js_printer: re-wrap delete of folded import/cjs-export identifier

src/js_printer/lib.rs

@@ -1216,6 +1216,20 @@ fn is_identifier_or_numeric_constant_or_property_access(expr: &js_ast::Expr) ->
     use js_ast::ExprData;
     match &expr.data {
         ExprData::EIdentifier(_) | ExprData::EDot(_) | ExprData::EIndex(_) => true,
+        // These are produced by the visit pass (namespace-import rewrite, cjs2esm,
+        // `module.exports`/`import.meta.hot`/`require` inlining) and in at least
+        // one output mode print as a bare identifier or a property access. Without
+        // the `(0, ...)` wrap the printed `delete` sees a Reference and its
+        // result/effect differ from the source. Over-wrapping the variants that can
+        // also print as a value literal is harmless.
+        ExprData::EImportIdentifier(_)
+        | ExprData::ECommonjsExportIdentifier(_)
+        | ExprData::ESpecial(_)
+        | ExprData::ERequireCallTarget
+        | ExprData::ERequireResolveCallTarget
+        | ExprData::ERequireMain
+        | ExprData::EImportMeta(_) => true,
+        ExprData::EInlinedEnum(e) => is_identifier_or_numeric_constant_or_property_access(&e.value),
         ExprData::ENumber(e) => e.value().is_infinite() || e.value().is_nan(),
         _ => false,
     }

test/bundler/bundler_cjs2esm.test.ts

@@ -392,6 +392,55 @@ describe("bundler", () => {
       stdout: '[[{"xyz":456},456],[{"xyz":123},123],[{"xyz":456},456],[{"xyz":123},123]]',
     },
   });
+  // `delete (null ?? exports.a)` evaluates to a value, so the result is `true`
+  // with no effect on the property. Under cjs2esm, `exports.a` is rewritten to
+  // an `ECommonjsExportIdentifier`; the printer has to re-wrap it as `(0, ...)`
+  // so `delete` still sees a value instead of the hoisted binding.
+  itBundled("cjs2esm/DeleteFoldedExportsPropertyRef", {
+    files: {
+      "/entry.js": /* js */ `
+        exports.a = 1;
+        console.log(delete (null ?? exports.a), exports.a);
+        console.log(delete (0, exports.a), exports.a);
+      `,
+    },
+    onAfterBundle: api => {
+      const code = api.readFile("out.js");
+      expect(code).not.toMatch(/^[^"]*delete\s+\$a\b/m);
+    },
+    run: { stdout: "true 1\ntrue 1" },
+  });
+  itBundled("cjs2esm/DeleteFoldedExportsPropertyRefConsumer", {
+    files: {
+      "/entry.js": /* js */ `
+        import { a } from "./lib.js";
+        console.log(a);
+      `,
+      "/lib.js": /* js */ `
+        exports.a = 1;
+        console.log(delete (null ?? exports.a), exports.a);
+      `,
+    },
+    run: { stdout: "true 1\n1" },
+  });
+  // `module.exports` under cjs2esm rewrites to ESpecial::ModuleExports, which
+  // prints as the `exports_*` namespace symbol. Output-shape check only: a bare
+  // `module.exports` value-read under cjs2esm currently emits a reference that
+  // has no declaration (a separate pre-existing issue), so the bundle cannot be
+  // executed here.
+  itBundled("cjs2esm/DeleteFoldedModuleExportsRef", {
+    files: {
+      "/entry.js": /* js */ `
+        exports.a = 1;
+        globalThis.r = delete (null ?? module.exports);
+      `,
+    },
+    onAfterBundle: api => {
+      const code = api.readFile("out.js");
+      expect(code).toMatch(/delete\s+\(0,\s*exports_\w+\)/);
+      expect(code).not.toMatch(/delete\s+exports_\w+\b/);
+    },
+  });
   // https://github.com/oven-sh/bun/issues/4565
   // `exports.x = ...` as the unbraced body of if/while/do/else must not be
   // converted to `var $x = ...; export { $x as x };` because `export` is only

test/bundler/bundler_edgecase.test.ts

@@ -2858,6 +2858,96 @@ describe("bundler", () => {
       expect(out).not.toContain("require_foo\u2014bar");
     },
   });
+  // `delete (null ?? ns.x)` evaluates its operand to a value, so the result is
+  // `true` with no side effect. When bundling rewrites `ns.x` to the local
+  // binding (EImportIdentifier) after folding `??`, the printer must re-wrap
+  // the operand so `delete` still sees a value instead of the binding itself.
+  // Without the wrap the output is `delete x`, a strict-mode SyntaxError.
+  itBundled("edgecase/DeleteFoldedNamespacePropertyRef", {
+    files: {
+      "/entry.js": /* js */ `
+        import * as ns from "./m.js";
+        console.log(delete (null ?? ns.x), ns.x);
+        console.log(delete (0, ns.x), ns.x);
+        console.log(delete (true ? ns.x : 0), ns.x);
+      `,
+      "/m.js": /* js */ `
+        export let x = 1;
+      `,
+    },
+    onAfterBundle: api => {
+      const code = api.readFile("out.js");
+      expect(code).not.toMatch(/delete\s+x\b/);
+      expect(code).not.toMatch(/delete\s+ns\.x\b/);
+    },
+    run: { stdout: "true 1\ntrue 1\ntrue 1" },
+  });
+  itBundled("edgecase/DeleteFoldedNamespacePropertyRefMinify", {
+    files: {
+      "/entry.js": /* js */ `
+        import * as ns from "./m.js";
+        console.log(delete (null ?? ns.x), ns.x);
+      `,
+      "/m.js": /* js */ `
+        export let x = 1;
+      `,
+    },
+    minifySyntax: true,
+    minifyWhitespace: true,
+    run: { stdout: "true 1" },
+  });
+  // Same path via a direct named import: the identifier becomes an
+  // EImportIdentifier during the visit pass.
+  itBundled("edgecase/DeleteFoldedImportedBindingRef", {
+    files: {
+      "/entry.js": /* js */ `
+        import { x } from "./m.js";
+        console.log(delete (null ?? x), x);
+      `,
+      "/m.js": /* js */ `
+        export let x = 1;
+      `,
+    },
+    onAfterBundle: api => {
+      expect(api.readFile("out.js")).not.toMatch(/delete\s+x\b/);
+    },
+    run: { stdout: "true 1" },
+  });
+  // The bundler rewrites bare `require`/`require.main`/`require.resolve` to an
+  // ERequireCallTarget / ERequireMain / ERequireResolveCallTarget that prints
+  // as `__require` / `__require.main` / `__require.resolve`.
+  itBundled("edgecase/DeleteFoldedRequireRefs", {
+    files: {
+      "/entry.js": /* js */ `
+        console.log(delete (null ?? require));
+        console.log(delete (null ?? require.main));
+        console.log(delete (null ?? require.resolve));
+      `,
+    },
+    onAfterBundle: api => {
+      const code = api.readFile("out.js");
+      expect(code).not.toMatch(/delete\s+__require\b/);
+      expect(code).not.toMatch(/delete\s+require\b/);
+    },
+    run: { stdout: "true\ntrue\ntrue" },
+  });
+  // A same-file `const enum` member is inlined to an EInlinedEnum wrapping an
+  // ENumber during the visit pass, so the NaN/Infinity check has to look
+  // through the wrapper.
+  itBundled("edgecase/DeleteFoldedInlinedConstEnumNaN", {
+    files: {
+      "/entry.ts": /* ts */ `
+        const enum E { N = 0/0, I = 1/0, V = 1 }
+        console.log(delete (null ?? E.N), delete (null ?? E.I), delete (null ?? E.V));
+      `,
+    },
+    onAfterBundle: api => {
+      const code = api.readFile("out.js");
+      expect(code).not.toMatch(/delete\s+NaN\b/);
+      expect(code).not.toMatch(/delete\s+Infinity\b/);
+    },
+    run: { stdout: "true true true" },
+  });
 });
 
 for (const backend of ["api", "cli"] as const) {