the spec do not warn -- because the body or child unit may depend on it. if Present (Pack) and then Renamed_Entity (Pack) = Lunit then exit; elsif Unreferenced_In_Spec (Item) then Error_Msg_N -- CODEFIX ("?unit& is not referenced in spec!", Name (Item)); elsif No_Entities_Ref_In_Spec (Item) then Error_Msg_N -- CODEFIX ("?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 -- CODEFIX ("\?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 -- CODEFIX ("?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 -- CODEFIX ("\?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; ---------------------- -- Goto_Spec_Entity -- ---------------------- function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is begin if Is_Formal (E) and then Present (Spec_Entity (E)) then return Spec_Entity (E); else return E; end if; end Goto_Spec_Entity; -------------------------------------- -- Has_Pragma_Unmodified_Check_Spec -- -------------------------------------- function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean is begin if Is_Formal (E) and then Present (Spec_Entity (E)) then -- Note: use of OR instead of OR ELSE here is deliberate, we want -- to mess with Unmodified flags on both body and spec entities. return Has_Unmodified (E) or Has_Unmodified (Spec_Entity (E)); else return Has_Unmodified (E); end if; end Has_Pragma_Unmodified_Check_Spec; ---------------------------------------- -- Has_Pragma_Unreferenced_Check_Spec -- ---------------------------------------- function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean is begin if Is_Formal (E) and then Present (Spec_Entity (E)) then -- Note: use of OR here instead of OR ELSE is deliberate, we want -- to mess with flags on both entities. return Has_Unreferenced (E) or Has_Unreferenced (Spec_Entity (E)); else return Has_Unreferenced (E); end if; end Has_Pragma_Unreferenced_Check_Spec; ---------------- -- Initialize -- ---------------- procedure Initialize is begin Warnings_Off_Pragmas.Init; Unreferenced_Entities.Init; In_Out_Warnings.Init; end Initialize; ------------------------------------ -- Never_Set_In_Source_Check_Spec -- ------------------------------------ function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is begin if Is_Formal (E) and then Present (Spec_Entity (E)) then return Never_Set_In_Source (E) and then Never_Set_In_Source (Spec_Entity (E)); else return Never_Set_In_Source (E); end if; end Never_Set_In_Source_Check_Spec; ------------------------------------- -- 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 Has_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_Non_Modified_In_Out_Warnings -- ----------------------------------------- procedure Output_Non_Modified_In_Out_Warnings is function No_Warn_On_In_Out (E : Entity_Id) return Boolean; -- Given a formal parameter entity E, determines if there is a reason to -- suppress IN OUT warnings (not modified, could be IN) for formals of -- the subprogram. We suppress these warnings if Warnings Off is set, or -- if we have seen the address of the subprogram being taken, or if the -- subprogram is used as a generic actual (in the latter cases the -- context may force use of IN OUT, even if the parameter is not -- modifies for this particular case. ----------------------- -- No_Warn_On_In_Out -- ----------------------- function No_Warn_On_In_Out (E : Entity_Id) return Boolean is S : constant Entity_Id := Scope (E); SE : constant Entity_Id := Spec_Entity (E); begin -- Do not warn if address is taken, since funny business may be going -- on in treating the parameter indirectly as IN OUT. if Address_Taken (S) or else (Present (SE) and then Address_Taken (Scope (SE))) then return True; -- Do not warn if used as a generic actual, since the generic may be -- what is forcing the use of an "unnecessary" IN OUT. elsif Used_As_Generic_Actual (S) or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE))) then return True; -- Else test warnings off elsif Warnings_Off_Check_Spec (S) then return True; -- All tests for suppressing warning failed else return False; end if; end No_Warn_On_In_Out; -- Start of processing for Output_Non_Modified_In_Out_Warnings begin -- Loop through entities for which a warning may be needed for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop declare E1 : constant Entity_Id := In_Out_Warnings.Table (J); begin -- Suppress warning in specific cases (see details in comments for -- No_Warn_On_In_Out), or if there is a pragma Unmodified. if Has_Pragma_Unmodified_Check_Spec (E1) or else No_Warn_On_In_Out (E1) then null; -- Here we generate the warning else -- If -gnatwc is set then output message that we could be IN if not Is_Trivial_Subprogram (Scope (E1)) then if Warn_On_Constant then Error_Msg_N ("?formal parameter & is not modified!", E1); Error_Msg_N ("\?mode could be IN instead of `IN OUT`!", E1); -- We do not generate warnings for IN OUT parameters -- unless we have at least -gnatwu. This is deliberately -- inconsistent with the treatment of variables, but -- otherwise we get too many unexpected warnings in -- default mode. elsif Check_Unreferenced then Error_Msg_N ("?formal parameter& is read but " & "never assigned!", E1); end if; end if; -- Kill any other warnings on this entity, since this is the -- one that should dominate any other unreferenced warning. Set_Warnings_Off (E1); end if; end; end loop; end Output_Non_Modified_In_Out_Warnings; ---------------------------------------- -- 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_In (E, E_Component, 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 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop if Obsolescent_Warnings.Table (J).Ent = E then String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg); Error_Msg_Strlen := Name_Len; Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len); Error_Msg_N ("\\?~", N); exit; end if; end loop; end Output_Obsolescent_Entity_Warnings; ---------------------------------- -- Output_Unreferenced_Messages -- ---------------------------------- procedure Output_Unreferenced_Messages is begin for J in Unreferenced_Entities.First .. Unreferenced_Entities.Last loop Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J)); end loop; end Output_Unreferenced_Messages; ----------------------------------------- -- Output_Unused_Warnings_Off_Warnings -- ----------------------------------------- procedure Output_Unused_Warnings_Off_Warnings is begin for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop declare Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J); N : Node_Id renames Wentry.N; E : Node_Id renames Wentry.E; begin -- Turn off Warnings_Off, or we won't get the warning! Set_Warnings_Off (E, False); -- Nothing to do if pragma was used to suppress a general warning if Warnings_Off_Used (E) then null; -- If pragma was used both in unmodified and unreferenced contexts -- then that's as good as the general case, no warning. elsif Warnings_Off_Used_Unmodified (E) and Warnings_Off_Used_Unreferenced (E) then null; -- Used only in context where Unmodified would have worked elsif Warnings_Off_Used_Unmodified (E) then Error_Msg_NE ("?could use Unmodified instead of " & "Warnings Off for &", Pragma_Identifier (N), E); -- Used only in context where Unreferenced would have worked elsif Warnings_Off_Used_Unreferenced (E) then Error_Msg_NE ("?could use Unreferenced instead of " & "Warnings Off for &", Pragma_Identifier (N), E); -- Not used at all else Error_Msg_NE ("?pragma Warnings Off for & unused, " & "could be omitted", N, E); end if; end; end loop; end Output_Unused_Warnings_Off_Warnings; --------------------------- -- Referenced_Check_Spec -- --------------------------- function Referenced_Check_Spec (E : Entity_Id) return Boolean is begin if Is_Formal (E) and then Present (Spec_Entity (E)) then return Referenced (E) or else Referenced (Spec_Entity (E)); else return Referenced (E); end if; end Referenced_Check_Spec; ---------------------------------- -- Referenced_As_LHS_Check_Spec -- ---------------------------------- function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is begin if Is_Formal (E) and then Present (Spec_Entity (E)) then return Referenced_As_LHS (E) or else Referenced_As_LHS (Spec_Entity (E)); else return Referenced_As_LHS (E); end if; end Referenced_As_LHS_Check_Spec; -------------------------------------------- -- Referenced_As_Out_Parameter_Check_Spec -- -------------------------------------------- function Referenced_As_Out_Parameter_Check_Spec (E : Entity_Id) return Boolean is begin if Is_Formal (E) and then Present (Spec_Entity (E)) then return Referenced_As_Out_Parameter (E) or else Referenced_As_Out_Parameter (Spec_Entity (E)); else return Referenced_As_Out_Parameter (E); end if; end Referenced_As_Out_Parameter_Check_Spec; ----------------------------- -- Warn_On_Known_Condition -- ----------------------------- procedure Warn_On_Known_Condition (C : Node_Id) is P : Node_Id; Orig : constant Node_Id := Original_Node (C); Test_Result : Boolean; function Is_Known_Branch return Boolean; -- If the type of the condition is Boolean, the constant value of the -- condition is a boolean literal. If the type is a derived boolean -- type, the constant is wrapped in a type conversion of the derived -- literal. If the value of the condition is not a literal, no warnings -- can be produced. This function returns True if the result can be -- determined, and Test_Result is set True/False accordingly. Otherwise -- False is returned, and Test_Result is unchanged. 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. --------------------- -- Is_Known_Branch -- --------------------- function Is_Known_Branch return Boolean is begin if Etype (C) = Standard_Boolean and then Is_Entity_Name (C) and then (Entity (C) = Standard_False or else Entity (C) = Standard_True) then Test_Result := Entity (C) = Standard_True; return True; elsif Is_Boolean_Type (Etype (C)) and then Nkind (C) = N_Unchecked_Type_Conversion and then Is_Entity_Name (Expression (C)) and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal then Test_Result := Chars (Entity (Expression (C))) = Chars (Standard_True); return True; else return False; end if; end Is_Known_Branch; ----------- -- 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 -- Adjust SCO condition if from source if Generate_SCO and then Comes_From_Source (Orig) and then Is_Known_Branch then declare Atrue : Boolean; begin Atrue := Test_Result; if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then Atrue := not Atrue; end if; Set_SCO_Condition (Orig, Atrue); end; end if; -- 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 Is_Known_Branch 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 or check 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 (Pragma_Name (Original_Node (P)) = Name_Assert or else Pragma_Name (Original_Node (P)) = Name_Check) 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 := Test_Result; 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_Modified_As_Out_Parameter -- --------------------------------------- function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is begin return (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E)) or else Warn_On_All_Unread_Out_Parameters; end Warn_On_Modified_As_Out_Parameter; --------------------------------- -- Warn_On_Overlapping_Actuals -- --------------------------------- procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is Act1, Act2 : Node_Id; Form1, Form2 : Entity_Id; begin if not Warn_On_Overlap then return; end if; -- Exclude calls rewritten as enumeration literals if not Nkind_In (N, N_Function_Call, N_Procedure_Call_Statement) then return; end if; -- Exclude calls to library subprograms. Container operations specify -- safe behavior when source and target coincide. if Is_Predefined_File_Name (Unit_File_Name (Get_Source_Unit (Sloc (Subp)))) then return; end if; Form1 := First_Formal (Subp); Act1 := First_Actual (N); while Present (Form1) and then Present (Act1) loop if Ekind (Form1) /= E_In_Parameter then Form2 := First_Formal (Subp); Act2 := First_Actual (N); while Present (Form2) and then Present (Act2) loop if Form1 /= Form2 and then Ekind (Form2) /= E_Out_Parameter and then (Denotes_Same_Object (Act1, Act2) or else Denotes_Same_Prefix (Act1, Act2)) then -- Exclude generic types and guard against previous errors. if Error_Posted (N) or else No (Etype (Act1)) or else No (Etype (Act2)) then null; elsif Is_Generic_Type (Etype (Act1)) or else Is_Generic_Type (Etype (Act2)) then null; -- If the actual is a function call in prefix notation, -- there is no real overlap. elsif Nkind (Act2) = N_Function_Call then null; -- If type is not by-copy we can assume that the aliasing is -- intended. elsif Is_By_Reference_Type (Underlying_Type (Etype (Form1))) then null; else declare Act : Node_Id; Form : Entity_Id; begin -- Find matching actual Act := First_Actual (N); Form := First_Formal (Subp); while Act /= Act2 loop Next_Formal (Form); Next_Actual (Act); end loop; if Is_Elementary_Type (Etype (Act1)) and then Ekind (Form2) = E_In_Parameter then null; -- No real aliasing elsif Is_Elementary_Type (Etype (Act2)) and then Ekind (Form2) = E_In_Parameter then null; -- Ditto -- If the call was written in prefix notation, and -- thus its prefix before rewriting was a selected -- component, count only visible actuals in the call. elsif Is_Entity_Name (First_Actual (N)) and then Nkind (Original_Node (N)) = Nkind (N) and then Nkind (Name (Original_Node (N))) = N_Selected_Component and then Is_Entity_Name (Prefix (Name (Original_Node (N)))) and then Entity (Prefix (Name (Original_Node (N)))) = Entity (First_Actual (N)) then if Act1 = First_Actual (N) then Error_Msg_FE ("`IN OUT` prefix overlaps with actual for&?", Act1, Form); else -- For greater clarity, give name of formal. Error_Msg_Node_2 := Form; Error_Msg_FE ("writable actual for & overlaps with" & " actual for&?", Act1, Form); end if; else Error_Msg_Node_2 := Form; Error_Msg_FE ("writable actual for & overlaps with" & " actual for&?", Act1, Form1); end if; end; end if; return; end if; Next_Formal (Form2); Next_Actual (Act2); end loop; end if; Next_Formal (Form1); Next_Actual (Act1); end loop; end Warn_On_Overlapping_Actuals; ------------------------------ -- 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 limit 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 (Root_Type (Typ) = Standard_String or else Root_Type (Typ) = Standard_Wide_String or else Root_Type (Typ) = Standard_Wide_Wide_String) and then not Has_Warnings_Off (Typ) 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 -- CODEFIX ("?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. Such 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 -- CODEFIX ("\suggested replacement: `&''First`", X, Ent); else Error_Msg_Uint_1 := Intval (X) - Low_Bound; Error_Msg_FE -- CODEFIX ("\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; -- Parentheses 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 -- CODEFIX ("\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_Tested (Ent) then Test_Suspicious_Index; end if; end if; end if; end Warn_On_Suspicious_Index; -------------------------------------- -- Warn_On_Unassigned_Out_Parameter -- -------------------------------------- procedure Warn_On_Unassigned_Out_Parameter (Return_Node : Node_Id; Scope_Id : Entity_Id) is Form : Entity_Id; Form2 : Entity_Id; begin -- Ignore if procedure or return statement does not come from source if not Comes_From_Source (Scope_Id) or else not Comes_From_Source (Return_Node) then return; end if; -- Loop through formals Form := First_Formal (Scope_Id); while Present (Form) loop -- We are only interested in OUT parameters that come from source -- and are never set in the source, and furthermore only in scalars -- since non-scalars generate too many false positives. if Ekind (Form) = E_Out_Parameter and then Never_Set_In_Source_Check_Spec (Form) and then Is_Scalar_Type (Etype (Form)) and then not Present (Unset_Reference (Form)) then -- Before we issue the warning, an add ad hoc defence against the -- most common case of false positives with this warning which is -- the case where there is a Boolean OUT parameter that has been -- set, and whose meaning is "ignore the values of the other -- parameters". We can't of course reliably tell this case at -- compile time, but the following test kills a lot of false -- positives, without generating a significant number of false -- negatives (missed real warnings). Form2 := First_Formal (Scope_Id); while Present (Form2) loop if Ekind (Form2) = E_Out_Parameter and then Root_Type (Etype (Form2)) = Standard_Boolean and then not Never_Set_In_Source_Check_Spec (Form2) then return; end if; Next_Formal (Form2); end loop; -- Here all conditions are met, record possible unset reference Set_Unset_Reference (Form, Return_Node); end if; Next_Formal (Form); end loop; end Warn_On_Unassigned_Out_Parameter; --------------------------------- -- Warn_On_Unreferenced_Entity -- --------------------------------- procedure Warn_On_Unreferenced_Entity (Spec_E : Entity_Id; Body_E : Entity_Id := Empty) is E : Entity_Id := Spec_E; begin if not Referenced_Check_Spec (E) and then not Has_Pragma_Unreferenced_Check_Spec (E) and then not Warnings_Off_Check_Spec (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, is aliased, or is a renaming, or is imported. if Referenced_As_LHS_Check_Spec (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_Aliased (E) and then No (Renamed_Object (E)) then if not Has_Pragma_Unmodified_Check_Spec (E) then Error_Msg_N -- CODEFIX ("?variable & is assigned but never read!", E); end if; Set_Last_Assignment (E, Empty); end if; -- Normal case of neither assigned nor read (exclude variables -- referenced as out parameters, since we already generated -- appropriate warnings at the call point in this case). elsif not Referenced_As_Out_Parameter (E) then -- 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 -- CODEFIX ("?renamed variable & is not referenced!", E); else Error_Msg_N -- CODEFIX ("?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 -- CODEFIX ("?renamed constant & is not referenced!", E); else Error_Msg_N -- CODEFIX ("?constant & is not referenced!", E); end if; when E_In_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 -- Suppress this message for an IN OUT parameter of a -- non-scalar type, since it is normal to have only an -- assignment in such a case. if Ekind (E) = E_In_Parameter or else not Referenced_As_LHS_Check_Spec (E) or else Is_Scalar_Type (Etype (E)) then if Present (Body_E) then E := Body_E; end if; if not Is_Trivial_Subprogram (Scope (E)) then Error_Msg_NE -- CODEFIX ("?formal parameter & is not referenced!", E, Spec_E); end if; end if; end if; when E_Out_Parameter => null; when E_Discriminant => Error_Msg_N ("?discriminant & is not referenced!", E); when E_Named_Integer | E_Named_Real => Error_Msg_N -- CODEFIX ("?named number & is not referenced!", E); when Formal_Object_Kind => Error_Msg_N -- CODEFIX ("?formal object & is not referenced!", E); when E_Enumeration_Literal => Error_Msg_N -- CODEFIX ("?literal & is not referenced!", E); when E_Function => Error_Msg_N -- CODEFIX ("?function & is not referenced!", E); when E_Procedure => Error_Msg_N -- CODEFIX ("?procedure & is not referenced!", E); when E_Package => Error_Msg_N -- CODEFIX ("?package & is not referenced!", E); when E_Exception => Error_Msg_N -- CODEFIX ("?exception & is not referenced!", E); when E_Label => Error_Msg_N -- CODEFIX ("?label & is not referenced!", E); when E_Generic_Procedure => Error_Msg_N -- CODEFIX ("?generic procedure & is never instantiated!", E); when E_Generic_Function => Error_Msg_N -- CODEFIX ("?generic function & is never instantiated!", E); when Type_Kind => Error_Msg_N -- CODEFIX ("?type & is not referenced!", E); when others => Error_Msg_N -- CODEFIX ("?& is not referenced!", E); end case; -- Kill warnings on the entity on which the message has been posted Set_Warnings_Off (E); end if; end Warn_On_Unreferenced_Entity; -------------------------------- -- Warn_On_Useless_Assignment -- -------------------------------- procedure Warn_On_Useless_Assignment (Ent : Entity_Id; N : Node_Id := Empty) 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 scalar or access -- variable with the last assignment field set, with warnings enabled, -- and which is not imported or exported. We also check that it is OK -- to capture the value. We are not going to capture any value, but -- the warning message depends on the same kind of conditions. if Is_Assignable (Ent) and then not Is_Return_Object (Ent) and then Present (Last_Assignment (Ent)) and then not Is_Imported (Ent) and then not Is_Exported (Ent) and then Safe_To_Capture_Value (N, Ent) and then not Has_Pragma_Unreferenced_Check_Spec (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 -- Case of assigned value never referenced if No (N) then declare LA : constant Node_Id := Last_Assignment (Ent); begin -- Don't give this for OUT and IN OUT formals, since -- clearly caller may reference the assigned value. Also -- never give such warnings for internal variables. if Ekind (Ent) = E_Variable and then not Is_Internal_Name (Chars (Ent)) then -- Give appropriate message, distinguishing between -- assignment statements and out parameters. if Nkind_In (Parent (LA), N_Procedure_Call_Statement, N_Parameter_Association) then Error_Msg_NE ("?& modified by call, but value never " & "referenced", LA, Ent); else Error_Msg_NE -- CODEFIX ("?useless assignment to&, value never " & "referenced!", LA, Ent); end if; end if; end; -- Case of assigned value overwritten else declare LA : constant Node_Id := Last_Assignment (Ent); begin Error_Msg_Sloc := Sloc (N); -- Give appropriate message, distinguishing between -- assignment statements and out parameters. if Nkind_In (Parent (LA), N_Procedure_Call_Statement, N_Parameter_Association) then Error_Msg_NE ("?& modified by call, but value overwritten #!", LA, Ent); else Error_Msg_NE -- CODEFIX ("?useless assignment to&, value overwritten #!", LA, Ent); end if; end; end if; -- Clear last assignment indication and we are done 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 accessed 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, or if the entity in question -- is an OUT or IN OUT parameter, which which case -- the caller can reference it after the exception -- handler completes. else if Is_Formal (Ent) then Set_Last_Assignment (Ent, Empty); return; 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; 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; ----------------------------- -- Warnings_Off_Check_Spec -- ----------------------------- function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is begin if Is_Formal (E) and then Present (Spec_Entity (E)) then -- Note: use of OR here instead of OR ELSE is deliberate, we want -- to mess with flags on both entities. return Has_Warnings_Off (E) or Has_Warnings_Off (Spec_Entity (E)); else return Has_Warnings_Off (E); end if; end Warnings_Off_Check_Spec; end Sem_Warn;
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