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Diffstat (limited to 'gcc-4.2.1/gcc/ada/sem_warn.adb')
-rw-r--r-- | gcc-4.2.1/gcc/ada/sem_warn.adb | 1884 |
1 files changed, 0 insertions, 1884 deletions
diff --git a/gcc-4.2.1/gcc/ada/sem_warn.adb b/gcc-4.2.1/gcc/ada/sem_warn.adb deleted file mode 100644 index 5f8394e79..000000000 --- a/gcc-4.2.1/gcc/ada/sem_warn.adb +++ /dev/null @@ -1,1884 +0,0 @@ ------------------------------------------------------------------------------- --- -- --- GNAT COMPILER COMPONENTS -- --- -- --- S E M _ W A R N -- --- -- --- B o d y -- --- -- --- Copyright (C) 1999-2006, Free Software Foundation, Inc. -- --- -- --- GNAT is free software; you can redistribute it and/or modify it under -- --- terms of the GNU General Public License as published by the Free Soft- -- --- ware Foundation; either version 2, or (at your option) any later ver- -- --- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- --- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- --- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- --- for more details. You should have received a copy of the GNU General -- --- Public License distributed with GNAT; see file COPYING. If not, write -- --- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- --- Boston, MA 02110-1301, USA. -- --- -- --- GNAT was originally developed by the GNAT team at New York University. -- --- Extensive contributions were provided by Ada Core Technologies Inc. -- --- -- ------------------------------------------------------------------------------- - -with Alloc; -with Atree; use Atree; -with Einfo; use Einfo; -with Errout; use Errout; -with Fname; use Fname; -with Lib; use Lib; -with Nlists; use Nlists; -with Opt; use Opt; -with Sem; use Sem; -with Sem_Ch8; use Sem_Ch8; -with Sem_Util; use Sem_Util; -with Sinfo; use Sinfo; -with Sinput; use Sinput; -with Snames; use Snames; -with Stand; use Stand; -with Table; - -package body Sem_Warn is - - -- The following table collects Id's of entities that are potentially - -- unreferenced. See Check_Unset_Reference for further details. - - package Unreferenced_Entities is new Table.Table ( - Table_Component_Type => Entity_Id, - Table_Index_Type => Nat, - Table_Low_Bound => 1, - Table_Initial => Alloc.Unreferenced_Entities_Initial, - Table_Increment => Alloc.Unreferenced_Entities_Increment, - Table_Name => "Unreferenced_Entities"); - - ------------------------------ - -- Handling of Conditionals -- - ------------------------------ - - -- Note: this is work in progress, the data structures and general approach - -- are defined, but are not in use yet. ??? - - -- An entry is made in the following table for each branch of conditional, - -- e.g. an if-then-elsif-else-endif structure creates three entries in this - -- table. - - type Branch_Entry is record - Sloc : Source_Ptr; - -- Location for warnings associated with this branch - - Defs : Elist_Id; - -- List of entities defined for the first time in this branch. On exit - -- from a conditional structure, any entity that is in the list of all - -- branches is removed (and the entity flagged as defined by the - -- conditional as a whole). Thus after processing a conditional, Defs - -- contains a list of entities defined in this branch for the first - -- time, but not defined at all in some other branch of the same - -- conditional. A value of No_Elist is used to represent the initial - -- empty list. - - Next : Nat; - -- Index of next branch for this conditional, zero = last branch - end record; - - package Branch_Table is new Table.Table ( - Table_Component_Type => Branch_Entry, - Table_Index_Type => Nat, - Table_Low_Bound => 1, - Table_Initial => Alloc.Branches_Initial, - Table_Increment => Alloc.Branches_Increment, - Table_Name => "Branches"); - - -- The following table is used to represent conditionals, there is one - -- entry in this table for each conditional structure. - - type Conditional_Entry is record - If_Stmt : Boolean; - -- True for IF statement, False for CASE statement - - First_Branch : Nat; - -- Index in Branch table of first branch, zero = none yet - - Current_Branch : Nat; - -- Index in Branch table of current branch, zero = none yet - end record; - - package Conditional_Table is new Table.Table ( - Table_Component_Type => Conditional_Entry, - Table_Index_Type => Nat, - Table_Low_Bound => 1, - Table_Initial => Alloc.Conditionals_Initial, - Table_Increment => Alloc.Conditionals_Increment, - Table_Name => "Conditionals"); - - -- The following table is a stack that keeps track of the current - -- conditional. The Last entry is the top of the stack. An Empty entry - -- represents the start of a compilation unit. Non-zero entries in the - -- stack are indexes into the conditional table. - - package Conditional_Stack is new Table.Table ( - Table_Component_Type => Nat, - Table_Index_Type => Nat, - Table_Low_Bound => 1, - Table_Initial => Alloc.Conditional_Stack_Initial, - Table_Increment => Alloc.Conditional_Stack_Increment, - Table_Name => "Conditional_Stack"); - - pragma Warnings (Off, Branch_Table); - pragma Warnings (Off, Conditional_Table); - pragma Warnings (Off, Conditional_Stack); - -- Not yet referenced, see note above ??? - - ----------------------- - -- Local Subprograms -- - ----------------------- - - function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean; - -- This returns true if the entity E is declared within a generic package. - -- The point of this is to detect variables which are not assigned within - -- the generic, but might be assigned outside the package for any given - -- instance. These are cases where we leave the warnings to be posted - -- for the instance, when we will know more. - - function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean; - -- This function traverses the expression tree represented by the node N - -- and determines if any sub-operand is a reference to an entity for which - -- the Warnings_Off flag is set. True is returned if such an entity is - -- encountered, and False otherwise. - - ---------------------- - -- Check_References -- - ---------------------- - - procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is - E1 : Entity_Id; - UR : Node_Id; - - function Missing_Subunits return Boolean; - -- We suppress warnings when there are missing subunits, because this - -- may generate too many false positives: entities in a parent may only - -- be referenced in one of the subunits. We make an exception for - -- subunits that contain no other stubs. - - procedure Output_Reference_Error (M : String); - -- Used to output an error message. Deals with posting the error on the - -- body formal in the accept case. - - function Publicly_Referenceable (Ent : Entity_Id) return Boolean; - -- This is true if the entity in question is potentially referenceable - -- from another unit. This is true for entities in packages that are at - -- the library level. - - ---------------------- - -- Missing_Subunits -- - ---------------------- - - function Missing_Subunits return Boolean is - D : Node_Id; - - begin - if not Unloaded_Subunits then - - -- Normal compilation, all subunits are present - - return False; - - elsif E /= Main_Unit_Entity then - - -- No warnings on a stub that is not the main unit - - return True; - - elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then - D := First (Declarations (Unit_Declaration_Node (E))); - while Present (D) loop - - -- No warnings if the proper body contains nested stubs - - if Nkind (D) in N_Body_Stub then - return True; - end if; - - Next (D); - end loop; - - return False; - - else - -- Missing stubs elsewhere - - return True; - end if; - end Missing_Subunits; - - ---------------------------- - -- Output_Reference_Error -- - ---------------------------- - - procedure Output_Reference_Error (M : String) is - begin - -- Other than accept case, post error on defining identifier - - if No (Anod) then - Error_Msg_N (M, E1); - - -- Accept case, find body formal to post the message - - else - declare - Parm : Node_Id; - Enod : Node_Id; - Defid : Entity_Id; - - begin - Enod := Anod; - - if Present (Parameter_Specifications (Anod)) then - Parm := First (Parameter_Specifications (Anod)); - while Present (Parm) loop - Defid := Defining_Identifier (Parm); - - if Chars (E1) = Chars (Defid) then - Enod := Defid; - exit; - end if; - - Next (Parm); - end loop; - end if; - - Error_Msg_NE (M, Enod, E1); - end; - end if; - end Output_Reference_Error; - - ---------------------------- - -- Publicly_Referenceable -- - ---------------------------- - - function Publicly_Referenceable (Ent : Entity_Id) return Boolean is - P : Node_Id; - Prev : Node_Id; - - begin - -- Examine parents to look for a library level package spec. But if - -- we find a body or block or other similar construct along the way, - -- we cannot be referenced. - - Prev := Ent; - P := Parent (Ent); - loop - case Nkind (P) is - - -- If we get to top of tree, then publicly referenceable - - when N_Empty => - return True; - - -- If we reach a generic package declaration, then always - -- consider this referenceable, since any instantiation will - -- have access to the entities in the generic package. Note - -- that the package itself may not be instantiated, but then - -- we will get a warning for the package entity. - - -- Note that generic formal parameters are themselves not - -- publicly referenceable in an instance, and warnings on - -- them are useful. - - when N_Generic_Package_Declaration => - return - not Is_List_Member (Prev) - or else List_Containing (Prev) - /= Generic_Formal_Declarations (P); - - -- Similarly, the generic formals of a generic subprogram - -- are not accessible. - - when N_Generic_Subprogram_Declaration => - if Is_List_Member (Prev) - and then List_Containing (Prev) = - Generic_Formal_Declarations (P) - then - return False; - else - P := Parent (P); - end if; - - -- If we reach a subprogram body, entity is not referenceable - -- unless it is the defining entity of the body. This will - -- happen, e.g. when a function is an attribute renaming that - -- is rewritten as a body. - - when N_Subprogram_Body => - if Ent /= Defining_Entity (P) then - return False; - else - P := Parent (P); - end if; - - -- If we reach any other body, definitely not referenceable - - when N_Package_Body | - N_Task_Body | - N_Entry_Body | - N_Protected_Body | - N_Block_Statement | - N_Subunit => - return False; - - -- For all other cases, keep looking up tree - - when others => - Prev := P; - P := Parent (P); - end case; - end loop; - end Publicly_Referenceable; - - -- Start of processing for Check_References - - begin - -- No messages if warnings are suppressed, or if we have detected any - -- real errors so far (this last check avoids junk messages resulting - -- from errors, e.g. a subunit that is not loaded). - - if Warning_Mode = Suppress - or else Serious_Errors_Detected /= 0 - then - return; - end if; - - -- We also skip the messages if any subunits were not loaded (see - -- comment in Sem_Ch10 to understand how this is set, and why it is - -- necessary to suppress the warnings in this case). - - if Missing_Subunits then - return; - end if; - - -- Otherwise loop through entities, looking for suspicious stuff - - E1 := First_Entity (E); - while Present (E1) loop - - -- We only look at source entities with warning flag on - - if Comes_From_Source (E1) and then not Warnings_Off (E1) then - - -- We are interested in variables and out parameters, but we - -- exclude protected types, too complicated to worry about. - - if Ekind (E1) = E_Variable - or else - (Ekind (E1) = E_Out_Parameter - and then not Is_Protected_Type (Current_Scope)) - then - -- Post warning if this object not assigned. Note that we do - -- not consider the implicit initialization of an access type - -- to be the assignment of a value for this purpose. - - if Ekind (E1) = E_Out_Parameter - and then Present (Spec_Entity (E1)) - then - UR := Unset_Reference (Spec_Entity (E1)); - else - UR := Unset_Reference (E1); - end if; - - -- If the entity is an out parameter of the current subprogram - -- body, check the warning status of the parameter in the spec. - - if Ekind (E1) = E_Out_Parameter - and then Present (Spec_Entity (E1)) - and then Warnings_Off (Spec_Entity (E1)) - then - null; - - elsif Present (UR) - and then Is_Access_Type (Etype (E1)) - then - - -- For access types, the only time we made a UR entry was - -- for a dereference, and so we post the appropriate warning - -- here (note that the dereference may not be explicit in - -- the source, for example in the case of a dispatching call - -- with an anonymous access controlling formal, or of an - -- assignment of a pointer involving discriminant check on - -- the designated object). - - Error_Msg_NE ("& may be null?", UR, E1); - goto Continue; - - elsif Never_Set_In_Source (E1) - and then not Generic_Package_Spec_Entity (E1) - then - if Warn_On_No_Value_Assigned then - - -- Do not output complaint about never being assigned a - -- value if a pragma Unreferenced applies to the variable - -- or if it is a parameter, to the corresponding spec. - - if Has_Pragma_Unreferenced (E1) - or else (Is_Formal (E1) - and then Present (Spec_Entity (E1)) - and then - Has_Pragma_Unreferenced (Spec_Entity (E1))) - then - null; - - -- Pragma Unreferenced not set, so output message - - else - Output_Reference_Error - ("& is never assigned a value?"); - - -- Deal with special case where this variable is - -- hidden by a loop variable - - if Ekind (E1) = E_Variable - and then Present (Hiding_Loop_Variable (E1)) - then - Error_Msg_Sloc := Sloc (E1); - Error_Msg_N - ("declaration hides &#?", - Hiding_Loop_Variable (E1)); - Error_Msg_N - ("for loop implicitly declares loop variable?", - Hiding_Loop_Variable (E1)); - end if; - end if; - end if; - goto Continue; - - -- Case of variable that could be a constant. Note that we - -- never signal such messages for generic package entities, - -- since a given instance could have modifications outside - -- the package. - - elsif Warn_On_Constant - and then Ekind (E1) = E_Variable - and then Is_True_Constant (E1) - and then not Generic_Package_Spec_Entity (E1) - then - -- A special case, if this variable is volatile and not - -- imported, it is not helpful to tell the programmer - -- to mark the variable as constant, since this would be - -- illegal by virtue of RM C.6(13). - - if (Is_Volatile (E1) or else Has_Volatile_Components (E1)) - and then not Is_Imported (E1) - then - Error_Msg_N - ("& is not modified, volatile has no effect?", E1); - else - Error_Msg_N - ("& is not modified, could be declared constant?", E1); - end if; - end if; - - -- Check for unset reference, note that we exclude access - -- types from this check, since access types do always have - -- a null value, and that seems legitimate in this case. - - if Warn_On_No_Value_Assigned and then Present (UR) then - - -- For other than access type, go back to original node - -- to deal with case where original unset reference - -- has been rewritten during expansion. - - UR := Original_Node (UR); - - -- In some cases, the original node may be a type - -- conversion or qualification, and in this case - -- we want the object entity inside. - - while Nkind (UR) = N_Type_Conversion - or else Nkind (UR) = N_Qualified_Expression - loop - UR := Expression (UR); - end loop; - - -- Here we issue the warning, all checks completed If the - -- unset reference is prefix of a selected component that - -- comes from source, mention the component as well. If the - -- selected component comes from expansion, all we know is - -- that the entity is not fully initialized at the point of - -- the reference. Locate an unintialized component to get a - -- better error message. - - if Nkind (Parent (UR)) = N_Selected_Component then - Error_Msg_Node_2 := Selector_Name (Parent (UR)); - - if not Comes_From_Source (Parent (UR)) then - declare - Comp : Entity_Id; - - begin - Comp := First_Entity (Etype (E1)); - while Present (Comp) loop - if Ekind (Comp) = E_Component - and then Nkind (Parent (Comp)) = - N_Component_Declaration - and then No (Expression (Parent (Comp))) - then - Error_Msg_Node_2 := Comp; - exit; - end if; - - Next_Entity (Comp); - end loop; - end; - end if; - - Error_Msg_N - ("`&.&` may be referenced before it has a value?", - UR); - else - Error_Msg_N - ("& may be referenced before it has a value?", - UR); - end if; - - goto Continue; - end if; - end if; - - -- Then check for unreferenced entities. Note that we are only - -- interested in entities which do not have the Referenced flag - -- set. The Referenced_As_LHS flag is interesting only if the - -- Referenced flag is not set. - - if not Referenced (E1) - - -- Check that warnings on unreferenced entities are enabled - - and then ((Check_Unreferenced and then not Is_Formal (E1)) - or else - (Check_Unreferenced_Formals and then Is_Formal (E1)) - or else - (Warn_On_Modified_Unread - and then Referenced_As_LHS (E1))) - - -- Labels, and enumeration literals, and exceptions. The - -- warnings are also placed on local packages that cannot be - -- referenced from elsewhere, including those declared within a - -- package body. - - and then (Is_Object (E1) - or else - Is_Type (E1) - or else - Ekind (E1) = E_Label - or else - Ekind (E1) = E_Exception - or else - Ekind (E1) = E_Named_Integer - or else - Ekind (E1) = E_Named_Real - or else - Is_Overloadable (E1) - or else - (Ekind (E1) = E_Package - and then - (Ekind (E) = E_Function - or else Ekind (E) = E_Package_Body - or else Ekind (E) = E_Procedure - or else Ekind (E) = E_Subprogram_Body - or else Ekind (E) = E_Block))) - - -- Exclude instantiations, since there is no reason why every - -- entity in an instantiation should be referenced. - - and then Instantiation_Location (Sloc (E1)) = No_Location - - -- Exclude formal parameters from bodies if the corresponding - -- spec entity has been referenced in the case where there is - -- a separate spec. - - and then not (Is_Formal (E1) - and then - Ekind (Scope (E1)) = E_Subprogram_Body - and then - Present (Spec_Entity (E1)) - and then - Referenced (Spec_Entity (E1))) - - -- Consider private type referenced if full view is referenced - -- If there is not full view, this is a generic type on which - -- warnings are also useful. - - and then - not (Is_Private_Type (E1) - and then - Present (Full_View (E1)) - and then Referenced (Full_View (E1))) - - -- Don't worry about full view, only about private type - - and then not Has_Private_Declaration (E1) - - -- Eliminate dispatching operations from consideration, we - -- cannot tell if these are referenced or not in any easy - -- manner (note this also catches Adjust/Finalize/Initialize) - - and then not Is_Dispatching_Operation (E1) - - -- Check entity that can be publicly referenced (we do not give - -- messages for such entities, since there could be other - -- units, not involved in this compilation, that contain - -- relevant references. - - and then not Publicly_Referenceable (E1) - - -- Class wide types are marked as source entities, but they are - -- not really source entities, and are always created, so we do - -- not care if they are not referenced. - - and then Ekind (E1) /= E_Class_Wide_Type - - -- Objects other than parameters of task types are allowed to - -- be non-referenced, since they start up tasks! - - and then ((Ekind (E1) /= E_Variable - and then Ekind (E1) /= E_Constant - and then Ekind (E1) /= E_Component) - or else not Is_Task_Type (Etype (E1))) - - -- For subunits, only place warnings on the main unit itself, - -- since parent units are not completely compiled - - and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit - or else - Get_Source_Unit (E1) = Main_Unit) - then - -- Suppress warnings in internal units if not in -gnatg mode - -- (these would be junk warnings for an applications program, - -- since they refer to problems in internal units) - - if GNAT_Mode - or else not - Is_Internal_File_Name - (Unit_File_Name (Get_Source_Unit (E1))) - then - -- We do not immediately flag the error. This is because we - -- have not expanded generic bodies yet, and they may have - -- the missing reference. So instead we park the entity on a - -- list, for later processing. However, for the accept case, - -- post the error right here, since we have the information - -- now in this case. - - if Present (Anod) then - Output_Reference_Error ("& is not referenced?"); - - else - Unreferenced_Entities.Increment_Last; - Unreferenced_Entities.Table - (Unreferenced_Entities.Last) := E1; - end if; - end if; - - -- Generic units are referenced in the generic body, but if they - -- are not public and never instantiated we want to force a - -- warning on them. We treat them as redundant constructs to - -- minimize noise. - - elsif Is_Generic_Subprogram (E1) - and then not Is_Instantiated (E1) - and then not Publicly_Referenceable (E1) - and then Instantiation_Depth (Sloc (E1)) = 0 - and then Warn_On_Redundant_Constructs - then - Unreferenced_Entities.Increment_Last; - Unreferenced_Entities.Table (Unreferenced_Entities.Last) := E1; - - -- Force warning on entity - - Set_Referenced (E1, False); - end if; - end if; - - -- Recurse into nested package or block. Do not recurse into a - -- formal package, because the correponding body is not analyzed. - - <<Continue>> - if ((Ekind (E1) = E_Package or else Ekind (E1) = E_Generic_Package) - and then Nkind (Parent (E1)) = N_Package_Specification - and then - Nkind (Original_Node (Unit_Declaration_Node (E1))) - /= N_Formal_Package_Declaration) - - or else Ekind (E1) = E_Block - then - Check_References (E1); - end if; - - Next_Entity (E1); - end loop; - end Check_References; - - --------------------------- - -- Check_Unset_Reference -- - --------------------------- - - procedure Check_Unset_Reference (N : Node_Id) is - begin - -- Nothing to do if warnings suppressed - - if Warning_Mode = Suppress then - return; - end if; - - -- Ignore reference to non-scalar if not from source. Almost always such - -- references are bogus (e.g. calls to init procs to set default - -- discriminant values). - - if not Comes_From_Source (N) - and then not Is_Scalar_Type (Etype (N)) - then - return; - end if; - - -- Otherwise see what kind of node we have. If the entity already - -- has an unset reference, it is not necessarily the earliest in - -- the text, because resolution of the prefix of selected components - -- is completed before the resolution of the selected component itself. - -- as a result, given (R /= null and then R.X > 0), the occurrences - -- of R are examined in right-to-left order. If there is already an - -- unset reference, we check whether N is earlier before proceeding. - - case Nkind (N) is - when N_Identifier | N_Expanded_Name => - declare - E : constant Entity_Id := Entity (N); - - begin - if (Ekind (E) = E_Variable - or else Ekind (E) = E_Out_Parameter) - and then Never_Set_In_Source (E) - and then (No (Unset_Reference (E)) - or else Earlier_In_Extended_Unit - (Sloc (N), Sloc (Unset_Reference (E)))) - and then not Warnings_Off (E) - then - -- We may have an unset reference. The first test is whether - -- we are accessing a discriminant of a record or a - -- component with default initialization. Both of these - -- cases can be ignored, since the actual object that is - -- referenced is definitely initialized. Note that this - -- covers the case of reading discriminants of an out - -- parameter, which is OK even in Ada 83. - - -- Note that we are only interested in a direct reference to - -- a record component here. If the reference is via an - -- access type, then the access object is being referenced, - -- not the record, and still deserves an unset reference. - - if Nkind (Parent (N)) = N_Selected_Component - and not Is_Access_Type (Etype (N)) - then - declare - ES : constant Entity_Id := - Entity (Selector_Name (Parent (N))); - - begin - if Ekind (ES) = E_Discriminant - or else Present (Expression (Declaration_Node (ES))) - then - return; - end if; - end; - end if; - - -- Here we have a potential unset reference. But before we - -- get worried about it, we have to make sure that the - -- entity declaration is in the same procedure as the - -- reference, since if they are in separate procedures, then - -- we have no idea about sequential execution. - - -- The tests in the loop below catch all such cases, but do - -- allow the reference to appear in a loop, block, or - -- package spec that is nested within the declaring scope. - -- As always, it is possible to construct cases where the - -- warning is wrong, that is why it is a warning! - - declare - SR : Entity_Id; - SE : constant Entity_Id := Scope (E); - - begin - SR := Current_Scope; - while SR /= SE loop - if SR = Standard_Standard - or else Is_Subprogram (SR) - or else Is_Concurrent_Body (SR) - or else Is_Concurrent_Type (SR) - then - return; - end if; - - SR := Scope (SR); - end loop; - - -- Case of reference has an access type. This is special - -- case since access types are always set to null so - -- cannot be truly uninitialized, but we still want to - -- warn about cases of obvious null dereference. - - if Is_Access_Type (Etype (N)) then - Access_Type_Case : declare - P : Node_Id; - - function Process - (N : Node_Id) - return Traverse_Result; - -- Process function for instantation of Traverse - -- below. Checks if N contains reference to other - -- than a dereference. - - function Ref_In (Nod : Node_Id) return Boolean; - -- Determines whether Nod contains a reference to - -- the entity E that is not a dereference. - - ------------- - -- Process -- - ------------- - - function Process - (N : Node_Id) - return Traverse_Result - is - begin - if Is_Entity_Name (N) - and then Entity (N) = E - and then not Is_Dereferenced (N) - then - return Abandon; - else - return OK; - end if; - end Process; - - ------------ - -- Ref_In -- - ------------ - - function Ref_In (Nod : Node_Id) return Boolean is - function Traverse is new Traverse_Func (Process); - begin - return Traverse (Nod) = Abandon; - end Ref_In; - - -- Start of processing for Access_Type_Case - - begin - -- Don't bother if we are inside an instance, - -- since the compilation of the generic template - -- is where the warning should be issued. - - if In_Instance then - return; - end if; - - -- Don't bother if this is not the main unit. - -- If we try to give this warning for with'ed - -- units, we get some false positives, since - -- we do not record references in other units. - - if not In_Extended_Main_Source_Unit (E) - or else - not In_Extended_Main_Source_Unit (N) - then - return; - end if; - - -- We are only interested in deferences - - if not Is_Dereferenced (N) then - return; - end if; - - -- One more check, don't bother with references - -- that are inside conditional statements or while - -- loops if the condition references the entity in - -- question. This avoids most false positives. - - P := Parent (N); - loop - P := Parent (P); - exit when No (P); - - if (Nkind (P) = N_If_Statement - or else - Nkind (P) = N_Elsif_Part) - and then Ref_In (Condition (P)) - then - return; - - elsif Nkind (P) = N_Loop_Statement - and then Present (Iteration_Scheme (P)) - and then - Ref_In (Condition (Iteration_Scheme (P))) - then - return; - end if; - end loop; - end Access_Type_Case; - end if; - - -- Here we definitely have a case for giving a warning - -- for a reference to an unset value. But we don't give - -- the warning now. Instead we set the Unset_Reference - -- field of the identifier involved. The reason for this - -- is that if we find the variable is never ever assigned - -- a value then that warning is more important and there - -- is no point in giving the reference warning. - - -- If this is an identifier, set the field directly - - if Nkind (N) = N_Identifier then - Set_Unset_Reference (E, N); - - -- Otherwise it is an expanded name, so set the field - -- of the actual identifier for the reference. - - else - Set_Unset_Reference (E, Selector_Name (N)); - end if; - end; - end if; - end; - - when N_Indexed_Component | N_Slice => - Check_Unset_Reference (Prefix (N)); - - when N_Selected_Component => - - if Present (Entity (Selector_Name (N))) - and then Ekind (Entity (Selector_Name (N))) = E_Discriminant - then - -- A discriminant is always initialized - - null; - - else - Check_Unset_Reference (Prefix (N)); - end if; - - when N_Type_Conversion | N_Qualified_Expression => - Check_Unset_Reference (Expression (N)); - - when others => - null; - - end case; - end Check_Unset_Reference; - - ------------------------ - -- Check_Unused_Withs -- - ------------------------ - - procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is - Cnode : Node_Id; - Item : Node_Id; - Lunit : Node_Id; - Ent : Entity_Id; - - Munite : constant Entity_Id := Cunit_Entity (Main_Unit); - -- This is needed for checking the special renaming case - - procedure Check_One_Unit (Unit : Unit_Number_Type); - -- Subsidiary procedure, performs checks for specified unit - - -------------------- - -- Check_One_Unit -- - -------------------- - - procedure Check_One_Unit (Unit : Unit_Number_Type) is - Is_Visible_Renaming : Boolean := False; - Pack : Entity_Id; - - procedure Check_Inner_Package (Pack : Entity_Id); - -- Pack is a package local to a unit in a with_clause. Both the - -- unit and Pack are referenced. If none of the entities in Pack - -- are referenced, then the only occurrence of Pack is in a use - -- clause or a pragma, and a warning is worthwhile as well. - - function Check_System_Aux return Boolean; - -- Before giving a warning on a with_clause for System, check - -- whether a system extension is present. - - function Find_Package_Renaming - (P : Entity_Id; - L : Entity_Id) return Entity_Id; - -- The only reference to a context unit may be in a renaming - -- declaration. If this renaming declares a visible entity, do - -- not warn that the context clause could be moved to the body, - -- because the renaming may be intented to re-export the unit. - - ------------------------- - -- Check_Inner_Package -- - ------------------------- - - procedure Check_Inner_Package (Pack : Entity_Id) is - E : Entity_Id; - Un : constant Node_Id := Sinfo.Unit (Cnode); - - function Check_Use_Clause (N : Node_Id) return Traverse_Result; - -- If N is a use_clause for Pack, emit warning - - procedure Check_Use_Clauses is new - Traverse_Proc (Check_Use_Clause); - - ---------------------- - -- Check_Use_Clause -- - ---------------------- - - function Check_Use_Clause (N : Node_Id) return Traverse_Result is - Nam : Node_Id; - - begin - if Nkind (N) = N_Use_Package_Clause then - Nam := First (Names (N)); - while Present (Nam) loop - if Entity (Nam) = Pack then - Error_Msg_Qual_Level := 1; - Error_Msg_NE - ("no entities of package& are referenced?", - Nam, Pack); - Error_Msg_Qual_Level := 0; - end if; - - Next (Nam); - end loop; - end if; - - return OK; - end Check_Use_Clause; - - -- Start of processing for Check_Inner_Package - - begin - E := First_Entity (Pack); - while Present (E) loop - if Referenced (E) then - return; - end if; - - Next_Entity (E); - end loop; - - -- No entities of the package are referenced. Check whether the - -- reference to the package itself is a use clause, and if so - -- place a warning on it. - - Check_Use_Clauses (Un); - end Check_Inner_Package; - - ---------------------- - -- Check_System_Aux -- - ---------------------- - - function Check_System_Aux return Boolean is - Ent : Entity_Id; - - begin - if Chars (Lunit) = Name_System - and then Scope (Lunit) = Standard_Standard - and then Present_System_Aux - then - Ent := First_Entity (System_Aux_Id); - while Present (Ent) loop - if Referenced (Ent) then - return True; - end if; - - Next_Entity (Ent); - end loop; - end if; - - return False; - end Check_System_Aux; - - --------------------------- - -- Find_Package_Renaming -- - --------------------------- - - function Find_Package_Renaming - (P : Entity_Id; - L : Entity_Id) return Entity_Id - is - E1 : Entity_Id; - R : Entity_Id; - - begin - Is_Visible_Renaming := False; - - E1 := First_Entity (P); - while Present (E1) loop - if Ekind (E1) = E_Package - and then Renamed_Object (E1) = L - then - Is_Visible_Renaming := not Is_Hidden (E1); - return E1; - - elsif Ekind (E1) = E_Package - and then No (Renamed_Object (E1)) - and then not Is_Generic_Instance (E1) - then - R := Find_Package_Renaming (E1, L); - - if Present (R) then - Is_Visible_Renaming := not Is_Hidden (R); - return R; - end if; - end if; - - Next_Entity (E1); - end loop; - - return Empty; - end Find_Package_Renaming; - - -- Start of processing for Check_One_Unit - - begin - Cnode := Cunit (Unit); - - -- Only do check in units that are part of the extended main unit. - -- This is actually a necessary restriction, because in the case of - -- subprogram acting as its own specification, there can be with's in - -- subunits that we will not see. - - if not In_Extended_Main_Source_Unit (Cnode) then - return; - - -- In configurable run time mode, we remove the bodies of non-inlined - -- subprograms, which may lead to spurious warnings, which are - -- clearly undesirable. - - elsif Configurable_Run_Time_Mode - and then Is_Predefined_File_Name (Unit_File_Name (Unit)) - then - return; - end if; - - -- Loop through context items in this unit - - Item := First (Context_Items (Cnode)); - while Present (Item) loop - if Nkind (Item) = N_With_Clause - and then not Implicit_With (Item) - and then In_Extended_Main_Source_Unit (Item) - then - Lunit := Entity (Name (Item)); - - -- Check if this unit is referenced - - if not Referenced (Lunit) then - - -- Suppress warnings in internal units if not in -gnatg mode - -- (these would be junk warnings for an application program, - -- since they refer to problems in internal units) - - if GNAT_Mode - or else not Is_Internal_File_Name (Unit_File_Name (Unit)) - then - -- Here we definitely have a non-referenced unit. If it - -- is the special call for a spec unit, then just set the - -- flag to be read later. - - if Unit = Spec_Unit then - Set_Unreferenced_In_Spec (Item); - - -- Otherwise simple unreferenced message - - else - Error_Msg_N - ("unit& is not referenced?", Name (Item)); - end if; - end if; - - -- If main unit is a renaming of this unit, then we consider - -- the with to be OK (obviously it is needed in this case!) - - elsif Present (Renamed_Entity (Munite)) - and then Renamed_Entity (Munite) = Lunit - then - null; - - -- If this unit is referenced, and it is a package, we do - -- another test, to see if any of the entities in the package - -- are referenced. If none of the entities are referenced, we - -- still post a warning. This occurs if the only use of the - -- package is in a use clause, or in a package renaming - -- declaration. - - elsif Ekind (Lunit) = E_Package then - - -- If Is_Instantiated is set, it means that the package is - -- implicitly instantiated (this is the case of parent - -- instance or an actual for a generic package formal), and - -- this counts as a reference. - - if Is_Instantiated (Lunit) then - null; - - -- If no entities in package, and there is a pragma - -- Elaborate_Body present, then assume that this with is - -- done for purposes of this elaboration. - - elsif No (First_Entity (Lunit)) - and then Has_Pragma_Elaborate_Body (Lunit) - then - null; - - -- Otherwise see if any entities have been referenced - - else - if Limited_Present (Item) then - Ent := First_Entity (Limited_View (Lunit)); - else - Ent := First_Entity (Lunit); - end if; - - loop - -- No more entities, and we did not find one that was - -- referenced. Means we have a definite case of a with - -- none of whose entities was referenced. - - if No (Ent) then - - -- If in spec, just set the flag - - if Unit = Spec_Unit then - Set_No_Entities_Ref_In_Spec (Item); - - elsif Check_System_Aux then - null; - - -- Else give the warning - - else - Error_Msg_N - ("no entities of & are referenced?", - Name (Item)); - - -- Look for renamings of this package, and flag - -- them as well. If the original package has - -- warnings off, we suppress the warning on the - -- renaming as well. - - Pack := Find_Package_Renaming (Munite, Lunit); - - if Present (Pack) - and then not Warnings_Off (Lunit) - then - Error_Msg_NE - ("no entities of & are referenced?", - Unit_Declaration_Node (Pack), - Pack); - end if; - end if; - - exit; - - -- Case of next entity is referenced - - elsif Referenced (Ent) - or else Referenced_As_LHS (Ent) - then - -- This means that the with is indeed fine, in that - -- it is definitely needed somewhere, and we can - -- quite worrying about this one. - - -- Except for one little detail, if either of the - -- flags was set during spec processing, this is - -- where we complain that the with could be moved - -- from the spec. If the spec contains a visible - -- renaming of the package, inhibit warning to move - -- with_clause to body. - - if Ekind (Munite) = E_Package_Body then - Pack := - Find_Package_Renaming - (Spec_Entity (Munite), Lunit); - end if; - - if Unreferenced_In_Spec (Item) then - Error_Msg_N - ("unit& is not referenced in spec?", - Name (Item)); - - elsif No_Entities_Ref_In_Spec (Item) then - Error_Msg_N - ("no entities of & are referenced in spec?", - Name (Item)); - - else - if Ekind (Ent) = E_Package then - Check_Inner_Package (Ent); - end if; - - exit; - end if; - - if not Is_Visible_Renaming then - Error_Msg_N - ("\with clause might be moved to body?", - Name (Item)); - end if; - - exit; - - -- Move to next entity to continue search - - else - Next_Entity (Ent); - end if; - end loop; - end if; - - -- For a generic package, the only interesting kind of - -- reference is an instantiation, since entities cannot be - -- referenced directly. - - elsif Is_Generic_Unit (Lunit) then - - -- Unit was never instantiated, set flag for case of spec - -- call, or give warning for normal call. - - if not Is_Instantiated (Lunit) then - if Unit = Spec_Unit then - Set_Unreferenced_In_Spec (Item); - else - Error_Msg_N - ("unit& is never instantiated?", Name (Item)); - end if; - - -- If unit was indeed instantiated, make sure that flag is - -- not set showing it was uninstantiated in the spec, and if - -- so, give warning. - - elsif Unreferenced_In_Spec (Item) then - Error_Msg_N - ("unit& is not instantiated in spec?", Name (Item)); - Error_Msg_N - ("\with clause can be moved to body?", Name (Item)); - end if; - end if; - end if; - - Next (Item); - end loop; - - end Check_One_Unit; - - -- Start of processing for Check_Unused_Withs - - begin - if not Opt.Check_Withs - or else Operating_Mode = Check_Syntax - then - return; - end if; - - -- Flag any unused with clauses, but skip this step if we are compiling - -- a subunit on its own, since we do not have enough information to - -- determine whether with's are used. We will get the relevant warnings - -- when we compile the parent. This is the normal style of GNAT - -- compilation in any case. - - if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then - return; - end if; - - -- Process specified units - - if Spec_Unit = No_Unit then - - -- For main call, check all units - - for Unit in Main_Unit .. Last_Unit loop - Check_One_Unit (Unit); - end loop; - - else - -- For call for spec, check only the spec - - Check_One_Unit (Spec_Unit); - end if; - end Check_Unused_Withs; - - --------------------------------- - -- Generic_Package_Spec_Entity -- - --------------------------------- - - function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is - S : Entity_Id; - - begin - if Is_Package_Body_Entity (E) then - return False; - - else - S := Scope (E); - loop - if S = Standard_Standard then - return False; - - elsif Ekind (S) = E_Generic_Package then - return True; - - elsif Ekind (S) = E_Package then - S := Scope (S); - - else - return False; - end if; - end loop; - end if; - end Generic_Package_Spec_Entity; - - ------------------------------------- - -- Operand_Has_Warnings_Suppressed -- - ------------------------------------- - - function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is - - function Check_For_Warnings (N : Node_Id) return Traverse_Result; - -- Function used to check one node to see if it is or was originally - -- a reference to an entity for which Warnings are off. If so, Abandon - -- is returned, otherwise OK_Orig is returned to continue the traversal - -- of the original expression. - - function Traverse is new Traverse_Func (Check_For_Warnings); - -- Function used to traverse tree looking for warnings - - ------------------------ - -- Check_For_Warnings -- - ------------------------ - - function Check_For_Warnings (N : Node_Id) return Traverse_Result is - R : constant Node_Id := Original_Node (N); - - begin - if Nkind (R) in N_Has_Entity - and then Present (Entity (R)) - and then Warnings_Off (Entity (R)) - then - return Abandon; - else - return OK_Orig; - end if; - end Check_For_Warnings; - - -- Start of processing for Operand_Has_Warnings_Suppressed - - begin - return Traverse (N) = Abandon; - - -- If any exception occurs, then something has gone wrong, and this is - -- only a minor aesthetic issue anyway, so just say we did not find what - -- we are looking for, rather than blow up. - - exception - when others => - return False; - end Operand_Has_Warnings_Suppressed; - - ---------------------------------- - -- Output_Unreferenced_Messages -- - ---------------------------------- - - procedure Output_Unreferenced_Messages is - E : Entity_Id; - - begin - for J in Unreferenced_Entities.First .. - Unreferenced_Entities.Last - loop - E := Unreferenced_Entities.Table (J); - - if not Referenced (E) and then not Warnings_Off (E) then - case Ekind (E) is - when E_Variable => - - -- Case of variable that is assigned but not read. We - -- suppress the message if the variable is volatile, has an - -- address clause, or is imported. - - if Referenced_As_LHS (E) - and then No (Address_Clause (E)) - and then not Is_Volatile (E) - then - if Warn_On_Modified_Unread - and then not Is_Imported (E) - - -- Suppress the message for aliased or renamed - -- variables, since there may be other entities read - -- the same memory location. - - and then not Is_Aliased (E) - and then No (Renamed_Object (E)) - - then - Error_Msg_N - ("variable & is assigned but never read?", E); - end if; - - -- Normal case of neither assigned nor read - - else - if Present (Renamed_Object (E)) - and then Comes_From_Source (Renamed_Object (E)) - then - Error_Msg_N - ("renamed variable & is not referenced?", E); - else - Error_Msg_N - ("variable & is not referenced?", E); - end if; - end if; - - when E_Constant => - if Present (Renamed_Object (E)) - and then Comes_From_Source (Renamed_Object (E)) - then - Error_Msg_N ("renamed constant & is not referenced?", E); - else - Error_Msg_N ("constant & is not referenced?", E); - end if; - - when E_In_Parameter | - E_Out_Parameter | - E_In_Out_Parameter => - - -- Do not emit message for formals of a renaming, because - -- they are never referenced explicitly. - - if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) - /= N_Subprogram_Renaming_Declaration - then - Error_Msg_N ("formal parameter & is not referenced?", E); - end if; - - when E_Named_Integer | - E_Named_Real => - Error_Msg_N ("named number & is not referenced?", E); - - when E_Enumeration_Literal => - Error_Msg_N ("literal & is not referenced?", E); - - when E_Function => - Error_Msg_N ("function & is not referenced?", E); - - when E_Procedure => - Error_Msg_N ("procedure & is not referenced?", E); - - when E_Generic_Procedure => - Error_Msg_N - ("generic procedure & is never instantiated?", E); - - when E_Generic_Function => - Error_Msg_N ("generic function & is never instantiated?", E); - - when Type_Kind => - Error_Msg_N ("type & is not referenced?", E); - - when others => - Error_Msg_N ("& is not referenced?", E); - end case; - - Set_Warnings_Off (E); - end if; - end loop; - end Output_Unreferenced_Messages; - - ------------------------ - -- Set_Warning_Switch -- - ------------------------ - - function Set_Warning_Switch (C : Character) return Boolean is - begin - case C is - when 'a' => - Check_Unreferenced := True; - Check_Unreferenced_Formals := True; - Check_Withs := True; - Constant_Condition_Warnings := True; - Implementation_Unit_Warnings := True; - Ineffective_Inline_Warnings := True; - Warn_On_Ada_2005_Compatibility := True; - Warn_On_Bad_Fixed_Value := True; - Warn_On_Constant := True; - Warn_On_Export_Import := True; - Warn_On_Modified_Unread := True; - Warn_On_No_Value_Assigned := True; - Warn_On_Obsolescent_Feature := True; - Warn_On_Redundant_Constructs := True; - Warn_On_Unchecked_Conversion := True; - Warn_On_Unrecognized_Pragma := True; - - when 'A' => - Check_Unreferenced := False; - Check_Unreferenced_Formals := False; - Check_Withs := False; - Constant_Condition_Warnings := False; - Elab_Warnings := False; - Implementation_Unit_Warnings := False; - Ineffective_Inline_Warnings := False; - Warn_On_Ada_2005_Compatibility := False; - Warn_On_Bad_Fixed_Value := False; - Warn_On_Constant := False; - Warn_On_Dereference := False; - Warn_On_Export_Import := False; - Warn_On_Hiding := False; - Warn_On_Modified_Unread := False; - Warn_On_No_Value_Assigned := False; - Warn_On_Obsolescent_Feature := False; - Warn_On_Redundant_Constructs := False; - Warn_On_Unchecked_Conversion := False; - Warn_On_Unrecognized_Pragma := False; - - when 'b' => - Warn_On_Bad_Fixed_Value := True; - - when 'B' => - Warn_On_Bad_Fixed_Value := False; - - when 'c' => - Constant_Condition_Warnings := True; - - when 'C' => - Constant_Condition_Warnings := False; - - when 'd' => - Warn_On_Dereference := True; - - when 'D' => - Warn_On_Dereference := False; - - when 'e' => - Warning_Mode := Treat_As_Error; - - when 'f' => - Check_Unreferenced_Formals := True; - - when 'F' => - Check_Unreferenced_Formals := False; - - when 'g' => - Warn_On_Unrecognized_Pragma := True; - - when 'G' => - Warn_On_Unrecognized_Pragma := False; - - when 'h' => - Warn_On_Hiding := True; - - when 'H' => - Warn_On_Hiding := False; - - when 'i' => - Implementation_Unit_Warnings := True; - - when 'I' => - Implementation_Unit_Warnings := False; - - when 'j' => - Warn_On_Obsolescent_Feature := True; - - when 'J' => - Warn_On_Obsolescent_Feature := False; - - when 'k' => - Warn_On_Constant := True; - - when 'K' => - Warn_On_Constant := False; - - when 'l' => - Elab_Warnings := True; - - when 'L' => - Elab_Warnings := False; - - when 'm' => - Warn_On_Modified_Unread := True; - - when 'M' => - Warn_On_Modified_Unread := False; - - when 'n' => - Warning_Mode := Normal; - - when 'o' => - Address_Clause_Overlay_Warnings := True; - - when 'O' => - Address_Clause_Overlay_Warnings := False; - - when 'p' => - Ineffective_Inline_Warnings := True; - - when 'P' => - Ineffective_Inline_Warnings := False; - - when 'r' => - Warn_On_Redundant_Constructs := True; - - when 'R' => - Warn_On_Redundant_Constructs := False; - - when 's' => - Warning_Mode := Suppress; - - when 'u' => - Check_Unreferenced := True; - Check_Withs := True; - Check_Unreferenced_Formals := True; - - when 'U' => - Check_Unreferenced := False; - Check_Withs := False; - Check_Unreferenced_Formals := False; - - when 'v' => - Warn_On_No_Value_Assigned := True; - - when 'V' => - Warn_On_No_Value_Assigned := False; - - when 'x' => - Warn_On_Export_Import := True; - - when 'X' => - Warn_On_Export_Import := False; - - when 'y' => - Warn_On_Ada_2005_Compatibility := True; - - when 'Y' => - Warn_On_Ada_2005_Compatibility := False; - - when 'z' => - Warn_On_Unchecked_Conversion := True; - - when 'Z' => - Warn_On_Unchecked_Conversion := False; - - -- Allow and ignore 'w' so that the old - -- format (e.g. -gnatwuwl) will work. - - when 'w' => - null; - - when others => - return False; - end case; - - return True; - end Set_Warning_Switch; - - ----------------------------- - -- Warn_On_Known_Condition -- - ----------------------------- - - procedure Warn_On_Known_Condition (C : Node_Id) is - P : Node_Id; - - begin - -- Argument replacement in an inlined body can make conditions static. - -- Do not emit warnings in this case. - - if In_Inlined_Body then - return; - end if; - - if Constant_Condition_Warnings - and then Nkind (C) = N_Identifier - and then - (Entity (C) = Standard_False or else Entity (C) = Standard_True) - and then Comes_From_Source (Original_Node (C)) - and then not In_Instance - then - -- See if this is in a statement or a declaration - - P := Parent (C); - loop - -- If tree is not attached, do not issue warning (this is very - -- peculiar, and probably arises from some other error condition) - - if No (P) then - return; - - -- If we are in a declaration, then no warning, since in practice - -- conditionals in declarations are used for intended tests which - -- may be known at compile time, e.g. things like - - -- x : constant Integer := 2 + (Word'Size = 32); - - -- And a warning is annoying in such cases - - elsif Nkind (P) in N_Declaration - or else - Nkind (P) in N_Later_Decl_Item - then - return; - - -- Don't warn in assert pragma, since presumably tests in such - -- a context are very definitely intended, and might well be - -- known at compile time. Note that we have to test the original - -- node, since assert pragmas get rewritten at analysis time. - - elsif Nkind (Original_Node (P)) = N_Pragma - and then Chars (Original_Node (P)) = Name_Assert - then - return; - end if; - - exit when Is_Statement (P); - P := Parent (P); - end loop; - - -- Here we issue the warning unless some sub-operand has warnings - -- set off, in which case we suppress the warning for the node. If - -- the original expression is an inequality, it has been expanded - -- into a negation, and the value of the original expression is the - -- negation of the equality. If the expression is an entity that - -- appears within a negation, it is clearer to flag the negation - -- itself, and report on its constant value. - - if not Operand_Has_Warnings_Suppressed (C) then - declare - True_Branch : Boolean := Entity (C) = Standard_True; - Cond : Node_Id := C; - - begin - if Present (Parent (C)) - and then Nkind (Parent (C)) = N_Op_Not - then - True_Branch := not True_Branch; - Cond := Parent (C); - end if; - - if True_Branch then - if Is_Entity_Name (Original_Node (C)) - and then Nkind (Cond) /= N_Op_Not - then - Error_Msg_NE - ("object & is always True?", Cond, Original_Node (C)); - else - Error_Msg_N ("condition is always True?", Cond); - end if; - else - Error_Msg_N ("condition is always False?", Cond); - end if; - end; - end if; - end if; - end Warn_On_Known_Condition; - -end Sem_Warn; |