bug#499: 23.0.60; minibuffer tab completion regression

bug#499: 23.0.60; minibuffer tab completion regression

[James Cloos]

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the emacs-pretest-bug@gnu.org mailing list.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

Sometime in the last week tab completion of pathnames in the minibuffer
when running commands like gnus-mime-save-part has broken.

Before, it would give a prompt for the specified filename in the last
directory I'd saved something to (or ~/ the first time it is called)
and I could simply type in the pathname with tab completion just like
in bash.

Now, the tab completion seems to treat the proffered filename as part
of what it should be completing, rather than ignoring it as it used to.

In short, pathname tab completion used to ignore everything at and right
of point whereas now it does not.

It worked with a build from the 14th; I /think/ also with one from the
21st.  It is broken with a build from the 27th.


If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/usr/share/emacs/23.0.60/etc/DEBUG for instructions.


In GNU Emacs 23.0.60.1 (i686-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2008-06-27 on lugabout
Windowing system distributor `The X.Org Foundation', version 11.0.10599001
configured using `configure  '--prefix=/usr' '--host=i686-pc-linux-gnu' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--datadir=/usr/share' '--sysconfdir=/etc' '--localstatedir=/var/lib' '--program-suffix=-emacs-23' '--infodir=/usr/share/info/emacs-23' '--without-carbon' '--with-sound' '--with-x' '--with-toolkit-scroll-bars' '--with-gif' '--with-jpeg' '--with-png' '--with-rsvg' '--with-tiff' '--with-xpm' '--enable-font-backend' '--with-freetype' '--with-xft' '--with-libotf' '--with-m17n-flt' '--with-x-toolkit=athena' '--without-hesiod' '--with-kerberos' '--with-kerberos5' '--with-gpm' '--with-dbus' '--build=i686-pc-linux-gnu' 'build_alias=i686-pc-linux-gnu' 'host_alias=i686-pc-linux-gnu' 'CC=i686-pc-linux-gnu-gcc' 'CFLAGS=-march=pentium3 -O2 -Wno-error' 'LDFLAGS= -Wl,--as-needed,-
 O1,--hash-style=gnu,--sort-common ''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: C
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: C
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Group

Minor modes in effect:
  gnus-undo-mode: t
  show-paren-mode: t
  display-time-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t

Recent input:
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <up> 
<up> <up> <up> <up> <up> <up> <up> <up> <up> SPC n 
n = <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> c 
y A m i n b o x <return> M-g 4 3 g 4 3 l M-< M-> s 
p p p p p p p p p p p p p p p SPC / . SPC W S SPC SPC 
q p SPC SPC q p p p p p p SPC SPC * SPC SPC SPC SPC 
SPC n n n SPC * n n SPC * q SPC SPC q b C-g C-g 4 3 
l M-< M-> p p p p SPC ^ C-n C-n C-n C C-x b <return> 
M-g p SPC SPC q p p p p p p p p p p p p p p p M-g n 
M-g M-g p p SPC SPC q SPC SPC n n n n n 2 K o <return> 
h * SPC n c SPC M-x r e p o <tab> r <tab> b <tab> 
<return>

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bug#499: 23.0.60; minibuffer tab completion regression

[Stefan Monnier]

> In short, pathname tab completion used to ignore everything at and right
> of point whereas now it does not.

Indeed, it does now: it constrains the list of possible completions to
those that include the text after point.

E.g. if your minibuffer is "/foo/bat.c" you can place point after "bat"
and hit TAB to complete to a filename among "bat*.c".

You can get the old behavior with one of the following:
- C-k TAB C-y
- customizing completion-styles: you can for example replace `basic' by
  `emacs22' to get back Emacs-22's behavior.  Note that if you select
  `emacs21' you won't get this behavior since Emacs-21 (and all previous
  Emacs) did not ignore the text after point.


        Stefan