Update the Babel plugin to remove empty class constructors

.eslintignore

@@ -4,7 +4,7 @@ docs/
 node_modules/
 external/bcmaps/
 external/builder/fixtures/
-external/builder/fixtures_esprima/
+external/builder/fixtures_babel/
 external/quickjs/
 external/openjpeg/
 test/tmp/

.prettierignore

@@ -4,7 +4,7 @@ docs/
 node_modules/
 external/bcmaps/
 external/builder/fixtures/
-external/builder/fixtures_esprima/
+external/builder/fixtures_babel/
 external/quickjs/
 test/tmp/
 test/pdfs/

.stylelintignore

@@ -4,7 +4,7 @@ docs/
 node_modules/
 external/bcmaps/
 external/builder/fixtures/
-external/builder/fixtures_esprima/
+external/builder/fixtures_babel/
 external/quickjs/
 test/tmp/
 test/pdfs/

external/builder/babel-plugin-pdfjs-preprocessor.mjs

@@ -234,6 +234,26 @@ function babelPluginPDFJSPreprocessor(babel, ctx) {
           }
         },
       },
+      ClassMethod: {
+        exit(path) {
+          const {
+            node,
+            parentPath: { parent: classNode },
+          } = path;
+          if (
+            // Remove empty constructors. We only do this for
+            // base classes, as the default constructor of derived
+            // classes is not empty (and an empty constructor
+            // must throw at runtime when constructed).
+            node.kind === "constructor" &&
+            node.body.body.length === 0 &&
+            node.params.every(p => p.type === "Identifier") &&
+            !classNode.superClass
+          ) {
+            path.remove();
+          }
+        },
+      },
     },
   };
 }

external/builder/fixtures_babel/constructors-expected.js

@@ -0,0 +1,23 @@
+class A {
+  constructor() {
+    console.log("Hi!");
+  }
+}
+class B {
+  constructor(x = console.log("Hi!")) {}
+}
+class C {
+  constructor({
+    x
+  }) {}
+}
+class D {}
+class E extends A {
+  constructor() {}
+}
+class F {
+  constructor() {
+    var a = 0;
+  }
+}
+class G {}

external/builder/fixtures_babel/constructors.js

@@ -0,0 +1,37 @@
+class A {
+  constructor() {
+    console.log("Hi!");
+  }
+}
+
+class B {
+  constructor(x = console.log("Hi!")) {}
+}
+
+class C {
+  constructor({ x }) {}
+}
+
+class D {
+  constructor(x, y, z) {}
+}
+
+class E extends A {
+  constructor() {}
+}
+
+class F {
+  constructor() {
+    if (PDFJSDev.test('TRUE')) {
+      var a = 0;
+    }
+  }
+}
+
+class G {
+  constructor() {
+    if (PDFJSDev.test('FALSE')) {
+      var a = 0;
+    }
+  }
+}

external/builder/fixtures_esprima/evals.js → external/builder/fixtures_babel/evals.js

@@ -5,7 +5,7 @@ var d = PDFJSDev.test('FALSE');
 var e = PDFJSDev.eval('TRUE');
 var f = PDFJSDev.eval('TEXT');
 var g = PDFJSDev.eval('OBJ');
-var h = PDFJSDev.json('$ROOT/external/builder/fixtures_esprima/evals.json');
+var h = PDFJSDev.json('$ROOT/external/builder/fixtures_babel/evals.json');
 var i = typeof PDFJSDev === 'undefined' ? PDFJSDev.eval('FALSE') : '0';
 var j = typeof PDFJSDev !== 'undefined' ? PDFJSDev.eval('OBJ.obj') : '0';
 var k = !PDFJSDev.test('TRUE');

external/builder/test-fixtures_esprima.mjs → external/builder/test-fixtures_babel.mjs

@@ -7,7 +7,7 @@ const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
 let errors = 0;
 
-const baseDir = path.join(__dirname, "fixtures_esprima");
+const baseDir = path.join(__dirname, "fixtures_babel");
 const files = fs
   .readdirSync(baseDir)
   .filter(function (name) {
@@ -49,7 +49,7 @@ files.forEach(function (expectationFilename) {
     errors++;
 
     // Allow regenerating the expected output using
-    //   OVERWRITE=true node ./external/builder/test-fixtures_esprima.mjs
+    //   OVERWRITE=true node ./external/builder/test-fixtures_babel.mjs
     if (process.env.OVERWRITE) {
       fs.writeFileSync(expectationFilename, out + "\n");
     }

gulpfile.mjs

@@ -2414,8 +2414,8 @@ gulp.task("externaltest", function (done) {
   });
 
   console.log();
-  console.log("### Running test-fixtures_esprima.js");
-  safeSpawnSync("node", ["external/builder/test-fixtures_esprima.mjs"], {
+  console.log("### Running test-fixtures_babel.js");
+  safeSpawnSync("node", ["external/builder/test-fixtures_babel.mjs"], {
     stdio: "inherit",
   });
   done();