Add special error for bun builtins in bundler

src/bundler/bundle_v2.zig

@@ -628,6 +628,16 @@ pub const BundleV2 = struct {
                                     .{ import_record.kind.errorLabel(), path_to_use },
                                     import_record.kind,
                                 ) catch unreachable;
+                            } else if ((target == .browser or target == .node) and options.ExternalModules.isBunBuiltin(path_to_use)) {
+                                addError(
+                                    log,
+                                    source,
+                                    import_record.range,
+                                    this.graph.allocator,
+                                    "{s} build cannot {s} Bun module: \"{s}\". To use Bun builtins, set target to 'bun' or feature-detect the Bun global at runtime.",
+                                    .{ if (target == .browser) "Browser" else "Node", import_record.kind.errorLabel(), path_to_use },
+                                    import_record.kind,
+                                ) catch unreachable;
                             } else {
                                 addError(
                                     log,
@@ -2365,6 +2375,16 @@ pub const BundleV2 = struct {
                                         .{ import_record.kind.errorLabel(), import_record.path.text },
                                         import_record.kind,
                                     ) catch @panic("unexpected log error");
+                                } else if ((ast.target == .browser or ast.target == .node) and options.ExternalModules.isBunBuiltin(import_record.path.text)) {
+                                    addError(
+                                        this.bundler.log,
+                                        source,
+                                        import_record.range,
+                                        this.graph.allocator,
+                                        "{s} build cannot {s} Bun builtin: \"{s}\". To use Bun builtins, set target to 'bun' or feature-detect the Bun global at runtime.",
+                                        .{ if (ast.target == .browser) "Browser" else "Node", import_record.kind.errorLabel(), import_record.path.text },
+                                        import_record.kind,
+                                    ) catch @panic("unexpected log error");
                                 } else {
                                     addError(
                                         this.bundler.log,

src/options.zig

@@ -92,6 +92,10 @@ pub const ExternalModules = struct {
         return bun.JSC.HardcodedModule.Aliases.has(str, .node);
     }
 
+    pub fn isBunBuiltin(str: string) bool {
+        return bun.JSC.HardcodedModule.Aliases.has(str, .bun);
+    }
+
     const default_wildcard_patterns = &[_]WildcardPattern{
         .{
             .prefix = "/bun:",

test/bundler/bundler_browser.test.ts

@@ -56,7 +56,7 @@ describe("bundler", () => {
       stdout: "function\nfunction\nundefined",
     },
     onAfterBundle(api) {
-      api.expectFile('out.js').not.toInclude('import ');
+      api.expectFile("out.js").not.toInclude("import ");
     },
   });
   itBundled("browser/NodeTTY", {
@@ -73,7 +73,7 @@ describe("bundler", () => {
       stdout: "function\nfunction\nfalse",
     },
     onAfterBundle(api) {
-      api.expectFile('out.js').not.toInclude('import ');
+      api.expectFile("out.js").not.toInclude("import ");
     },
   });
   // TODO: use nodePolyfillList to generate the code in here.
@@ -228,11 +228,8 @@ describe("bundler", () => {
   const bunModules: Record<string, "no-op" | "polyfill" | "error"> = {
     "bun": "error",
     "bun:ffi": "error",
-    "bun:dns": "error",
     "bun:test": "error",
     "bun:sqlite": "error",
-    // "bun:wrap": "error",
-    "bun:internal": "error",
     "bun:jsc": "error",
   };
 
@@ -281,7 +278,33 @@ describe("bundler", () => {
     bundleErrors: {
       "/entry.js": Object.keys(bunModules)
         .filter(x => bunModules[x] === "error")
-        .map(x => `Could not resolve: "${x}". Maybe you need to "bun install"?`),
+        .map(
+          x =>
+            `Browser build cannot import Bun builtin: "${x}". To use Bun builtins, set target to 'bun' or feature-detect the Bun global at runtime.`,
+        ),
+    },
+  });
+
+  itBundled("browser/ImportBunErrorInNode", {
+    skipOnEsbuild: true,
+    files: {
+      "/entry.js": `
+        ${Object.keys(bunModules)
+          .map((x, i) => `import * as bun_${i} from "${x}";`)
+          .join("\n")}
+        ${Object.keys(bunModules)
+          .map((x, i) => `console.log("${x.padEnd(12, " ")}:", !!bun_${i});`)
+          .join("\n")}
+      `,
+    },
+    target: "node",
+    bundleErrors: {
+      "/entry.js": Object.keys(bunModules)
+        .filter(x => bunModules[x] === "error")
+        .map(
+          x =>
+            `Node build cannot import Bun builtin: "${x}". To use Bun builtins, set target to 'bun' or feature-detect the Bun global at runtime.`,
+        ),
     },
   });