[PATCH v2 0/7] var(win32): do report the GIT_SHELL_PATH that is actually used

Changes since v1:

 * This patch series now shares the logic that determines the path of the
   Unix shell that Git uses between prepare_shell_cmd() and git var
   GIT_SHELL_PATH.

Johannes Schindelin (7):
  run-command: refactor getting the Unix shell path into its own
    function
  strvec: declare the `strvec_push_nodup()` function globally
  win32: override `fspathcmp()` with a directory separator-aware version
  mingw(is_msys2_sh): handle forward slashes in the `sh.exe` path, too
  run-command(win32): resolve the path to the Unix shell early
  run-command: declare the `git_shell_path()` function globally
  var(win32): do report the GIT_SHELL_PATH that is actually used

 builtin/var.c             |  3 ++-
 compat/mingw.c            |  2 +-
 compat/win32/path-utils.c | 25 +++++++++++++++++++++++++
 compat/win32/path-utils.h |  2 ++
 dir.c                     |  2 +-
 dir.h                     |  2 +-
 git-compat-util.h         |  5 +++++
 run-command.c             | 17 ++++++++++++-----
 run-command.h             |  5 +++++
 strvec.c                  |  2 +-
 strvec.h                  |  3 +++
 t/t0007-git-var.sh        |  2 +-
 12 files changed, 59 insertions(+), 11 deletions(-)

base-commit: 06e570c0dfb2a2deb64d217db78e2ec21672f558
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1760%2Fdscho%2Fgit-var-on-windows-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1760/dscho/git-var-on-windows-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1760

Range-diff vs v1:

 -:  ----------- > 1:  e0970381042 run-command: refactor getting the Unix shell path into its own function
 -:  ----------- > 2:  91ebccbc39f strvec: declare the `strvec_push_nodup()` function globally
 -:  ----------- > 3:  a718183bb3b win32: override `fspathcmp()` with a directory separator-aware version
 -:  ----------- > 4:  f04cfd91bd9 mingw(is_msys2_sh): handle forward slashes in the `sh.exe` path, too
 -:  ----------- > 5:  707daf246bd run-command(win32): resolve the path to the Unix shell early
 -:  ----------- > 6:  a74a7b4bb11 run-command: declare the `git_shell_path()` function globally
 1:  ef62c3fc122 ! 7:  8bfd23cfa00 var(win32): do report the GIT_SHELL_PATH that is actually used
     @@ Commit message
          associated with the current directory.
      
          To that end, Git does not actually use the path `/bin/sh` that is
     -    recorded e.g. in Unix shell scripts' hash-bang lines. Instead, as of
     -    776297548e (Do not use SHELL_PATH from build system in prepare_shell_cmd
     -    on Windows, 2012-04-17), it re-interprets `/bin/sh` as "look up `sh` on
     -    the `PATH` and use the result instead".
     +    recorded e.g. when `run_command()` is called with a Unix shell
     +    command-line. Instead, as of 776297548e (Do not use SHELL_PATH from
     +    build system in prepare_shell_cmd on Windows, 2012-04-17), it
     +    re-interprets `/bin/sh` as "look up `sh` on the `PATH` and use the
     +    result instead".
     +
     +    This is the logic users expect to be followed when running `git var
     +    GIT_SHELL_PATH`.
      
          However, when 1e65721227 (var: add support for listing the shell,
          2023-06-27) introduced support for `git var GIT_SHELL_PATH`, Windows was
          not special-cased as above, which is why it outputs `/bin/sh` even
          though that disagrees with what Git actually uses.
      
     -    Let's fix this, and also adjust the corresponding test case to verify
     -    that it actually finds a working executable.
     +    Let's fix this by using the exact same logic as `prepare_shell_cmd()`,
     +    adjusting the Windows-specific `git var GIT_SHELL_PATH` test case to
     +    verify that it actually finds a working executable.
      
          Reported-by: Phillip Wood <phillip.wood123@gmail.com>
          Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
      
       ## builtin/var.c ##
     +@@
     + #include "refs.h"
     + #include "path.h"
     + #include "strbuf.h"
     ++#include "run-command.h"
     + 
     + static const char var_usage[] = "git var (-l | <variable>)";
     + 
      @@ builtin/var.c: static char *default_branch(int ident_flag UNUSED)
       
       static char *shell_path(int ident_flag UNUSED)
       {
     -+#ifdef WIN32
     -+	char *p = locate_in_PATH("sh");
     -+	convert_slashes(p);
     -+	return p;
     -+#else
     - 	return xstrdup(SHELL_PATH);
     -+#endif
     +-	return xstrdup(SHELL_PATH);
     ++	return git_shell_path();
       }
       
       static char *git_attr_val_system(int ident_flag UNUSED)