| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- S E M _ W A R N -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 1999-2001 Free Software Foundation, Inc. -- |
| -- -- |
| -- GNAT is free software; you can redistribute it and/or modify it under -- |
| -- terms of the GNU General Public License as published by the Free Soft- -- |
| -- ware Foundation; either version 2, or (at your option) any later ver- -- |
| -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- |
| -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- |
| -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- |
| -- for more details. You should have received a copy of the GNU General -- |
| -- Public License distributed with GNAT; see file COPYING. If not, write -- |
| -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- |
| -- MA 02111-1307, USA. -- |
| -- -- |
| -- GNAT was originally developed by the GNAT team at New York University. -- |
| -- 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 |
| |
| ------------------------------------------ |
| -- 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; |
