[PATCH v2] hooks--pre-commit: detect non-ASCII when renaming

From: Julian Prein <druckdev@protonmail.com>

When diff.renames is turned on, the diff-filter will not return renamed files (or copied ones with diff.renames=copy) and potential non-ASCII characters would not be caught by this hook.

Use the plumbing command diff-index instead of the porcelain one to not be affected by diff.rename.

Signed-off-by: Julian Prein <druckdev@protonmail.com>
---
    hooks--pre-commit: detect non-ASCII when renaming
    
    A bit later than I expected, but here is v2.
    
    Changes since v1:
    
     * Switched to using diff-index and back to just the A filter as
       suggested by Junio C Hamano

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1291%2Fdruckdev%2Fpre-commit-renames-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1291/druckdev/pre-commit-renames-v2
Pull-Request: https://github.com/git/git/pull/1291

Range-diff vs v1:

 1:  101f327a040 ! 1:  1f6ca0dd3eb hooks--pre-commit: detect non-ASCII when renaming
     @@ Metadata
       ## Commit message ##
          hooks--pre-commit: detect non-ASCII when renaming
      
     -    Currently the diff-filter that is used to check for non-ASCII characters
     -    in filenames only checks new additions.
     +    When diff.renames is turned on, the diff-filter will not return renamed
     +    files (or copied ones with diff.renames=copy) and potential non-ASCII
     +    characters would not be caught by this hook.
      
     -    Extend the diff-filter in the pre-commit sample to include `CR` as well.
     -    This way non-ASCII character in filenames are detected on a rename/copy
     -    as well.
     +    Use the plumbing command diff-index instead of the porcelain one to not
     +    be affected by diff.rename.
      
          Signed-off-by: Julian Prein <druckdev@protonmail.com>
      
     @@ templates/hooks--pre-commit.sample: if [ "$allownonascii" != "true" ] &&
       	# even required, for portability to Solaris 10's /usr/bin/tr), since
       	# the square bracket bytes happen to fall in the designated range.
      -	test $(git diff --cached --name-only --diff-filter=A -z $against |
     -+	test $(git diff --cached --name-only --diff-filter=ACR -z $against |
     ++	test $(git diff-index --cached --name-only --diff-filter=A -z $against |
       	  LC_ALL=C tr -d '[ -~]\0' | wc -c) != 0
       then
       	cat <<\EOF

 templates/hooks--pre-commit.sample | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)