Merge pull request #11771 from Snuffleupagus/issue-11762

Fail early, in modern `GENERIC` builds, if certain required browser functionality is missing (issue 11762)

external/dist/lib/README.md

@@ -3,5 +3,5 @@ pre-built library as found in e.g. the `/build`, `/web`, and `/image_decoders`
 folders in the root of this repository.
 
 Please note that the "lib" build target exists mostly to enable unit-testing in
-Node.js/Travis, and that you'll need to handle e.g. any Node.js dependencies
-yourself if using the files in this folder.
+Node.js/Travis, and that you'll need to handle e.g. any necessary polyfills
+and/or Node.js dependencies yourself if using the files in this folder.

gulpfile.js

@@ -1150,9 +1150,7 @@ gulp.task("jsdoc", function(done) {
   });
 });
 
-gulp.task(
-  "lib",
-  gulp.series("buildnumber", "default_preferences", function() {
+function buildLib(defines, dir) {
   // When we create a bundle, webpack is run on the source and it will replace
   // require with __webpack_require__. When we want to use the real require,
   // __non_webpack_require__ has to be used.
@@ -1171,8 +1169,7 @@ gulp.task(
   }
   function preprocess(content) {
     var skipBabel =
-        bundleDefines.SKIP_BABEL ||
-        /\/\*\s*no-babel-preset\s*\*\//.test(content);
+      bundleDefines.SKIP_BABEL || /\/\*\s*no-babel-preset\s*\*\//.test(content);
     content = preprocessor2.preprocessPDFJSCode(ctx, content);
     content = babel.transform(content, {
       sourceType: "module",
@@ -1190,19 +1187,14 @@ gulp.task(
       ],
     }).code;
     var removeCjsSrc = /^(var\s+\w+\s*=\s*(_interopRequireDefault\()?require\(".*?)(?:\/src)(\/[^"]*"\)\)?;)$/gm;
-      content = content.replace(
-        removeCjsSrc,
-        (all, prefix, interop, suffix) => {
+    content = content.replace(removeCjsSrc, (all, prefix, interop, suffix) => {
       return prefix + suffix;
-        }
-      );
+    });
     return licenseHeaderLibre + content;
   }
   var babel = require("@babel/core");
   var versionInfo = getVersionJSON();
-    var bundleDefines = builder.merge(DEFINES, {
-      GENERIC: true,
-      LIB: true,
+  var bundleDefines = builder.merge(defines, {
     BUNDLE_VERSION: versionInfo.version,
     BUNDLE_BUILD: versionInfo.commit,
     TESTING: process.env["TESTING"] === "true",
@@ -1235,7 +1227,28 @@ gulp.task(
     gulp.src("test/unit/*.js", { base: "." }),
   ])
     .pipe(transform("utf8", preprocess))
-      .pipe(gulp.dest("build/lib/"));
+    .pipe(gulp.dest(dir));
+}
+
+gulp.task(
+  "lib",
+  gulp.series("buildnumber", "default_preferences", function() {
+    var defines = builder.merge(DEFINES, { GENERIC: true, LIB: true });
+
+    return buildLib(defines, "build/lib/");
+  })
+);
+
+gulp.task(
+  "lib-es5",
+  gulp.series("buildnumber", "default_preferences", function() {
+    var defines = builder.merge(DEFINES, {
+      GENERIC: true,
+      LIB: true,
+      SKIP_BABEL: false,
+    });
+
+    return buildLib(defines, "build/lib-es5/");
   })
 );
 
@@ -1371,7 +1384,7 @@ gulp.task("baseline", function(done) {
 
 gulp.task(
   "unittestcli",
-  gulp.series("testing-pre", "lib", function(done) {
+  gulp.series("testing-pre", "lib-es5", function(done) {
     var options = [
       "node_modules/jasmine/bin/jasmine",
       "JASMINE_CONFIG_PATH=test/unit/clitests.json",

src/core/worker.js

@@ -136,6 +136,21 @@ var WorkerMessageHandler = {
             "; thus breaking e.g. `for...in` iteration of `Array`s."
         );
       }
+
+      // Ensure that (primarily) Node.js users won't accidentally attempt to use
+      // a non-translated/non-polyfilled build of the library, since that would
+      // quickly fail anyway because of missing functionality (such as e.g.
+      // `ReadableStream).
+      if (
+        (typeof PDFJSDev === "undefined" || PDFJSDev.test("SKIP_BABEL")) &&
+        typeof ReadableStream === "undefined"
+      ) {
+        throw new Error(
+          "The browser/environment lacks native support for critical " +
+            "functionality used by the PDF.js library (e.g. `ReadableStream`); " +
+            "please use an ES5-compatible build instead."
+        );
+      }
     }
 
     var docId = docParams.docId;

src/shared/compatibility.js

@@ -14,11 +14,9 @@
  */
 /* eslint no-var: error */
 
-// Skip compatibility checks for modern builds (unless we're running the
-// unit-tests in Node.js/Travis) and if we already ran the module.
+// Skip compatibility checks for modern builds and if we already ran the module.
 if (
-  (typeof PDFJSDev === "undefined" ||
-    PDFJSDev.test("!SKIP_BABEL || (LIB && TESTING)")) &&
+  (typeof PDFJSDev === "undefined" || !PDFJSDev.test("SKIP_BABEL")) &&
   (typeof globalThis === "undefined" || !globalThis._pdfjsCompatibilityChecked)
 ) {
   // Provides support for globalThis in legacy browsers.

test/unit/clitests.json

@@ -1,5 +1,5 @@
 {
-  "spec_dir": "build/lib/test/unit",
+  "spec_dir": "build/lib-es5/test/unit",
 
   "helpers": [
     "clitests_helper.js"