------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- S E M _ W A R N -- -- -- -- S p e c -- -- -- -- Copyright (C) 1999-2005, 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. -- -- -- ------------------------------------------------------------------------------ -- This package contains the routines used to deal with issuing warnings -- about uses of uninitialized variables and unused with's. It also has -- some unrelated routines related to the generation of warnings. with Types; use Types; package Sem_Warn is -------------------- -- Initialization -- -------------------- function Set_Warning_Switch (C : Character) return Boolean; -- This function sets the warning switch or switches corresponding to -- the given character. It is used for processing a -gnatw switch on the -- command line, or a string literal in pragma Warnings. ------------------------------------------ -- Routines to Handle Unused References -- ------------------------------------------ procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty); -- Called at the end of processing a declarative region. The entity E -- is the entity for the scope. All entities declared in the region, -- as indicated by First_Entity and the entity chain, are checked to -- see if they are variables for which warnings need to be posted for -- either no assignments, or a use before an assignment or no references -- at all. The Anod node is present for the case of an accept statement, -- and references the accept statement. This is used to place the warning -- messages in the right place. procedure Check_Unset_Reference (N : Node_Id); -- N is the node for an expression which occurs in a reference position, -- e.g. as the right side of an assignment. This procedure checks to see -- if the node is a reference to a variable entity where the entity has -- Not_Assigned set. If so, the Unset_Reference field is set if it is not -- the first occurrence. No warning is posted, instead warnings will be -- posted later by Check_References. The reason we do things that -- way is that if there are no assignments anywhere, we prefer to flag -- the entity, rather than a reference to it. Note that for the purposes -- of this routine, a type conversion or qualified expression whose -- expression is an entity is also processed. The reason that we do not -- process these at the point of occurrence is that both these constructs -- can occur in non-reference positions (e.g. as out parameters). procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit); -- This routine performs two kinds of checks. It checks that all with'ed -- units are referenced, and that at least one entity of each with'ed -- unit is referenced (the latter check catches units that are only -- referenced in a use or package renaming statement). Appropriate -- warning messages are generated if either of these situations is -- detected. -- -- A special case arises when a package body or a subprogram body with -- a separate spec is being compiled. In this case, a with may appear -- on the spec, but be needed only by the body. This still generates -- a warning, but the text is different (the with is not redundant, -- it is misplaced). -- -- This special case is implemented by making an initial call to this -- procedure with Spec_Unit set to the unit number of the separate spec. -- This call does not generate any warning messages, but instead may -- result in flags being set in the N_With_Clause node that record that -- there was no use in the spec. -- -- The main call (made after all units have been analyzed, with Spec_Unit -- set to the default value of No_Unit) generates the required warnings -- using the flags set by the initial call where appropriate to specialize -- the text of the warning messages. --------------------- -- Output Routines -- --------------------- procedure Output_Unreferenced_Messages; -- Warnings about unreferenced entities are collected till the end of -- the compilation process (see Check_Unset_Reference for further -- details). This procedure outputs waiting warnings, if any. ---------------------------- -- Other Warning Routines -- ---------------------------- procedure Warn_On_Known_Condition (C : Node_Id); -- C is a node for a boolean expression resluting from a relational -- or membership operation. If the expression has a compile time known -- value, then a warning is output if all the following conditions hold: -- -- 1. Original expression comes from source. We don't want to generate -- warnings for internally generated conditionals. -- -- 2. As noted above, the expression is a relational or membership -- test, we don't want to generate warnings for boolean variables -- since this is typical of conditional compilation in Ada. -- -- 3. The expression appears in a statement, rather than a declaration. -- In practice, most occurrences in declarations are legitimate -- conditionalizations, but occurrences in statements are often -- errors for which the warning is useful. -- -- 4. The expression does not occur within an instantiation. A non- -- static expression in a generic may become constant because of -- the attributes of the actuals, and we do not want to warn on -- these legitimate constant foldings. -- -- If all these conditions are met, the warning is issued noting that -- the result of the test is always false or always true as appropriate. end Sem_Warn;