[build] 04-05-25 Build maintenance

- Compile using Xcode 16 (LLVM 19) on macOS
- Clean up comments based on no longer using Dawn
- Build simdutf using SSE4.2 to avoid having to include fallback code path, reducing code size. We already require SSE4.2 for zlib, so this won't break compatibility with any systems.
- Clean up redundant Bazel arguments
- Minor Bazel/include cleanup based on IWYU

Author: fhanau

.bazelrc

@@ -241,14 +241,6 @@ build:macos --macos_minimum_os=13.5
 # information on the flag.
 build:macos --copt='-femit-dwarf-unwind=no-compact-unwind'
 
-# Bazel doesn't allow setting flags only for a specific build mode like fastbuild, but somehow has
-# a flag that does this for ObjC to set "-O0 -DDEBUG=1". Worse yet, options set by this flag cannot
-# be overwritten on the command line, which confusingly makes enabling optimization there not have
-# an effect. On macOS we build some ObjC as part of Dawn, set this flag to an empty string so we
-# can set the right configuration flags.
-# TODO(soon): File a bazel issue for the flag so we can drop this.
-build:macos --experimental_objc_fastbuild_options=""
-
 # Cross-Compilation
 # Only cross-compiling on macOS from Apple Silicon to x86_64 is supported – using apple_support
 # makes this much easier than on other platforms. We could define a configuration for cross-

.github/workflows/_bazel.yml

@@ -69,6 +69,11 @@ jobs:
           git config --show-scope --show-origin core.symlinks
           git config --system core.longpaths true
           [System.IO.File]::WriteAllLines((Join-Path -Path $env:USERPROFILE -ChildPath '.bazelrc'), 'startup --output_user_root=\\\\?\\C:\\tmp')
+      - name: Setup macOS
+        if: inputs.os_name == 'macOS'
+        run: |
+          # Build using Xcode 16.3 (equivalent to Clang 19)
+          sudo xcode-select -s "/Applications/Xcode_16.3.app"
       - name: Configure download mirrors
         shell: bash
         run: |

.github/workflows/release.yml

@@ -128,6 +128,8 @@ jobs:
           sudo ln -s -f $(brew --prefix lld)/bin/ld64.lld /usr/local/bin/ld64.lld
           # Enable lld identical code folding to significantly reduce binary size.
           echo "build:macos --config=macos_lld_icf" >> .bazelrc
+          # Build using Xcode 16.3 (equivalent to Clang 19)
+          sudo xcode-select -s "/Applications/Xcode_16.3.app"
       - name: Setup Windows
         if: runner.os == 'Windows'
         run: |

build/BUILD.simdutf

@@ -2,6 +2,11 @@ cc_library(
     name = "simdutf",
     srcs = ["simdutf.cpp"],
     hdrs = ["simdutf.h"],
-    copts = ["-w"],
+    copts = select({
+        # Enable SSE4.2 extensions, this reduces code size as the fallback code path for pre-Westmere
+        # CPUs is no longer needed.
+        "@platforms//cpu:x86_64": ["-msse4.2"],
+        "//conditions:default": [],
+    }) + ["-Wno-unused-function"],
     visibility = ["//visibility:public"],
 )

build/deps/build_deps.jsonc

@@ -23,7 +23,9 @@
       "file_regex": "^rules_python-.*\\.tar\\.gz$"
     },
     {
-      // Needed for objc_library starting with bazel 7, used to build dawn on macOS
+      // Previously used to allow building dawn on macOS – while the build should succeed with the
+      // default Linux toolchain configuration from rules_cc apple_support is still more tailored to
+      // macOS.
       "name": "build_bazel_apple_support",
       "type": "github_release",
       "owner": "bazelbuild",

src/cloudflare/BUILD.bazel

@@ -7,16 +7,12 @@ wd_ts_bundle(
     internal_modules = glob(
         [
             "internal/*.ts",
-            "internal/*.js",
         ],
-        allow_empty = True,
     ),
     modules = glob(
         [
             "*.ts",
-            "*.js",
         ],
-        allow_empty = True,
     ),
     schema_id = "0xbcc8f57c63814006",
     tsconfig_json = "tsconfig.json",

src/rust/dns/BUILD.bazel

@@ -2,9 +2,7 @@ load("//:build/wd_rust_crate.bzl", "wd_rust_crate")
 
 wd_rust_crate(
     name = "dns",
-    cxx_bridge_deps = [],
     cxx_bridge_src = "lib.rs",
-    test_deps = [],
     visibility = ["//visibility:public"],
     deps = [
         "//src/rust/cxx-integration",

src/rust/net/BUILD.bazel

@@ -2,9 +2,7 @@ load("//:build/wd_rust_crate.bzl", "wd_rust_crate")
 
 wd_rust_crate(
     name = "net",
-    cxx_bridge_deps = [],
     cxx_bridge_src = "lib.rs",
-    test_deps = [],
     visibility = ["//visibility:public"],
     deps = [
         "//src/rust/cxx-integration",

src/workerd/api/node/BUILD.bazel

@@ -9,28 +9,26 @@ wd_cc_library(
         "crypto.c++",
         "crypto-keys.c++",
         "diagnostics-channel.c++",
-        "dns.c++",
         "timers.c++",
+        "util.c++",
         "zlib-util.c++",
     ],
     hdrs = [
         "crypto.h",
         "diagnostics-channel.h",
-        "dns.h",
         "node.h",
         "timers.h",
+        "util.h",
         "zlib-util.h",
     ],
     implementation_deps = [
-        "//src/rust/cxx-integration",
-        "//src/rust/dns",
-        "//src/workerd/io",
         "@capnp-cpp//src/kj/compat:kj-gzip",
     ],
     visibility = ["//visibility:public"],
     deps = [
         ":node-core",
         "//src/node",
+        "//src/workerd/io",
         "@capnp-cpp//src/kj/compat:kj-brotli",
         "@ncrypto",
     ],
@@ -42,30 +40,32 @@ wd_cc_library(
     srcs = [
         "async-hooks.c++",
         "buffer.c++",
+        "dns.c++",
         "i18n.c++",
         "module.c++",
         "url.c++",
-        "util.c++",
     ],
     hdrs = [
         "async-hooks.h",
         "buffer.h",
         "buffer-string-search.h",
+        "dns.h",
         "i18n.h",
         "module.h",
         "url.h",
-        "util.h",
     ],
     implementation_deps = [
+        "//src/rust/cxx-integration",
+        "//src/rust/dns",
+        "//src/rust/net",
         "@ada-url",
         "@nbytes",
         "@simdutf",
     ],
     visibility = ["//visibility:public"],
     deps = [
-        "//src/rust/cxx-integration",
-        "//src/rust/net",
-        "//src/workerd/io",
+        # Do not add the io target here – this target is intended for code that does not depend on
+        # it, move files to the main node target if needed.
         "//src/workerd/io:compatibility-date_capnp",
         "//src/workerd/jsg",
         "//src/workerd/util:mimetype",

src/workerd/api/node/module.c++

@@ -3,7 +3,6 @@
 //     https://opensource.org/licenses/Apache-2.0
 #include "module.h"
 
-#include <workerd/io/features.h>
 #include <workerd/jsg/url.h>
 
 namespace workerd::api::node {