🏗 Shorter, uniform ignore lists (ampproject#36357)

Fixes ampproject#36354

### `amp clean`

- Uses `.gitignore` as source of truth

- Finds paths recursively like `.gitignore` does:

    > #### [Pattern format][1]
    > [1]: https://git-scm.com/docs/gitignore#_pattern_format
    >
    > If there is a separator at the beginning or middle (or both) of the pattern, then the pattern is relative to the directory level of the particular `.gitignore` file itself. Otherwise the pattern may also match at any level below the `.gitignore` level.

### `amp check-ignore-list`

- Ensures that `.gitignore`, `.eslintignore` and `.prettierignore` stay in sync
- Runs during CI checks.

### `.*ignore` files

- Use a shorter list to take advantage of recursive behavior
- Added header to determine uniform section

.eslintignore

@@ -1,46 +1,32 @@
-# Local cache directories
-# Keep this list in sync with .gitignore, .prettierignore, and build-system/tasks/clean.js
-.babel-cache
-.css-cache
-.jss-cache
-.pre-closure-cache
+# Files and directories explicitly ignored by eslint
+**/node_modules/**
+build-system/babel-plugins/**/fixtures/**/*.js
+build-system/babel-plugins/**/fixtures/**/*.mjs
+build-system/tasks/make-extension/template/**/*
+examples/amp-script/todomvc.ssr.js
+examples/amp-script/vue-todomvc.js
+extensions/amp-a4a/0.1/test/testdata/**
+src/purifier/noop.js
+testing/local-amp-chrome-extension/**
+third_party/**
+validator/**
+
+# [GLOBALLY IGNORED]
+# (Don't edit or remove the above comment!)
+# The rules below are synced between .gitignore and .prettierignore, and are
+# removed by `amp clean`.
 
-# Output directories
-# Keep this list in sync with .gitignore, .prettierignore, and build-system/tasks/clean.js
+.*cache
 .amp-dep-check
 build
-build-system/dist
-build-system/server/new-server/transforms/dist
 build-system/tasks/performance/cache
 build-system/tasks/performance/results.json
 dist
 dist.3p
 dist.tools
 export
 examples/storybook
-extensions/**/dist
 /release
 result-reports
-src/purifier/dist
 test/coverage
 test/coverage-e2e
-validator/**/dist
-validator/export
-
-# User configuration files
-# Keep this list in sync with .gitignore, .prettierignore, and build-system/tasks/clean.js
-build-system/global-configs/custom-config.json
-build-system/global-configs/custom-flavors-config.json
-
-# Files and directories explicitly ignored by eslint
-**/node_modules/**
-build-system/babel-plugins/**/fixtures/**/*.js
-build-system/babel-plugins/**/fixtures/**/*.mjs
-build-system/tasks/make-extension/template/**/*
-examples/amp-script/todomvc.ssr.js
-examples/amp-script/vue-todomvc.js
-extensions/amp-a4a/0.1/test/testdata/**
-src/purifier/noop.js
-testing/local-amp-chrome-extension/**
-third_party/**
-validator/**

.gitignore

@@ -1,37 +1,3 @@
-# Local cache directories
-# Keep this list in sync with .eslintignore, .prettierignore, and build-system/tasks/clean.js
-.babel-cache
-.css-cache
-.jss-cache
-.pre-closure-cache
-
-# Output directories
-# Keep this list in sync with .eslintignore, .prettierignore, and build-system/tasks/clean.js
-.amp-dep-check
-build
-build-system/dist
-build-system/server/new-server/transforms/dist
-build-system/tasks/performance/cache
-build-system/tasks/performance/results.json
-dist
-dist.3p
-dist.tools
-export
-examples/storybook
-extensions/**/dist
-/release
-result-reports
-src/purifier/dist
-test/coverage
-test/coverage-e2e
-validator/**/dist
-validator/export
-
-# User configuration files
-# Keep this list in sync with .eslintignore, .prettierignore, and build-system/tasks/clean.js
-build-system/global-configs/custom-config.json
-build-system/global-configs/custom-flavors-config.json
-
 # OS level files
 .DS_Store
 .g4ignore
@@ -47,3 +13,28 @@ npm-debug.log
 .firebase
 firebase
 firebase.json
+
+# User configuration files
+# Keep this list in sync with clean.js
+/build-system/global-configs/custom-config.json
+/build-system/global-configs/custom-flavors-config.json
+
+# [GLOBALLY IGNORED]
+# (Don't edit or remove the above comment!)
+# The rules below are synced between .gitignore and .prettierignore, and are
+# removed by `amp clean`.
+
+.*cache
+.amp-dep-check
+build
+build-system/tasks/performance/cache
+build-system/tasks/performance/results.json
+dist
+dist.3p
+dist.tools
+export
+examples/storybook
+/release
+result-reports
+test/coverage
+test/coverage-e2e

.prettierignore

@@ -1,37 +1,23 @@
-# Local cache directories
-# Keep this list in sync with .gitignore, .eslintignore, and build-system/tasks/clean.js
-.babel-cache
-.css-cache
-.jss-cache
-.pre-closure-cache
+# Files and directories explicitly ignored
+**/package*.json
+**/node_modules/**
 
-# Output directories
-# Keep this list in sync with .gitignore, .eslintignore, and build-system/tasks/clean.js
+# [GLOBALLY IGNORED]
+# (Don't edit or remove the above comment!)
+# The rules below are synced between .gitignore and .prettierignore, and are
+# removed by `amp clean`.
+
+.*cache
 .amp-dep-check
 build
-build-system/dist
-build-system/server/new-server/transforms/dist
 build-system/tasks/performance/cache
 build-system/tasks/performance/results.json
 dist
 dist.3p
 dist.tools
 export
 examples/storybook
-extensions/**/dist
 /release
 result-reports
-src/purifier/dist
 test/coverage
 test/coverage-e2e
-validator/**/dist
-validator/export
-
-# User configuration files
-# Keep this list in sync with .gitignore, .eslintignore, and build-system/tasks/clean.js
-build-system/global-configs/custom-config.json
-build-system/global-configs/custom-flavors-config.json
-
-# Files and directories explicitly ignored by prettier
-**/package*.json
-**/node_modules/**

amp.js

@@ -28,6 +28,7 @@ createTask('check-analytics-vendors-list', 'checkAnalyticsVendorsList');
 createTask('check-asserts', 'checkAsserts');
 createTask('check-build-system', 'checkBuildSystem');
 createTask('check-exact-versions', 'checkExactVersions');
+createTask('check-ignore-lists', 'checkIgnoreLists');
 createTask('check-invalid-whitespaces', 'checkInvalidWhitespaces');
 createTask('check-links', 'checkLinks');
 createTask('check-owners', 'checkOwners');

build-system/pr-check/build-targets.js

@@ -12,6 +12,7 @@ const path = require('path');
 const {cyan} = require('kleur/colors');
 const {getLoggingPrefix, logWithoutTimestamp} = require('../common/logging');
 const {gitDiffNameOnlyMain} = require('../common/git');
+const {ignoreListFiles} = require('../tasks/check-ignore-lists');
 const {isCiBuild} = require('../common/ci');
 
 /**
@@ -38,6 +39,7 @@ const Targets = {
   DOCS: 'DOCS',
   E2E_TEST: 'E2E_TEST',
   HTML_FIXTURES: 'HTML_FIXTURES',
+  IGNORE_LIST: 'IGNORE_LIST',
   INTEGRATION_TEST: 'INTEGRATION_TEST',
   INVALID_WHITESPACES: 'INVALID_WHITESPACES',
   LINT: 'LINT',
@@ -66,6 +68,7 @@ const nonRuntimeTargets = [
   Targets.DEV_DASHBOARD,
   Targets.DOCS,
   Targets.E2E_TEST,
+  Targets.IGNORE_LIST,
   Targets.INTEGRATION_TEST,
   Targets.OWNERS,
   Targets.RENOVATE_CONFIG,
@@ -188,6 +191,13 @@ const targetMatchers = {
       file.startsWith('build-system/test-configs')
     );
   },
+  [Targets.IGNORE_LIST]: (file) => {
+    return (
+      ignoreListFiles.includes(file) ||
+      file === 'build-system/tasks/check-ignore-list.js' ||
+      file === 'build-system/tasks/clean.js'
+    );
+  },
   [Targets.INTEGRATION_TEST]: (file) => {
     if (isOwnersFile(file)) {
       return false;

build-system/pr-check/checks.js

@@ -21,6 +21,7 @@ function pushBuildWorkflow() {
   timedExecOrDie('amp prettify');
   timedExecOrDie('amp ava');
   timedExecOrDie('amp check-build-system');
+  timedExecOrDie('amp check-ignore-list');
   timedExecOrDie('amp babel-plugin-tests');
   timedExecOrDie('amp caches-json');
   timedExecOrDie('amp check-exact-versions');
@@ -50,6 +51,10 @@ function prBuildWorkflow() {
     timedExecOrDie('amp check-invalid-whitespaces');
   }
 
+  if (buildTargetsInclude(Targets.IGNORE_LIST)) {
+    timedExecOrDie(`amp check-ignore-lists`);
+  }
+
   if (buildTargetsInclude(Targets.HTML_FIXTURES)) {
     timedExecOrDie('amp validate-html-fixtures');
   }

build-system/tasks/check-ignore-lists.js

@@ -0,0 +1,44 @@
+const {readFile} = require('fs-extra');
+const {writeDiffOrFail} = require('../common/diff');
+
+const ignoreFile = '.gitignore';
+const syncIgnoreFiles = ['.prettierignore', '.eslintignore'];
+
+const ignoreListFiles = [ignoreFile, ...syncIgnoreFiles];
+
+const header = '# [GLOBALLY IGNORED]';
+
+/**
+ * @param {string} source
+ * @return {string[]}
+ */
+function splitIgnoreListByHeader(source) {
+  return source.split(header, 2);
+}
+
+/**
+ * @return {!Promise}
+ */
+async function checkIgnoreLists() {
+  const [, below] = splitIgnoreListByHeader(await readFile(ignoreFile, 'utf8'));
+
+  for (const file of syncIgnoreFiles) {
+    const [above] = splitIgnoreListByHeader(await readFile(file, 'utf8'));
+    const tentative = [above, below].join(header);
+    await writeDiffOrFail('check-ignore-list', file, tentative);
+  }
+}
+
+checkIgnoreLists.description =
+  'Check ignore lists to make sure they are in sync';
+
+checkIgnoreLists.flags = {
+  'fix': `Fix files out of sync`,
+};
+
+module.exports = {
+  checkIgnoreLists,
+  ignoreListFiles,
+  ignoreFile,
+  splitIgnoreListByHeader,
+};