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   1  =head1 NAME
   2  
   3  perl570delta - what's new for perl v5.7.0
   4  
   5  =head1 DESCRIPTION
   6  
   7  This document describes differences between the 5.6.0 release and
   8  the 5.7.0 release.
   9  
  10  =head1 Security Vulnerability Closed
  11  
  12  A potential security vulnerability in the optional suidperl component
  13  of Perl has been identified.  suidperl is neither built nor installed
  14  by default.  As of September the 2nd, 2000, the only known vulnerable
  15  platform is Linux, most likely all Linux distributions.  CERT and
  16  various vendors have been alerted about the vulnerability.
  17  
  18  The problem was caused by Perl trying to report a suspected security
  19  exploit attempt using an external program, /bin/mail.  On Linux
  20  platforms the /bin/mail program had an undocumented feature which
  21  when combined with suidperl gave access to a root shell, resulting in
  22  a serious compromise instead of reporting the exploit attempt.  If you
  23  don't have /bin/mail, or if you have 'safe setuid scripts', or if
  24  suidperl is not installed, you are safe.
  25  
  26  The exploit attempt reporting feature has been completely removed from
  27  the Perl 5.7.0 release, so that particular vulnerability isn't there
  28  anymore.  However, further security vulnerabilities are,
  29  unfortunately, always possible.  The suidperl code is being reviewed
  30  and if deemed too risky to continue to be supported, it may be
  31  completely removed from future releases.  In any case, suidperl should
  32  only be used by security experts who know exactly what they are doing
  33  and why they are using suidperl instead of some other solution such as
  34  sudo ( see http://www.courtesan.com/sudo/ ).
  35  
  36  =head1 Incompatible Changes
  37  
  38  =over 4
  39  
  40  =item *
  41  
  42  Arrays now always interpolate into double-quoted strings:
  43  constructs like "foo@bar" now always assume C<@bar> is an array,
  44  whether or not the compiler has seen use of C<@bar>.
  45  
  46  =item *
  47  
  48  The semantics of bless(REF, REF) were unclear and until someone proves
  49  it to make some sense, it is forbidden.
  50  
  51  =item *
  52  
  53  A reference to a reference now stringify as "REF(0x81485ec)" instead
  54  of "SCALAR(0x81485ec)" in order to be more consistent with the return
  55  value of ref().
  56  
  57  =item *
  58  
  59  The very dusty examples in the eg/ directory have been removed.
  60  Suggestions for new shiny examples welcome but the main issue is that
  61  the examples need to be documented, tested and (most importantly)
  62  maintained.
  63  
  64  =item *
  65  
  66  The obsolete chat2 library that should never have been allowed
  67  to escape the laboratory has been decommissioned.
  68  
  69  =item *
  70  
  71  The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
  72  recognised but now cause fatal errors.  The previous behaviour of
  73  ignoring them by default and warning if requested was unacceptable
  74  since it, in a way, falsely promised that the features could be used.
  75  
  76  =item *
  77  
  78  The (bogus) escape sequences \8 and \9 now give an optional warning
  79  ("Unrecognized escape passed through").  There is no need to \-escape
  80  any C<\w> character.
  81  
  82  =item *
  83  
  84  lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
  85  In future releases this may become a fatal error.
  86  
  87  =item *
  88  
  89  The long deprecated uppercase aliases for the string comparison
  90  operators (EQ, NE, LT, LE, GE, GT) have now been removed.
  91  
  92  =item *
  93  
  94  The regular expression captured submatches ($1, $2, ...) are now
  95  more consistently unset if the match fails, instead of leaving false
  96  data lying around in them.
  97  
  98  =item *
  99  
 100  The tr///C and tr///U features have been removed and will not return;
 101  the interface was a mistake.  Sorry about that.  For similar
 102  functionality, see pack('U0', ...) and pack('C0', ...).
 103  
 104  =back
 105  
 106  =head1 Core Enhancements
 107  
 108  =over 4
 109  
 110  =item *
 111  
 112  C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
 113  in multiple arguments.)
 114  
 115  =item *
 116  
 117  my __PACKAGE__ $obj now works.
 118  
 119  =item *
 120  
 121  C<no Module;> now works even if there is no "sub unimport" in the Module.
 122  
 123  =item *
 124  
 125  The numerical comparison operators return C<undef> if either operand
 126  is a NaN.  Previously the behaviour was unspecified.
 127  
 128  =item *
 129  
 130  C<pack('U0a*', ...)> can now be used to force a string to UTF-8.
 131  
 132  =item *
 133  
 134  prototype(\&) is now available.
 135  
 136  =item *
 137  
 138  There is now an UNTIE method.
 139  
 140  =back
 141  
 142  =head1 Modules and Pragmata
 143  
 144  =head2 New Modules
 145  
 146  =over 4
 147  
 148  =item *
 149  
 150  File::Temp allows one to create temporary files and directories in an
 151  easy, portable, and secure way.
 152  
 153  =item *
 154  
 155  Storable gives persistence to Perl data structures by allowing the
 156  storage and retrieval of Perl data to and from files in a fast and
 157  compact binary format.
 158  
 159  =back
 160  
 161  =head2 Updated And Improved Modules and Pragmata
 162  
 163  =over 4
 164  
 165  =item *
 166  
 167  The following independently supported modules have been updated to
 168  newer versions from CPAN: CGI, CPAN, DB_File, File::Spec, Getopt::Long,
 169  the podlators bundle, Pod::LaTeX, Pod::Parser, Term::ANSIColor, Test.
 170  
 171  =item *
 172  
 173  Bug fixes and minor enhancements have been applied to B::Deparse,
 174  Data::Dumper, IO::Poll, IO::Socket::INET, Math::BigFloat,
 175  Math::Complex, Math::Trig, Net::protoent, the re pragma, SelfLoader,
 176  Sys::SysLog, Test::Harness, Text::Wrap, UNIVERSAL, and the warnings
 177  pragma.
 178  
 179  =item *
 180  
 181  The attributes::reftype() now works on tied arguments.
 182  
 183  =item *
 184  
 185  AutoLoader can now be disabled with C<no AutoLoader;>,
 186  
 187  =item *
 188  
 189  The English module can now be used without the infamous performance
 190  hit by saying
 191  
 192      use English '-no_performance_hit';
 193  
 194  (Assuming, of course, that one doesn't need the troublesome variables
 195  C<$`>, C<$&>, or C<$'>.)  Also, introduced C<@LAST_MATCH_START> and
 196  C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
 197  
 198  =item *
 199  
 200  File::Find now has pre- and post-processing callbacks.  It also
 201  correctly changes directories when chasing symbolic links.  Callbacks
 202  (naughtily) exiting with "next;" instead of "return;" now work.
 203  
 204  =item *
 205  
 206  File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
 207  prototype mismatch with CORE::glob().
 208  
 209  =item *
 210  
 211  IPC::Open3 now allows the use of numeric file descriptors.
 212  
 213  =item *
 214  
 215  use lib now works identically to @INC.  Removing directories
 216  with 'no lib' now works.
 217  
 218  =item *
 219  
 220  C<%INC> now localised in a Safe compartment so that use/require work.
 221  
 222  =item *
 223  
 224  The Shell module now has an OO interface.
 225  
 226  =back
 227  
 228  =head1 Utility Changes
 229  
 230  =over 4
 231  
 232  =item *
 233  
 234  The Emacs perl mode (emacs/cperl-mode.el) has been updated to version
 235  4.31.
 236  
 237  =item *
 238  
 239  Perlbug is now much more robust.  It also sends the bug report to
 240  perl.org, not perl.com.
 241  
 242  =item *
 243  
 244  The perlcc utility has been rewritten and its user interface (that is,
 245  command line) is much more like that of the UNIX C compiler, cc.
 246  
 247  =item *
 248  
 249  The xsubpp utility for extension writers now understands POD
 250  documentation embedded in the *.xs files.
 251  
 252  =back
 253  
 254  =head1 New Documentation
 255  
 256  =over 4
 257  
 258  =item *
 259  
 260  perl56delta details the changes between the 5.005 release and the
 261  5.6.0 release.
 262  
 263  =item *
 264  
 265  perldebtut is a Perl debugging tutorial.
 266  
 267  =item *
 268  
 269  perlebcdic contains considerations for running Perl on EBCDIC platforms.
 270  Note that unfortunately EBCDIC platforms that used to supported back in
 271  Perl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
 272  bring them back to the fold.  
 273  
 274  =item *
 275  
 276  perlnewmod tells about writing and submitting a new module.
 277  
 278  =item *
 279  
 280  perlposix-bc explains using Perl on the POSIX-BC platform
 281  (an EBCDIC mainframe platform).
 282  
 283  =item *
 284  
 285  perlretut is a regular expression tutorial.
 286  
 287  =item *
 288  
 289  perlrequick is a regular expressions quick-start guide.
 290  Yes, much quicker than perlretut.
 291  
 292  =item *
 293  
 294  perlutil explains the command line utilities packaged with the Perl
 295  distribution.
 296  
 297  =back
 298  
 299  =head1 Performance Enhancements
 300  
 301  =over 4
 302  
 303  =item *
 304  
 305  map() that changes the size of the list should now work faster.
 306  
 307  =item *
 308  
 309  sort() has been changed to use mergesort internally as opposed to the
 310  earlier quicksort.  For very small lists this may result in slightly
 311  slower sorting times, but in general the speedup should be at least
 312  20%.  Additional bonuses are that the worst case behaviour of sort()
 313  is now better (in computer science terms it now runs in time O(N log N),
 314  as opposed to quicksort's Theta(N**2) worst-case run time behaviour),
 315  and that sort() is now stable (meaning that elements with identical
 316  keys will stay ordered as they were before the sort).
 317  
 318  =back
 319  
 320  =head1 Installation and Configuration Improvements
 321  
 322  =head2 Generic Improvements
 323  
 324  =over 4
 325  
 326  =item *
 327  
 328  INSTALL now explains how you can configure Perl to use 64-bit
 329  integers even on non-64-bit platforms.
 330  
 331  =item *
 332  
 333  Policy.sh policy change: if you are reusing a Policy.sh file
 334  (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
 335  Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
 336  them will now be changed to the new prefix, /foo/bar.  (Previously
 337  only $prefix changed.)  If you do not like this new behaviour,
 338  specify prefix, siteprefix, and vendorprefix explicitly.
 339  
 340  =item *
 341  
 342  A new optional location for Perl libraries, otherlibdirs, is available.
 343  It can be used for example for vendor add-ons without disturbing Perl's
 344  own library directories.
 345  
 346  =item *
 347  
 348  In many platforms the vendor-supplied 'cc' is too stripped-down to
 349  build Perl (basically, 'cc' doesn't do ANSI C).  If this seems
 350  to be the case and 'cc' does not seem to be the GNU C compiler
 351  'gcc', an automatic attempt is made to find and use 'gcc' instead.
 352  
 353  =item *
 354  
 355  gcc needs to closely track the operating system release to avoid
 356  build problems. If Configure finds that gcc was built for a different
 357  operating system release than is running, it now gives a clearly visible
 358  warning that there may be trouble ahead.
 359  
 360  =item *
 361  
 362  If binary compatibility with the 5.005 release is not wanted, Configure
 363  no longer suggests including the 5.005 modules in @INC.
 364  
 365  =item *
 366  
 367  Configure C<-S> can now run non-interactively.
 368  
 369  =item *
 370  
 371  configure.gnu now works with options with whitespace in them.
 372  
 373  =item *
 374  
 375  installperl now outputs everything to STDERR.
 376  
 377  =item *
 378  
 379  $Config{byteorder} is now computed dynamically (this is more robust
 380  with "fat binaries" where an executable image contains binaries for
 381  more than one binary platform.)
 382  
 383  =back
 384  
 385  =head1 Selected Bug Fixes
 386  
 387  =over 4
 388  
 389  =item *
 390  
 391  Several debugger fixes: exit code now reflects the script exit code,
 392  condition C<"0"> now treated correctly, the C<d> command now checks
 393  line number, the C<$.> no longer gets corrupted, all debugger output now
 394  goes correctly to the socket if RemotePort is set.
 395  
 396  =item *
 397  
 398  C<*foo{FORMAT}> now works.
 399  
 400  =item *
 401  
 402  Lexical warnings now propagating correctly between scopes.
 403  
 404  =item *
 405  
 406  Line renumbering with eval and C<#line> now works.
 407  
 408  =item *
 409  
 410  Fixed numerous memory leaks, especially in eval "".
 411  
 412  =item *
 413  
 414  Modulus of unsigned numbers now works (4063328477 % 65535 used to
 415  return 27406, instead of 27047).
 416  
 417  =item *
 418  
 419  Some "not a number" warnings introduced in 5.6.0 eliminated to be
 420  more compatible with 5.005.  Infinity is now recognised as a number.
 421  
 422  =item *
 423  
 424  our() variables will not cause "will not stay shared" warnings.
 425  
 426  =item *
 427  
 428  pack "Z" now correctly terminates the string with "\0".
 429  
 430  =item *
 431  
 432  Fix password routines which in some shadow password platforms
 433  (e.g. HP-UX) caused getpwent() to return every other entry.
 434  
 435  =item *
 436  
 437  printf() no longer resets the numeric locale to "C".
 438  
 439  =item *
 440  
 441  C<q(a\\b)> now parses correctly as C<'a\\b'>.
 442  
 443  =item *
 444  
 445  Printing quads (64-bit integers) with printf/sprintf now works
 446  without the q L ll prefixes (assuming you are on a quad-capable platform).
 447  
 448  =item *
 449  
 450  Regular expressions on references and overloaded scalars now work.
 451  
 452  =item *
 453  
 454  scalar() now forces scalar context even when used in void context.
 455  
 456  =item *
 457  
 458  sort() arguments are now compiled in the right wantarray context
 459  (they were accidentally using the context of the sort() itself).
 460  
 461  =item *
 462  
 463  Changed the POSIX character class C<[[:space:]]> to include the (very
 464  rare) vertical tab character.  Added a new POSIX-ish character class
 465  C<[[:blank:]]> which stands for horizontal whitespace (currently,
 466  the space and the tab).
 467  
 468  =item *
 469  
 470  $AUTOLOAD, sort(), lock(), and spawning subprocesses
 471  in multiple threads simultaneously are now thread-safe.
 472  
 473  =item *
 474  
 475  Allow read-only string on left hand side of non-modifying tr///.
 476  
 477  =item *
 478  
 479  Several Unicode fixes (but still not perfect).
 480  
 481  =over 8
 482  
 483  =item *
 484  
 485  BOMs (byte order marks) in the beginning of Perl files
 486  (scripts, modules) should now be transparently skipped.
 487  UTF-16 (UCS-2) encoded Perl files should now be read correctly.
 488  
 489  =item *
 490  
 491  The character tables have been updated to Unicode 3.0.1.
 492  
 493  =item *
 494  
 495  chr() for values greater than 127 now create utf8 when under use
 496  utf8.
 497  
 498  =item *
 499  
 500  Comparing with utf8 data does not magically upgrade non-utf8 data into
 501  utf8.
 502  
 503  =item *
 504  
 505  C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
 506  
 507  =item *
 508  
 509  Concatenation with the C<.> operator or via variable interpolation,
 510  C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
 511  substitution with C<s///>, single-quoted UTF-8, should now work--in
 512  theory.
 513  
 514  =item *
 515  
 516  The C<tr///> operator now works I<slightly> better but is still rather
 517  broken.  Note that the C<tr///CU> functionality has been removed (but
 518  see pack('U0', ...)).
 519  
 520  =item *
 521  
 522  vec() now refuses to deal with characters >255.
 523  
 524  =item *
 525  
 526  Zero entries were missing from the Unicode classes like C<IsDigit>.
 527  
 528  =back
 529  
 530  =item *
 531  
 532  UNIVERSAL::isa no longer caches methods incorrectly.  (This broke
 533  the Tk extension with 5.6.0.)
 534  
 535  =back
 536  
 537  =head2 Platform Specific Changes and Fixes
 538  
 539  =over 4
 540  
 541  =item *
 542  
 543  BSDI 4.*
 544  
 545  Perl now works on post-4.0 BSD/OSes.
 546  
 547  =item *
 548  
 549  All BSDs
 550  
 551  Setting C<$0> now works (as much as possible; see perlvar for details).
 552  
 553  =item *
 554  
 555  Cygwin
 556  
 557  Numerous updates; currently synchronised with Cygwin 1.1.4.
 558  
 559  =item *
 560  
 561  EPOC
 562  
 563  EPOC update after Perl 5.6.0.  See README.epoc.
 564  
 565  =item *
 566  
 567  FreeBSD 3.*
 568  
 569  Perl now works on post-3.0 FreeBSDs.
 570  
 571  =item *
 572  
 573  HP-UX
 574  
 575  README.hpux updated; C<Configure -Duse64bitall> now almost works.
 576  
 577  =item *
 578  
 579  IRIX
 580  
 581  Numerous compilation flag and hint enhancements; accidental mixing
 582  of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
 583  
 584  =item *
 585  
 586  Linux
 587  
 588  Long doubles should now work (see INSTALL).
 589  
 590  =item *
 591  
 592  Mac OS Classic
 593  
 594  Compilation of the standard Perl distribution in Mac OS Classic should
 595  now work if you have the Metrowerks development environment and the
 596  missing Mac-specific toolkit bits.  Contact the macperl mailing list
 597  for details.
 598  
 599  =item *
 600  
 601  MPE/iX
 602  
 603  MPE/iX update after Perl 5.6.0.  See README.mpeix.
 604  
 605  =item *
 606  
 607  NetBSD/sparc
 608  
 609  Perl now works on NetBSD/sparc.
 610  
 611  =item *
 612  
 613  OS/2
 614  
 615  Now works with usethreads (see INSTALL).
 616  
 617  =item *
 618  
 619  Solaris
 620  
 621  64-bitness using the Sun Workshop compiler now works.
 622  
 623  =item *
 624  
 625  Tru64 (aka Digital UNIX, aka DEC OSF/1)
 626  
 627  The operating system version letter now recorded in $Config{osvers}.
 628  Allow compiling with gcc (previously explicitly forbidden).  Compiling
 629  with gcc still not recommended because buggy code results, even with
 630  gcc 2.95.2.
 631  
 632  =item *
 633  
 634  Unicos
 635  
 636  Fixed various alignment problems that lead into core dumps either
 637  during build or later; no longer dies on math errors at runtime;
 638  now using full quad integers (64 bits), previously was using 
 639  only 46 bit integers for speed.
 640  
 641  =item *
 642  
 643  VMS
 644  
 645  chdir() now works better despite a CRT bug; now works with MULTIPLICITY
 646  (see INSTALL); now works with Perl's malloc.
 647  
 648  =item *
 649  
 650  Windows
 651  
 652  =over 8
 653  
 654  =item *
 655  
 656  accept() no longer leaks memory.
 657  
 658  =item *
 659  
 660  Better chdir() return value for a non-existent directory.
 661  
 662  =item *
 663  
 664  New %ENV entries now propagate to subprocesses.
 665  
 666  =item *
 667  
 668  $ENV{LIB} now used to search for libs under Visual C.
 669  
 670  =item *
 671  
 672  A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
 673  
 674  =item *
 675  
 676  Allow REG_EXPAND_SZ keys in the registry.
 677  
 678  =item *
 679  
 680  Can now send() from all threads, not just the first one.
 681  
 682  =item *
 683  
 684  Fake signal handling reenabled, bugs and all.
 685  
 686  =item *
 687  
 688  Less stack reserved per thread so that more threads can run
 689  concurrently. (Still 16M per thread.)
 690  
 691  =item *
 692  
 693  C<< File::Spec->tmpdir() >> now prefers C:/temp over /tmp
 694  (works better when perl is running as service).
 695  
 696  =item *
 697  
 698  Better UNC path handling under ithreads.
 699  
 700  =item *
 701  
 702  wait() and waitpid() now work much better.
 703  
 704  =item *
 705  
 706  winsock handle leak fixed.
 707  
 708  =back
 709  
 710  =back
 711  
 712  =head1 New or Changed Diagnostics
 713  
 714  All regular expression compilation error messages are now hopefully
 715  easier to understand both because the error message now comes before
 716  the failed regex and because the point of failure is now clearly
 717  marked.
 718  
 719  The various "opened only for", "on closed", "never opened" warnings
 720  drop the C<main::> prefix for filehandles in the C<main> package,
 721  for example C<STDIN> instead of <main::STDIN>. 
 722  
 723  The "Unrecognized escape" warning has been extended to include C<\8>,
 724  C<\9>, and C<\_>.  There is no need to escape any of the C<\w> characters.
 725  
 726  =head1 Changed Internals
 727  
 728  =over 4
 729  
 730  =item *
 731  
 732  perlapi.pod (a companion to perlguts) now attempts to document the
 733  internal API.
 734  
 735  =item *
 736  
 737  You can now build a really minimal perl called microperl.
 738  Building microperl does not require even running Configure;
 739  C<make -f Makefile.micro> should be enough.  Beware: microperl makes
 740  many assumptions, some of which may be too bold; the resulting
 741  executable may crash or otherwise misbehave in wondrous ways.
 742  For careful hackers only.
 743  
 744  =item *
 745  
 746  Added rsignal(), whichsig(), do_join() to the publicised API.
 747  
 748  =item *
 749  
 750  Made possible to propagate customised exceptions via croak()ing.
 751  
 752  =item *
 753  
 754  Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and utf8_to_bytes().
 755  
 756  =item *
 757  
 758  Now xsubs can have attributes just like subs.
 759  
 760  =back
 761  
 762  =head1 Known Problems
 763  
 764  =head2 Unicode Support Still Far From Perfect
 765  
 766  We're working on it.  Stay tuned.
 767  
 768  =head2 EBCDIC Still A Lost Platform
 769  
 770  The plan is to bring them back.
 771  
 772  =head2 Building Extensions Can Fail Because Of Largefiles
 773  
 774  Certain extensions like mod_perl and BSD::Resource are known to have
 775  issues with `largefiles', a change brought by Perl 5.6.0 in which file
 776  offsets default to 64 bits wide, where supported.  Modules may fail to
 777  compile at all or compile and work incorrectly.  Currently there is no
 778  good solution for the problem, but Configure now provides appropriate
 779  non-largefile ccflags, ldflags, libswanted, and libs in the %Config
 780  hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
 781  having problems can try configuring themselves without the
 782  largefileness.  This is admittedly not a clean solution, and the
 783  solution may not even work at all.  One potential failure is whether
 784  one can (or, if one can, whether it's a good idea) link together at
 785  all binaries with different ideas about file offsets, all this is
 786  platform-dependent.
 787  
 788  =head2 ftmp-security tests warn 'system possibly insecure'
 789  
 790  Don't panic.  Read INSTALL 'make test' section instead. 
 791  
 792  =head2 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX
 793  
 794  If perl is configured with -Duse64bitall, the successful result of the
 795  subtest 10 of lib/posix may arrive before the successful result of the
 796  subtest 9, which confuses the test harness so much that it thinks the
 797  subtest 9 failed.
 798  
 799  =head2 Long Doubles Still Don't Work In Solaris
 800  
 801  The experimental long double support is still very much so in Solaris.
 802  (Other platforms like Linux and Tru64 are beginning to solidify in
 803  this area.)
 804  
 805  =head2 Linux With Sfio Fails op/misc Test 48
 806  
 807  No known fix.
 808  
 809  =head2 Storable tests fail in some platforms
 810  
 811  If any Storable tests fail the use of Storable is not advisable.
 812  
 813  =over 4
 814  
 815  =item *
 816  
 817  Many Storable tests fail on AIX configured with 64 bit integers.
 818  
 819  So far unidentified problems break Storable in AIX if Perl is
 820  configured to use 64 bit integers.  AIX in 32-bit mode works and
 821  other 64-bit platforms work with Storable.
 822  
 823  =item *
 824  
 825  DOS DJGPP may hang when testing Storable.
 826  
 827  =item *
 828  
 829  st-06compat fails in UNICOS and UNICOS/mk.
 830  
 831  This means that you cannot read old (pre-Storable-0.7) Storable images
 832  made in other platforms.
 833  
 834  =item *
 835  
 836  st-store.t and st-retrieve may fail with Compaq C 6.2 on OpenVMS Alpha 7.2.
 837  
 838  =back
 839  
 840  =head2 Threads Are Still Experimental
 841  
 842  Multithreading is still an experimental feature.  Some platforms
 843  emit the following message for lib/thr5005
 844  
 845      #
 846      # This is a KNOWN FAILURE, and one of the reasons why threading
 847      # is still an experimental feature.  It is here to stop people
 848      # from deploying threads in production. ;-)
 849      #
 850  
 851  and another known thread-related warning is
 852  
 853     pragma/overload......Unbalanced saves: 3 more saves than restores
 854     panic: magic_mutexfree during global destruction.
 855     ok
 856     lib/selfloader.......Unbalanced saves: 3 more saves than restores
 857     panic: magic_mutexfree during global destruction.
 858     ok
 859     lib/st-dclone........Unbalanced saves: 3 more saves than restores
 860     panic: magic_mutexfree during global destruction.
 861     ok
 862  
 863  =head2 The Compiler Suite Is Still Experimental
 864  
 865  The compiler suite is slowly getting better but is nowhere near
 866  working order yet.  The backend part that has seen perhaps the most
 867  progress is the bytecode compiler.
 868  
 869  =head1 Reporting Bugs
 870  
 871  If you find what you think is a bug, you might check the articles
 872  recently posted to the comp.lang.perl.misc newsgroup and the perl
 873  bug database at http://bugs.perl.org/  There may also be
 874  information at http://www.perl.com/perl/ , the Perl Home Page.
 875  
 876  If you believe you have an unreported bug, please run the B<perlbug>
 877  program included with your release.  Be sure to trim your bug down
 878  to a tiny but sufficient test case.  Your bug report, along with the
 879  output of C<perl -V>, will be sent off to perlbug@perl.org to be
 880  analysed by the Perl porting team.
 881  
 882  =head1 SEE ALSO
 883  
 884  The F<Changes> file for exhaustive details on what changed.
 885  
 886  The F<INSTALL> file for how to build Perl.
 887  
 888  The F<README> file for general stuff.
 889  
 890  The F<Artistic> and F<Copying> files for copyright information.
 891  
 892  =head1 HISTORY
 893  
 894  Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
 895  from The Perl Porters and Perl Users submitting feedback and patches.
 896  
 897  Send omissions or corrections to <F<perlbug@perl.org>>.
 898  
 899  =cut