1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
10 -- Copyright (C) 1999-2001 Free Software Foundation, Inc. --
12 -- GNAT is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNAT; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
21 -- MA 02111-1307, USA. --
23 -- GNAT was originally developed by the GNAT team at New York University. --
24 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
26 ------------------------------------------------------------------------------
28 -- This package contains the routines used to deal with issuing warnings
29 -- about uses of uninitialized variables and unused with's. It also has
30 -- some unrelated routines related to the generation of warnings.
32 with Types; use Types;
36 ------------------------------------------
37 -- Routines to Handle Unused References --
38 ------------------------------------------
40 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty);
41 -- Called at the end of processing a declarative region. The entity E
42 -- is the entity for the scope. All entities declared in the region,
43 -- as indicated by First_Entity and the entity chain, are checked to
44 -- see if they are variables for which warnings need to be posted for
45 -- either no assignments, or a use before an assignment or no references
46 -- at all. The Anod node is present for the case of an accept statement,
47 -- and references the accept statement. This is used to place the warning
48 -- messages in the right place.
50 procedure Check_Unset_Reference (N : Node_Id);
51 -- N is the node for an expression which occurs in a reference position,
52 -- e.g. as the right side of an assignment. This procedure checks to see
53 -- if the node is a reference to a variable entity where the entity has
54 -- Not_Assigned set. If so, the Unset_Reference field is set if it is not
55 -- the first occurrence. No warning is posted, instead warnings will be
56 -- posted later by Check_References. The reason we do things that
57 -- way is that if there are no assignments anywhere, we prefer to flag
58 -- the entity, rather than a reference to it. Note that for the purposes
59 -- of this routine, a type conversion or qualified expression whose
60 -- expression is an entity is also processed. The reason that we do not
61 -- process these at the point of occurrence is that both these constructs
62 -- can occur in non-reference positions (e.g. as out parameters).
64 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit);
65 -- This routine performs two kinds of checks. It checks that all with'ed
66 -- units are referenced, and that at least one entity of each with'ed
67 -- unit is referenced (the latter check catches units that are only
68 -- referenced in a use or package renaming statement). Appropriate
69 -- warning messages are generated if either of these situations is
72 -- A special case arises when a package body or a subprogram body with
73 -- a separate spec is being compiled. In this case, a with may appear
74 -- on the spec, but be needed only by the body. This still generates
75 -- a warning, but the text is different (the with is not redundant,
78 -- This special case is implemented by making an initial call to this
79 -- procedure with Spec_Unit set to the unit number of the separate spec.
80 -- This call does not generate any warning messages, but instead may
81 -- result in flags being set in the N_With_Clause node that record that
82 -- there was no use in the spec.
84 -- The main call (made after all units have been analyzed, with Spec_Unit
85 -- set to the default value of No_Unit) generates the required warnings
86 -- using the flags set by the initial call where appropriate to specialize
87 -- the text of the warning messages.
93 procedure Output_Unreferenced_Messages;
94 -- Warnings about unreferenced entities are collected till the end of
95 -- the compilation process (see Check_Unset_Reference for further
96 -- details). This procedure outputs waiting warnings, if any.
98 ----------------------------
99 -- Other Warning Routines --
100 ----------------------------
102 procedure Warn_On_Known_Condition (C : Node_Id);
103 -- C is a node for a boolean expression resluting from a relational
104 -- or membership operation. If the expression has a compile time known
105 -- value, then a warning is output if all the following conditions hold:
107 -- 1. Original expression comes from source. We don't want to generate
108 -- warnings for internally generated conditionals.
110 -- 2. As noted above, the expression is a relational or membership
111 -- test, we don't want to generate warnings for boolean variables
112 -- since this is typical of conditional compilation in Ada.
114 -- 3. The expression appears in a statement, rather than a declaration.
115 -- In practice, most occurrences in declarations are legitimate
116 -- conditionalizations, but occurrences in statements are often
117 -- errors for which the warning is useful.
119 -- 4. The expression does not occur within an instantiation. A non-
120 -- static expression in a generic may become constant because of
121 -- the attributes of the actuals, and we do not want to warn on
122 -- these legitimate constant foldings.
124 -- If all these conditions are met, the warning is issued noting that
125 -- the result of the test is always false or always true as appropriate.
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