warn patch maintainer to remove patch

brave/brave#49

lib/updatePatches.js

@@ -6,17 +6,42 @@ const util = require('../lib/util')
 const updatePatches = (options) => {
   config.update(options)
 
-  const runOptions = { cwd: config.projects.chrome.dir }
   const patchDir = path.join(config.projects.antimuon.dir, 'patches')
 
+  const runOptionsChrome = { cwd: config.projects.chrome.dir }
+  const runOptionsPatch = { cwd: patchDir }
+
+  const desiredReplacementSeparator = '-'
+  const patchExtension = '.patch'
+
   console.log('updatePatches writing files to: ' + patchDir)
 
   // grab Modified (and later Deleted) files but not Created (since we copy those)
   const modifiedDiffArgs = ['diff', '--diff-filter=M', '--name-only', '--ignore-space-at-eol']
-  let modifiedDiff = util.run('git', modifiedDiffArgs, runOptions)
-  let moddedFileList = modifiedDiff.stdout.toString().split('\n').filter(s => s.length > 0)
+  let modifiedDiff = util.run('git', modifiedDiffArgs, runOptionsChrome)
+  let modifiedFileList = modifiedDiff.stdout.toString().split('\n').filter(s => s.length > 0)
+
+  // copy array
+  let substitutedFileList = modifiedFileList.slice()
+
+  // replacing forward slashes and adding the patch extension to get nice filenames
+  // since git on Windows doesn't use backslashes, this is sufficient
+  substitutedFileList = substitutedFileList.map(s => s.replace(/\//g, desiredReplacementSeparator) + patchExtension)
+
+  // grab every existing patch file in the dir (at this point, patchfiles for now-unmodified files live on)
+  const existingFileArgs = ['ls-files', '--exclude-standard']
+  let existingFileOutput = util.run('git', existingFileArgs, runOptionsPatch)
+  let existingFileList = existingFileOutput.stdout.toString().split('\n').filter(s => s.length > 0)
 
-  let n = moddedFileList.length
+  // Add files here we specifically want to keep around regardless
+  const exclusionList = []
+
+  // Subtract to find which patchfiles no longer have diffs, yet still exist
+  const minuhend = existingFileList
+  const subtrahend = substitutedFileList.concat(exclusionList)
+  const difference = minuhend.filter(x => !subtrahend.includes(x))
+
+  const potentialCruftList = difference
 
   // When splitting one large diff into a per-file diff, there are a few ways
   // you can go about it. Because different files can have the same name
@@ -28,27 +53,34 @@ const updatePatches = (options) => {
   // appear, you can quickly patch this by changing the separator, even
   // to something longer
 
-  const desiredReplacementSeparator = '-'
-  const patchExtension = '.patch'
+  let n = modifiedFileList.length
 
   for (var i = 0; i < n; i++) {
-    const old = moddedFileList[i]
-    let revised = old
-
-    //replacing forward slashes
-    //since git on Windows doesn't use backslashes, this is sufficient
-    revised = revised.replace(/\//g, desiredReplacementSeparator)
+    const old = modifiedFileList[i]
+    const revised = substitutedFileList[i]
 
     const singleDiffArgs = ['diff', '--src-prefix=a/', '--dst-prefix=b/', '--full-index', old]
-    let singleDiff = util.run('git', singleDiffArgs, runOptions)
+    let singleDiff = util.run('git', singleDiffArgs, runOptionsChrome)
 
     const contents = singleDiff.stdout.toString()
-    const filename = revised + patchExtension
+    const filename = revised
 
     fs.writeFileSync(path.join(patchDir, filename), contents)
 
     console.log('updatePatches wrote ' + (1 + i) + '/' + n + ': ' + filename)
   }
+
+  // emit a warning to patch maintainers
+  if (potentialCruftList.length > 0) {
+    console.log('--------------------------------------------------------------')
+    console.log('NOTICE: The following patchfiles have now-unmodified targets.')
+    console.log('        Check to see if you need need to use `git rm`')
+    console.log('        Alternatively, add them to the exclusion list.')
+    console.log('Patch dir: ' + patchDir)
+    console.log('--------------------------------------------------------------')
+    potentialCruftList.filter(x => console.log(x))
+    console.log('--------------------------------------------------------------')
+  }
 }
 
 module.exports = updatePatches