pre-commit: git unadd changes lost if hook fails on windows

The best approach I can come up with is to temporarily set core.autocrlf = false when applying patches. Replacing \r characters out of a patch will likely break other things, and using git apply --ignore-whitespace causes it to incorrectly modify other line endings.

I’ll try and make a patch for this – I also think this is probably a bug in git (a patch generated by git diff-index --patch cannot be applied by git apply)

OK! I can finally reproduce this.

Here’s my minimal reproduction (also reproducing on linux, but I don’t think anyone uses autocrlf=true on linux):

Script

#!/bin/bash
set -ex

rm -rf foo
git init foo
cd foo

# Commit crlf into repository
git config --local core.autocrlf false
python3 -c 'open("foo", "wb").write(b"1\r\n2\r\n")'
git add foo
git commit -m "Initial commit with crlf"

# Change whitespace mode to autocrlf, "commit lf, checkout crlf"
git config --local core.autocrlf true
python3 -c 'open("foo", "wb").write(b"1\r\n2\r\n\r\n\r\n\r\n")'

# Run pre-commit
head -4 ~/workspace/pre-commit/.pre-commit-config.yaml > .pre-commit-config.yaml
~/workspace/pre-commit/venv*/bin/pre-commit

Output

+ rm -rf foo
+ git init foo
Initialized empty Git repository in /tmp/foo/.git/
+ cd foo
+ git config --local core.autocrlf false
+ python3 -c 'open("foo", "wb").write(b"1\r\n2\r\n")'
+ git add foo
+ git commit -m 'Initial commit with crlf'
[master (root-commit) 6644acc] Initial commit with crlf
 1 file changed, 2 insertions(+)
 create mode 100644 foo
+ git config --local core.autocrlf true
+ python3 -c 'open("foo", "wb").write(b"1\r\n2\r\n\r\n\r\n\r\n")'
+ head -4 /home/asottile/workspace/pre-commit/.pre-commit-config.yaml
+ /home/asottile/workspace/pre-commit/venv/bin/pre-commit
[WARNING] Unstaged files detected.
[INFO] Stashing unstaged files to /home/asottile/.pre-commit/patch1501609946.
Trim Trailing Whitespace.............................(no files to check)Skipped
[WARNING] Stashed changes conflicted with hook auto-fixes... Rolling back fixes...
An unexpected error has occurred: CalledProcessError: Command: ('/usr/bin/git', 'apply', '/home/asottile/.pre-commit/patch1501609946', '--whitespace=nowarn')
Return code: 1
Expected return code: 0
Output: (none)
Errors: 
    error: patch failed: foo:1
    error: foo: patch does not apply
    

Check the log at ~/.pre-commit/pre-commit.log

D:\CubeadProjects\devops [test +0 ~1 -0 | +0 ~1 -0 !]> git status
On branch test
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

        modified:   svnchecker_stylelint_support/install.py

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   svnchecker_stylelint_support/checks/Stylelint.py

D:\CubeadProjects\devops [test +0 ~1 -0 | +0 ~1 -0 !]> git diff --ignore-submodules --binary --exit-code --no-color --no-ext-diff
diff --git a/svnchecker_stylelint_support/checks/Stylelint.py b/svnchecker_stylelint_support/checks/Stylelint.py
index 4422b4d..83fe854 100644
--- a/svnchecker_stylelint_support/checks/Stylelint.py
+++ b/svnchecker_stylelint_support/checks/Stylelint.py
@@ -20,3 +20,6 @@ def run(transaction, config):
             return ('{}\n{}'.format(stdoutdata, stderrdata), 1)

     return ("", 0)
+
+
+

D:\CubeadProjects\devops [test]> git version
git version 2.13.2.windows.1
D:\CubeadProjects\devops [test]> pre-commit -V
pre-commit 0.15.4

local git config

[core]
	repositoryformatversion = 0
	filemode = false
	bare = false
	logallrefupdates = true
	symlinks = false
	ignorecase = true
	autocrlf = true
	whitespace = fix
[branch "master"]
[branch "devops_cubead_dev"]
[remote "origin"]
	url = git@github.com:CubeADGroup/devops.git
	fetch = +refs/heads/*:refs/remotes/origin/*
[user]
	name = RunningToTheEdgeOfTheWorld
[branch "master"]
	remote = origin
	merge = refs/heads/master

global git config

[filter "lfs"]
	process = git-lfs filter-process
	required = true
	clean = git-lfs clean -- %f
	smudge = git-lfs smudge -- %f
[user]
	name = ZJ
[user]
	email = 569290339@qq.com
[gui]
	recentrepo = D:/CubeadProjects/omms
[alias]
	s = status
	cm = commit -m
	co = checkout
    a = add
    b = branch
    p = push
    d = diff
    dt = difftool
[core]
	autocrlf = true
[diff]
	tool = gvimdiff
[difftool]
	prompt = No
[apply]
	whitespace = nowarn