fix: only run git add on staged files matched to a task

# Conflicts:
#	lib/gitWorkflow.js

lib/gitWorkflow.js

@@ -3,6 +3,7 @@
 const debug = require('debug')('lint-staged:git')
 const path = require('path')
 
+const chunkFiles = require('./chunkFiles')
 const execGit = require('./execGit')
 const { readFile, unlink, writeFile } = require('./file')
 
@@ -52,14 +53,15 @@ const handleError = (error, ctx) => {
 }
 
 class GitWorkflow {
-  constructor({ allowEmpty, gitConfigDir, gitDir, stagedFileChunks }) {
+  constructor({ allowEmpty, gitConfigDir, gitDir, matchedFiles, maxArgLength }) {
     this.execGit = (args, options = {}) => execGit(args, { ...options, cwd: gitDir })
     this.deletedFiles = []
     this.gitConfigDir = gitConfigDir
     this.gitDir = gitDir
     this.unstagedDiff = null
     this.allowEmpty = allowEmpty
-    this.stagedFileChunks = stagedFileChunks
+    this.matchedFiles = matchedFiles
+    this.maxArgLength = maxArgLength
 
     /**
      * These three files hold state about an ongoing git merge
@@ -235,12 +237,22 @@ class GitWorkflow {
    */
   async applyModifications(ctx) {
     debug('Adding task modifications to index...')
-    // stagedFileChunks includes staged files that lint-staged originally detected.
+    // `matchedFiles` includes staged files that lint-staged originally detected and matched against a task.
     // Add only these files so any 3rd-party edits to other files won't be included in the commit.
-    // This is run "serially" to prevent race conditions because `git add` is a locking operation.
-    for (const stagedFiles of this.stagedFileChunks) {
-      await this.execGit(['add', '--', ...stagedFiles])
+    const files = Array.from(this.matchedFiles)
+    // Chunk files for better Windows compatibility
+    const matchedFileChunks = chunkFiles({
+      baseDir: this.gitDir,
+      files,
+      maxArgLength: this.maxArgLength
+    })
+
+    // These additions per chunk are run "serially" to prevent race conditions.
+    // Git add creates a lockfile in the repo causing concurrent operations to fail.
+    for (const files of matchedFileChunks) {
+      await this.execGit(['add', '--', ...files])
     }
+
     debug('Done adding task modifications to index!')
 
     const stagedFilesAfterAdd = await this.execGit(['diff', '--name-only', '--cached'])

lib/runAll.js

@@ -125,6 +125,9 @@ const runAll = async (
 
   const listrTasks = []
 
+  // Set of all staged files that matched a task glob. Values in a set are unique.
+  const matchedFiles = new Set()
+
   for (const [index, files] of stagedFileChunks.entries()) {
     const chunkTasks = generateTasks({ config, cwd, gitDir, files, relative })
     const chunkListrTasks = []
@@ -137,6 +140,11 @@ const runAll = async (
         shell
       })
 
+      // Add files from task to match set
+      task.fileList.forEach(file => {
+        matchedFiles.add(file)
+      })
+
       hasDeprecatedGitAdd = subTasks.some(subTask => subTask.command === 'git add')
 
       chunkListrTasks.push({
@@ -188,7 +196,7 @@ const runAll = async (
     return 'No tasks to run.'
   }
 
-  const git = new GitWorkflow({ allowEmpty, gitConfigDir, gitDir, stagedFileChunks })
+  const git = new GitWorkflow({ allowEmpty, gitConfigDir, gitDir, matchedFiles, maxArgLength })
 
   const runner = new Listr(
     [