fix(cmake): download baseline WebKit for x64 baseline builds

[robobun]

Summary

• Adds -baseline suffix to WebKit download URL when ENABLE_BASELINE is set for x64 builds, so baseline Bun links against a WebKit compiled without AVX/AVX2 instructions
• Removes unused WEBKIT_PREVIEW_PR variable (WebKit PR Error using custom npm registry in bunfig.toml #140 was already merged)

Root cause

When ENABLE_BASELINE is set, Bun's own code is compiled with -march=nehalem (SSE4.2 only, no AVX). However, SetupWebKit.cmake was downloading the regular WebKit tarball (bun-webkit-linux-amd64.tar.gz) which is compiled with AVX/AVX2 support. When baseline Bun called into WebKit/JSC on a non-AVX CPU, it hit AVX instructions and crashed with SIGILL (exit code 132).

Fix

The suffix computation now includes a check for ENABLE_BASELINE:

if(ENABLE_BASELINE AND WEBKIT_ARCH STREQUAL "amd64")
  set(WEBKIT_SUFFIX "${WEBKIT_SUFFIX}-baseline")
endif()

This produces the correct artifact names matching oven-sh/WebKit PR #137:

• bun-webkit-linux-amd64-baseline.tar.gz
• bun-webkit-linux-amd64-baseline-lto.tar.gz
• bun-webkit-linux-amd64-musl-baseline.tar.gz
• bun-webkit-linux-amd64-musl-baseline-lto.tar.gz

Dependencies

This fix requires oven-sh/WebKit PR #137 to be merged first so that the baseline WebKit artifacts exist in releases. Until then, baseline CI builds will fail to download WebKit (which is the desired behavior - it's better to fail loudly at build time than to silently link AVX-enabled WebKit into a baseline binary).

Test plan

• Verify suffix computation produces correct download URLs for all combinations (baseline, baseline+musl, baseline+lto, baseline+musl+lto)
• After oven-sh/WebKit PR Bug with multiple simultaneous connections in Bun.serve when sending a file #137 is merged: verify baseline x64 build downloads and links against the correct WebKit
• After oven-sh/WebKit PR Bug with multiple simultaneous connections in Bun.serve when sending a file #137 is merged: verify baseline Bun runs without SIGILL on non-AVX CPUs

Closes #27006

🤖 Generated with Claude Code

[robobun]

^{Updated 1:19 PM PT - Feb 13th, 2026}

❌ Your commit 883ea966 has 9 failures in Build #37200 (All Failures):

• test/js/web/fetch/fetch.test.ts - 1 failing on 🪟 2019 x64
• test/js/web/fetch/fetch.test.ts - 1 failing on 🐧 3.23 aarch64
• test/js/web/fetch/fetch.test.ts - 1 failing on 🐧 3.23 x64
• test/js/web/fetch/fetch.tls.test.ts - 5 failing on 🪟 2019 x64
• test/js/web/fetch/fetch.tls.test.ts - 5 failing on 🐧 3.23 aarch64
• test/js/web/fetch/fetch.tls.test.ts - 5 failing on 🐧 3.23 x64
• test/integration/next-pages/test/dev-server.test.ts - 1 failing on 🍎 13 aarch64
• test/integration/next-pages/test/dev-server.test.ts - 1 failing on 🍎 14 aarch64
• test/js/bun/test/parallel/test-https-should-work-when-sending-request-with-agent-false.ts - code 1 on 🪟 2019 x64
• test/js/bun/test/parallel/test-https-should-work-when-sending-request-with-agent-false.ts - code 1 on 🐧 3.23 aarch64
• test/js/bun/test/parallel/test-https-should-work-when-sending-request-with-agent-false.ts - code 1 on 🐧 3.23 x64
• test/js/workerd/html-rewriter.test.js - 1 failing on 🪟 2019 x64
• test/js/workerd/html-rewriter.test.js - 1 failing on 🐧 3.23 aarch64
• test/js/workerd/html-rewriter.test.js - 1 failing on 🐧 3.23 x64
• test/js/node/http2/node-http2.test.js - 6 failing on 🪟 2019 x64
• test/js/node/http2/node-http2.test.js - 6 failing on 🐧 3.23 x64
• test/js/node/http2/node-http2.test.js - 6 failing on 🐧 3.23 aarch64
• test/js/bun/http/proxy.test.js - 4 failing on 🪟 2019 x64
• test/js/bun/http/proxy.test.js - 4 failing on 🐧 3.23 x64
• test/js/bun/http/proxy.test.js - 4 failing on 🐧 3.23 aarch64
• test/internal/ban-words.test.ts - 1 failing on 🍎 14 x64
• test/internal/ban-words.test.ts - 1 failing on 🪟 2019 x64
• test/internal/ban-words.test.ts - 1 failing on 🐧 13 x64-asan
• test/internal/ban-words.test.ts - 1 failing on 🍎 13 x64
• test/internal/ban-words.test.ts - 1 failing on 🍎 13 aarch64
• test/internal/ban-words.test.ts - 1 failing on 🍎 14 aarch64
• test/internal/ban-words.test.ts - 1 failing on 🐧 13 aarch64
• test/internal/ban-words.test.ts - 1 failing on 🐧 25.04 aarch64
• test/internal/ban-words.test.ts - 1 failing on 🐧 3.23 aarch64
• test/internal/ban-words.test.ts - 1 failing on 🐧 3.23 x64
• test/internal/ban-words.test.ts - 1 failing on 🐧 25.04 x64
• test/internal/ban-words.test.ts - 1 failing on 🐧 13 x64
• cmake/targets/BuildBun.cmake - cmake error on 🐧 x64-baseline - build-zig
• cmake/targets/BuildBun.cmake - cmake error on 🪟 x64-baseline - build-zig
• cmake/targets/BuildBun.cmake - cmake error on 🐧 x64-musl-baseline - build-cpp
• cmake/targets/BuildBun.cmake - cmake error on 🐧 x64-musl-baseline - build-zig
• cmake/targets/BuildBun.cmake - cmake error on 🐧 x64-baseline - build-cpp
• cmake/targets/BuildBun.cmake - cmake error on 🪟 x64-baseline - build-cpp
• cmake/targets/BuildBun.cmake - cmake error on 🪟 x64-baseline - build-cpp

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🧪   To try this PR locally:

bunx bun-pr 27007

That installs a local version of the PR into your bun-27007 executable, so you can run:

bun-27007 --bun

[coderabbitai]

Walkthrough

Modified WebKit CMake configuration to remove WEBKIT_PREVIEW_PR definition and introduce baseline build suffix handling. When ENABLE_BASELINE is enabled and WEBKIT_ARCH is amd64, the script appends -baseline to WEBKIT_SUFFIX in two locations, affecting artifact naming and download URLs for baseline builds.

Changes

Cohort / File(s)	Summary
WebKit Build Configuration cmake/tools/SetupWebKit.cmake	Removed WEBKIT_PREVIEW_PR 140 definition. Added baseline build suffix (-baseline) to WEBKIT_SUFFIX when ENABLE_BASELINE is enabled and WEBKIT_ARCH is amd64, applied in two locations affecting WEBKIT_NAME, WEBKIT_FILENAME, and download URL construction.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Merge Conflict Detection	⚠️ Warning	❌ Merge conflicts detected (6 files): ⚔️ cmake/tools/SetupWebKit.cmake (content) ⚔️ src/CLAUDE.md (content) ⚔️ src/bun.js/bindings/webcore/SerializedScriptValue.cpp (content) ⚔️ src/linker.zig (content) ⚔️ src/logger.zig (content) ⚔️ src/s3/credentials.zig (content) These conflicts must be resolved before merging into main.	Resolve conflicts locally and push changes to this branch.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding baseline WebKit download functionality for x64 baseline builds, which is the primary purpose of this PR.
Description check	✅ Passed	The PR description thoroughly covers both required template sections: a clear summary of what the PR does and comprehensive documentation of how the changes were verified and tested.

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[claude]

Code Review

Newest first

✅ 883ea — Looks good!

Reviewed 1 file in cmake/tools/: Adds a -baseline suffix to the WebKit download URL for x64 baseline builds to prevent SIGILL crashes on non-AVX CPUs, and removes unused WEBKIT_PREVIEW_PR variable.

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