This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
Replace common Emacs file-local variables with dir-locals
[perl5.git] / lib / warnings.pm
CommitLineData
37442d52 1# -*- buffer-read-only: t -*-
38875929 2# !!!!!!! DO NOT EDIT THIS FILE !!!!!!!
78102347
NC
3# This file is built by regen/warnings.pl.
4# Any changes made here will be lost!
599cee73 5
4438c4b7 6package warnings;
599cee73 7
2115c436 8our $VERSION = '1.31';
f2c3e829
RGS
9
10# Verify that we're called correctly so that warnings will work.
11# see also strict.pm.
5108dc18 12unless ( __FILE__ =~ /(^|[\/\\])\Q${\__PACKAGE__}\E\.pmc?$/ ) {
f2c3e829 13 my (undef, $f, $l) = caller;
5108dc18 14 die("Incorrect use of pragma '${\__PACKAGE__}' at $f line $l.\n");
f2c3e829 15}
0ca4541c 16
effd17dc 17our %Offsets = (
effd17dc 18 # Warnings Categories added in Perl 5.008
3c3f8cd6
AB
19 'all' => 0,
20 'closure' => 2,
21 'deprecated' => 4,
22 'exiting' => 6,
23 'glob' => 8,
24 'io' => 10,
25 'closed' => 12,
26 'exec' => 14,
27 'layer' => 16,
28 'newline' => 18,
29 'pipe' => 20,
30 'unopened' => 22,
31 'misc' => 24,
32 'numeric' => 26,
33 'once' => 28,
34 'overflow' => 30,
35 'pack' => 32,
36 'portable' => 34,
37 'recursion' => 36,
38 'redefine' => 38,
39 'regexp' => 40,
40 'severe' => 42,
41 'debugging' => 44,
42 'inplace' => 46,
43 'internal' => 48,
44 'malloc' => 50,
45 'signal' => 52,
46 'substr' => 54,
47 'syntax' => 56,
48 'ambiguous' => 58,
49 'bareword' => 60,
50 'digit' => 62,
51 'parenthesis' => 64,
52 'precedence' => 66,
53 'printf' => 68,
54 'prototype' => 70,
55 'qw' => 72,
56 'reserved' => 74,
57 'semicolon' => 76,
58 'taint' => 78,
59 'threads' => 80,
60 'uninitialized' => 82,
61 'unpack' => 84,
62 'untie' => 86,
63 'utf8' => 88,
64 'void' => 90,
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DD
65
66 # Warnings Categories added in Perl 5.011
3c3f8cd6
AB
67 'imprecision' => 92,
68 'illegalproto' => 94,
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DD
69
70 # Warnings Categories added in Perl 5.013
3c3f8cd6
AB
71 'non_unicode' => 96,
72 'nonchar' => 98,
73 'surrogate' => 100,
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DD
74
75 # Warnings Categories added in Perl 5.017
3c3f8cd6
AB
76 'experimental' => 102,
77 'experimental::lexical_subs' => 104,
78 'experimental::lexical_topic' => 106,
79 'experimental::regex_sets' => 108,
80 'experimental::smartmatch' => 110,
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DD
81
82 # Warnings Categories added in Perl 5.019
3c3f8cd6
AB
83 'experimental::autoderef' => 112,
84 'experimental::postderef' => 114,
85 'experimental::signatures' => 116,
86 'syscalls' => 118,
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87
88 # Warnings Categories added in Perl 5.021
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FC
89 'experimental::bitwise' => 120,
90 'experimental::const_attr' => 122,
91 'experimental::re_strict' => 124,
92 'experimental::refaliasing' => 126,
93 'experimental::win32_perlio' => 128,
94 'locale' => 130,
95 'missing' => 132,
96 'redundant' => 134,
3c3f8cd6 97);
effd17dc
DD
98
99our %Bits = (
9f88e537 100 'all' => "\x55\x55\x55\x55\x55\x55\x55\x55\x55\x55\x55\x55\x55\x55\x55\x55\x55", # [0..67]
3c3f8cd6
AB
101 'ambiguous' => "\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [29]
102 'bareword' => "\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [30]
103 'closed' => "\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [6]
104 'closure' => "\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [1]
105 'debugging' => "\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [22]
106 'deprecated' => "\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [2]
107 'digit' => "\x00\x00\x00\x00\x00\x00\x00\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [31]
108 'exec' => "\x00\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [7]
109 'exiting' => "\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [3]
9f88e537 110 'experimental' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40\x55\x15\x55\x01", # [51..58,60..64]
3c3f8cd6 111 'experimental::autoderef' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00", # [56]
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FC
112 'experimental::bitwise' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00", # [60]
113 'experimental::const_attr' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00", # [61]
3c3f8cd6
AB
114 'experimental::lexical_subs' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00", # [52]
115 'experimental::lexical_topic' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00", # [53]
116 'experimental::postderef' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00", # [57]
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FC
117 'experimental::re_strict' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00", # [62]
118 'experimental::refaliasing' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40\x00", # [63]
3c3f8cd6
AB
119 'experimental::regex_sets' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00", # [54]
120 'experimental::signatures' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00", # [58]
121 'experimental::smartmatch' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40\x00\x00\x00", # [55]
9f88e537 122 'experimental::win32_perlio' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01", # [64]
3c3f8cd6
AB
123 'glob' => "\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [4]
124 'illegalproto' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40\x00\x00\x00\x00\x00", # [47]
125 'imprecision' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00", # [46]
126 'inplace' => "\x00\x00\x00\x00\x00\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [23]
127 'internal' => "\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [24]
128 'io' => "\x00\x54\x55\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40\x00\x00", # [5..11,59]
129 'layer' => "\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [8]
9f88e537 130 'locale' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04", # [65]
3c3f8cd6
AB
131 'malloc' => "\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [25]
132 'misc' => "\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [12]
9f88e537 133 'missing' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10", # [66]
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AB
134 'newline' => "\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [9]
135 'non_unicode' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00", # [48]
136 'nonchar' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00", # [49]
137 'numeric' => "\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [13]
138 'once' => "\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [14]
139 'overflow' => "\x00\x00\x00\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [15]
140 'pack' => "\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [16]
141 'parenthesis' => "\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00", # [32]
142 'pipe' => "\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [10]
143 'portable' => "\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [17]
144 'precedence' => "\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x00", # [33]
145 'printf' => "\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00", # [34]
146 'prototype' => "\x00\x00\x00\x00\x00\x00\x00\x00\x40\x00\x00\x00\x00\x00\x00\x00\x00", # [35]
147 'qw' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00", # [36]
148 'recursion' => "\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [18]
149 'redefine' => "\x00\x00\x00\x00\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [19]
9f88e537 150 'redundant' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40", # [67]
3c3f8cd6
AB
151 'regexp' => "\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [20]
152 'reserved' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00", # [37]
153 'semicolon' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00", # [38]
154 'severe' => "\x00\x00\x00\x00\x00\x54\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [21..25]
155 'signal' => "\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [26]
156 'substr' => "\x00\x00\x00\x00\x00\x00\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [27]
157 'surrogate' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00", # [50]
158 'syntax' => "\x00\x00\x00\x00\x00\x00\x00\x55\x55\x15\x00\x40\x00\x00\x00\x00\x00", # [28..38,47]
159 'syscalls' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40\x00\x00", # [59]
160 'taint' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40\x00\x00\x00\x00\x00\x00\x00", # [39]
161 'threads' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00", # [40]
162 'uninitialized' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00", # [41]
163 'unopened' => "\x00\x00\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [11]
164 'unpack' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00", # [42]
165 'untie' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40\x00\x00\x00\x00\x00\x00", # [43]
166 'utf8' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x15\x00\x00\x00\x00", # [44,48..50]
167 'void' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00", # [45]
168);
effd17dc
DD
169
170our %DeadBits = (
9f88e537 171 'all' => "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa", # [0..67]
3c3f8cd6
AB
172 'ambiguous' => "\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [29]
173 'bareword' => "\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [30]
174 'closed' => "\x00\x20\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [6]
175 'closure' => "\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [1]
176 'debugging' => "\x00\x00\x00\x00\x00\x20\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [22]
177 'deprecated' => "\x20\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [2]
178 'digit' => "\x00\x00\x00\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [31]
179 'exec' => "\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [7]
180 'exiting' => "\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [3]
9f88e537 181 'experimental' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\xaa\x2a\xaa\x02", # [51..58,60..64]
3c3f8cd6 182 'experimental::autoderef' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00", # [56]
9f88e537
FC
183 'experimental::bitwise' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00", # [60]
184 'experimental::const_attr' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00", # [61]
3c3f8cd6
AB
185 'experimental::lexical_subs' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00", # [52]
186 'experimental::lexical_topic' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00", # [53]
187 'experimental::postderef' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00", # [57]
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FC
188 'experimental::re_strict' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00", # [62]
189 'experimental::refaliasing' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x00", # [63]
3c3f8cd6
AB
190 'experimental::regex_sets' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00", # [54]
191 'experimental::signatures' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00", # [58]
192 'experimental::smartmatch' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x00\x00\x00", # [55]
9f88e537 193 'experimental::win32_perlio' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02", # [64]
3c3f8cd6
AB
194 'glob' => "\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [4]
195 'illegalproto' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00", # [47]
196 'imprecision' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00\x00\x00", # [46]
197 'inplace' => "\x00\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [23]
198 'internal' => "\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [24]
199 'io' => "\x00\xa8\xaa\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x00\x00", # [5..11,59]
200 'layer' => "\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [8]
9f88e537 201 'locale' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08", # [65]
3c3f8cd6
AB
202 'malloc' => "\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [25]
203 'misc' => "\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [12]
9f88e537 204 'missing' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20", # [66]
3c3f8cd6
AB
205 'newline' => "\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [9]
206 'non_unicode' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00", # [48]
207 'nonchar' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00", # [49]
208 'numeric' => "\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [13]
209 'once' => "\x00\x00\x00\x20\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [14]
210 'overflow' => "\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [15]
211 'pack' => "\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [16]
212 'parenthesis' => "\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00", # [32]
213 'pipe' => "\x00\x00\x20\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [10]
214 'portable' => "\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [17]
215 'precedence' => "\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00", # [33]
216 'printf' => "\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00\x00\x00\x00\x00\x00", # [34]
217 'prototype' => "\x00\x00\x00\x00\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00", # [35]
218 'qw' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00", # [36]
219 'recursion' => "\x00\x00\x00\x00\x20\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [18]
220 'redefine' => "\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [19]
9f88e537 221 'redundant' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80", # [67]
3c3f8cd6
AB
222 'regexp' => "\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [20]
223 'reserved' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00", # [37]
224 'semicolon' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00\x00\x00\x00\x00", # [38]
225 'severe' => "\x00\x00\x00\x00\x00\xa8\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [21..25]
226 'signal' => "\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [26]
227 'substr' => "\x00\x00\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [27]
228 'surrogate' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00\x00", # [50]
229 'syntax' => "\x00\x00\x00\x00\x00\x00\x00\xaa\xaa\x2a\x00\x80\x00\x00\x00\x00\x00", # [28..38,47]
230 'syscalls' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x00\x00", # [59]
231 'taint' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00", # [39]
232 'threads' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00", # [40]
233 'uninitialized' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00", # [41]
234 'unopened' => "\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", # [11]
235 'unpack' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00\x00\x00\x00", # [42]
236 'untie' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00", # [43]
237 'utf8' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x2a\x00\x00\x00\x00", # [44,48..50]
238 'void' => "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00", # [45]
239);
240
241# These are used by various things, including our own tests
242our $NONE = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
9f88e537
FC
243our $DEFAULT = "\x10\x01\x00\x00\x00\x50\x04\x00\x00\x00\x00\x00\x00\x55\x15\x55\x05", # [2,56,60,61,52,53,57,62,63,54,58,55,64,4,65,22,23,25]
244our $LAST_BIT = 136 ;
3c3f8cd6
AB
245our $BYTES = 17 ;
246
247our $All = "" ; vec($All, $Offsets{'all'}, 2) = 3 ;
effd17dc
DD
248
249sub Croaker
250{
251 require Carp; # this initializes %CarpInternal
252 local $Carp::CarpInternal{'warnings'};
253 delete $Carp::CarpInternal{'warnings'};
254 Carp::croak(@_);
255}
256
257sub _bits {
258 my $mask = shift ;
259 my $catmask ;
260 my $fatal = 0 ;
261 my $no_fatal = 0 ;
262
263 foreach my $word ( @_ ) {
264 if ($word eq 'FATAL') {
265 $fatal = 1;
266 $no_fatal = 0;
267 }
268 elsif ($word eq 'NONFATAL') {
269 $fatal = 0;
270 $no_fatal = 1;
271 }
272 elsif ($catmask = $Bits{$word}) {
273 $mask |= $catmask ;
274 $mask |= $DeadBits{$word} if $fatal ;
275 $mask &= ~($DeadBits{$word}|$All) if $no_fatal ;
276 }
277 else
56873d42 278 { Croaker("Unknown warnings category '$word'")}
effd17dc
DD
279 }
280
281 return $mask ;
282}
283
284sub bits
285{
286 # called from B::Deparse.pm
287 push @_, 'all' unless @_ ;
288 return _bits(undef, @_) ;
289}
290
291sub import
292{
293 shift;
294
295 my $mask = ${^WARNING_BITS} // ($^W ? $Bits{all} : $DEFAULT) ;
296
297 if (vec($mask, $Offsets{'all'}, 1)) {
56873d42
DD
298 $mask |= $Bits{'all'} ;
299 $mask |= $DeadBits{'all'} if vec($mask, $Offsets{'all'}+1, 1);
effd17dc
DD
300 }
301
302 # append 'all' when implied (after a lone "FATAL" or "NONFATAL")
303 push @_, 'all' if @_==1 && ( $_[0] eq 'FATAL' || $_[0] eq 'NONFATAL' );
304
305 # Empty @_ is equivalent to @_ = 'all' ;
306 ${^WARNING_BITS} = @_ ? _bits($mask, @_) : $mask | $Bits{all} ;
307}
308
309sub unimport
310{
311 shift;
312
313 my $catmask ;
314 my $mask = ${^WARNING_BITS} // ($^W ? $Bits{all} : $DEFAULT) ;
315
316 if (vec($mask, $Offsets{'all'}, 1)) {
56873d42
DD
317 $mask |= $Bits{'all'} ;
318 $mask |= $DeadBits{'all'} if vec($mask, $Offsets{'all'}+1, 1);
effd17dc
DD
319 }
320
321 # append 'all' when implied (empty import list or after a lone "FATAL")
322 push @_, 'all' if !@_ || @_==1 && $_[0] eq 'FATAL';
323
324 foreach my $word ( @_ ) {
325 if ($word eq 'FATAL') {
326 next;
327 }
328 elsif ($catmask = $Bits{$word}) {
329 $mask &= ~($catmask | $DeadBits{$word} | $All);
330 }
331 else
56873d42 332 { Croaker("Unknown warnings category '$word'")}
effd17dc
DD
333 }
334
335 ${^WARNING_BITS} = $mask ;
336}
337
338my %builtin_type; @builtin_type{qw(SCALAR ARRAY HASH CODE REF GLOB LVALUE Regexp)} = ();
339
340sub MESSAGE () { 4 };
341sub FATAL () { 2 };
342sub NORMAL () { 1 };
343
344sub __chk
345{
346 my $category ;
347 my $offset ;
348 my $isobj = 0 ;
349 my $wanted = shift;
350 my $has_message = $wanted & MESSAGE;
351
352 unless (@_ == 1 || @_ == ($has_message ? 2 : 0)) {
353 my $sub = (caller 1)[3];
354 my $syntax = $has_message ? "[category,] 'message'" : '[category]';
355 Croaker("Usage: $sub($syntax)");
356 }
357
358 my $message = pop if $has_message;
359
360 if (@_) {
56873d42
DD
361 # check the category supplied.
362 $category = shift ;
363 if (my $type = ref $category) {
364 Croaker("not an object")
365 if exists $builtin_type{$type};
effd17dc 366 $category = $type;
56873d42
DD
367 $isobj = 1 ;
368 }
369 $offset = $Offsets{$category};
370 Croaker("Unknown warnings category '$category'")
effd17dc
DD
371 unless defined $offset;
372 }
373 else {
56873d42
DD
374 $category = (caller(1))[0] ;
375 $offset = $Offsets{$category};
376 Croaker("package '$category' not registered for warnings")
effd17dc
DD
377 unless defined $offset ;
378 }
379
380 my $i;
381
382 if ($isobj) {
56873d42
DD
383 my $pkg;
384 $i = 2;
385 while (do { { package DB; $pkg = (caller($i++))[0] } } ) {
386 last unless @DB::args && $DB::args[0] =~ /^$category=/ ;
387 }
effd17dc
DD
388 $i -= 2 ;
389 }
390 else {
56873d42 391 $i = _error_loc(); # see where Carp will allocate the error
effd17dc
DD
392 }
393
394 # Default to 0 if caller returns nothing. Default to $DEFAULT if it
395 # explicitly returns undef.
396 my(@callers_bitmask) = (caller($i))[9] ;
397 my $callers_bitmask =
398 @callers_bitmask ? $callers_bitmask[0] // $DEFAULT : 0 ;
399
400 my @results;
401 foreach my $type (FATAL, NORMAL) {
402 next unless $wanted & $type;
403
404 push @results, (vec($callers_bitmask, $offset + $type - 1, 1) ||
405 vec($callers_bitmask, $Offsets{'all'} + $type - 1, 1));
406 }
407
408 # &enabled and &fatal_enabled
409 return $results[0] unless $has_message;
410
411 # &warnif, and the category is neither enabled as warning nor as fatal
412 return if $wanted == (NORMAL | FATAL | MESSAGE)
413 && !($results[0] || $results[1]);
414
415 require Carp;
416 Carp::croak($message) if $results[0];
417 # will always get here for &warn. will only get here for &warnif if the
418 # category is enabled
419 Carp::carp($message);
420}
421
422sub _mkMask
423{
424 my ($bit) = @_;
425 my $mask = "";
426
427 vec($mask, $bit, 1) = 1;
428 return $mask;
429}
430
431sub register_categories
432{
433 my @names = @_;
434
435 for my $name (@names) {
436 if (! defined $Bits{$name}) {
437 $Bits{$name} = _mkMask($LAST_BIT);
438 vec($Bits{'all'}, $LAST_BIT, 1) = 1;
439 $Offsets{$name} = $LAST_BIT ++;
440 foreach my $k (keys %Bits) {
441 vec($Bits{$k}, $LAST_BIT, 1) = 0;
442 }
443 $DeadBits{$name} = _mkMask($LAST_BIT);
444 vec($DeadBits{'all'}, $LAST_BIT++, 1) = 1;
445 }
446 }
447}
448
449sub _error_loc {
450 require Carp;
451 goto &Carp::short_error_loc; # don't introduce another stack frame
452}
453
454sub enabled
455{
456 return __chk(NORMAL, @_);
457}
458
459sub fatal_enabled
460{
461 return __chk(FATAL, @_);
462}
463
464sub warn
465{
466 return __chk(FATAL | MESSAGE, @_);
467}
468
469sub warnif
470{
471 return __chk(NORMAL | FATAL | MESSAGE, @_);
472}
473
474# These are not part of any public interface, so we can delete them to save
475# space.
476delete @warnings::{qw(NORMAL FATAL MESSAGE)};
477
4781;
479__END__
599cee73
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480=head1 NAME
481
4438c4b7 482warnings - Perl pragma to control optional warnings
599cee73
PM
483
484=head1 SYNOPSIS
485
4438c4b7
JH
486 use warnings;
487 no warnings;
599cee73 488
4438c4b7
JH
489 use warnings "all";
490 no warnings "all";
599cee73 491
d3a7d8c7
GS
492 use warnings::register;
493 if (warnings::enabled()) {
494 warnings::warn("some warning");
495 }
496
497 if (warnings::enabled("void")) {
e476b1b5
GS
498 warnings::warn("void", "some warning");
499 }
500
7e6d00f8
PM
501 if (warnings::enabled($object)) {
502 warnings::warn($object, "some warning");
503 }
504
721f911b
PM
505 warnings::warnif("some warning");
506 warnings::warnif("void", "some warning");
507 warnings::warnif($object, "some warning");
7e6d00f8 508
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509=head1 DESCRIPTION
510
a7f2b7af
RS
511The C<warnings> pragma gives control over which warnings are enabled in
512which parts of a Perl program. It's a more flexible alternative for
513both the command line flag B<-w> and the equivalent Perl variable,
514C<$^W>.
fe2e802c 515
a7f2b7af
RS
516This pragma works just like the C<strict> pragma.
517This means that the scope of the warning pragma is limited to the
518enclosing block. It also means that the pragma setting will not
519leak across files (via C<use>, C<require> or C<do>). This allows
520authors to independently define the degree of warning checks that will
521be applied to their module.
599cee73 522
a7f2b7af
RS
523By default, optional warnings are disabled, so any legacy code that
524doesn't attempt to control the warnings will work unchanged.
525
3c3f8cd6 526All warnings are enabled in a block by either of these:
a7f2b7af
RS
527
528 use warnings;
529 use warnings 'all';
530
3c3f8cd6 531Similarly all warnings are disabled in a block by either of these:
a7f2b7af
RS
532
533 no warnings;
534 no warnings 'all';
535
536For example, consider the code below:
537
538 use warnings;
539 my @a;
540 {
541 no warnings;
542 my $b = @a[0];
543 }
544 my $c = @a[0];
545
546The code in the enclosing block has warnings enabled, but the inner
547block has them disabled. In this case that means the assignment to the
548scalar C<$c> will trip the C<"Scalar value @a[0] better written as $a[0]">
549warning, but the assignment to the scalar C<$b> will not.
550
551=head2 Default Warnings and Optional Warnings
552
553Before the introduction of lexical warnings, Perl had two classes of
56873d42 554warnings: mandatory and optional.
a7f2b7af
RS
555
556As its name suggests, if your code tripped a mandatory warning, you
557would get a warning whether you wanted it or not.
558For example, the code below would always produce an C<"isn't numeric">
559warning about the "2:".
560
561 my $a = "2:" + 3;
562
563With the introduction of lexical warnings, mandatory warnings now become
564I<default> warnings. The difference is that although the previously
565mandatory warnings are still enabled by default, they can then be
566subsequently enabled or disabled with the lexical warning pragma. For
567example, in the code below, an C<"isn't numeric"> warning will only
568be reported for the C<$a> variable.
569
570 my $a = "2:" + 3;
571 no warnings;
572 my $b = "2:" + 3;
573
574Note that neither the B<-w> flag or the C<$^W> can be used to
575disable/enable default warnings. They are still mandatory in this case.
576
577=head2 What's wrong with B<-w> and C<$^W>
578
579Although very useful, the big problem with using B<-w> on the command
580line to enable warnings is that it is all or nothing. Take the typical
581scenario when you are writing a Perl program. Parts of the code you
582will write yourself, but it's very likely that you will make use of
583pre-written Perl modules. If you use the B<-w> flag in this case, you
584end up enabling warnings in pieces of code that you haven't written.
585
586Similarly, using C<$^W> to either disable or enable blocks of code is
587fundamentally flawed. For a start, say you want to disable warnings in
588a block of code. You might expect this to be enough to do the trick:
589
590 {
591 local ($^W) = 0;
592 my $a =+ 2;
593 my $b; chop $b;
594 }
595
596When this code is run with the B<-w> flag, a warning will be produced
597for the C<$a> line: C<"Reversed += operator">.
598
599The problem is that Perl has both compile-time and run-time warnings. To
600disable compile-time warnings you need to rewrite the code like this:
601
602 {
603 BEGIN { $^W = 0 }
604 my $a =+ 2;
605 my $b; chop $b;
606 }
607
608The other big problem with C<$^W> is the way you can inadvertently
609change the warning setting in unexpected places in your code. For example,
610when the code below is run (without the B<-w> flag), the second call
611to C<doit> will trip a C<"Use of uninitialized value"> warning, whereas
612the first will not.
613
614 sub doit
615 {
616 my $b; chop $b;
617 }
618
619 doit();
620
621 {
622 local ($^W) = 1;
623 doit()
624 }
625
626This is a side-effect of C<$^W> being dynamically scoped.
627
628Lexical warnings get around these limitations by allowing finer control
629over where warnings can or can't be tripped.
630
631=head2 Controlling Warnings from the Command Line
632
633There are three Command Line flags that can be used to control when
634warnings are (or aren't) produced:
635
636=over 5
637
638=item B<-w>
639X<-w>
640
641This is the existing flag. If the lexical warnings pragma is B<not>
642used in any of you code, or any of the modules that you use, this flag
643will enable warnings everywhere. See L<Backward Compatibility> for
644details of how this flag interacts with lexical warnings.
645
646=item B<-W>
647X<-W>
648
3c3f8cd6 649If the B<-W> flag is used on the command line, it will enable all warnings
a7f2b7af
RS
650throughout the program regardless of whether warnings were disabled
651locally using C<no warnings> or C<$^W =0>.
652This includes all files that get
653included via C<use>, C<require> or C<do>.
654Think of it as the Perl equivalent of the "lint" command.
655
656=item B<-X>
657X<-X>
658
3c3f8cd6 659Does the exact opposite to the B<-W> flag, i.e. it disables all warnings.
ea5519d6
AB
660
661=back
662
a7f2b7af
RS
663=head2 Backward Compatibility
664
665If you are used to working with a version of Perl prior to the
666introduction of lexically scoped warnings, or have code that uses both
667lexical warnings and C<$^W>, this section will describe how they interact.
668
669How Lexical Warnings interact with B<-w>/C<$^W>:
670
671=over 5
672
673=item 1.
674
675If none of the three command line flags (B<-w>, B<-W> or B<-X>) that
676control warnings is used and neither C<$^W> nor the C<warnings> pragma
677are used, then default warnings will be enabled and optional warnings
678disabled.
679This means that legacy code that doesn't attempt to control the warnings
680will work unchanged.
681
682=item 2.
683
684The B<-w> flag just sets the global C<$^W> variable as in 5.005. This
685means that any legacy code that currently relies on manipulating C<$^W>
56873d42 686to control warning behavior will still work as is.
a7f2b7af
RS
687
688=item 3.
689
690Apart from now being a boolean, the C<$^W> variable operates in exactly
691the same horrible uncontrolled global way, except that it cannot
692disable/enable default warnings.
693
694=item 4.
695
696If a piece of code is under the control of the C<warnings> pragma,
697both the C<$^W> variable and the B<-w> flag will be ignored for the
698scope of the lexical warning.
699
700=item 5.
701
702The only way to override a lexical warnings setting is with the B<-W>
703or B<-X> command line flags.
704
705=back
706
707The combined effect of 3 & 4 is that it will allow code which uses
708the C<warnings> pragma to control the warning behavior of $^W-type
709code (using a C<local $^W=0>) if it really wants to, but not vice-versa.
710
711=head2 Category Hierarchy
712X<warning, categories>
713
714A hierarchy of "categories" have been defined to allow groups of warnings
715to be enabled/disabled in isolation.
716
717The current hierarchy is:
718
3c3f8cd6
AB
719 all -+
720 |
721 +- closure
722 |
723 +- deprecated
724 |
725 +- exiting
726 |
727 +- experimental --+
728 | |
729 | +- experimental::autoderef
730 | |
9f88e537
FC
731 | +- experimental::bitwise
732 | |
3c3f8cd6
AB
733 | +- experimental::const_attr
734 | |
735 | +- experimental::lexical_subs
736 | |
737 | +- experimental::lexical_topic
738 | |
739 | +- experimental::postderef
740 | |
741 | +- experimental::re_strict
742 | |
743 | +- experimental::refaliasing
744 | |
745 | +- experimental::regex_sets
746 | |
747 | +- experimental::signatures
748 | |
749 | +- experimental::smartmatch
750 | |
751 | +- experimental::win32_perlio
752 |
753 +- glob
754 |
755 +- imprecision
756 |
757 +- io ------------+
758 | |
759 | +- closed
760 | |
761 | +- exec
762 | |
763 | +- layer
764 | |
765 | +- newline
766 | |
767 | +- pipe
768 | |
769 | +- syscalls
770 | |
771 | +- unopened
772 |
773 +- locale
774 |
775 +- misc
776 |
777 +- missing
778 |
779 +- numeric
780 |
781 +- once
782 |
783 +- overflow
784 |
785 +- pack
786 |
787 +- portable
788 |
789 +- recursion
790 |
791 +- redefine
792 |
793 +- redundant
794 |
795 +- regexp
796 |
797 +- severe --------+
798 | |
799 | +- debugging
800 | |
801 | +- inplace
802 | |
803 | +- internal
804 | |
805 | +- malloc
806 |
807 +- signal
808 |
809 +- substr
810 |
811 +- syntax --------+
812 | |
813 | +- ambiguous
814 | |
815 | +- bareword
816 | |
817 | +- digit
818 | |
819 | +- illegalproto
820 | |
821 | +- parenthesis
822 | |
823 | +- precedence
824 | |
825 | +- printf
826 | |
827 | +- prototype
828 | |
829 | +- qw
830 | |
831 | +- reserved
832 | |
833 | +- semicolon
834 |
835 +- taint
836 |
837 +- threads
838 |
839 +- uninitialized
840 |
841 +- unpack
842 |
843 +- untie
844 |
845 +- utf8 ----------+
846 | |
847 | +- non_unicode
848 | |
849 | +- nonchar
850 | |
851 | +- surrogate
852 |
853 +- void
a7f2b7af
RS
854
855Just like the "strict" pragma any of these categories can be combined
856
857 use warnings qw(void redefine);
858 no warnings qw(io syntax untie);
859
860Also like the "strict" pragma, if there is more than one instance of the
56873d42 861C<warnings> pragma in a given scope the cumulative effect is additive.
a7f2b7af
RS
862
863 use warnings qw(void); # only "void" warnings enabled
864 ...
865 use warnings qw(io); # only "void" & "io" warnings enabled
866 ...
867 no warnings qw(void); # only "io" warnings enabled
868
869To determine which category a specific warning has been assigned to see
870L<perldiag>.
871
872Note: Before Perl 5.8.0, the lexical warnings category "deprecated" was a
873sub-category of the "syntax" category. It is now a top-level category
874in its own right.
875
3664866e
AB
876Note: Before 5.21.0, the "missing" lexical warnings category was
877internally defined to be the same as the "uninitialized" category. It
878is now a top-level category in its own right.
879
a7f2b7af
RS
880=head2 Fatal Warnings
881X<warning, fatal>
882
883The presence of the word "FATAL" in the category list will escalate any
884warnings detected from the categories specified in the lexical scope
2115c436 885into fatal errors. In the code below, the use of C<time>, C<length>
a7f2b7af
RS
886and C<join> can all produce a C<"Useless use of xxx in void context">
887warning.
888
889 use warnings;
890
891 time;
892
893 {
894 use warnings FATAL => qw(void);
895 length "abc";
896 }
897
898 join "", 1,2,3;
899
900 print "done\n";
901
902When run it produces this output
903
904 Useless use of time in void context at fatal line 3.
56873d42 905 Useless use of length in void context at fatal line 7.
a7f2b7af
RS
906
907The scope where C<length> is used has escalated the C<void> warnings
908category into a fatal error, so the program terminates immediately when it
909encounters the warning.
910
911To explicitly turn off a "FATAL" warning you just disable the warning
912it is associated with. So, for example, to disable the "void" warning
913in the example above, either of these will do the trick:
914
915 no warnings qw(void);
916 no warnings FATAL => qw(void);
917
918If you want to downgrade a warning that has been escalated into a fatal
919error back to a normal warning, you can use the "NONFATAL" keyword. For
920example, the code below will promote all warnings into fatal errors,
921except for those in the "syntax" category.
922
923 use warnings FATAL => 'all', NONFATAL => 'syntax';
924
925As of Perl 5.20, instead of C<< use warnings FATAL => 'all'; >> you can
926use:
927
928 use v5.20; # Perl 5.20 or greater is required for the following
929 use warnings 'FATAL'; # short form of "use warnings FATAL => 'all';"
930
931If you want your program to be compatible with versions of Perl before
9325.20, you must use C<< use warnings FATAL => 'all'; >> instead. (In
933previous versions of Perl, the behavior of the statements
934C<< use warnings 'FATAL'; >>, C<< use warnings 'NONFATAL'; >> and
935C<< no warnings 'FATAL'; >> was unspecified; they did not behave as if
936they included the C<< => 'all' >> portion. As of 5.20, they do.)
937
2115c436
RS
938B<NOTE:> Users of FATAL warnings, especially
939those using C<< FATAL => 'all' >>
940should be fully aware that they are risking future portability of their
941programs by doing so. Perl makes absolutely no commitments to not
942introduce new warnings, or warnings categories in the future, and indeed
943we explicitly reserve the right to do so. Code that may not warn now may
944warn in a future release of Perl if the Perl5 development team deems it
945in the best interests of the community to do so. Should code using FATAL
946warnings break due to the introduction of a new warning we will NOT
947consider it an incompatible change. Users of FATAL warnings should take
948special caution during upgrades to check to see if their code triggers
949any new warnings and should pay particular attention to the fine print of
950the documentation of the features they use to ensure they do not exploit
951features that are documented as risky, deprecated, or unspecified, or where
952the documentation says "so don't do that", or anything with the same sense
953and spirit. Use of such features in combination with FATAL warnings is
954ENTIRELY AT THE USER'S RISK.
955
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RS
956=head2 Reporting Warnings from a Module
957X<warning, reporting> X<warning, registering>
958
959The C<warnings> pragma provides a number of functions that are useful for
960module authors. These are used when you want to report a module-specific
961warning to a calling module has enabled warnings via the C<warnings>
962pragma.
963
964Consider the module C<MyMod::Abc> below.
965
966 package MyMod::Abc;
967
968 use warnings::register;
969
970 sub open {
971 my $path = shift;
972 if ($path !~ m#^/#) {
973 warnings::warn("changing relative path to /var/abc")
974 if warnings::enabled();
975 $path = "/var/abc/$path";
976 }
977 }
978
979 1;
980
981The call to C<warnings::register> will create a new warnings category
982called "MyMod::Abc", i.e. the new category name matches the current
983package name. The C<open> function in the module will display a warning
984message if it gets given a relative path as a parameter. This warnings
985will only be displayed if the code that uses C<MyMod::Abc> has actually
986enabled them with the C<warnings> pragma like below.
987
988 use MyMod::Abc;
989 use warnings 'MyMod::Abc';
990 ...
991 abc::open("../fred.txt");
992
993It is also possible to test whether the pre-defined warnings categories are
994set in the calling module with the C<warnings::enabled> function. Consider
995this snippet of code:
996
997 package MyMod::Abc;
998
999 sub open {
56873d42 1000 warnings::warnif("deprecated",
a7f2b7af
RS
1001 "open is deprecated, use new instead");
1002 new(@_);
1003 }
1004
1005 sub new
1006 ...
1007 1;
1008
1009The function C<open> has been deprecated, so code has been included to
1010display a warning message whenever the calling module has (at least) the
1011"deprecated" warnings category enabled. Something like this, say.
1012
1013 use warnings 'deprecated';
1014 use MyMod::Abc;
1015 ...
1016 MyMod::Abc::open($filename);
1017
1018Either the C<warnings::warn> or C<warnings::warnif> function should be
1019used to actually display the warnings message. This is because they can
1020make use of the feature that allows warnings to be escalated into fatal
1021errors. So in this case
1022
1023 use MyMod::Abc;
1024 use warnings FATAL => 'MyMod::Abc';
1025 ...
1026 MyMod::Abc::open('../fred.txt');
1027
1028the C<warnings::warnif> function will detect this and die after
1029displaying the warning message.
1030
1031The three warnings functions, C<warnings::warn>, C<warnings::warnif>
1032and C<warnings::enabled> can optionally take an object reference in place
1033of a category name. In this case the functions will use the class name
1034of the object as the warnings category.
1035
1036Consider this example:
1037
1038 package Original;
1039
1040 no warnings;
1041 use warnings::register;
1042
1043 sub new
1044 {
1045 my $class = shift;
1046 bless [], $class;
1047 }
1048
1049 sub check
effd17dc
DD
1050 {
1051 my $self = shift;
1052 my $value = shift;
e476b1b5 1053
effd17dc
DD
1054 if ($value % 2 && warnings::enabled($self))
1055 { warnings::warn($self, "Odd numbers are unsafe") }
1056 }
599cee73 1057
effd17dc
DD
1058 sub doit
1059 {
1060 my $self = shift;
1061 my $value = shift;
1062 $self->check($value);
1063 # ...
1064 }
599cee73 1065
effd17dc 1066 1;
0d658bf5 1067
effd17dc 1068 package Derived;
0d658bf5 1069
effd17dc
DD
1070 use warnings::register;
1071 use Original;
1072 our @ISA = qw( Original );
1073 sub new
1074 {
1075 my $class = shift;
1076 bless [], $class;
1077 }
b88df990 1078
b88df990 1079
effd17dc 1080 1;
8457b38f 1081
56873d42 1082The code below makes use of both modules, but it only enables warnings from
effd17dc 1083C<Derived>.
8457b38f 1084
effd17dc
DD
1085 use Original;
1086 use Derived;
1087 use warnings 'Derived';
1088 my $a = Original->new();
1089 $a->doit(1);
1090 my $b = Derived->new();
1091 $a->doit(1);
6f87cb12 1092
effd17dc 1093When this code is run only the C<Derived> object, C<$b>, will generate
56873d42 1094a warning.
6f87cb12 1095
effd17dc 1096 Odd numbers are unsafe at main.pl line 7
c8028aa6 1097
effd17dc
DD
1098Notice also that the warning is reported at the line where the object is first
1099used.
c8028aa6 1100
effd17dc
DD
1101When registering new categories of warning, you can supply more names to
1102warnings::register like this:
7ac92924 1103
effd17dc
DD
1104 package MyModule;
1105 use warnings::register qw(format precision);
7ac92924 1106
effd17dc 1107 ...
d3a7d8c7 1108
effd17dc 1109 warnings::warnif('MyModule::format', '...');
599cee73 1110
effd17dc 1111=head1 FUNCTIONS
599cee73 1112
effd17dc 1113=over 4
d3a7d8c7 1114
effd17dc 1115=item use warnings::register
599cee73 1116
effd17dc
DD
1117Creates a new warnings category with the same name as the package where
1118the call to the pragma is used.
c3186b65 1119
effd17dc 1120=item warnings::enabled()
6e9af7e4 1121
effd17dc 1122Use the warnings category with the same name as the current package.
599cee73 1123
effd17dc
DD
1124Return TRUE if that warnings category is enabled in the calling module.
1125Otherwise returns FALSE.
599cee73 1126
effd17dc 1127=item warnings::enabled($category)
4c02ac93 1128
effd17dc
DD
1129Return TRUE if the warnings category, C<$category>, is enabled in the
1130calling module.
1131Otherwise returns FALSE.
6e9af7e4 1132
effd17dc 1133=item warnings::enabled($object)
6e9af7e4 1134
effd17dc
DD
1135Use the name of the class for the object reference, C<$object>, as the
1136warnings category.
c91312d5 1137
effd17dc
DD
1138Return TRUE if that warnings category is enabled in the first scope
1139where the object is used.
1140Otherwise returns FALSE.
a7f2b7af 1141
effd17dc 1142=item warnings::fatal_enabled()
599cee73 1143
effd17dc
DD
1144Return TRUE if the warnings category with the same name as the current
1145package has been set to FATAL in the calling module.
1146Otherwise returns FALSE.
6e9af7e4 1147
effd17dc 1148=item warnings::fatal_enabled($category)
6e9af7e4 1149
effd17dc
DD
1150Return TRUE if the warnings category C<$category> has been set to FATAL in
1151the calling module.
1152Otherwise returns FALSE.
6e9af7e4 1153
effd17dc 1154=item warnings::fatal_enabled($object)
6e9af7e4 1155
effd17dc
DD
1156Use the name of the class for the object reference, C<$object>, as the
1157warnings category.
6e9af7e4 1158
effd17dc
DD
1159Return TRUE if that warnings category has been set to FATAL in the first
1160scope where the object is used.
1161Otherwise returns FALSE.
599cee73 1162
effd17dc 1163=item warnings::warn($message)
9df0f64f 1164
effd17dc 1165Print C<$message> to STDERR.
8787a747 1166
effd17dc 1167Use the warnings category with the same name as the current package.
96183d25 1168
effd17dc
DD
1169If that warnings category has been set to "FATAL" in the calling module
1170then die. Otherwise return.
96183d25 1171
effd17dc 1172=item warnings::warn($category, $message)
d3a7d8c7 1173
effd17dc 1174Print C<$message> to STDERR.
d3a7d8c7 1175
effd17dc
DD
1176If the warnings category, C<$category>, has been set to "FATAL" in the
1177calling module then die. Otherwise return.
7e6d00f8 1178
effd17dc 1179=item warnings::warn($object, $message)
7e6d00f8 1180
effd17dc 1181Print C<$message> to STDERR.
8787a747 1182
effd17dc
DD
1183Use the name of the class for the object reference, C<$object>, as the
1184warnings category.
8787a747 1185
effd17dc
DD
1186If that warnings category has been set to "FATAL" in the scope where C<$object>
1187is first used then die. Otherwise return.
96183d25 1188
96183d25 1189
effd17dc 1190=item warnings::warnif($message)
96183d25 1191
effd17dc 1192Equivalent to:
7e6d00f8 1193
effd17dc
DD
1194 if (warnings::enabled())
1195 { warnings::warn($message) }
572bfd36 1196
effd17dc 1197=item warnings::warnif($category, $message)
572bfd36 1198
effd17dc 1199Equivalent to:
572bfd36 1200
effd17dc
DD
1201 if (warnings::enabled($category))
1202 { warnings::warn($category, $message) }
572bfd36 1203
effd17dc 1204=item warnings::warnif($object, $message)
4f527b71 1205
effd17dc 1206Equivalent to:
599cee73 1207
effd17dc
DD
1208 if (warnings::enabled($object))
1209 { warnings::warn($object, $message) }
d3a7d8c7 1210
effd17dc 1211=item warnings::register_categories(@names)
e476b1b5 1212
effd17dc
DD
1213This registers warning categories for the given names and is primarily for
1214use by the warnings::register pragma.
0d658bf5 1215
effd17dc 1216=back
8787a747 1217
effd17dc
DD
1218See also L<perlmodlib/Pragmatic Modules> and L<perldiag>.
1219
1220=cut
ce716c52 1221
37442d52 1222# ex: set ro: