fix(@angular/build): prevent IIFE wrapper interleaving for adjacent classes in minified files

In 22.1.0, the Babel-based advancedOptimizations pass was replaced with oxc-parser + magic-string. When wrapping a class declaration in a pure IIFE, appendLeft was used for the opener and appendRight for the closer.

In minified bundles where sibling top-level class declarations are adjacent without whitespace (classA.end === classB.start), magic-string emits appendLeft content before appendRight content at a shared index. This caused class B's IIFE opener to be emitted ahead of class A's IIFE closer, interleaving the wrappers and resulting in duplicate symbol declarations in subsequent build phases.

This change swaps the insertion methods to use appendRight for the opening fragment and appendLeft for the closing fragment (and when splitting default exports), ensuring correct ordering at shared boundaries.

closes #33699

Author: alan-agius4

packages/angular/build/src/tools/babel/plugins/adjust-static-class-members_oxc_spec.ts

@@ -998,4 +998,106 @@ describe('adjust-static-class-members oxc-transform implementation', () => {
       `,
     }),
   );
+
+  it(
+    'wraps adjacent class declarations without interleaving',
+    testCase({
+      input: 'class A{static s=[1]}class B{static s=[2]}',
+      expected: `
+        let A = /*#__PURE__*/ (() => {
+          class A {
+            static s = [1]
+          }
+          return A;
+        })();
+        let B = /*#__PURE__*/ (() => {
+          class B {
+            static s = [2]
+          }
+          return B;
+        })();
+      `,
+    }),
+  );
+
+  it(
+    'wraps adjacent exported class declarations without interleaving',
+    testCase({
+      input: 'export class A{static s=[1]}export class B{static s=[2]}',
+      expected: `
+        export let A = /*#__PURE__*/ (() => {
+          class A {
+            static s = [1]
+          }
+          return A;
+        })();
+        export let B = /*#__PURE__*/ (() => {
+          class B {
+            static s = [2]
+          }
+          return B;
+        })();
+      `,
+    }),
+  );
+
+  it(
+    'wraps adjacent default export and class declarations without interleaving',
+    testCase({
+      input: 'export default class A{static s=[1]}class B{static s=[2]}',
+      expected: `
+        let A = /*#__PURE__*/ (() => {
+          class A {
+            static s = [1]
+          }
+          return A;
+        })();
+        export { A as default };
+        let B = /*#__PURE__*/ (() => {
+          class B {
+            static s = [2]
+          }
+          return B;
+        })();
+      `,
+    }),
+  );
+
+  it(
+    'splits default export without interleaving with adjacent class declaration',
+    testCase({
+      input: 'export default class A{}class B{static s=[2]}',
+      expected: `
+        class A {}
+        export { A as default };
+        let B = /*#__PURE__*/ (() => {
+          class B {
+            static s = [2]
+          }
+          return B;
+        })();
+      `,
+    }),
+  );
+
+  it(
+    'wraps adjacent variable class declarations without interleaving',
+    testCase({
+      input: 'let A=class A{static s=[1]};class B{static s=[2]}',
+      expected: `
+        let A = /*#__PURE__*/ (() => {
+          let A = class A {
+            static s = [1]
+          };
+          return A;
+        })();
+        let B = /*#__PURE__*/ (() => {
+          class B {
+            static s = [2]
+          }
+          return B;
+        })();
+      `,
+    }),
+  );
 });

packages/angular/build/src/tools/babel/plugins/oxc-transform.ts

@@ -584,25 +584,25 @@ export function transform(filename: string, code: string, options: OxcTransformO
           // 1. Remove `export default `
           s.overwrite(statement.start, classNode.start, '');
           // 2. Wrap in IIFE
-          s.appendLeft(classNode.start, `let ${classIdName} = /*#__PURE__*/ (() => {\n`);
-          s.appendRight(
+          s.appendRight(classNode.start, `let ${classIdName} = /*#__PURE__*/ (() => {\n`);
+          s.appendLeft(
             lastStatement.end,
             `\nreturn ${classIdName};\n})();\nexport { ${classIdName} as default };`,
           );
         } else if (isExportNamed) {
           // 1. Export is kept, turn `class` into `let ClassName = IIFE`
-          s.appendLeft(classNode.start, `let ${classIdName} = /*#__PURE__*/ (() => {\n`);
-          s.appendRight(lastStatement.end, `\nreturn ${classIdName};\n})();`);
+          s.appendRight(classNode.start, `let ${classIdName} = /*#__PURE__*/ (() => {\n`);
+          s.appendLeft(lastStatement.end, `\nreturn ${classIdName};\n})();`);
         } else if (isVariableClass) {
           // Wrap class inside init: `/*#__PURE__*/ (() => { let ClassName = class ClassName {}; return ClassName; })()`
-          s.appendLeft(classNode.start, `/*#__PURE__*/ (() => {\nlet ${classIdName} = `);
+          s.appendRight(classNode.start, `/*#__PURE__*/ (() => {\nlet ${classIdName} = `);
           const terminator = activeWrapPaths.length === 0 ? ';' : '';
           const iifeClosing = activeWrapPaths.length === 0 ? '})()' : '})();';
-          s.appendRight(lastStatement.end, `${terminator}\nreturn ${classIdName};\n${iifeClosing}`);
+          s.appendLeft(lastStatement.end, `${terminator}\nreturn ${classIdName};\n${iifeClosing}`);
         } else {
           // Standard ClassDeclaration
-          s.appendLeft(classNode.start, `let ${classIdName} = /*#__PURE__*/ (() => {\n`);
-          s.appendRight(lastStatement.end, `\nreturn ${classIdName};\n})();`);
+          s.appendRight(classNode.start, `let ${classIdName} = /*#__PURE__*/ (() => {\n`);
+          s.appendLeft(lastStatement.end, `\nreturn ${classIdName};\n})();`);
         }
 
         markEdited(statement.start, lastStatement.end);
@@ -612,7 +612,7 @@ export function transform(filename: string, code: string, options: OxcTransformO
       } else if (isExportDefault && !hasPotentialSideEffects) {
         // Splitting default export even when not wrapped
         s.overwrite(statement.start, classNode.start, '');
-        s.appendRight(classNode.end, `\nexport { ${classIdName} as default };`);
+        s.appendLeft(classNode.end, `\nexport { ${classIdName} as default };`);
         markEdited(statement.start, classNode.end);
       }
     }