1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2001 Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 -- This package contains the routines used to deal with issuing warnings
28 -- about uses of uninitialized variables and unused with's. It also has
29 -- some unrelated routines related to the generation of warnings.
31 with Types; use Types;
35 ------------------------------------------
36 -- Routines to Handle Unused References --
37 ------------------------------------------
39 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty);
40 -- Called at the end of processing a declarative region. The entity E
41 -- is the entity for the scope. All entities declared in the region,
42 -- as indicated by First_Entity and the entity chain, are checked to
43 -- see if they are variables for which warnings need to be posted for
44 -- either no assignments, or a use before an assignment or no references
45 -- at all. The Anod node is present for the case of an accept statement,
46 -- and references the accept statement. This is used to place the warning
47 -- messages in the right place.
49 procedure Check_Unset_Reference (N : Node_Id);
50 -- N is the node for an expression which occurs in a reference position,
51 -- e.g. as the right side of an assignment. This procedure checks to see
52 -- if the node is a reference to a variable entity where the entity has
53 -- Not_Assigned set. If so, the Unset_Reference field is set if it is not
54 -- the first occurrence. No warning is posted, instead warnings will be
55 -- posted later by Check_References. The reason we do things that
56 -- way is that if there are no assignments anywhere, we prefer to flag
57 -- the entity, rather than a reference to it. Note that for the purposes
58 -- of this routine, a type conversion or qualified expression whose
59 -- expression is an entity is also processed. The reason that we do not
60 -- process these at the point of occurrence is that both these constructs
61 -- can occur in non-reference positions (e.g. as out parameters).
63 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit);
64 -- This routine performs two kinds of checks. It checks that all with'ed
65 -- units are referenced, and that at least one entity of each with'ed
66 -- unit is referenced (the latter check catches units that are only
67 -- referenced in a use or package renaming statement). Appropriate
68 -- warning messages are generated if either of these situations is
71 -- A special case arises when a package body or a subprogram body with
72 -- a separate spec is being compiled. In this case, a with may appear
73 -- on the spec, but be needed only by the body. This still generates
74 -- a warning, but the text is different (the with is not redundant,
77 -- This special case is implemented by making an initial call to this
78 -- procedure with Spec_Unit set to the unit number of the separate spec.
79 -- This call does not generate any warning messages, but instead may
80 -- result in flags being set in the N_With_Clause node that record that
81 -- there was no use in the spec.
83 -- The main call (made after all units have been analyzed, with Spec_Unit
84 -- set to the default value of No_Unit) generates the required warnings
85 -- using the flags set by the initial call where appropriate to specialize
86 -- the text of the warning messages.
92 procedure Output_Unreferenced_Messages;
93 -- Warnings about unreferenced entities are collected till the end of
94 -- the compilation process (see Check_Unset_Reference for further
95 -- details). This procedure outputs waiting warnings, if any.
97 ----------------------------
98 -- Other Warning Routines --
99 ----------------------------
101 procedure Warn_On_Known_Condition (C : Node_Id);
102 -- C is a node for a boolean expression resluting from a relational
103 -- or membership operation. If the expression has a compile time known
104 -- value, then a warning is output if all the following conditions hold:
106 -- 1. Original expression comes from source. We don't want to generate
107 -- warnings for internally generated conditionals.
109 -- 2. As noted above, the expression is a relational or membership
110 -- test, we don't want to generate warnings for boolean variables
111 -- since this is typical of conditional compilation in Ada.
113 -- 3. The expression appears in a statement, rather than a declaration.
114 -- In practice, most occurrences in declarations are legitimate
115 -- conditionalizations, but occurrences in statements are often
116 -- errors for which the warning is useful.
118 -- 4. The expression does not occur within an instantiation. A non-
119 -- static expression in a generic may become constant because of
120 -- the attributes of the actuals, and we do not want to warn on
121 -- these legitimate constant foldings.
123 -- If all these conditions are met, the warning is issued noting that
124 -- the result of the test is always false or always true as appropriate.
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