view tests/test-issue522.t @ 24028:a78888d98606

color: be more conservative about setting ANSI mode on Windows (BC)

The current color mode detection on Windows assumes the presence of the
TERM environment variable assumes ANSI is supported. However, this isn't
always true. In MSYS (commonly found as part of MinGW), TERM is set to
"cygwin" and the auto resolved color mode of "ansi" results in escape
sequences getting printed literally to the terminal. The output is
very difficult to read and results in a bad user experience. A
workaround is to activate the pager and have it attend all commands (GNU
less in MSYS can render ANSI terminal sequences properly).

In Cygwin, TERM is set to "xterm." Furthermore, Cygwin supports
displaying these terminal sequences properly (unlike MSYS).

This patch changes the mode auto-detection logic on Windows to be more
conservative about selecting the "ansi" mode. We now only select the
"ansi" mode if TERM is set and it contains the string "xterm" or if
we were unable to talk to win32 APIs to determine the settings. There is
a chance this may take away "ansi" from a terminal that actually
supports it. The recourse for this would be to patch the detection to
act appropriately and to override color.mode until that patch has
landed. However, the author believes this regression is tolerable, since
it means MSYS users won't have gibberish printed by default.

Since MSYS's common pager (less) supports display of ANSI sequences,
there is room to patch the color extensions so it can select the ANSI
color mode if a pager is activated.

Mozilla (being an active user of MSYS) would really appreciate this
being part of the stable branch. However, since I believe it is BC, I
haven't explicitly requested application to stable since I figure that
request will be denied.

http://mercurial.selenic.com/bts/issue522

In the merge below, the file "foo" has the same contents in both
parents, but if we look at the file-level history, we'll notice that
the version in p1 is an ancestor of the version in p2. This test makes
sure that we'll use the version from p2 in the manifest of the merge
revision.

  $ hg init

  $ echo foo > foo
  $ hg ci -qAm 'add foo'

  $ echo bar >> foo
  $ hg ci -m 'change foo'

  $ hg backout -r tip -m 'backout changed foo'
  reverting foo
  changeset 2:4d9e78aaceee backs out changeset 1:b515023e500e

  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ touch bar
  $ hg ci -qAm 'add bar'

  $ hg merge --debug
    searching for copies back to rev 1
    unmatched files in local:
     bar
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: bbd179dfa0a7, local: 71766447bdbb+, remote: 4d9e78aaceee
   foo: remote is newer -> g
  getting foo
  updating: foo 1/1 files (100.00%)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg debugstate | grep foo
  m   0         -2 unset               foo

  $ hg st -A foo
  M foo

  $ hg ci -m 'merge'

  $ hg manifest --debug | grep foo
  c6fc755d7e68f49f880599da29f15add41f42f5a 644   foo

  $ hg debugindex foo
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       5  .....       0 2ed2a3912a0b 000000000000 000000000000 (re)
       1         5       9  .....       1 6f4310b00b9a 2ed2a3912a0b 000000000000 (re)
       2        14       5  .....       2 c6fc755d7e68 6f4310b00b9a 000000000000 (re)