+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNAT COMPILER COMPONENTS --
--- --
--- S E M _ W A R N --
--- --
--- S p e c --
--- --
--- $Revision: 1.2.10.1 $
--- --
--- 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;
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