[PATCH 00/10] Prepare Git's test suite for symbolic link support on Windows

Git for Windows has supported symbolic links for quite some time: In https://github.com/git-for-windows/git/pull/156, this support was introduced already into Git for Windows v2.4.2.windows.1 in May 2015.

However, the Git for Windows CI never ran the test suite with symbolic link support because the MSYS2 runtime (i.e. the POSIX emulation layer required to run Git's test suite because the latter is written in Unix shell script) does not support symbolic links right out of the box. This is for historical reasons: Symbolic link support was introduced in Windows 7, where these links could only be created by administrators by default, and it took until Windows 10 Build 14972 that at least in Developer Mode, non-administrators would be permitted to create them.

The MSYS2 runtime does have some sort of support for symbolic links, although with caveats: seeing as it expects the inputs as Unix-like paths, but the outputs need to be Win32 symbolic links pointing to Win32 paths, some normalization has to be performed in the process. This leads to sometimes surprising behavior e.g. when a link target like a/b/.. is normalized to a.

It has been a minute or three since the time when Windows versions without symbolic link support were common, therefore there are plans to turn on that support in the MSYS2 runtime on these Windows versions by default, see https://github.com/msys2/msys2-runtime/pull/114 for more details about this.

To prepare for this, I am working toward upstreaming Git for Windows' own support for symbolic links. And to prepare for that, in turn, I am hereby contributing preemptively the fixes required to eventually let Git's test suite pass when both MSYS2 runtime and Git support symbolic links.

As a bonus, this patch series also contains fixes for the Perl tests (which were broken for a few years, unnoticed because the CI runs need to save on runtime and therefore skip the Perl tests because the consume a lot of time).

Johannes Schindelin (10):
  t9700: accommodate for Windows paths
  apply: symbolic links lack a "trustable executable bit"
  mingw: special-case `open(symlink, O_CREAT | O_EXCL)`
  t0001: handle `diff --no-index` gracefully
  t0301: another fix for Windows compatibility
  t0600: fix incomplete prerequisite for a test case
  t1006: accommodate for symlink support in MSYS2
  t1305: skip symlink tests that do not apply to Windows
  t6423: introduce Windows-specific handling for symlinking to /dev/null
  t7800: work around the MSYS path conversion on Windows

 apply.c                             |  2 +-
 compat/mingw.c                      | 14 ++++++++++++++
 t/t0001-init.sh                     |  5 ++++-
 t/t0301-credential-cache.sh         |  3 ++-
 t/t0600-reffiles-backend.sh         |  2 +-
 t/t1006-cat-file.sh                 | 24 +++++++++++++++++-------
 t/t1305-config-include.sh           |  4 ++--
 t/t6423-merge-rename-directories.sh |  9 +++++++--
 t/t7800-difftool.sh                 |  8 ++++----
 t/t9700/test.pl                     |  9 +++++++--
 10 files changed, 59 insertions(+), 21 deletions(-)

base-commit: 9a2fb147f2c61d0cab52c883e7e26f5b7948e3ed
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2009%2Fdscho%2Fprepare-the-test-suite-for-symlink-support-on-windows-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2009/dscho/prepare-the-test-suite-for-symlink-support-on-windows-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2009