[core] Restrict top level imports that target CJS modules

.eslintrc.js

@@ -52,6 +52,17 @@ module.exports = {
       {
         patterns: [
           '@material-ui/*/*/*',
+          // Begin block: Packages with files instead of packages in the top level
+          // Importing from the top level pulls in CommonJS instead of ES modules
+          // Allowing /icons as to reduce cold-start of dev builds significantly.
+          // There's nothing to tree-shake when importing from /icons this way:
+          // '@material-ui/icons/*/',
+          '@material-ui/system/*',
+          '@material-ui/utils/*',
+          // End block
+          // Macros are fine since their import path is transpiled away
+          '!@material-ui/utils/macros',
+          '@material-ui/utils/macros/*',
           '!@material-ui/utils/macros/*.macro',
           // public API: https://next.material-ui-pickers.dev/getting-started/installation#peer-library
           '!@material-ui/pickers/adapter/*',

azure-pipelines.yml

@@ -98,6 +98,7 @@ steps:
     displayName: Cache nextjs build
 
   - script: |
+      set -o pipefail
       mkdir -p scripts/sizeSnapshot/build	
       yarn docs:build | tee scripts/sizeSnapshot/build/docs.next
     displayName: 'build docs for size snapshot'

docs/src/modules/redux/optionsReducer.js

@@ -1,5 +1,4 @@
 import { ACTION_TYPES, CODE_VARIANTS } from 'docs/src/modules/constants';
-import memoize from '@material-ui/system/memoize';
 import mapTranslations from 'docs/src/modules/utils/mapTranslations';
 
 const req = require.context('docs/translations', false, /translations.*\.json$/);
@@ -15,7 +14,7 @@ function getPath(obj, path) {
 
 const warnOnce = {};
 
-const getT = memoize((userLanguage) => (key, options = {}) => {
+const getT = (userLanguage) => (key, options = {}) => {
   const { ignoreWarning = false } = options;
   const wordings = translations[userLanguage];
 
@@ -37,7 +36,7 @@ const getT = memoize((userLanguage) => (key, options = {}) => {
   }
 
   return translation;
-});
+};
 
 const mapping = {
   [ACTION_TYPES.OPTIONS_CHANGE]: (state, action) => {