Some escapes were mentioned twice, although they're not qr//-specific
[p5sagit/p5-mst-13.2.git] / lib / diagnostics.pm
CommitLineData
4633a7c4 1package diagnostics;
4633a7c4 2
3=head1 NAME
4
c7bcd97d 5diagnostics, splain - produce verbose warning diagnostics
4633a7c4 6
7=head1 SYNOPSIS
8
c7bcd97d 9Using the C<diagnostics> pragma:
4633a7c4 10
11 use diagnostics;
12 use diagnostics -verbose;
13
14 enable diagnostics;
15 disable diagnostics;
16
c7bcd97d 17Using the C<splain> standalone filter program:
4633a7c4 18
19 perl program 2>diag.out
20 splain [-v] [-p] diag.out
21
58618f23 22Using diagnostics to get stack traces from a misbehaving script:
23
24 perl -Mdiagnostics=-traceonly my_script.pl
25
4633a7c4 26=head1 DESCRIPTION
27
28=head2 The C<diagnostics> Pragma
29
30This module extends the terse diagnostics normally emitted by both the
c411974d 31perl compiler and the perl interpreter (from running perl with a -w
32switch or C<use warnings>), augmenting them with the more
4633a7c4 33explicative and endearing descriptions found in L<perldiag>. Like the
1fef88e7 34other pragmata, it affects the compilation phase of your program rather
4633a7c4 35than merely the execution phase.
36
37To use in your program as a pragma, merely invoke
38
39 use diagnostics;
40
41at the start (or near the start) of your program. (Note
42that this I<does> enable perl's B<-w> flag.) Your whole
43compilation will then be subject(ed :-) to the enhanced diagnostics.
44These still go out B<STDERR>.
45
ae2c041d 46Due to the interaction between runtime and compiletime issues,
4633a7c4 47and because it's probably not a very good idea anyway,
ae2c041d 48you may not use C<no diagnostics> to turn them off at compiletime.
3d0ae7ba 49However, you may control their behaviour at runtime using the
4633a7c4 50disable() and enable() methods to turn them off and on respectively.
51
52The B<-verbose> flag first prints out the L<perldiag> introduction before
1fef88e7 53any other diagnostics. The $diagnostics::PRETTY variable can generate nicer
54escape sequences for pagers.
4633a7c4 55
097b73fc 56Warnings dispatched from perl itself (or more accurately, those that match
57descriptions found in L<perldiag>) are only displayed once (no duplicate
49704364 58descriptions). User code generated warnings a la warn() are unaffected,
097b73fc 59allowing duplicate user messages to be displayed.
60
58618f23 61This module also adds a stack trace to the error message when perl dies.
62This is useful for pinpointing what caused the death. The B<-traceonly> (or
3c4b39be 63just B<-t>) flag turns off the explanations of warning messages leaving just
58618f23 64the stack traces. So if your script is dieing, run it again with
65
66 perl -Mdiagnostics=-traceonly my_bad_script
67
68to see the call stack at the time of death. By supplying the B<-warntrace>
69(or just B<-w>) flag, any warnings emitted will also come with a stack
70trace.
71
4633a7c4 72=head2 The I<splain> Program
73
74While apparently a whole nuther program, I<splain> is actually nothing
75more than a link to the (executable) F<diagnostics.pm> module, as well as
76a link to the F<diagnostics.pod> documentation. The B<-v> flag is like
77the C<use diagnostics -verbose> directive.
78The B<-p> flag is like the
79$diagnostics::PRETTY variable. Since you're post-processing with
80I<splain>, there's no sense in being able to enable() or disable() processing.
81
82Output from I<splain> is directed to B<STDOUT>, unlike the pragma.
83
84=head1 EXAMPLES
85
86The following file is certain to trigger a few errors at both
ae2c041d 87runtime and compiletime:
4633a7c4 88
89 use diagnostics;
90 print NOWHERE "nothing\n";
91 print STDERR "\n\tThis message should be unadorned.\n";
92 warn "\tThis is a user warning";
93 print "\nDIAGNOSTIC TESTER: Please enter a <CR> here: ";
94 my $a, $b = scalar <STDIN>;
95 print "\n";
96 print $x/$y;
97
98If you prefer to run your program first and look at its problem
99afterwards, do this:
100
101 perl -w test.pl 2>test.out
102 ./splain < test.out
103
104Note that this is not in general possible in shells of more dubious heritage,
1fef88e7 105as the theoretical
4633a7c4 106
107 (perl -w test.pl >/dev/tty) >& test.out
108 ./splain < test.out
109
110Because you just moved the existing B<stdout> to somewhere else.
111
112If you don't want to modify your source code, but still have on-the-fly
113warnings, do this:
114
115 exec 3>&1; perl -w test.pl 2>&1 1>&3 3>&- | splain 1>&2 3>&-
116
117Nifty, eh?
118
119If you want to control warnings on the fly, do something like this.
120Make sure you do the C<use> first, or you won't be able to get
121at the enable() or disable() methods.
122
123 use diagnostics; # checks entire compilation phase
124 print "\ntime for 1st bogus diags: SQUAWKINGS\n";
125 print BOGUS1 'nada';
126 print "done with 1st bogus\n";
127
128 disable diagnostics; # only turns off runtime warnings
129 print "\ntime for 2nd bogus: (squelched)\n";
130 print BOGUS2 'nada';
131 print "done with 2nd bogus\n";
132
133 enable diagnostics; # turns back on runtime warnings
134 print "\ntime for 3rd bogus: SQUAWKINGS\n";
135 print BOGUS3 'nada';
136 print "done with 3rd bogus\n";
137
138 disable diagnostics;
139 print "\ntime for 4th bogus: (squelched)\n";
140 print BOGUS4 'nada';
141 print "done with 4th bogus\n";
142
143=head1 INTERNALS
144
145Diagnostic messages derive from the F<perldiag.pod> file when available at
146runtime. Otherwise, they may be embedded in the file itself when the
147splain package is built. See the F<Makefile> for details.
148
149If an extant $SIG{__WARN__} handler is discovered, it will continue
1fef88e7 150to be honored, but only after the diagnostics::splainthis() function
4633a7c4 151(the module's $SIG{__WARN__} interceptor) has had its way with your
152warnings.
153
154There is a $diagnostics::DEBUG variable you may set if you're desperately
155curious what sorts of things are being intercepted.
156
157 BEGIN { $diagnostics::DEBUG = 1 }
158
159
160=head1 BUGS
161
162Not being able to say "no diagnostics" is annoying, but may not be
163insurmountable.
164
165The C<-pretty> directive is called too late to affect matters.
864e1151 166You have to do this instead, and I<before> you load the module.
4633a7c4 167
168 BEGIN { $diagnostics::PRETTY = 1 }
169
170I could start up faster by delaying compilation until it should be
a6006777 171needed, but this gets a "panic: top_level" when using the pragma form
172in Perl 5.001e.
4633a7c4 173
174While it's true that this documentation is somewhat subserious, if you use
175a program named I<splain>, you should expect a bit of whimsy.
176
177=head1 AUTHOR
178
352854fa 179Tom Christiansen <F<tchrist@mox.perl.com>>, 25 June 1995.
4633a7c4 180
181=cut
182
7a4340ed 183use strict;
d923656e 184use 5.009001;
5f05dabc 185use Carp;
58618f23 186$Carp::Internal{__PACKAGE__.""}++;
5f05dabc 187
d923656e 188our $VERSION = 1.17;
7a4340ed 189our $DEBUG;
190our $VERBOSE;
191our $PRETTY;
58618f23 192our $TRACEONLY = 0;
193our $WARNTRACE = 0;
1e4e2d84 194
5f05dabc 195use Config;
7a4340ed 196my($privlib, $archlib) = @Config{qw(privlibexp archlibexp)};
5f05dabc 197if ($^O eq 'VMS') {
91a06757 198 require VMS::Filespec;
199 $privlib = VMS::Filespec::unixify($privlib);
200 $archlib = VMS::Filespec::unixify($archlib);
5f05dabc 201}
7a4340ed 202my @trypod = (
7ec2cea4 203 "$archlib/pod/perldiag.pod",
0ff3fa1a 204 "$privlib/pod/perldiag-$Config{version}.pod",
5459498c 205 "$privlib/pod/perldiag.pod",
7ec2cea4 206 "$archlib/pods/perldiag.pod",
0ff3fa1a 207 "$privlib/pods/perldiag-$Config{version}.pod",
5459498c 208 "$privlib/pods/perldiag.pod",
7ec2cea4 209 );
fb73857a 210# handy for development testing of new warnings etc
211unshift @trypod, "./pod/perldiag.pod" if -e "pod/perldiag.pod";
7a4340ed 212(my $PODFILE) = ((grep { -e } @trypod), $trypod[$#trypod])[0];
5f05dabc 213
95e8664e 214if ($^O eq 'MacOS') {
215 # just updir one from each lib dir, we'll find it ...
216 ($PODFILE) = grep { -e } map { "$_:pod:perldiag.pod" } @INC;
217}
218
219
4633a7c4 220$DEBUG ||= 0;
221my $WHOAMI = ref bless []; # nobody's business, prolly not even mine
222
7a4340ed 223local $| = 1;
d923656e 224my $_;
4633a7c4 225
7a4340ed 226my $standalone;
227my(%HTML_2_Troff, %HTML_2_Latin_1, %HTML_2_ASCII_7);
228
4633a7c4 229CONFIG: {
7a4340ed 230 our $opt_p = our $opt_d = our $opt_v = our $opt_f = '';
4633a7c4 231
7a4340ed 232 unless (caller) {
4633a7c4 233 $standalone++;
234 require Getopt::Std;
91a06757 235 Getopt::Std::getopts('pdvf:')
236 or die "Usage: $0 [-v] [-p] [-f splainpod]";
4633a7c4 237 $PODFILE = $opt_f if $opt_f;
238 $DEBUG = 2 if $opt_d;
239 $VERBOSE = $opt_v;
240 $PRETTY = $opt_p;
7a4340ed 241 }
4633a7c4 242
243 if (open(POD_DIAG, $PODFILE)) {
244 warn "Happy happy podfile from real $PODFILE\n" if $DEBUG;
245 last CONFIG;
246 }
247
248 if (caller) {
249 INCPATH: {
7a4340ed 250 for my $file ( (map { "$_/$WHOAMI.pm" } @INC), $0) {
4633a7c4 251 warn "Checking $file\n" if $DEBUG;
252 if (open(POD_DIAG, $file)) {
253 while (<POD_DIAG>) {
7a4340ed 254 next unless
255 /^__END__\s*# wish diag dbase were more accessible/;
4633a7c4 256 print STDERR "podfile is $file\n" if $DEBUG;
257 last INCPATH;
258 }
259 }
260 }
261 }
262 } else {
263 print STDERR "podfile is <DATA>\n" if $DEBUG;
264 *POD_DIAG = *main::DATA;
265 }
266}
267if (eof(POD_DIAG)) {
268 die "couldn't find diagnostic data in $PODFILE @INC $0";
269}
270
271
272%HTML_2_Troff = (
273 'amp' => '&', # ampersand
274 'lt' => '<', # left chevron, less-than
275 'gt' => '>', # right chevron, greater-than
276 'quot' => '"', # double quote
277
278 "Aacute" => "A\\*'", # capital A, acute accent
279 # etc
280
281);
282
283%HTML_2_Latin_1 = (
284 'amp' => '&', # ampersand
285 'lt' => '<', # left chevron, less-than
286 'gt' => '>', # right chevron, greater-than
287 'quot' => '"', # double quote
288
289 "Aacute" => "\xC1" # capital A, acute accent
290
291 # etc
292);
293
294%HTML_2_ASCII_7 = (
295 'amp' => '&', # ampersand
296 'lt' => '<', # left chevron, less-than
297 'gt' => '>', # right chevron, greater-than
298 'quot' => '"', # double quote
299
300 "Aacute" => "A" # capital A, acute accent
301 # etc
302);
303
7a4340ed 304our %HTML_Escapes;
4633a7c4 305*HTML_Escapes = do {
306 if ($standalone) {
307 $PRETTY ? \%HTML_2_Latin_1 : \%HTML_2_ASCII_7;
308 } else {
309 \%HTML_2_Latin_1;
310 }
311};
312
313*THITHER = $standalone ? *STDOUT : *STDERR;
314
49704364 315my %transfmt = ();
7a4340ed 316my $transmo = <<EOFUNC;
4633a7c4 317sub transmo {
599cee73 318 #local \$^W = 0; # recursive warnings we do NOT need!
4633a7c4 319 study;
320EOFUNC
321
7a4340ed 322my %msg;
323{
4633a7c4 324 print STDERR "FINISHING COMPILATION for $_\n" if $DEBUG;
7a4340ed 325 local $/ = '';
7a4340ed 326 my $header;
327 my $for_item;
4633a7c4 328 while (<POD_DIAG>) {
4633a7c4 329
330 unescape();
331 if ($PRETTY) {
332 sub noop { return $_[0] } # spensive for a noop
333 sub bold { my $str =$_[0]; $str =~ s/(.)/$1\b$1/g; return $str; }
334 sub italic { my $str = $_[0]; $str =~ s/(.)/_\b$1/g; return $str; }
67612b68 335 s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/bold($+)/ges;
4633a7c4 336 s/[LIF]<(.*?)>/italic($1)/ges;
337 } else {
67612b68 338 s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/$+/gs;
4633a7c4 339 s/[LIF]<(.*?)>/$1/gs;
340 }
341 unless (/^=/) {
342 if (defined $header) {
343 if ( $header eq 'DESCRIPTION' &&
344 ( /Optional warnings are enabled/
345 || /Some of these messages are generic./
346 ) )
347 {
348 next;
49704364 349 }
4633a7c4 350 s/^/ /gm;
351 $msg{$header} .= $_;
7a4340ed 352 undef $for_item;
4633a7c4 353 }
354 next;
355 }
7a4340ed 356 unless ( s/=item (.*?)\s*\z//) {
4633a7c4 357
358 if ( s/=head1\sDESCRIPTION//) {
359 $msg{$header = 'DESCRIPTION'} = '';
7a4340ed 360 undef $for_item;
4633a7c4 361 }
7a4340ed 362 elsif( s/^=for\s+diagnostics\s*\n(.*?)\s*\z// ) {
363 $for_item = $1;
364 }
4633a7c4 365 next;
366 }
4fdae800 367
5cd5c422 368 if( $for_item ) { $header = $for_item; undef $for_item }
369 else {
370 $header = $1;
371 while( $header =~ /[;,]\z/ ) {
372 <POD_DIAG> =~ /^\s*(.*?)\s*\z/;
373 $header .= ' '.$1;
374 }
375 }
376
49704364 377 # strip formatting directives from =item line
7a4340ed 378 $header =~ s/[A-Z]<(.*?)>/$1/g;
4633a7c4 379
49704364 380 my @toks = split( /(%l?[dx]|%c|%(?:\.\d+)?s)/, $header );
381 if (@toks > 1) {
382 my $conlen = 0;
383 for my $i (0..$#toks){
384 if( $i % 2 ){
385 if( $toks[$i] eq '%c' ){
386 $toks[$i] = '.';
387 } elsif( $toks[$i] eq '%d' ){
388 $toks[$i] = '\d+';
389 } elsif( $toks[$i] eq '%s' ){
390 $toks[$i] = $i == $#toks ? '.*' : '.*?';
391 } elsif( $toks[$i] =~ '%.(\d+)s' ){
392 $toks[$i] = ".{$1}";
393 } elsif( $toks[$i] =~ '^%l*x$' ){
394 $toks[$i] = '[\da-f]+';
395 }
396 } elsif( length( $toks[$i] ) ){
8ec7363a 397 $toks[$i] = quotemeta $toks[$i];
49704364 398 $conlen += length( $toks[$i] );
399 }
400 }
401 my $lhs = join( '', @toks );
402 $transfmt{$header}{pat} =
403 " s{^$lhs}\n {\Q$header\E}s\n\t&& return 1;\n";
404 $transfmt{$header}{len} = $conlen;
4633a7c4 405 } else {
49704364 406 $transfmt{$header}{pat} =
407 " m{^\Q$header\E} && return 1;\n";
408 $transfmt{$header}{len} = length( $header );
4633a7c4 409 }
410
eff9c6e2 411 print STDERR "$WHOAMI: Duplicate entry: \"$header\"\n"
412 if $msg{$header};
4633a7c4 413
414 $msg{$header} = '';
415 }
416
417
418 close POD_DIAG unless *main::DATA eq *POD_DIAG;
419
420 die "No diagnostics?" unless %msg;
421
49704364 422 # Apply patterns in order of decreasing sum of lengths of fixed parts
423 # Seems the best way of hitting the right one.
424 for my $hdr ( sort { $transfmt{$b}{len} <=> $transfmt{$a}{len} }
425 keys %transfmt ){
426 $transmo .= $transfmt{$hdr}{pat};
427 }
4633a7c4 428 $transmo .= " return 0;\n}\n";
429 print STDERR $transmo if $DEBUG;
430 eval $transmo;
431 die $@ if $@;
7a4340ed 432}
4633a7c4 433
434if ($standalone) {
435 if (!@ARGV and -t STDIN) { print STDERR "$0: Reading from STDIN\n" }
7a4340ed 436 while (defined (my $error = <>)) {
4633a7c4 437 splainthis($error) || print THITHER $error;
438 }
439 exit;
7a4340ed 440}
441
442my $olddie;
443my $oldwarn;
4633a7c4 444
445sub import {
446 shift;
7a4340ed 447 $^W = 1; # yup, clobbered the global variable;
448 # tough, if you want diags, you want diags.
0dc02ca5 449 return if defined $SIG{__WARN__} && ($SIG{__WARN__} eq \&warn_trap);
4633a7c4 450
451 for (@_) {
452
453 /^-d(ebug)?$/ && do {
454 $DEBUG++;
455 next;
456 };
457
458 /^-v(erbose)?$/ && do {
459 $VERBOSE++;
460 next;
461 };
462
463 /^-p(retty)?$/ && do {
464 print STDERR "$0: I'm afraid it's too late for prettiness.\n";
465 $PRETTY++;
466 next;
467 };
b4e8c6dd 468 # matches trace and traceonly for legacy doc mixup reasons
469 /^-t(race(only)?)?$/ && do {
58618f23 470 $TRACEONLY++;
471 next;
472 };
b4e8c6dd 473 /^-w(arntrace)?$/ && do {
58618f23 474 $WARNTRACE++;
475 next;
476 };
477
4633a7c4 478 warn "Unknown flag: $_";
479 }
480
481 $oldwarn = $SIG{__WARN__};
482 $olddie = $SIG{__DIE__};
483 $SIG{__WARN__} = \&warn_trap;
484 $SIG{__DIE__} = \&death_trap;
485}
486
487sub enable { &import }
488
489sub disable {
490 shift;
4633a7c4 491 return unless $SIG{__WARN__} eq \&warn_trap;
3d0ae7ba 492 $SIG{__WARN__} = $oldwarn || '';
493 $SIG{__DIE__} = $olddie || '';
4633a7c4 494}
495
496sub warn_trap {
497 my $warning = $_[0];
498 if (caller eq $WHOAMI or !splainthis($warning)) {
58618f23 499 if ($WARNTRACE) {
500 print STDERR Carp::longmess($warning);
501 } else {
502 print STDERR $warning;
503 }
4633a7c4 504 }
58618f23 505 goto &$oldwarn if defined $oldwarn and $oldwarn and $oldwarn ne \&warn_trap;
4633a7c4 506};
507
508sub death_trap {
509 my $exception = $_[0];
55497cff 510
511 # See if we are coming from anywhere within an eval. If so we don't
512 # want to explain the exception because it's going to get caught.
513 my $in_eval = 0;
514 my $i = 0;
58618f23 515 while (my $caller = (caller($i++))[3]) {
55497cff 516 if ($caller eq '(eval)') {
517 $in_eval = 1;
518 last;
519 }
520 }
521
522 splainthis($exception) unless $in_eval;
4633a7c4 523 if (caller eq $WHOAMI) { print STDERR "INTERNAL EXCEPTION: $exception"; }
37120919 524 &$olddie if defined $olddie and $olddie and $olddie ne \&death_trap;
55497cff 525
d23f0205 526 return if $in_eval;
527
55497cff 528 # We don't want to unset these if we're coming from an eval because
d23f0205 529 # then we've turned off diagnostics.
530
531 # Switch off our die/warn handlers so we don't wind up in our own
532 # traps.
533 $SIG{__DIE__} = $SIG{__WARN__} = '';
534
535 # Have carp skip over death_trap() when showing the stack trace.
6f48387a 536 local($Carp::CarpLevel) = 1;
d23f0205 537
6f48387a 538 confess "Uncaught exception from user code:\n\t$exception";
4633a7c4 539 # up we go; where we stop, nobody knows, but i think we die now
540 # but i'm deeply afraid of the &$olddie guy reraising and us getting
541 # into an indirect recursion loop
542};
543
7a4340ed 544my %exact_duplicate;
545my %old_diag;
546my $count;
547my $wantspace;
4633a7c4 548sub splainthis {
58618f23 549 return 0 if $TRACEONLY;
d923656e 550 $_ = shift;
5025c45a 551 local $\;
2a6a970f 552 local $!;
4633a7c4 553 ### &finish_compilation unless %msg;
554 s/\.?\n+$//;
555 my $orig = $_;
556 # return unless defined;
49704364 557
558 # get rid of the where-are-we-in-input part
4633a7c4 559 s/, <.*?> (?:line|chunk).*$//;
49704364 560
561 # Discard 1st " at <file> line <no>" and all text beyond
562 # but be aware of messsages containing " at this-or-that"
563 my $real = 0;
564 my @secs = split( / at / );
18d238e4 565 return unless @secs;
49704364 566 $_ = $secs[0];
567 for my $i ( 1..$#secs ){
568 if( $secs[$i] =~ /.+? (?:line|chunk) \d+/ ){
569 $real = 1;
570 last;
571 } else {
572 $_ .= ' at ' . $secs[$i];
573 }
574 }
575
576 # remove parenthesis occurring at the end of some messages
4633a7c4 577 s/^\((.*)\)$/$1/;
49704364 578
097b73fc 579 if ($exact_duplicate{$orig}++) {
580 return &transmo;
49704364 581 } else {
097b73fc 582 return 0 unless &transmo;
583 }
49704364 584
4633a7c4 585 $orig = shorten($orig);
586 if ($old_diag{$_}) {
587 autodescribe();
588 print THITHER "$orig (#$old_diag{$_})\n";
589 $wantspace = 1;
590 } else {
591 autodescribe();
592 $old_diag{$_} = ++$count;
593 print THITHER "\n" if $wantspace;
594 $wantspace = 0;
595 print THITHER "$orig (#$old_diag{$_})\n";
596 if ($msg{$_}) {
597 print THITHER $msg{$_};
598 } else {
599 if (0 and $standalone) {
600 print THITHER " **** Error #$old_diag{$_} ",
601 ($real ? "is" : "appears to be"),
602 " an unknown diagnostic message.\n\n";
603 }
604 return 0;
605 }
606 }
607 return 1;
608}
609
610sub autodescribe {
611 if ($VERBOSE and not $count) {
612 print THITHER &{$PRETTY ? \&bold : \&noop}("DESCRIPTION OF DIAGNOSTICS"),
613 "\n$msg{DESCRIPTION}\n";
614 }
615}
616
617sub unescape {
618 s {
619 E<
620 ( [A-Za-z]+ )
621 >
622 } {
623 do {
624 exists $HTML_Escapes{$1}
625 ? do { $HTML_Escapes{$1} }
626 : do {
f02a87df 627 warn "Unknown escape: E<$1> in $_";
4633a7c4 628 "E<$1>";
629 }
630 }
631 }egx;
632}
633
634sub shorten {
635 my $line = $_[0];
774d564b 636 if (length($line) > 79 and index($line, "\n") == -1) {
4633a7c4 637 my $space_place = rindex($line, ' ', 79);
638 if ($space_place != -1) {
639 substr($line, $space_place, 1) = "\n\t";
640 }
641 }
642 return $line;
643}
644
645
4633a7c4 6461 unless $standalone; # or it'll complain about itself
647__END__ # wish diag dbase were more accessible