[internal] Keep the .cjs extension when compiling source files

Gulpfile.mjs

@@ -11,6 +11,7 @@ import babel from "gulp-babel";
 import camelCase from "lodash/camelCase.js";
 import fancyLog from "fancy-log";
 import filter from "gulp-filter";
+import revertPath from "gulp-revert-path";
 import gulp from "gulp";
 import { rollup } from "rollup";
 import { babel as rollupBabel } from "@rollup/plugin-babel";
@@ -229,6 +230,10 @@ function buildBabel(exclude) {
         },
       })
     )
+    .pipe(
+      // gulp-babel always converts the extension to .js, but we want to keep the original one
+      revertPath()
+    )
     .pipe(
       // Passing 'file.relative' because newer() above uses a relative
       // path and this keeps it consistent.

package.json

@@ -54,6 +54,7 @@
     "gulp-filter": "^5.1.0",
     "gulp-newer": "^1.0.0",
     "gulp-plumber": "^1.2.1",
+    "gulp-revert-path": "^2.0.0",
     "husky": "^3.0.0",
     "jest": "^26.6.1",
     "lint-staged": "^9.2.0",

packages/babel-core/src/config/pattern-to-regex.js

@@ -2,7 +2,7 @@
 import path from "path";
 
 // $FlowIgnore
-import escapeRegExp from "./helpers/escape-regexp";
+import escapeRegExp from "./helpers/escape-regexp.cjs";
 
 const sep = `\\${path.sep}`;
 const endSep = `(?:${sep}|$)`;

packages/babel-helper-transform-fixture-test-runner/src/index.js

@@ -15,7 +15,7 @@ import path from "path";
 import vm from "vm";
 import checkDuplicatedNodes from "babel-check-duplicated-nodes";
 import QuickLRU from "quick-lru";
-import escapeRegExp from "./escape-regexp";
+import escapeRegExp from "./escape-regexp.cjs";
 
 const cachedScripts = new QuickLRU({ maxSize: 10 });
 const contextModuleCache = new WeakMap();

packages/babel-register/src/node.js

@@ -7,7 +7,7 @@ import { addHook } from "pirates";
 import fs from "fs";
 import path from "path";
 import Module from "module";
-import escapeRegExp from "./escape-regexp";
+import escapeRegExp from "./escape-regexp.cjs";
 
 const maps = {};
 let transformOpts = {};

yarn.lock

@@ -4851,6 +4851,7 @@ __metadata:
     gulp-filter: ^5.1.0
     gulp-newer: ^1.0.0
     gulp-plumber: ^1.2.1
+    gulp-revert-path: ^2.0.0
     husky: ^3.0.0
     jest: ^26.6.1
     lint-staged: ^9.2.0
@@ -7722,6 +7723,15 @@ fsevents@^1.2.7:
   languageName: node
   linkType: hard
 
+"gulp-revert-path@npm:^2.0.0":
+  version: 2.0.0
+  resolution: "gulp-revert-path@npm:2.0.0"
+  dependencies:
+    through2: ^2.0.0
+  checksum: c2b01db2942c084f8cb11cecff22663a3ab894cdf43daed601bdaa9c713797e11739415b46f18342171fb0c65c1fe57d18dd40f93da403002e99f453b5661d77
+  languageName: node
+  linkType: hard
+
 "gulp@npm:^4.0.2":
   version: 4.0.2
   resolution: "gulp@npm:4.0.2"