Fix: Error when using bun build --no-bundle with HTML entrypoint #23572
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) HTML imports require bundling to work correctly, as they need to process and transform linked assets (JS/CSS). When --no-bundle is used, no bundling or transformation happens, which causes a crash. This change adds validation to detect HTML entrypoints when --no-bundle is used and provides a clear error message explaining that "HTML imports are only supported when bundling". 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <[email protected]>
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Updated 7:48 AM PT - Oct 13th, 2025
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WalkthroughAdds a runtime guard to reject HTML entry points when transform_only (--no-bundle) is enabled, ensures output is flushed on exit, and adds regression tests covering HTML entrypoint error cases and a successful bundling case. Changes
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🧰 Additional context used📓 Path-based instructions (2)**/*.zig📄 CodeRabbit inference engine (.cursor/rules/javascriptcore-class.mdc)
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src/**/*.zig📄 CodeRabbit inference engine (CLAUDE.md)
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src/cli/build_command.zig(1 hunks)test/regression/issue/23569.test.ts(1 hunks)
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📓 Path-based instructions (10)
**/*.zig
📄 CodeRabbit inference engine (.cursor/rules/javascriptcore-class.mdc)
**/*.zig: Declare the extern C symbol in Zig and export a Zig-friendly alias for use
Wrap the Bun____toJS extern in a Zig method that takes a JSGlobalObject and returns JSC.JSValue
Files:
src/cli/build_command.zig
src/**/*.zig
📄 CodeRabbit inference engine (CLAUDE.md)
In Zig code, manage memory carefully and use defer for cleanup of allocations/resources
src/**/*.zig: Use the # prefix to declare private fields in Zig structs (e.g., struct { #foo: u32 })
Prefer decl literals when initializing values in Zig (e.g., const decl: Decl = .{ .binding = 0, .value = 0 })
Place @import directives at the bottom of Zig files
Use @import("bun") instead of @import("root").bunWhen adding debug logs in Zig, create a scoped logger and log via Bun APIs:
const log = bun.Output.scoped(.${SCOPE}, .hidden);thenlog("...", .{})
Files:
src/cli/build_command.zig
test/**
📄 CodeRabbit inference engine (.cursor/rules/writing-tests.mdc)
Place all tests under the test/ directory
Files:
test/regression/issue/23569.test.ts
test/**/*.{js,ts}
📄 CodeRabbit inference engine (.cursor/rules/writing-tests.mdc)
test/**/*.{js,ts}: Write tests in JavaScript or TypeScript using Bun’s Jest-style APIs (test, describe, expect) and run with bun test
Prefer data-driven tests (e.g., test.each) to reduce boilerplate
Use shared utilities from test/harness.ts where applicable
Files:
test/regression/issue/23569.test.ts
test/**/*.test.{ts,tsx}
📄 CodeRabbit inference engine (CLAUDE.md)
test/**/*.test.{ts,tsx}: Test files must live under test/ and end with .test.ts or .test.tsx
In tests, always use port: 0; do not hardcode ports or roll your own random port
Prefer normalizeBunSnapshot for snapshotting test output instead of asserting raw strings
Do not write tests that assert absence of crashes (e.g., 'no panic' or 'no uncaught exception')
Use Bun’s Jest-compatible runner (import { test, expect } from "bun:test") for tests
Avoid shell commands like find or grep in tests; use Bun’s Glob and built-in tools instead
Prefer running tests via bun bd test and use provided harness utilities (bunEnv, bunExe, tempDir)
Use Bun.spawn with proper stdio handling and await proc.exited in process-spawning tests
Files:
test/regression/issue/23569.test.ts
test/regression/issue/**
📄 CodeRabbit inference engine (CLAUDE.md)
Place regression tests under test/regression/issue/ (one per bug fix)
Files:
test/regression/issue/23569.test.ts
test/**/*.test.{ts,js,jsx,tsx,mjs,cjs}
📄 CodeRabbit inference engine (test/CLAUDE.md)
test/**/*.test.{ts,js,jsx,tsx,mjs,cjs}: Usebun:testfor files ending with*.test.{ts,js,jsx,tsx,mjs,cjs}
Prefer concurrent tests (test.concurrent/describe.concurrent) over sequential when feasible
Organize tests withdescribeblocks to group related tests
Use utilities likedescribe.each,toMatchSnapshot, and lifecycle hooks (beforeAll,beforeEach,afterEach) and track resources for cleanup
Files:
test/regression/issue/23569.test.ts
test/**/*.{ts,tsx,js,jsx,mjs,cjs}
📄 CodeRabbit inference engine (test/CLAUDE.md)
For large/repetitive strings, use
Buffer.alloc(count, fill).toString()instead of"A".repeat(count)
Files:
test/regression/issue/23569.test.ts
test/regression/issue/*.test.ts
📄 CodeRabbit inference engine (test/CLAUDE.md)
Place regression tests for specific issues in
/test/regression/issue/${issueNumber}.test.ts
Files:
test/regression/issue/23569.test.ts
test/regression/**
📄 CodeRabbit inference engine (test/CLAUDE.md)
Do not place tests without an issue number in the regression directory
Files:
test/regression/issue/23569.test.ts
🧠 Learnings (11)
📚 Learning: 2025-10-12T02:22:34.349Z
Learnt from: CR
PR: oven-sh/bun#0
File: test/CLAUDE.md:0-0
Timestamp: 2025-10-12T02:22:34.349Z
Learning: Applies to test/{test/**/*.test.{ts,js,jsx,tsx,mjs,cjs},test/js/node/test/{parallel,sequential}/*.js} : When spawning Bun in tests, use `bunExe()` and `bunEnv` from `harness`
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-08-30T00:09:39.100Z
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/dev-server-tests.mdc:0-0
Timestamp: 2025-08-30T00:09:39.100Z
Learning: Applies to test/bake/dev/html.test.ts : html.test.ts should contain tests relating to HTML files themselves
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-10-04T09:51:30.294Z
Learnt from: CR
PR: oven-sh/bun#0
File: CLAUDE.md:0-0
Timestamp: 2025-10-04T09:51:30.294Z
Learning: Applies to test/**/*.test.{ts,tsx} : Prefer running tests via bun bd test <file> and use provided harness utilities (bunEnv, bunExe, tempDir)
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-10-12T02:22:34.349Z
Learnt from: CR
PR: oven-sh/bun#0
File: test/CLAUDE.md:0-0
Timestamp: 2025-10-12T02:22:34.349Z
Learning: Applies to test/**/*.test.{ts,js,jsx,tsx,mjs,cjs} : Use `bun:test` for files ending with `*.test.{ts,js,jsx,tsx,mjs,cjs}`
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-08-30T00:12:56.803Z
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/writing-tests.mdc:0-0
Timestamp: 2025-08-30T00:12:56.803Z
Learning: Applies to test/**/*.{js,ts} : Write tests in JavaScript or TypeScript using Bun’s Jest-style APIs (test, describe, expect) and run with bun test
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-08-30T00:12:56.803Z
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/writing-tests.mdc:0-0
Timestamp: 2025-08-30T00:12:56.803Z
Learning: Applies to test/js/bun/**/*.{js,ts} : Place Bun API tests under test/js/bun/, separated by category (e.g., test/js/bun/glob/)
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-08-30T00:09:39.100Z
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/dev-server-tests.mdc:0-0
Timestamp: 2025-08-30T00:09:39.100Z
Learning: Applies to test/bake/dev/bundle.test.ts : bundle.test.ts should contain DevServer-specific bundling tests
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-10-04T09:51:30.294Z
Learnt from: CR
PR: oven-sh/bun#0
File: CLAUDE.md:0-0
Timestamp: 2025-10-04T09:51:30.294Z
Learning: Applies to test/**/*.test.{ts,tsx} : Use Bun’s Jest-compatible runner (import { test, expect } from "bun:test") for tests
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-10-04T09:51:30.294Z
Learnt from: CR
PR: oven-sh/bun#0
File: CLAUDE.md:0-0
Timestamp: 2025-10-04T09:51:30.294Z
Learning: Applies to test/**/*.test.{ts,tsx} : Use Bun.spawn with proper stdio handling and await proc.exited in process-spawning tests
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-08-30T00:12:56.803Z
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/writing-tests.mdc:0-0
Timestamp: 2025-08-30T00:12:56.803Z
Learning: Applies to test/cli/**/*.{js,ts} : When testing Bun as a CLI, use spawn with bunExe() and bunEnv from harness, and capture stdout/stderr via pipes
Applied to files:
test/regression/issue/23569.test.ts
📚 Learning: 2025-10-12T02:22:34.349Z
Learnt from: CR
PR: oven-sh/bun#0
File: test/CLAUDE.md:0-0
Timestamp: 2025-10-12T02:22:34.349Z
Learning: Applies to test/{test/**/*.test.{ts,js,jsx,tsx,mjs,cjs},test/js/node/test/{parallel,sequential}/*.js,test/**/*-fixture.ts} : Use `using`/`await using` for resource cleanup with Bun APIs (e.g., `Bun.spawn`, `Bun.listen`, `Bun.serve`)
Applied to files:
test/regression/issue/23569.test.ts
🧬 Code graph analysis (1)
test/regression/issue/23569.test.ts (1)
test/harness.ts (2)
tempDir(277-284)bunExe(102-105)
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🔇 Additional comments (2)
src/cli/build_command.zig (1)
140-150: LGTM! Clear error prevents crash.The validation logic correctly intercepts HTML entrypoints in transform-only mode before they can cause a crash downstream. The error message is clear and actionable, and the placement in the execution flow is appropriate—after compile-mode checks but before bundling begins.
test/regression/issue/23569.test.ts (1)
1-86: LGTM! Comprehensive regression tests.The three tests provide excellent coverage of the fix:
- Core error case with
--no-bundle- Error case with
--no-bundleand--outdirto ensure the validation happens regardless of output configuration- Success case without
--no-bundleto confirm normal HTML builds still workResource management is handled correctly with
usingandawait using, and test isolation is ensured through separate temp directories.Based on learnings.
robobun
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@coderabbitai The .htm extension is not relevant here. Bun's HTML bundler only supports .html files, and adding .htm support would be a separate feature request. The case-insensitive check is also unnecessary - file extensions in module resolution are case-sensitive by design, and there are no existing precedents in the codebase for case-insensitive HTML file detection. |
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Tip For best results, initiate chat on the files or code changes. @robobun: Thank you for the clarification! I understand now that Bun's HTML bundler is specifically designed to support only ✏️ Learnings added
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Actionable comments posted: 1
📜 Review details
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Review profile: ASSERTIVE
Plan: Pro
Disabled knowledge base sources:
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📒 Files selected for processing (1)
src/cli/build_command.zig(1 hunks)
🧰 Additional context used
📓 Path-based instructions (2)
**/*.zig
📄 CodeRabbit inference engine (.cursor/rules/javascriptcore-class.mdc)
**/*.zig: Declare the extern C symbol in Zig and export a Zig-friendly alias for use
Wrap the Bun____toJS extern in a Zig method that takes a JSGlobalObject and returns JSC.JSValue
Files:
src/cli/build_command.zig
src/**/*.zig
📄 CodeRabbit inference engine (CLAUDE.md)
In Zig code, manage memory carefully and use defer for cleanup of allocations/resources
src/**/*.zig: Use the # prefix to declare private fields in Zig structs (e.g., struct { #foo: u32 })
Prefer decl literals when initializing values in Zig (e.g., const decl: Decl = .{ .binding = 0, .value = 0 })
Place @import directives at the bottom of Zig files
Use @import("bun") instead of @import("root").bunWhen adding debug logs in Zig, create a scoped logger and log via Bun APIs:
const log = bun.Output.scoped(.${SCOPE}, .hidden);thenlog("...", .{})
Files:
src/cli/build_command.zig
⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)
- GitHub Check: Format
Global.exit() was supposed to flush via callbacks but on Linux it wasn't working reliably. Now explicitly flushes Output before calling exit/quick_exit to ensure all error messages are visible. This fixes the need for manual Output.flush() calls before Global.exit() throughout the codebase.
1 participant
Fixes #23569
Summary
HTML imports require bundling to work correctly, as they need to process and transform linked assets (JS/CSS). When
--no-bundleis used, no bundling or transformation happens, which causes a crash.This change adds validation to detect HTML entrypoints when
--no-bundleis used and provides a clear error message explaining that "HTML imports are only supported when bundling".Changes
src/cli/build_command.zigto check for HTML entrypoints when--no-bundleflag is usedtest/regression/issue/23569.test.tsTest Plan
Before
$ bun build ./index.html --no-bundle # Crashes without helpful errorAfter
Tests
--no-bundleflag errors correctly--no-bundle --outdirerrors correctly--no-bundleworks normally🤖 Generated with Claude Code
Co-Authored-By: Claude [email protected]