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1 | package B::Lint; |
2 | |
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3 | our $VERSION = '1.01'; |
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4 | |
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5 | =head1 NAME |
6 | |
7 | B::Lint - Perl lint |
8 | |
9 | =head1 SYNOPSIS |
10 | |
11 | perl -MO=Lint[,OPTIONS] foo.pl |
12 | |
13 | =head1 DESCRIPTION |
14 | |
15 | The B::Lint module is equivalent to an extended version of the B<-w> |
16 | option of B<perl>. It is named after the program B<lint> which carries |
17 | out a similar process for C programs. |
18 | |
19 | =head1 OPTIONS AND LINT CHECKS |
20 | |
21 | Option words are separated by commas (not whitespace) and follow the |
22 | usual conventions of compiler backend options. Following any options |
23 | (indicated by a leading B<->) come lint check arguments. Each such |
24 | argument (apart from the special B<all> and B<none> options) is a |
25 | word representing one possible lint check (turning on that check) or |
26 | is B<no-foo> (turning off that check). Before processing the check |
27 | arguments, a standard list of checks is turned on. Later options |
28 | override earlier ones. Available options are: |
29 | |
30 | =over 8 |
31 | |
32 | =item B<context> |
33 | |
34 | Produces a warning whenever an array is used in an implicit scalar |
35 | context. For example, both of the lines |
36 | |
37 | $foo = length(@bar); |
38 | $foo = @bar; |
39 | will elicit a warning. Using an explicit B<scalar()> silences the |
40 | warning. For example, |
41 | |
42 | $foo = scalar(@bar); |
43 | |
44 | =item B<implicit-read> and B<implicit-write> |
45 | |
46 | These options produce a warning whenever an operation implicitly |
47 | reads or (respectively) writes to one of Perl's special variables. |
48 | For example, B<implicit-read> will warn about these: |
49 | |
50 | /foo/; |
51 | |
52 | and B<implicit-write> will warn about these: |
53 | |
54 | s/foo/bar/; |
55 | |
56 | Both B<implicit-read> and B<implicit-write> warn about this: |
57 | |
58 | for (@a) { ... } |
59 | |
60 | =item B<dollar-underscore> |
61 | |
62 | This option warns whenever $_ is used either explicitly anywhere or |
63 | as the implicit argument of a B<print> statement. |
64 | |
65 | =item B<private-names> |
66 | |
67 | This option warns on each use of any variable, subroutine or |
68 | method name that lives in a non-current package but begins with |
69 | an underscore ("_"). Warnings aren't issued for the special case |
70 | of the single character name "_" by itself (e.g. $_ and @_). |
71 | |
72 | =item B<undefined-subs> |
73 | |
74 | This option warns whenever an undefined subroutine is invoked. |
75 | This option will only catch explicitly invoked subroutines such |
76 | as C<foo()> and not indirect invocations such as C<&$subref()> |
77 | or C<$obj-E<gt>meth()>. Note that some programs or modules delay |
78 | definition of subs until runtime by means of the AUTOLOAD |
79 | mechanism. |
80 | |
81 | =item B<regexp-variables> |
82 | |
83 | This option warns whenever one of the regexp variables $', $& or |
84 | $' is used. Any occurrence of any of these variables in your |
85 | program can slow your whole program down. See L<perlre> for |
86 | details. |
87 | |
88 | =item B<all> |
89 | |
90 | Turn all warnings on. |
91 | |
92 | =item B<none> |
93 | |
94 | Turn all warnings off. |
95 | |
96 | =back |
97 | |
98 | =head1 NON LINT-CHECK OPTIONS |
99 | |
100 | =over 8 |
101 | |
102 | =item B<-u Package> |
103 | |
104 | Normally, Lint only checks the main code of the program together |
105 | with all subs defined in package main. The B<-u> option lets you |
106 | include other package names whose subs are then checked by Lint. |
107 | |
108 | =back |
109 | |
110 | =head1 BUGS |
111 | |
112 | This is only a very preliminary version. |
113 | |
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114 | This module doesn't work correctly on thread-enabled perls. |
115 | |
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116 | =head1 AUTHOR |
117 | |
118 | Malcolm Beattie, mbeattie@sable.ox.ac.uk. |
119 | |
120 | =cut |
121 | |
122 | use strict; |
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123 | use B qw(walkoptree_slow main_root walksymtable svref_2object parents |
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124 | OPf_WANT_LIST OPf_WANT OPf_STACKED G_ARRAY |
125 | ); |
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126 | |
127 | my $file = "unknown"; # shadows current filename |
128 | my $line = 0; # shadows current line number |
129 | my $curstash = "main"; # shadows current stash |
130 | |
131 | # Lint checks |
132 | my %check; |
133 | my %implies_ok_context; |
134 | BEGIN { |
135 | map($implies_ok_context{$_}++, |
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136 | qw(scalar av2arylen aelem aslice helem hslice |
137 | keys values hslice defined undef delete)); |
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138 | } |
139 | |
140 | # Lint checks turned on by default |
141 | my @default_checks = qw(context); |
142 | |
143 | my %valid_check; |
144 | # All valid checks |
145 | BEGIN { |
146 | map($valid_check{$_}++, |
147 | qw(context implicit_read implicit_write dollar_underscore |
148 | private_names undefined_subs regexp_variables)); |
149 | } |
150 | |
151 | # Debugging options |
152 | my ($debug_op); |
153 | |
154 | my %done_cv; # used to mark which subs have already been linted |
155 | my @extra_packages; # Lint checks mainline code and all subs which are |
156 | # in main:: or in one of these packages. |
157 | |
158 | sub warning { |
159 | my $format = (@_ < 2) ? "%s" : shift; |
160 | warn sprintf("$format at %s line %d\n", @_, $file, $line); |
161 | } |
162 | |
163 | # This gimme can't cope with context that's only determined |
164 | # at runtime via dowantarray(). |
165 | sub gimme { |
166 | my $op = shift; |
167 | my $flags = $op->flags; |
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168 | if ($flags & OPf_WANT) { |
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169 | return(($flags & OPf_WANT) == OPf_WANT_LIST ? 1 : 0); |
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170 | } |
171 | return undef; |
172 | } |
173 | |
174 | sub B::OP::lint {} |
175 | |
176 | sub B::COP::lint { |
177 | my $op = shift; |
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178 | if ($op->name eq "nextstate") { |
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179 | $file = $op->file; |
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180 | $line = $op->line; |
181 | $curstash = $op->stash->NAME; |
182 | } |
183 | } |
184 | |
185 | sub B::UNOP::lint { |
186 | my $op = shift; |
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187 | my $opname = $op->name; |
188 | if ($check{context} && ($opname eq "rv2av" || $opname eq "rv2hv")) { |
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189 | my $parent = parents->[0]; |
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190 | my $pname = $parent->name; |
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191 | return if gimme($op) || $implies_ok_context{$pname}; |
192 | # Two special cases to deal with: "foreach (@foo)" and "delete $a{$b}" |
193 | # null out the parent so we have to check for a parent of pp_null and |
194 | # a grandparent of pp_enteriter or pp_delete |
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195 | if ($pname eq "null") { |
196 | my $gpname = parents->[1]->name; |
197 | return if $gpname eq "enteriter" || $gpname eq "delete"; |
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198 | } |
199 | warning("Implicit scalar context for %s in %s", |
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200 | $opname eq "rv2av" ? "array" : "hash", $parent->desc); |
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201 | } |
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202 | if ($check{private_names} && $opname eq "method") { |
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203 | my $methop = $op->first; |
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204 | if ($methop->name eq "const") { |
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205 | my $method = $methop->sv->PV; |
206 | if ($method =~ /^_/ && !defined(&{"$curstash\::$method"})) { |
207 | warning("Illegal reference to private method name $method"); |
208 | } |
209 | } |
210 | } |
211 | } |
212 | |
213 | sub B::PMOP::lint { |
214 | my $op = shift; |
215 | if ($check{implicit_read}) { |
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216 | if ($op->name eq "match" && !($op->flags & OPf_STACKED)) { |
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217 | warning('Implicit match on $_'); |
218 | } |
219 | } |
220 | if ($check{implicit_write}) { |
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221 | if ($op->name eq "subst" && !($op->flags & OPf_STACKED)) { |
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222 | warning('Implicit substitution on $_'); |
223 | } |
224 | } |
225 | } |
226 | |
227 | sub B::LOOP::lint { |
228 | my $op = shift; |
229 | if ($check{implicit_read} || $check{implicit_write}) { |
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230 | if ($op->name eq "enteriter") { |
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231 | my $last = $op->last; |
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232 | if ($last->name eq "gv" && $last->gv->NAME eq "_") { |
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233 | warning('Implicit use of $_ in foreach'); |
234 | } |
235 | } |
236 | } |
237 | } |
238 | |
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239 | sub B::SVOP::lint { |
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240 | my $op = shift; |
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241 | if ($check{dollar_underscore} && $op->name eq "gvsv" |
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242 | && $op->gv->NAME eq "_") |
243 | { |
244 | warning('Use of $_'); |
245 | } |
246 | if ($check{private_names}) { |
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247 | my $opname = $op->name; |
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248 | if ($opname eq "gv" || $opname eq "gvsv") { |
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249 | my $gv = $op->gv; |
250 | if ($gv->NAME =~ /^_./ && $gv->STASH->NAME ne $curstash) { |
251 | warning('Illegal reference to private name %s', $gv->NAME); |
252 | } |
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253 | } |
254 | } |
255 | if ($check{undefined_subs}) { |
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256 | if ($op->name eq "gv" |
257 | && $op->next->name eq "entersub") |
258 | { |
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259 | my $gv = $op->gv; |
260 | my $subname = $gv->STASH->NAME . "::" . $gv->NAME; |
261 | no strict 'refs'; |
262 | if (!defined(&$subname)) { |
263 | $subname =~ s/^main:://; |
264 | warning('Undefined subroutine %s called', $subname); |
265 | } |
266 | } |
267 | } |
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268 | if ($check{regexp_variables} && $op->name eq "gvsv") { |
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269 | my $name = $op->gv->NAME; |
270 | if ($name =~ /^[&'`]$/) { |
271 | warning('Use of regexp variable $%s', $name); |
272 | } |
273 | } |
274 | } |
275 | |
276 | sub B::GV::lintcv { |
277 | my $gv = shift; |
278 | my $cv = $gv->CV; |
279 | #warn sprintf("lintcv: %s::%s (done=%d)\n", |
280 | # $gv->STASH->NAME, $gv->NAME, $done_cv{$$cv});#debug |
281 | return if !$$cv || $done_cv{$$cv}++; |
282 | my $root = $cv->ROOT; |
283 | #warn " root = $root (0x$$root)\n";#debug |
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284 | walkoptree_slow($root, "lint") if $$root; |
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285 | } |
286 | |
287 | sub do_lint { |
288 | my %search_pack; |
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289 | walkoptree_slow(main_root, "lint") if ${main_root()}; |
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290 | |
291 | # Now do subs in main |
292 | no strict qw(vars refs); |
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293 | local(*glob); |
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294 | for my $sym (keys %main::) { |
295 | next if $sym =~ /::$/; |
296 | *glob = $main::{$sym}; |
297 | svref_2object(\*glob)->EGV->lintcv; |
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298 | } |
299 | |
300 | # Now do subs in non-main packages given by -u options |
301 | map { $search_pack{$_} = 1 } @extra_packages; |
302 | walksymtable(\%{"main::"}, "lintcv", sub { |
303 | my $package = shift; |
304 | $package =~ s/::$//; |
305 | #warn "Considering $package\n";#debug |
306 | return exists $search_pack{$package}; |
307 | }); |
308 | } |
309 | |
310 | sub compile { |
311 | my @options = @_; |
312 | my ($option, $opt, $arg); |
313 | # Turn on default lint checks |
314 | for $opt (@default_checks) { |
315 | $check{$opt} = 1; |
316 | } |
317 | OPTION: |
318 | while ($option = shift @options) { |
319 | if ($option =~ /^-(.)(.*)/) { |
320 | $opt = $1; |
321 | $arg = $2; |
322 | } else { |
323 | unshift @options, $option; |
324 | last OPTION; |
325 | } |
326 | if ($opt eq "-" && $arg eq "-") { |
327 | shift @options; |
328 | last OPTION; |
329 | } elsif ($opt eq "D") { |
330 | $arg ||= shift @options; |
331 | foreach $arg (split(//, $arg)) { |
332 | if ($arg eq "o") { |
333 | B->debug(1); |
334 | } elsif ($arg eq "O") { |
335 | $debug_op = 1; |
336 | } |
337 | } |
338 | } elsif ($opt eq "u") { |
339 | $arg ||= shift @options; |
340 | push(@extra_packages, $arg); |
341 | } |
342 | } |
343 | foreach $opt (@default_checks, @options) { |
344 | $opt =~ tr/-/_/; |
345 | if ($opt eq "all") { |
346 | %check = %valid_check; |
347 | } |
348 | elsif ($opt eq "none") { |
349 | %check = (); |
350 | } |
351 | else { |
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352 | if ($opt =~ s/^no_//) { |
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353 | $check{$opt} = 0; |
354 | } |
355 | else { |
356 | $check{$opt} = 1; |
357 | } |
358 | warn "No such check: $opt\n" unless defined $valid_check{$opt}; |
359 | } |
360 | } |
361 | # Remaining arguments are things to check |
362 | |
363 | return \&do_lint; |
364 | } |
365 | |
366 | 1; |