TODO

   1 ************************************************************************
   2 * Official mandoc TODO.
   3 * $Id: TODO,v 1.205 2015/04/06 22:06:23 schwarze Exp $
   4 ************************************************************************
   5
   6 Many issues are annotated for difficulty as follows:
   7
   8  - loc = locality of the issue
   9     *    single file issue, affects file only, or very few
  10     **   single module issue, affects several files of one module
  11     ***  cross-module issue, significantly impacts multiple modules
  12          and may require substantial changes to internal interfaces
  13  - exist = difficulty of the existing code in this area
  14     *    affected code is straightforward and easy to read and change
  15     **   affected code is somewhat complex, but once you understand
  16          the design, not particularly difficult to understand
  17     ***  affected code uses a special, exceptionally tricky design
  18  - algo = difficulty of the new algorithm to be written
  19     *    the required logic and code is straightforward
  20     **   the required logic is somewhat complex and needs a careful design
  21     ***  the required logic is exceptionally tricky,
  22          maybe an approach to solve that is not even known yet
  23  - size = the amount of code to be written or changed
  24     *    a small number of lines (at most 100, usually much less)
  25     **   a considerable amount of code (several dozen to a few hundred)
  26     ***  a large amount of code (many hundreds, maybe thousands)
  27  - imp = importance of the issue
  28     *    mostly for completeness
  29     **   would be nice to have
  30     ***  issue causes considerable inconvenience
  31
  32 Obviously, as the issues have not been solved yet, these annotations
  33 are mere guesses, and some may be wrong.
  34
  35 ************************************************************************
  36 * crashes
  37 ************************************************************************
  38
  39 - The abort() in bufcat(), html.c, can be triggered via buffmt_includes()
  40   by running -Thtml -Oincludes on a file containing a long .In argument.
  41   Fixing this will probably require reworking the whole bufcat() concept.
  42   loc **  exist *  algo *  size **  imp **
  43
  44 ************************************************************************
  45 * missing features
  46 ************************************************************************
  47
  48 --- missing roff features ----------------------------------------------
  49
  50 - .ad (adjust margins)
  51   .ad l -- adjust left margin only (flush left)
  52   .ad r -- adjust right margin only (flush right)
  53   .ad c -- center text on line
  54   .ad b -- adjust both margins (alias: .ad n)
  55   .na   -- temporarily disable adjustment without changing the mode
  56   .ad   -- re-enable adjustment without changing the mode
  57   Adjustment mode is ignored while in no-fill mode (.nf).
  58   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
  59
  60 - .fc (field control)
  61   found by naddy@ in xloadimage(1)
  62   loc **  exist ***  algo *  size *  imp *
  63
  64 - .nr third argument (auto-increment step size, requires \n+)
  65   found by bentley@ in sbcl(1)  Mon, 9 Dec 2013 18:36:57 -0700
  66   loc *  exist *  algo *  size *  imp **
  67
  68 - .ns (no-space mode) occurs in xine-config(1)
  69   when implementing this, also let .TH set it
  70   reported by brad@  Sat, 15 Jan 2011 15:45:23 -0500
  71   loc ***  exist ***  algo ***  size **  imp *
  72
  73 - .ta (tab settings)
  74   #1 most important issue naddy@ Mon, 16 Feb 2015 20:59:17 +0100
  75   ircbug(1) gnats(1) reported by brad@  Sat, 15 Jan 2011 15:50:51 -0500
  76   also Tcl_NewStringObj(3) via wiz@  Wed, 5 Mar 2014 22:27:43 +0100
  77   also posix2time(3) Carsten Kunze  Mon, 1 Dec 2014 13:03:10 +0100
  78   loc **  exist ***  algo **  size **  imp ***
  79
  80 - .ti (temporary indent)
  81   found by naddy@ in xloadimage(1) [devel/libvstr] vstr(3)
  82   found by bentley@ in nmh(1)  Mon, 23 Apr 2012 13:38:28 -0600
  83   loc **  exist **  algo **  size *  imp ** (parser reorg helps a lot)
  84
  85 - .while and .shift
  86   found by jca@ in ratpoison(1)  Sun, 30 Jun 2013 12:01:09 +0200
  87   loc *  exist **  algo **  size **  imp **
  88
  89 - \h horizontal move
  90   #2 most important issue naddy@  Mon, 16 Feb 2015 20:59:17 +0100
  91   found in cclive(1) nasm(1) bogofilter(1) asciidoc/DocBook output
  92   bentley@ on discuss@  Sat, 21 Sep 2013 22:29:34 -0600
  93   naddy@  Thu, 4 Dec 2014 16:26:41 +0100
  94   loc **  exist **  algo **  size *  imp *** (parser reorg helps a lot)
  95
  96 - \n+ and \n- numerical register increment and decrement
  97   found by bentley@ in sbcl(1)  Mon, 9 Dec 2013 18:36:57 -0700
  98   loc *  exist *  algo *  size *  imp **
  99
 100 - \n(.$ macro argument count number register; ocserv(8) by autogen
 101   found by sthen@  Thu, 19 Feb 2015 22:03:01 +0000
 102   loc *  exist **  algo *  size *  imp **
 103
 104 - \w'' improve width measurements
 105   would not be very useful without an expression parser, see below
 106   needed for Tcl_NewStringObj(3) via wiz@  Wed, 5 Mar 2014 22:27:43 +0100
 107   loc **  exist ***  algo ***  size *  imp ***
 108
 109 - \\ in high-level macro arguments
 110   Currently, \\ is expanded in two situations:
 111   1) macro and string definition (roff.c setstrn())
 112   2) macro argument parsing (mandoc.c mandoc_getarg())
 113   For user defined macros, the second happens in time because of ROFF_REPARSE.
 114   But for standard high-level macros, it only happens after entering the
 115   high level parsers, which is too late because the code doesn't get
 116   back to roff.c roff_res() from that point.  Because this requires
 117   distinguishing requests, user-defined macros and standard macros
 118   on the roff_res() level, it is hard to solve without the parser reorg.
 119   Found by naddy@ in devel/cutils cobfusc(1)  Mon, 16 Feb 2015 19:10:52 +0100
 120   loc ***  exist ***  algo ***  size **  imp *
 121
 122 - using undefined strings or macros defines them to be empty
 123   wl@  Mon, 14 Nov 2011 14:37:01 +0000
 124   loc *  exist *  algo *  size *  imp *
 125
 126 --- missing mdoc features ----------------------------------------------
 127
 128 - .Bl -column .Xo support is missing
 129   ultimate goal:
 130   restore .Xr and .Dv to
 131   lib/libc/compat-43/sigvec.3
 132   lib/libc/gen/signal.3
 133   lib/libc/sys/sigaction.2
 134   loc *  exist ***  algo ***  size *  imp **
 135
 136 - edge case: decide how to deal with blk_full bad nesting, e.g.
 137   .Sh .Nm .Bk .Nm .Ek .Sh found by jmc@ in ssh-keygen(1)
 138   from jmc@  Wed, 14 Jul 2010 18:10:32 +0100
 139   loc *  exist ***  algo ***  size **  imp **
 140
 141 - .Bd -centered implies -filled, not -unfilled, which is not
 142   easy to implement; it requires code similar to .ce, which
 143   we don't have either.
 144   Besides, groff has bug causing text right *before* .Bd -centered
 145   to be centered as well.
 146   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
 147
 148 - .Bd -filled should not be the same as .Bd -ragged, but align both
 149   the left and right margin.  In groff, it is implemented in terms
 150   of .ad b, which we don't have either.  Found in cksum(1).
 151   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
 152
 153 - implement blank `Bl -column', such as
 154   .Bl -column
 155   .It foo Ta bar
 156   .El
 157   loc *  exist ***  algo ***  size *  imp *
 158
 159 - explicitly disallow nested `Bl -column', which would clobber internal
 160   flags defined for struct mdoc_macro
 161   loc *  exist *  algo *  size *  imp **
 162
 163 - In .Bl -column .It, the end of the line probably has to be regarded
 164   as an implicit .Ta, if there could be one, see the following mildly
 165   ugly code from login.conf(5):
 166     .Bl -column minpasswordlen program xetcxmotd
 167     .It path Ta path Ta value of Dv _PATH_DEFPATH
 168     .br
 169     Default search path.
 170   reported by Michal Mazurek <akfaew at jasminek dot net>
 171   via jmc@ Thu, 7 Apr 2011 16:00:53 +0059
 172   loc *  exist ***  algo **  size *  imp **
 173
 174 - inside `.Bl -column' phrases, punctuation is handled like normal
 175   text, e.g. `.Bl -column .It Fl x . Ta ...' should give "-x -."
 176
 177 - inside `.Bl -column' phrases, TERMP_IGNDELIM handling by `Pf'
 178   is not safe, e.g. `.Bl -column .It Pf a b .' gives "ab."
 179   but should give "ab ."
 180
 181 - check whether it is correct that `D1' uses INDENT+1;
 182   does it need its own constant?
 183   loc *  exist **  algo **  size *  imp **
 184
 185 - prohibit `Nm' from having non-text HEAD children
 186   (e.g., NetBSD mDNSShared/dns-sd.1)
 187   (mdoc_html.c and mdoc_term.c `Nm' handlers can be slightly simplified)
 188
 189 - support translated section names
 190   e.g. x11/scrotwm scrotwm_es.1:21:2: error: NAME section must be first
 191   that one uses NOMBRE because it is spanish...
 192   deraadt tends to think that section-dependent macro behaviour
 193   is a bad idea in the first place, so this may be irrelevant
 194   loc **  exist **  algo **  size *  imp **
 195
 196 - When there is free text in the SYNOPSIS and that free text contains
 197   the .Nm macro, groff somehow understands to treat the .Nm as an in-line
 198   macro, while mandoc treats it as a block macro and breaks the line.
 199   No idea how the logic for distinguishing in-line and block instances
 200   should be, needs investigation.
 201   uqs@  Thu, 2 Jun 2011 11:03:51 +0200
 202   uqs@  Thu, 2 Jun 2011 11:33:35 +0200
 203   loc *  exist **  algo ***  size *  imp **
 204
 205 --- missing man features -----------------------------------------------
 206
 207 - -T[x]html doesn't stipulate non-collapsing spaces in literal mode
 208
 209 --- missing tbl features -----------------------------------------------
 210
 211 - look at the POSIX manuals in the books/man-pages-posix port,
 212   they use some unsupported tbl(7) features.
 213   loc *  exist **  algo **  size **  imp ***
 214
 215 - use Unicode U+2500 to U+256C for table borders
 216   in tbl(7) -Tutf-8 output
 217   suggested by bentley@  Tue, 14 Oct 2014 04:10:55 -0600
 218   loc *  exist **  algo *  size *  imp **
 219
 220 - allow standalone `.' to be interpreted as an end-of-layout
 221   delimiter instead of being thrown away as a no-op roff line
 222   reported by Yuri Pankov, Wed 18 May 2011 11:34:59 CEST
 223   loc **  exist **  algo **  size *  imp **
 224
 225 --- missing eqn features -----------------------------------------------
 226
 227 - The "size" keyword is parsed, but ignored by the formatter.
 228   loc *  exist *  algo *  size *  imp *
 229
 230 - The spacing characters `~', `^', and tab are currently ignored,
 231   see User's Guide (Second Edition) page 2 section 4.
 232   loc *  exist *  algo **  size *  imp **
 233
 234 - Mark and lineup are parsed and ignored,
 235   see User's Guide (Second Edition) page 5 section 15.
 236   loc **  exist **  algo **  size **  imp **
 237
 238 --- missing misc features ----------------------------------------------
 239
 240 - italic correction (\/) in PostScript mode
 241   Werner LEMBERG on groff at gnu dot org  Sun, 10 Nov 2013 12:47:46
 242   loc **  exist **  algo *  size *  imp *
 243
 244 - When makewhatis(8) encounters a FATAL parse error,
 245   it silently treats the file as formatted, which makes no sense
 246   at all for paths like man1/foo.1 - and which also contradicts
 247   what the manual says at the end of the description.
 248   The end result will be ENOENT for file names returned
 249   by mansearch() in manpage.file.
 250   loc *  exist *  algo *  size *  imp **
 251
 252 - makewhatis(8) for preformatted pages:
 253   parse the section number from the header line
 254   and compare to the section number from the directory name
 255   loc *  exist *  algo *  size *  imp **
 256
 257 - Does makewhatis(8) detect missing NAME sections, missing names,
 258   and missing descriptions in all the file formats?
 259   loc *  exist *  algo *  size *  imp ***
 260
 261 - clean up escape sequence handling, creating three classes:
 262   (1) fully implemented, or parsed and ignored without loss of content
 263   (2) unimplemented, potentially causing loss of content
 264       or serious mangling of formatting (e.g. \n) -> ERROR
 265       see textproc/mgdiff(1) for nice examples
 266   (3) undefined, just output the character -> perhaps WARNING
 267   loc ***  exist **  algo **  size **  imp *** (parser reorg helps)
 268
 269 - kettenis wants base roff, ms, and me  Fri, 1 Jan 2010 22:13:15 +0100 (CET)
 270   loc **  exist **  algo **  size ***  imp *
 271
 272 --- compatibility checks -----------------------------------------------
 273
 274 - write a configure check for [[:<:]] support and provide some
 275   fallback for whatis(1) when it doesn't work;
 276   Svyatoslav Mishyn  Wed, 17 Dec 2014 11:07:10 +0200
 277
 278 - is .Bk implemented correctly in modern groff?
 279   sobrado@  Tue, 19 Apr 2011 22:12:55 +0200
 280
 281 - compare output to Heirloom roff, Solaris roff, and
 282   http://repo.or.cz/w/neatroff.git  http://litcave.rudi.ir/
 283
 284 - look at AT&T DWB http://www2.research.att.com/sw/download
 285   Carsten Kunze <carsten dot kunze at arcor dot de> has patches
 286   Mon, 4 Aug 2014 17:01:28 +0200
 287
 288 - look at pages generated from reStructeredText, e.g. devel/mercurial hg(1)
 289   These are a weird mixture of man(7) and custom autogenerated low-level
 290   roff stuff.  Figure out to what extent we can cope.
 291   For details, see http://docutils.sourceforge.net/rst.html
 292   noted by stsp@  Sat, 24 Apr 2010 09:17:55 +0200
 293   reminded by nicm@  Mon, 3 May 2010 09:52:41 +0100
 294
 295 - look at pages generated from ronn(1) github.com/rtomayko/ronn
 296   (based on markdown)
 297
 298 - look at pages generated from Texinfo source by yat2m, e.g. security/gnupg
 299   First impression is not that bad.
 300
 301 - look at pages generated by pandoc; see
 302   https://github.com/jgm/pandoc/blob/master/src/Text/Pandoc/Writers/Man.hs
 303   porting planned by kili@  Thu, 19 Jun 2014 19:46:28 +0200
 304
 305 - check compatibility with Plan9:
 306   http://swtch.com/usr/local/plan9/tmac/tmac.an
 307   http://swtch.com/plan9port/man/man7/man.html
 308   "Anthony J. Bentley" <anthonyjbentley@gmail.com> 28 Dec 2010 21:58:40 -0700
 309
 310 - check compatibility with the man(7) formatter
 311   https://raw.githubusercontent.com/rofl0r/hardcore-utils/master/man.c
 312
 313 - check compatibility with
 314   http://ikiwiki.info/plugins/contrib/mandoc/
 315   https://github.com/schmonz/ikiwiki/compare/mandoc
 316   Amitai Schlair  Mon, 19 May 2014 14:05:53 -0400
 317
 318 ************************************************************************
 319 * formatting issues: ugly output
 320 ************************************************************************
 321
 322 - revisit empty in-line macros
 323   look at the difference between "Em x Em ." and "Sq x Em ."
 324   Carsten Kunze  Fri, 12 Dec 2014 00:15:41 +0100
 325   loc *** exist *** algo *** size * imp **
 326
 327 - a column list with blank `Ta' cells triggers a spurious
 328   start-with-whitespace printing of a newline
 329
 330 - In .Bl -column, .It a<tab>"b<tab>c"
 331   shows the quotes in groff, but not in mandoc
 332   loc * exist *** algo ** size * imp **
 333
 334 - In .Bl -column,
 335   .It Em Authentication<tab>Key Length
 336   ought to render "Key Length" with emphasis, too,
 337   see OpenBSD iked.conf(5).
 338   reported again Nicolas Joly via wiz@ Wed, 12 Oct 2011 00:20:00 +0200
 339   loc *  exist ***  algo ***  size **  imp ***
 340
 341 - empty phrases in .Bl column produce too few blanks
 342   try e.g. .Bl -column It Ta Ta
 343   reported by millert Fri, 02 Apr 2010 16:13:46 -0400
 344   loc *  exist ***  algo ***  size *  imp **
 345
 346 - .%T can have trailing punctuation.  Currently, it puts the trailing
 347   punctuation into a trailing MDOC_TEXT element inside its own scope.
 348   That element should rather be outside its scope, such that the
 349   punctuation does not get underlines.  This is not trivial to
 350   implement because .%T then needs some features of in_line_eoln() -
 351   slurp all arguments into one single text element - and one feature
 352   of in_line() - put trailing punctuation out of scope.
 353   Found in mount_nfs(8) and exports(5), search for "Appendix".
 354   loc **  exist **  algo ***  size *  imp **
 355
 356 - Trailing punctuation after .%T triggers EOS spacing, at least
 357   outside .Rs (eek!).  Simply setting ARGSFL_DELIM for .%T is not
 358   the right solution, it sends mandoc into an endless loop.
 359   reported by Nicolas Joly  Sat, 17 Nov 2012 11:49:54 +0100
 360   loc *  exist **  algo **  size *  imp **
 361
 362 - global variables in the SYNOPSIS of section 3 pages
 363   .Vt vs .Vt/.Va vs .Ft/.Va vs .Ft/.Fa ...
 364   from kristaps@  Tue, 08 Jun 2010 11:13:32 +0200
 365
 366 - in enclosures, mandoc sometimes fancies a bogus end of sentence
 367   reminded by jmc@  Thu, 23 Sep 2010 18:13:39 +0059
 368   loc *  exist **  algo ***  size *  imp ***
 369
 370 - a line starting with "\fB something" counts as starting with whitespace
 371   and triggers a line break; found in audio/normalize-mp3(1)
 372   loc **  exist *  algo **  size *  imp **
 373
 374 - formatting /usr/local/man/man1/latex2man.1 with groff and mandoc
 375   reveals lots of bugs both in groff and mandoc...
 376   reported by bentley@  Wed, 22 May 2013 23:49:30 -0600
 377
 378 --- PDF issues ---------------------------------------------------------
 379
 380 - PDF output doesn't use a monospaced font for .Bd -literal
 381   Example: "mandoc -Tpdf afterboot.8 > output.pdf && pdfviewer output.pdf".
 382   Search the text "Routing tables".
 383   Also check what PostScript mode does when fixing this.
 384   reported by juanfra@ Wed, 04 Jun 2014 21:44:58 +0200
 385   instructions from juanfra@  Wed, 11 Jun 2014 02:21:01 +0200
 386     add a new <</Type /Font>> block to the PDF files with /BaseFont /Courier
 387     and change the /Name from /F0 to the new font (/F5 (?)).
 388   loc *  exist **  algo **  size *  imp **
 389
 390 --- HTML issues --------------------------------------------------------
 391
 392 - <dl><dt><dd> formatting is ugly
 393   hints are easy to find on the web, e.g.
 394   http://stackoverflow.com/questions/1713048/
 395   see also matthew@  Fri, 18 Jul 2014 19:25:12 -0700
 396   loc *  exist *  algo **  size *  imp ***
 397
 398 - jsg on icb, Nov 3, 2014:
 399   try to guess Xr in man(7) for hyperlinking
 400
 401 - The tables used to render the three-part page headers actually force
 402   the width of the <body> to the max-width given for <html>.
 403   Not yet sure how to fix that...
 404   Observed by an Anonymous Coward on undeadly.org:
 405   http://undeadly.org/cgi?action=article&sid=20140925064244&pid=1
 406   loc *  exist *  algo **  size *  imp ***
 407
 408 - consider whether <var> can be used for Ar Dv Er Ev Fa Va.
 409   from bentley@  Wed, 13 Aug 2014 09:17:55 -0600
 410
 411 - check https://github.com/trentm/mdocml
 412
 413 ************************************************************************
 414 * formatting issues: gratuitous differences
 415 ************************************************************************
 416
 417 - .Fn reopens a new scope after punctuation in mandoc,
 418   but closes its scope for good in groff.
 419   Do we want to change mandoc or groff?
 420   Steffen Nurpmeso  Sat, 08 Nov 2014 13:34:59 +0100
 421   loc *  exist **  algo **  size *  imp **
 422
 423 - In .Bl -enum -width 0n, groff continues one the same line after
 424   the number, mandoc breaks the line.
 425   mail to kristaps@  Mon, 20 Jul 2009 02:21:39 +0200
 426   loc *  exist **  algo **  size *  imp **
 427
 428 - .Pp between two .It in .Bl -column should produce one,
 429   not two blank lines, see e.g. login.conf(5).
 430   reported by jmc@  Sun, 17 Apr 2011 14:04:58 +0059
 431   reported again by sthen@  Wed, 18 Jan 2012 02:09:39 +0000 (UTC)
 432   loc *  exist ***  algo **  size *  imp **
 433
 434 - If the *first* line after .It is .Pp, break the line right after
 435   the tag, do not pad with space characters before breaking.
 436   See the description of the a, c, and i commands in sed(1).
 437   loc *  exist **  algo **  size *  imp **
 438
 439 - If the first line after .It is .D1, do not assert a blank line
 440   in between, see for example tmux(1).
 441   reported by nicm@  13 Jan 2011 00:18:57 +0000
 442   loc *  exist **  algo **  size *  imp **
 443
 444 - Trailing punctuation after .It should trigger EOS spacing.
 445   reported by Nicolas Joly  Sat, 17 Nov 2012 11:49:54 +0100
 446   Probably, this should be fixed somewhere in termp_it_pre(), not sure.
 447   loc *  exist **  algo **  size *  imp **
 448
 449 - .Nx 1.0a
 450   should be "NetBSD 1.0A", not "NetBSD 1.0a",
 451   see OpenBSD ccdconfig(8).
 452   loc *  exist *  algo *  size *  imp **
 453
 454 - In .Bl -tag, if a tag exceeds the right margin and must be continued
 455   on the next line, it must be indented by -width, not width+1;
 456   see "rule block|pass" in OpenBSD ifconfig(8).
 457   loc *  exist ***  algo **  size *  imp **
 458
 459 - When the -width string contains macros, the macros must be rendered
 460   before measuring the width, for example
 461     .Bl -tag -width ".Dv message"
 462   in magic(5), located in src/usr.bin/file, is the same
 463   as -width 7n, not -width 11n.
 464   The same applies to .Bl -column column widths;
 465   reported again by Nicolas Joly Thu, 1 Mar 2012 13:41:26 +0100 via wiz@ 5 Mar
 466   reported again by Franco Fichtner Fri, 27 Sep 2013 21:02:28 +0200
 467   loc ***  exist ***  algo ***  size **  imp ***
 468   An easy partial fix would be to just skip the first word if it starts
 469   with a dot, including any following white space, when measuring.
 470   loc *  exist *  algo *  size *  imp ***
 471
 472 - The \& zero-width character counts as output.
 473   That is, when it is alone on a line between two .Pp,
 474   we want three blank lines, not two as in mandoc.
 475   loc **  exist **  algo **  size *  imp **
 476
 477 - Header lines of excessive length:
 478   Port OpenBSD man_term.c rev. 1.25 to mdoc_term.c
 479   and document it in mdoc(7) and man(7) COMPATIBILITY
 480   found while talking to Chris Bennett
 481   loc *  exist *  algo *  size *  imp *
 482
 483 - Sequences of multiple man(7) paragraphs (.PP, .IP) interspersed
 484   with .ps and .nf/.fi produce execessive blank lines, see libJudy
 485   The parser reorg may help with this.
 486
 487 - trailing whitespace must be ignored even when followed by a font escape,
 488   see for example
 489     makes
 490     \fBdig \fR
 491     operate in batch mode
 492   in dig(1).
 493   loc **  exist **  algo **  size *  imp **
 494
 495 ************************************************************************
 496 * portability
 497 ************************************************************************
 498
 499 - word boundaries in regular expressions for whatis(1)
 500   set up config tests to use [[:<:]], \<, or nothing
 501   reminded by Peter Bray Fri, 03 Apr 2015 23:02:16 +1100
 502
 503 ************************************************************************
 504 * warning issues
 505 ************************************************************************
 506
 507 - check that MANDOCERR_BADTAB is thrown in the right cases,
 508   i.e. when finding a literal tab character in fill mode,
 509   and possibly change the wording of the warning message
 510   to refer to fill mode, not literal mode
 511   See the mail from Werner LEMBERG on the groff list,
 512   Fri, 14 Feb 2014 18:54:42 +0100 (CET)
 513   loc *  exist **  algo **  size *  imp **
 514
 515 - warn about attempts to call non-callable macros
 516   Steffen Nurpmeso  Tue, 11 Nov 2014 22:55:16 +0100
 517   Note that formatting is inconsistent in groff.
 518   .Fn Po prints "Po()", .Ar Sh prints "file ..." and no "Sh".
 519   Relatively hard because the relevant code is scattered
 520   all over mdoc_macro.c and all subtly different.
 521   loc **  exist **  algo **  size **  imp **
 522
 523 - warn about "new sentence, new line"
 524   loc **  exist **  algo ***  size *  imp **
 525
 526 - mandoc_special does not really check the escape sequence,
 527   but just the overall format
 528   loc **  exist **  algo ***  size **  imp **
 529
 530 - integrate mdoclint into mandoc ("end-of-line whitespace" thread)
 531   from jmc@  Mon, 13 Jul 2009 17:12:09 +0100
 532   from kristaps@  Mon, 13 Jul 2009 18:34:53 +0200
 533   from jmc@  Mon, 13 Jul 2009 17:45:37 +0059
 534   from kristaps@  Mon, 13 Jul 2009 19:02:03 +0200
 535   (mostly done, check what remains)
 536
 537 - -Tlint parser errors and warnings to stdout
 538   to tech@mdocml, naddy@  Wed, 28 Sep 2011 11:21:46 +0200
 539   wait!  kristaps@  Sun, 02 Oct 2011 17:12:52 +0200
 540
 541 - for system errors, use errno/strerror/warn/err
 542
 543 ************************************************************************
 544 * documentation issues
 545 ************************************************************************
 546
 547 - mention hyphenation rules:
 548   breaking at letter-letter in text mode (not macro args)
 549   proper hyphenation is unimplemented
 550
 551 - talk about spacing around delimiters
 552   to jmc@, kristaps@  Sat, 23 Apr 2011 17:41:27 +0200
 553
 554 - mark macros as: page structure domain, manual domain, general text domain
 555   is this useful?
 556
 557 - mention /usr/share/misc/mdoc.template in mdoc(7)?
 558
 559 - Is all the content from http://www.std.com/obi/BSD/doc/usd/28.tbl/tbl
 560   covered in tbl(7)?
 561
 562 ************************************************************************
 563 * performance issues
 564 ************************************************************************
 565
 566 - Why are we using MAP_SHARED, not MAP_PRIVATE for mmap(2)?
 567   How does SQLITE_CONFIG_PAGECACHE actually work?  Document it!
 568   from kristaps@  Sat, 09 Aug 2014 13:51:36 +0200
 569
 570 Several areas can be cleaned up to make mandoc even faster.  These are
 571
 572 - improve hashing mechanism for macros (quite important: performance)
 573
 574 - improve hashing mechanism for characters (not as important)
 575
 576 - the PDF file is HUGE: this can be reduced by using relative offsets
 577
 578 - instead of re-initialising the roff predefined-strings set before each
 579   parse, create a read-only version the first time and copy it
 580   loc *  exist **  algo **  size *  imp **
 581
 582 ************************************************************************
 583 * structural issues
 584 ************************************************************************
 585
 586 - Improve -O suboption parsing.  Do it in the main program such that
 587   errors can be reported.  Pay attention to distinguishing the
 588   mandoc(1) and apropos(1) styles of both options.
 589   loc **  exist *  algo **  size **  imp ***
 590
 591 - Use libz directly instead of forking gunzip(1).
 592   Suggested by bapt at FreeBSD among others.
 593
 594 - We use the input line number at several places to distinguish
 595   same-line from different-line input.  That plainly doesn't work
 596   with user-defined macros, leading to random breakage.
 597
 598 - Find better ways to prevent endless loops
 599   in roff(7) macro and string expansion.
 600
 601 - Finish cleanup of date handling.
 602   Decide which formats should be recognized where.
 603   Update both mdoc(7) and man(7) documentation.
 604   Triggered by  Tim van der Molen  Tue, 22 Feb 2011 20:30:45 +0100
 605
 606 - struct mparse refactoring
 607   Steffen Nurpmeso  Thu, 04 Sep 2014 12:50:00 +0200
 608
 609 - Consider creating some views that will make the database more
 610   readable from the sqlite3 shell.  Consider using them to
 611   abstract from the database structure, too.
 612   suggested by espie@  Sat, 19 Apr 2014 14:52:57 +0200
 613
 614 ************************************************************************
 615 * CGI issues
 616 ************************************************************************
 617
 618  - Enable HTTP compression by detecting gzip encoding and filtering
 619    output through libz.
 620  - Sandbox (see OpenSSH).
 621  - Enable caching support via HTTP 304 and If-Modified-Since.
 622  - Allow for cgi.h to be overridden by CGI environment variables.
 623    Otherwise, binary distributions will inherit the compile-time
 624    behaviour, which is not optimal.
 625  - Have Mac OSX systems automatically disable -static compilation of the
 626    CGI: -static isn't supported.
 627
 628 ************************************************************************
 629 * to improve in the groff_mdoc(7) macros
 630 ************************************************************************
 631
 632 - use uname(1) to set doc-default-operating-system at install time
 633   tobimensch  Mon, 1 Dec 2014 00:25:07 +0100