Fix Bun.build() compile API to properly apply sourcemaps (#23916)

## Summary Fixes a bug where the `Bun.build()` API with `compile: true` did not properly apply sourcemaps, even when `sourcemap: "inline"` was specified. This resulted in error stack traces showing bundled virtual paths (`/$bunfs/root/`) instead of actual source file names and line numbers. ## Problem The CLI `bun build --compile --sourcemap` worked correctly, but the equivalent API call did not: ```javascript // This did NOT work (before fix) await Bun.build({ entrypoints: ['./app.js'], compile: true, sourcemap: "inline" // <-- Was ignored/broken }); ``` Error output showed bundled paths: ``` error: Error from helper module at helperFunction (/$bunfs/root/app.js:4:9) // ❌ Wrong path at main (/$bunfs/root/app.js:9:17) // ❌ Wrong line numbers ``` ## Root Cause The CLI explicitly overrides any sourcemap type to `.external` when compile mode is enabled (in `/workspace/bun/src/cli/Arguments.zig`): ```zig // when using --compile, only `external` works if (ctx.bundler_options.compile) { opts.source_map = .external; } ``` The API implementation in `JSBundler.zig` was missing this override. ## Solution Added the same sourcemap override logic to `JSBundler.zig` when compile mode is enabled: ```zig // When using --compile, only `external` sourcemaps work, as we do not // look at the source map comment. Override any other sourcemap type. if (this.source_map != .none) { this.source_map = .external; } ``` Now error output correctly shows source file names: ``` error: Error from helper module at helperFunction (helper.js:2:9) // ✅ Correct file at main (app.js:4:3) // ✅ Correct line numbers ``` ## Tests Added comprehensive test coverage in `/workspace/bun/test/bundler/bun-build-compile-sourcemap.test.ts`: - ✅ `sourcemap: "inline"` works - ✅ `sourcemap: true` works - ✅ `sourcemap: "external"` works - ✅ Multiple source files show correct file names - ✅ Without sourcemap, bundled paths are shown (expected behavior) All tests: - ✅ Fail with `USE_SYSTEM_BUN=1` (confirms bug exists) - ✅ Pass with `bun bd test` (confirms fix works) - ✅ Use `tempDir()` to avoid disk space issues 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> --------- Co-authored-by: Claude Bot <claude-bot@bun.sh> Co-authored-by: Claude <noreply@anthropic.com>
2026-02-02 15:08:46 +00:00 · 2025-10-21 14:25:08 -07:00
parent 840c6ca471
commit cd8043b76e
2 changed files with 153 additions and 0 deletions
--- a/test/bundler/bun-build-compile-sourcemap.test.ts
+++ b/test/bundler/bun-build-compile-sourcemap.test.ts
@@ -0,0 +1,147 @@
+import { describe, expect, test } from "bun:test";
+import { bunEnv, tempDir } from "harness";
+import { join } from "path";
+
+describe("Bun.build compile with sourcemap", () => {
+  const helperFiles = {
+    "helper.js": `export function helperFunction() {
+  throw new Error("Error from helper module");
+}`,
+    "app.js": `import { helperFunction } from "./helper.js";
+
+function main() {
+  helperFunction();
+}
+
+main();`,
+  };
+
+  async function testSourcemapOption(sourcemapValue: "inline" | "external" | true, testName: string) {
+    using dir = tempDir(`build-compile-sourcemap-${testName}`, helperFiles);
+
+    const result = await Bun.build({
+      entrypoints: [join(String(dir), "app.js")],
+      compile: true,
+      sourcemap: sourcemapValue,
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.outputs.length).toBe(1);
+
+    const executablePath = result.outputs[0].path;
+    expect(await Bun.file(executablePath).exists()).toBe(true);
+
+    // Run the compiled executable and capture the error
+    await using proc = Bun.spawn({
+      cmd: [executablePath],
+      env: bunEnv,
+      cwd: String(dir),
+      stdout: "pipe",
+      stderr: "pipe",
+    });
+
+    const [_stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+    // With sourcemaps working, we should see the actual file names
+    expect(stderr).toContain("helper.js");
+    expect(stderr).toContain("app.js");
+
+    // Should NOT see the bundled virtual path (/$bunfs/root/ on Unix, B:/~BUN/root/ on Windows)
+    expect(stderr).not.toMatch(/(\$bunfs|~BUN)\/root\//);
+
+    // Verify it failed (the error was thrown)
+    expect(exitCode).not.toBe(0);
+  }
+
+  test.each([
+    ["inline" as const, "inline"],
+    [true as const, "true"],
+    ["external" as const, "external"],
+  ])("compile with sourcemap: %s should work", async (sourcemapValue, testName) => {
+    await testSourcemapOption(sourcemapValue, testName);
+  });
+
+  test("compile without sourcemap should show bundled paths", async () => {
+    using dir = tempDir("build-compile-no-sourcemap", helperFiles);
+
+    const result = await Bun.build({
+      entrypoints: [join(String(dir), "app.js")],
+      compile: true,
+      // No sourcemap option
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.outputs.length).toBe(1);
+
+    const executablePath = result.outputs[0].path;
+    expect(await Bun.file(executablePath).exists()).toBe(true);
+
+    // Run the compiled executable and capture the error
+    await using proc = Bun.spawn({
+      cmd: [executablePath],
+      env: bunEnv,
+      cwd: String(dir),
+      stdout: "pipe",
+      stderr: "pipe",
+    });
+
+    const [_stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+    // Without sourcemaps, we should see the bundled virtual path (/$bunfs/root/ on Unix, B:/~BUN/root/ on Windows)
+    expect(stderr).toMatch(/(\$bunfs|~BUN)\/root\//);
+
+    // Verify it failed (the error was thrown)
+    expect(exitCode).not.toBe(0);
+  });
+
+  test("compile with multiple source files", async () => {
+    using dir = tempDir("build-compile-sourcemap-multiple-files", {
+      "utils.js": `export function utilError() {
+  throw new Error("Error from utils");
+}`,
+      "helper.js": `import { utilError } from "./utils.js";
+export function helperFunction() {
+  utilError();
+}`,
+      "app.js": `import { helperFunction } from "./helper.js";
+
+function main() {
+  helperFunction();
+}
+
+main();`,
+    });
+
+    const result = await Bun.build({
+      entrypoints: [join(String(dir), "app.js")],
+      compile: true,
+      sourcemap: "inline",
+    });
+
+    expect(result.success).toBe(true);
+    const executable = result.outputs[0].path;
+    expect(await Bun.file(executable).exists()).toBe(true);
+
+    // Run the executable
+    await using proc = Bun.spawn({
+      cmd: [executable],
+      env: bunEnv,
+      cwd: String(dir),
+      stdout: "pipe",
+      stderr: "pipe",
+    });
+
+    const [_stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+    // With sourcemaps, should show all three source file names
+    expect(stderr).toContain("utils.js");
+    expect(stderr).toContain("helper.js");
+    expect(stderr).toContain("app.js");
+
+    // Should NOT show bundled paths (/$bunfs/root/ on Unix, B:/~BUN/root/ on Windows)
+    expect(stderr).not.toMatch(/(\$bunfs|~BUN)\/root\//);
+
+    // Verify it failed (the error was thrown)
+    expect(exitCode).not.toBe(0);
+  });
+});