[build images] Disable -Wcharacter-conversion warning for LLVM 21

LLVM 21 introduces a new -Wcharacter-conversion warning that flags
implicit conversions between char16_t and char32_t in WebKit's
CodePointIterator.h. Since this is in vendored WebKit code that we
can't easily modify, disable the warning globally.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.buildkite/Dockerfile

@@ -1,5 +1,5 @@
-ARG LLVM_VERSION="19"
-ARG REPORTED_LLVM_VERSION="19.1.7"
+ARG LLVM_VERSION="21"
+ARG REPORTED_LLVM_VERSION="21.1.0"
 ARG OLD_BUN_VERSION="1.1.38"
 ARG BUILDKITE_AGENT_TAGS="queue=linux,os=linux,arch=${TARGETARCH}"
 

.buildkite/ci.mjs

@@ -109,9 +109,9 @@ const buildPlatforms = [
   { os: "linux", arch: "x64", distro: "amazonlinux", release: "2023", features: ["docker"] },
   { os: "linux", arch: "x64", baseline: true, distro: "amazonlinux", release: "2023", features: ["docker"] },
   { os: "linux", arch: "x64", profile: "asan", distro: "amazonlinux", release: "2023", features: ["docker"] },
-  { os: "linux", arch: "aarch64", abi: "musl", distro: "alpine", release: "3.22" },
-  { os: "linux", arch: "x64", abi: "musl", distro: "alpine", release: "3.22" },
-  { os: "linux", arch: "x64", abi: "musl", baseline: true, distro: "alpine", release: "3.22" },
+  { os: "linux", arch: "aarch64", abi: "musl", distro: "alpine", release: "3.23" },
+  { os: "linux", arch: "x64", abi: "musl", distro: "alpine", release: "3.23" },
+  { os: "linux", arch: "x64", abi: "musl", baseline: true, distro: "alpine", release: "3.23" },
   { os: "windows", arch: "x64", release: "2019" },
   { os: "windows", arch: "x64", baseline: true, release: "2019" },
 ];
@@ -131,9 +131,9 @@ const testPlatforms = [
   { os: "linux", arch: "aarch64", distro: "ubuntu", release: "25.04", tier: "latest" },
   { os: "linux", arch: "x64", distro: "ubuntu", release: "25.04", tier: "latest" },
   { os: "linux", arch: "x64", baseline: true, distro: "ubuntu", release: "25.04", tier: "latest" },
-  { os: "linux", arch: "aarch64", abi: "musl", distro: "alpine", release: "3.22", tier: "latest" },
-  { os: "linux", arch: "x64", abi: "musl", distro: "alpine", release: "3.22", tier: "latest" },
-  { os: "linux", arch: "x64", abi: "musl", baseline: true, distro: "alpine", release: "3.22", tier: "latest" },
+  { os: "linux", arch: "aarch64", abi: "musl", distro: "alpine", release: "3.23", tier: "latest" },
+  { os: "linux", arch: "x64", abi: "musl", distro: "alpine", release: "3.23", tier: "latest" },
+  { os: "linux", arch: "x64", abi: "musl", baseline: true, distro: "alpine", release: "3.23", tier: "latest" },
   { os: "windows", arch: "x64", release: "2019", tier: "oldest" },
   { os: "windows", arch: "x64", release: "2019", baseline: true, tier: "oldest" },
 ];
@@ -341,7 +341,7 @@ function getZigPlatform() {
     arch: "aarch64",
     abi: "musl",
     distro: "alpine",
-    release: "3.22",
+    release: "3.23",
   };
 }
 

.github/workflows/CLAUDE.md

@@ -33,8 +33,8 @@ The workflow runs all three formatters simultaneously:
 
 #### 3. Tool Installation
 
-##### Clang-format-19
-- Installs ONLY `clang-format-19` package (not the entire LLVM toolchain)
+##### Clang-format-21
+- Installs ONLY `clang-format-21` package (not the entire LLVM toolchain)
 - Uses `--no-install-recommends --no-install-suggests` to skip unnecessary packages
 - Quiet installation with `-qq` and `-o=Dpkg::Use-Pty=0`
 
@@ -85,7 +85,7 @@ The workflow runs all three formatters simultaneously:
 
 ```bash
 # Test the clang-format script
-export LLVM_VERSION_MAJOR=19
+export LLVM_VERSION_MAJOR=21
 ./scripts/run-clang-format.sh format
 
 # Test with check mode (no modifications)

.github/workflows/format.yml

@@ -10,8 +10,8 @@ on:
   merge_group:
 env:
   BUN_VERSION: "1.3.2"
-  LLVM_VERSION: "19.1.7"
-  LLVM_VERSION_MAJOR: "19"
+  LLVM_VERSION: "21.1.0"
+  LLVM_VERSION_MAJOR: "21"
 
 jobs:
   autofix:

CONTRIBUTING.md

@@ -35,7 +35,7 @@ $ sudo pacman -S base-devel cmake git go libiconv libtool make ninja pkg-config
 ```
 
 ```bash#Fedora
-$ sudo dnf install cargo clang19 llvm19 lld19 cmake git golang libtool ninja-build pkg-config rustc ruby libatomic-static libstdc++-static sed unzip which libicu-devel 'perl(Math::BigInt)'
+$ sudo dnf install cargo clang21 llvm21 lld21 cmake git golang libtool ninja-build pkg-config rustc ruby libatomic-static libstdc++-static sed unzip which libicu-devel 'perl(Math::BigInt)'
 ```
 
 ```bash#openSUSE Tumbleweed
@@ -90,17 +90,17 @@ Our build scripts will automatically detect and use `ccache` if available. You c
 
 ## Install LLVM
 
-Bun requires LLVM 19 (`clang` is part of LLVM). This version requirement is to match WebKit (precompiled), as mismatching versions will cause memory allocation failures at runtime. In most cases, you can install LLVM through your system package manager:
+Bun requires LLVM 21 (`clang` is part of LLVM). This version requirement is to match WebKit (precompiled), as mismatching versions will cause memory allocation failures at runtime. In most cases, you can install LLVM through your system package manager:
 
 {% codetabs group="os" %}
 
 ```bash#macOS (Homebrew)
-$ brew install llvm@19
+$ brew install llvm@21
 ```
 
 ```bash#Ubuntu/Debian
 $ # LLVM has an automatic installation script that is compatible with all versions of Ubuntu
-$ wget https://apt.llvm.org/llvm.sh -O - | sudo bash -s -- 19 all
+$ wget https://apt.llvm.org/llvm.sh -O - | sudo bash -s -- 21 all
 ```
 
 ```bash#Arch
@@ -112,17 +112,17 @@ $ sudo dnf install llvm clang lld-devel
 ```
 
 ```bash#openSUSE Tumbleweed
-$ sudo zypper install clang19 lld19 llvm19
+$ sudo zypper install clang21 lld21 llvm21
 ```
 
 {% /codetabs %}
 
-If none of the above solutions apply, you will have to install it [manually](https://github.com/llvm/llvm-project/releases/tag/llvmorg-19.1.7).
+If none of the above solutions apply, you will have to install it [manually](https://github.com/llvm/llvm-project/releases/tag/llvmorg-21.1.0).
 
-Make sure Clang/LLVM 19 is in your path:
+Make sure Clang/LLVM 21 is in your path:
 
 ```bash
-$ which clang-19
+$ which clang-21
 ```
 
 If not, run this to manually add it:
@@ -131,13 +131,13 @@ If not, run this to manually add it:
 
 ```bash#macOS (Homebrew)
 # use fish_add_path if you're using fish
-# use path+="$(brew --prefix llvm@19)/bin" if you are using zsh
-$ export PATH="$(brew --prefix llvm@19)/bin:$PATH"
+# use path+="$(brew --prefix llvm@21)/bin" if you are using zsh
+$ export PATH="$(brew --prefix llvm@21)/bin:$PATH"
 ```
 
 ```bash#Arch
 # use fish_add_path if you're using fish
-$ export PATH="$PATH:/usr/lib/llvm19/bin"
+$ export PATH="$PATH:/usr/lib/llvm21/bin"
 ```
 
 {% /codetabs %}
@@ -304,7 +304,7 @@ The issue may manifest when initially running `bun setup` as Clang being unable
 ```
 The C++ compiler
 
-  "/usr/bin/clang++-19"
+  "/usr/bin/clang++-21"
 
 is not able to compile a simple test program.
 ```

cmake/targets/BuildBun.cmake

@@ -988,6 +988,7 @@ if(NOT WIN32)
       -Wno-unused-function
       -Wno-c++23-lambda-attributes
       -Wno-nullability-completeness
+      -Wno-character-conversion
       -Werror
     )
   else()
@@ -1005,6 +1006,7 @@ if(NOT WIN32)
       -Werror=sometimes-uninitialized
       -Wno-c++23-lambda-attributes
       -Wno-nullability-completeness
+      -Wno-character-conversion
       -Werror
     )
 

cmake/tools/SetupLLVM.cmake

@@ -12,7 +12,7 @@ if(NOT ENABLE_LLVM)
   return()
 endif()
 
-set(DEFAULT_LLVM_VERSION "19.1.7")
+set(DEFAULT_LLVM_VERSION "21.1.0")
 
 optionx(LLVM_VERSION STRING "The version of LLVM to use" DEFAULT ${DEFAULT_LLVM_VERSION})
 

dockerhub/alpine/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.22 AS build
+FROM alpine:3.23 AS build
 
 # https://github.com/oven-sh/bun/releases
 ARG BUN_VERSION=latest
@@ -44,7 +44,7 @@ RUN apk --no-cache add ca-certificates curl dirmngr gpg gpg-agent unzip \
     && rm -f "bun-linux-$build.zip" SHASUMS256.txt.asc SHASUMS256.txt \
     && chmod +x /usr/local/bin/bun
 
-FROM alpine:3.22
+FROM alpine:3.23
 
 # Disable the runtime transpiler cache by default inside Docker containers.
 # On ephemeral containers, the cache is not useful

docs/project/building-windows.mdx

@@ -35,7 +35,7 @@ winget install "Visual Studio Community 2022" --override "--add Microsoft.Visual
 
 After Visual Studio, you need the following:
 
-- LLVM 19.1.7
+- LLVM 21.1.0
 - Go
 - Rust
 - NASM
@@ -51,7 +51,7 @@ After Visual Studio, you need the following:
 irm https://get.scoop.sh | iex
 scoop install nodejs-lts go rust nasm ruby perl ccache
 # scoop seems to be buggy if you install llvm and the rest at the same time
-scoop install llvm@19.1.7
+scoop install llvm@21.1.0
 ```
 
 <Note>

docs/project/contributing.mdx

@@ -40,7 +40,7 @@ sudo pacman -S base-devel cmake git go libiconv libtool make ninja pkg-config py
 ```
 
 ```bash Fedora
-sudo dnf install cargo clang19 llvm19 lld19 cmake git golang libtool ninja-build pkg-config rustc ruby libatomic-static libstdc++-static sed unzip which libicu-devel 'perl(Math::BigInt)'
+sudo dnf install cargo clang21 llvm21 lld21 cmake git golang libtool ninja-build pkg-config rustc ruby libatomic-static libstdc++-static sed unzip which libicu-devel 'perl(Math::BigInt)'
 ```
 
 ```bash openSUSE Tumbleweed
@@ -95,17 +95,17 @@ Our build scripts will automatically detect and use `ccache` if available. You c
 
 ## Install LLVM
 
-Bun requires LLVM 19 (`clang` is part of LLVM). This version requirement is to match WebKit (precompiled), as mismatching versions will cause memory allocation failures at runtime. In most cases, you can install LLVM through your system package manager:
+Bun requires LLVM 21 (`clang` is part of LLVM). This version requirement is to match WebKit (precompiled), as mismatching versions will cause memory allocation failures at runtime. In most cases, you can install LLVM through your system package manager:
 
 <CodeGroup>
 
 ```bash macOS (Homebrew)
-brew install llvm@19
+brew install llvm@21
 ```
 
 ```bash Ubuntu/Debian
 # LLVM has an automatic installation script that is compatible with all versions of Ubuntu
-wget https://apt.llvm.org/llvm.sh -O - | sudo bash -s -- 19 all
+wget https://apt.llvm.org/llvm.sh -O - | sudo bash -s -- 21 all
 ```
 
 ```bash Arch
@@ -117,17 +117,17 @@ sudo dnf install llvm clang lld-devel
 ```
 
 ```bash openSUSE Tumbleweed
-sudo zypper install clang19 lld19 llvm19
+sudo zypper install clang21 lld21 llvm21
 ```
 
 </CodeGroup>
 
-If none of the above solutions apply, you will have to install it [manually](https://github.com/llvm/llvm-project/releases/tag/llvmorg-19.1.7).
+If none of the above solutions apply, you will have to install it [manually](https://github.com/llvm/llvm-project/releases/tag/llvmorg-21.1.0).
 
-Make sure Clang/LLVM 19 is in your path:
+Make sure Clang/LLVM 21 is in your path:
 
 ```bash
-which clang-19
+which clang-21
 ```
 
 If not, run this to manually add it:
@@ -136,13 +136,13 @@ If not, run this to manually add it:
 
 ```bash macOS (Homebrew)
 # use fish_add_path if you're using fish
-# use path+="$(brew --prefix llvm@19)/bin" if you are using zsh
-export PATH="$(brew --prefix llvm@19)/bin:$PATH"
+# use path+="$(brew --prefix llvm@21)/bin" if you are using zsh
+export PATH="$(brew --prefix llvm@21)/bin:$PATH"
 ```
 
 ```bash Arch
 # use fish_add_path if you're using fish
-export PATH="$PATH:/usr/lib/llvm19/bin"
+export PATH="$PATH:/usr/lib/llvm21/bin"
 ```
 
 </CodeGroup>
@@ -314,7 +314,7 @@ The issue may manifest when initially running `bun setup` as Clang being unable
 ```txt
 The C++ compiler
 
-  "/usr/bin/clang++-19"
+  "/usr/bin/clang++-21"
 
 is not able to compile a simple test program.
 ```

flake.nix

@@ -26,10 +26,10 @@
           };
         };
 
-        # LLVM 19 - matching the bootstrap script (targets 19.1.7, actual version from nixpkgs-unstable)
-        llvm = pkgs.llvm_19;
-        clang = pkgs.clang_19;
-        lld = pkgs.lld_19;
+        # LLVM 21 - matching the bootstrap script (targets 21.1.0, actual version from nixpkgs-unstable)
+        llvm = pkgs.llvm_21;
+        clang = pkgs.clang_21;
+        lld = pkgs.lld_21;
 
         # Node.js 24 - matching the bootstrap script (targets 24.3.0, actual version from nixpkgs-unstable)
         nodejs = pkgs.nodejs_24;
@@ -42,7 +42,7 @@
           pkgs.pkg-config
           pkgs.ccache
 
-          # Compilers and toolchain - version pinned to LLVM 19
+          # Compilers and toolchain - version pinned to LLVM 21
           clang
           llvm
           lld

package.json

@@ -89,7 +89,7 @@
     "clean:zig": "rm -rf build/debug/cache/zig build/debug/CMakeCache.txt 'build/debug/*.o' .zig-cache zig-out || true",
     "machine:linux:ubuntu": "./scripts/machine.mjs ssh --cloud=aws --arch=x64 --instance-type c7i.2xlarge --os=linux --distro=ubuntu --release=25.04",
     "machine:linux:debian": "./scripts/machine.mjs ssh --cloud=aws --arch=x64 --instance-type c7i.2xlarge --os=linux --distro=debian --release=13",
-    "machine:linux:alpine": "./scripts/machine.mjs ssh --cloud=aws --arch=x64 --instance-type c7i.2xlarge --os=linux --distro=alpine --release=3.22",
+    "machine:linux:alpine": "./scripts/machine.mjs ssh --cloud=aws --arch=x64 --instance-type c7i.2xlarge --os=linux --distro=alpine --release=3.23",
     "machine:linux:amazonlinux": "./scripts/machine.mjs ssh --cloud=aws --arch=x64 --instance-type c7i.2xlarge --os=linux --distro=amazonlinux --release=2023",
     "machine:windows:2019": "./scripts/machine.mjs ssh --cloud=aws --arch=x64 --instance-type c7i.2xlarge --os=windows --release=2019",
     "machine:freebsd": "./scripts/machine.mjs ssh --cloud=aws --arch=x64 --instance-type c7i.2xlarge --os=freebsd --release=14.3",

scripts/bootstrap.ps1

@@ -1,4 +1,4 @@
-# Version: 11
+# Version: 12
 # A script that installs the dependencies needed to build and test Bun.
 # This should work on Windows 10 or newer with PowerShell.
 
@@ -387,7 +387,7 @@ function Install-PdbAddr2line {
 function Install-Llvm {
   Install-Package llvm `
     -Command clang-cl `
-    -Version "19.1.7"
+    -Version "21.1.0"
   Add-To-Path "$env:ProgramFiles\LLVM\bin"
 }
 

scripts/bootstrap.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-# Version: 26
+# Version: 27
 
 # A script that installs the dependencies needed to build and test Bun.
 # This should work on macOS and Linux with a POSIX shell.
@@ -1091,7 +1091,7 @@ install_build_essentials() {
 }
 
 llvm_version_exact() {
-	print "19.1.7"
+	print "21.1.0"
 }
 
 llvm_version() {
@@ -1101,28 +1101,20 @@ llvm_version() {
 install_llvm() {
 	case "$pm" in
 	apt)
-		# Debian 13 (Trixie) has LLVM 19 natively, and apt.llvm.org doesn't have a trixie repo
-		if [ "$distro" = "debian" ]; then
-			install_packages \
-				"llvm-$(llvm_version)" \
-				"clang-$(llvm_version)" \
-				"lld-$(llvm_version)" \
-				"llvm-$(llvm_version)-dev" \
-				"llvm-$(llvm_version)-tools" \
-				"libclang-rt-$(llvm_version)-dev"
-		else
-			bash="$(require bash)"
-			llvm_script="$(download_file "https://apt.llvm.org/llvm.sh")"
-			execute_sudo "$bash" "$llvm_script" "$(llvm_version)" all
+		# Use apt.llvm.org for all apt-based distros (Ubuntu, Debian)
+		# apt.llvm.org has LLVM 21 for trixie/bookworm/bullseye and all Ubuntu versions
+		bash="$(require bash)"
+		llvm_script="$(download_file "https://apt.llvm.org/llvm.sh")"
+		execute_sudo "$bash" "$llvm_script" "$(llvm_version)" all
 
-			# Install llvm-symbolizer explicitly to ensure it's available for ASAN
-			install_packages "llvm-$(llvm_version)-tools"
-		fi
+		# Install llvm-symbolizer explicitly to ensure it's available for ASAN
+		install_packages "llvm-$(llvm_version)-tools"
 		;;
 	brew)
 		install_packages "llvm@$(llvm_version)"
 		;;
 	apk)
+		# Alpine 3.23+ has LLVM 21 available
 		install_packages \
 			"llvm$(llvm_version)" \
 			"clang$(llvm_version)" \
@@ -1172,7 +1164,7 @@ install_gcc() {
 		;;
 	esac
 
-	llvm_v="19"
+	llvm_v="21"
 
 	append_to_profile "export CC=clang-${llvm_v}"
 	append_to_profile "export CXX=clang++-${llvm_v}"

scripts/build-jsc.ts

@@ -47,8 +47,8 @@ function findExecutable(names: string[]): string | null {
   return null;
 }
 
-const CC = findExecutable(["clang-19", "clang"]) || "clang";
-const CXX = findExecutable(["clang++-19", "clang++"]) || "clang++";
+const CC = findExecutable(["clang-21", "clang"]) || "clang";
+const CXX = findExecutable(["clang++-21", "clang++"]) || "clang++";
 
 // Build directory based on config
 const getBuildDir = (config: BuildConfig) => {

scripts/lldb-inline-tool.cpp

@@ -20,8 +20,8 @@
  * On Linux:
  *   c++ -std=c++17 -o lldb-inline lldb-inline-tool.cpp \
  *       -llldb \
- *       -L/usr/lib/llvm-14/lib \
- *       -I/usr/lib/llvm-14/include
+ *       -L/usr/lib/llvm-21/lib \
+ *       -I/usr/lib/llvm-21/include
  * 
  * USAGE:
  * ------

scripts/lldb-inline.sh

@@ -21,7 +21,7 @@ if [ ! -f "$TOOL_BINARY" ] || [ "$TOOL_SOURCE" -nt "$TOOL_BINARY" ]; then
     else
         # Linux - try to find LLVM installation
         LLVM_DIR=""
-        for version in 18 17 16 15 14 13 12; do
+        for version in 21 20 19 18 17 16 15 14; do
             if [ -d "/usr/lib/llvm-$version" ]; then
                 LLVM_DIR="/usr/lib/llvm-$version"
                 break

scripts/run-clang-format.sh

@@ -11,8 +11,8 @@ PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
 # Default to format mode (modify files)
 MODE="${1:-format}"
 
-# Use LLVM_VERSION_MAJOR from environment or default to 19
-LLVM_VERSION="${LLVM_VERSION_MAJOR:-19}"
+# Use LLVM_VERSION_MAJOR from environment or default to 21
+LLVM_VERSION="${LLVM_VERSION_MAJOR:-21}"
 
 # Ensure we have the specific clang-format version
 CLANG_FORMAT="clang-format-${LLVM_VERSION}"

shell.nix

@@ -8,9 +8,9 @@ pkgs.mkShell rec {
     # Core build tools (matching bootstrap.sh)
     cmake
     ninja
-    clang_19
-    llvm_19
-    lld_19
+    clang_21
+    llvm_21
+    lld_21
     nodejs_24
     bun
     rustc
@@ -77,10 +77,10 @@ pkgs.mkShell rec {
   ];
 
   shellHook = ''
-    export CC="${pkgs.lib.getExe pkgs.clang_19}"
-    export CXX="${pkgs.lib.getExe' pkgs.clang_19 "clang++"}"
-    export AR="${pkgs.llvm_19}/bin/llvm-ar"
-    export RANLIB="${pkgs.llvm_19}/bin/llvm-ranlib"
+    export CC="${pkgs.lib.getExe pkgs.clang_21}"
+    export CXX="${pkgs.lib.getExe' pkgs.clang_21 "clang++"}"
+    export AR="${pkgs.llvm_21}/bin/llvm-ar"
+    export RANLIB="${pkgs.llvm_21}/bin/llvm-ranlib"
     export CMAKE_C_COMPILER="$CC"
     export CMAKE_CXX_COMPILER="$CXX"
     export CMAKE_AR="$AR"
@@ -88,7 +88,7 @@ pkgs.mkShell rec {
     export CMAKE_SYSTEM_PROCESSOR=$(uname -m)
     export TMPDIR=''${TMPDIR:-/tmp}
   '' + pkgs.lib.optionalString pkgs.stdenv.isLinux ''
-    export LD="${pkgs.lib.getExe' pkgs.lld_19 "ld.lld"}"
+    export LD="${pkgs.lib.getExe' pkgs.lld_21 "ld.lld"}"
     export NIX_CFLAGS_LINK="''${NIX_CFLAGS_LINK:+$NIX_CFLAGS_LINK }-fuse-ld=lld"
     export LD_LIBRARY_PATH="${pkgs.lib.makeLibraryPath packages}''${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}"
   '' + ''

src/bun.js/bindings/EncodeURIComponent.cpp

@@ -39,7 +39,7 @@ static WebCore::ExceptionOr<void> encode(VM& vm, const WTF::BitSet<256>& doNotEs
         // 4-d-ii-1. Let V be the code unit value of C.
         char32_t codePoint;
         if (!U16_IS_LEAD(character))
-            codePoint = character;
+            codePoint = static_cast<char32_t>(character);
         else {
             // 4-d-iii. Else,
             // 4-d-iii-1. Increase k by 1.

src/bun.js/bindings/EncodingTables.h

@@ -58,14 +58,18 @@ inline void checkEncodingTableInvariants() {}
 struct CompareFirst {
     template<typename TypeA, typename TypeB> bool operator()(const TypeA& a, const TypeB& b)
     {
-        return a.first < b.first;
+        // Use std::common_type to safely compare different character types (e.g., char16_t vs char32_t)
+        using CommonType = std::common_type_t<decltype(a.first), decltype(b.first)>;
+        return static_cast<CommonType>(a.first) < static_cast<CommonType>(b.first);
     }
 };
 
 struct EqualFirst {
     template<typename TypeA, typename TypeB> bool operator()(const TypeA& a, const TypeB& b)
     {
-        return a.first == b.first;
+        // Use std::common_type to safely compare different character types (e.g., char16_t vs char32_t)
+        using CommonType = std::common_type_t<decltype(a.first), decltype(b.first)>;
+        return static_cast<CommonType>(a.first) == static_cast<CommonType>(b.first);
     }
 };
 
@@ -114,20 +118,23 @@ template<typename CollectionType> bool sortedFirstsAreUnique(const CollectionTyp
 
 template<typename CollectionType, typename KeyType> static auto findFirstInSortedPairs(const CollectionType& collection, const KeyType& key) -> std::optional<decltype(std::begin(collection)->second)>
 {
+    using CollectionKeyType = decltype(std::begin(collection)->first);
     if constexpr (std::is_integral_v<KeyType>) {
-        if (key != decltype(std::begin(collection)->first)(key))
+        if (static_cast<KeyType>(static_cast<CollectionKeyType>(key)) != key)
             return std::nullopt;
     }
     auto iterator = std::lower_bound(std::begin(collection), std::end(collection), makeFirstAdapter(key), CompareFirst {});
-    if (iterator == std::end(collection) || key < iterator->first)
+    using CommonType = std::common_type_t<KeyType, CollectionKeyType>;
+    if (iterator == std::end(collection) || static_cast<CommonType>(key) < static_cast<CommonType>(iterator->first))
         return std::nullopt;
     return iterator->second;
 }
 
 template<typename CollectionType, typename KeyType> static auto findInSortedPairs(const CollectionType& collection, const KeyType& key) -> std::span<std::remove_reference_t<decltype(*std::begin(collection))>>
 {
+    using CollectionKeyType = decltype(std::begin(collection)->first);
     if constexpr (std::is_integral_v<KeyType>) {
-        if (key != decltype(std::begin(collection)->first)(key))
+        if (static_cast<KeyType>(static_cast<CollectionKeyType>(key)) != key)
             return {};
     }
     return std::ranges::equal_range(collection, makeFirstAdapter(key), CompareFirst {});

src/bun.js/bindings/SecretsDarwin.cpp

@@ -136,23 +136,23 @@ private:
     bool load_functions()
     {
         CFRelease = (void (*)(CFTypeRef))dlsym(cf_handle, "CFRelease");
-        CFStringCreateWithCString = (CFStringRef(*)(CFAllocatorRef, const char*, CFStringEncoding))dlsym(cf_handle, "CFStringCreateWithCString");
-        CFDataCreate = (CFDataRef(*)(CFAllocatorRef, const UInt8*, CFIndex))dlsym(cf_handle, "CFDataCreate");
+        CFStringCreateWithCString = (CFStringRef (*)(CFAllocatorRef, const char*, CFStringEncoding))dlsym(cf_handle, "CFStringCreateWithCString");
+        CFDataCreate = (CFDataRef (*)(CFAllocatorRef, const UInt8*, CFIndex))dlsym(cf_handle, "CFDataCreate");
         CFDataGetBytePtr = (const UInt8* (*)(CFDataRef))dlsym(cf_handle, "CFDataGetBytePtr");
-        CFDataGetLength = (CFIndex(*)(CFDataRef))dlsym(cf_handle, "CFDataGetLength");
-        CFDictionaryCreateMutable = (CFMutableDictionaryRef(*)(CFAllocatorRef, CFIndex, const CFDictionaryKeyCallBacks*, const CFDictionaryValueCallBacks*))dlsym(cf_handle, "CFDictionaryCreateMutable");
+        CFDataGetLength = (CFIndex (*)(CFDataRef))dlsym(cf_handle, "CFDataGetLength");
+        CFDictionaryCreateMutable = (CFMutableDictionaryRef (*)(CFAllocatorRef, CFIndex, const CFDictionaryKeyCallBacks*, const CFDictionaryValueCallBacks*))dlsym(cf_handle, "CFDictionaryCreateMutable");
         CFDictionaryAddValue = (void (*)(CFMutableDictionaryRef, const void*, const void*))dlsym(cf_handle, "CFDictionaryAddValue");
-        CFStringGetCString = (Boolean(*)(CFStringRef, char*, CFIndex, CFStringEncoding))dlsym(cf_handle, "CFStringGetCString");
+        CFStringGetCString = (Boolean (*)(CFStringRef, char*, CFIndex, CFStringEncoding))dlsym(cf_handle, "CFStringGetCString");
         CFStringGetCStringPtr = (const char* (*)(CFStringRef, CFStringEncoding))dlsym(cf_handle, "CFStringGetCStringPtr");
-        CFStringGetLength = (CFIndex(*)(CFStringRef))dlsym(cf_handle, "CFStringGetLength");
-        CFStringGetMaximumSizeForEncoding = (CFIndex(*)(CFIndex, CFStringEncoding))dlsym(cf_handle, "CFStringGetMaximumSizeForEncoding");
+        CFStringGetLength = (CFIndex (*)(CFStringRef))dlsym(cf_handle, "CFStringGetLength");
+        CFStringGetMaximumSizeForEncoding = (CFIndex (*)(CFIndex, CFStringEncoding))dlsym(cf_handle, "CFStringGetMaximumSizeForEncoding");
 
-        SecItemAdd = (OSStatus(*)(CFDictionaryRef, CFTypeRef*))dlsym(handle, "SecItemAdd");
-        SecItemCopyMatching = (OSStatus(*)(CFDictionaryRef, CFTypeRef*))dlsym(handle, "SecItemCopyMatching");
-        SecItemUpdate = (OSStatus(*)(CFDictionaryRef, CFDictionaryRef))dlsym(handle, "SecItemUpdate");
-        SecItemDelete = (OSStatus(*)(CFDictionaryRef))dlsym(handle, "SecItemDelete");
-        SecCopyErrorMessageString = (CFStringRef(*)(OSStatus, void*))dlsym(handle, "SecCopyErrorMessageString");
-        SecAccessCreate = (OSStatus(*)(CFStringRef, CFArrayRef, SecAccessRef*))dlsym(handle, "SecAccessCreate");
+        SecItemAdd = (OSStatus (*)(CFDictionaryRef, CFTypeRef*))dlsym(handle, "SecItemAdd");
+        SecItemCopyMatching = (OSStatus (*)(CFDictionaryRef, CFTypeRef*))dlsym(handle, "SecItemCopyMatching");
+        SecItemUpdate = (OSStatus (*)(CFDictionaryRef, CFDictionaryRef))dlsym(handle, "SecItemUpdate");
+        SecItemDelete = (OSStatus (*)(CFDictionaryRef))dlsym(handle, "SecItemDelete");
+        SecCopyErrorMessageString = (CFStringRef (*)(OSStatus, void*))dlsym(handle, "SecCopyErrorMessageString");
+        SecAccessCreate = (OSStatus (*)(CFStringRef, CFArrayRef, SecAccessRef*))dlsym(handle, "SecAccessCreate");
 
         return CFRelease && CFStringCreateWithCString && CFDataCreate && CFDataGetBytePtr && CFDataGetLength && CFDictionaryCreateMutable && CFDictionaryAddValue && SecItemAdd && SecItemCopyMatching && SecItemUpdate && SecItemDelete && SecCopyErrorMessageString && SecAccessCreate && CFStringGetCString && CFStringGetCStringPtr && CFStringGetLength && CFStringGetMaximumSizeForEncoding;
     }

src/bun.js/bindings/SecretsLinux.cpp

@@ -199,19 +199,19 @@ private:
         g_free = (void (*)(gpointer))dlsym(glib_handle, "g_free");
         g_hash_table_new = (GHashTable * (*)(void*, void*)) dlsym(glib_handle, "g_hash_table_new");
         g_hash_table_destroy = (void (*)(GHashTable*))dlsym(glib_handle, "g_hash_table_destroy");
-        g_hash_table_lookup = (gpointer(*)(GHashTable*, gpointer))dlsym(glib_handle, "g_hash_table_lookup");
+        g_hash_table_lookup = (gpointer (*)(GHashTable*, gpointer))dlsym(glib_handle, "g_hash_table_lookup");
         g_hash_table_insert = (void (*)(GHashTable*, gpointer, gpointer))dlsym(glib_handle, "g_hash_table_insert");
         g_list_free = (void (*)(GList*))dlsym(glib_handle, "g_list_free");
         g_list_free_full = (void (*)(GList*, void (*)(gpointer)))dlsym(glib_handle, "g_list_free_full");
-        g_str_hash = (guint(*)(gpointer))dlsym(glib_handle, "g_str_hash");
-        g_str_equal = (gboolean(*)(gpointer, gpointer))dlsym(glib_handle, "g_str_equal");
+        g_str_hash = (guint (*)(gpointer))dlsym(glib_handle, "g_str_hash");
+        g_str_equal = (gboolean (*)(gpointer, gpointer))dlsym(glib_handle, "g_str_equal");
 
         // Load libsecret functions
-        secret_password_store_sync = (gboolean(*)(const SecretSchema*, const gchar*, const gchar*, const gchar*, void*, GError**, ...))
+        secret_password_store_sync = (gboolean (*)(const SecretSchema*, const gchar*, const gchar*, const gchar*, void*, GError**, ...))
             dlsym(secret_handle, "secret_password_store_sync");
         secret_password_lookup_sync = (gchar * (*)(const SecretSchema*, void*, GError**, ...))
             dlsym(secret_handle, "secret_password_lookup_sync");
-        secret_password_clear_sync = (gboolean(*)(const SecretSchema*, void*, GError**, ...))
+        secret_password_clear_sync = (gboolean (*)(const SecretSchema*, void*, GError**, ...))
             dlsym(secret_handle, "secret_password_clear_sync");
         secret_password_free = (void (*)(gchar*))dlsym(secret_handle, "secret_password_free");
         secret_service_search_sync = (GList * (*)(SecretService*, const SecretSchema*, GHashTable*, SecretSearchFlags, void*, GError**))
@@ -220,7 +220,7 @@ private:
         secret_value_get_text = (const gchar* (*)(SecretValue*))dlsym(secret_handle, "secret_value_get_text");
         secret_value_unref = (void (*)(gpointer))dlsym(secret_handle, "secret_value_unref");
         secret_item_get_attributes = (GHashTable * (*)(SecretItem*)) dlsym(secret_handle, "secret_item_get_attributes");
-        secret_item_load_secret_sync = (gboolean(*)(SecretItem*, void*, GError**))dlsym(secret_handle, "secret_item_load_secret_sync");
+        secret_item_load_secret_sync = (gboolean (*)(SecretItem*, void*, GError**))dlsym(secret_handle, "secret_item_load_secret_sync");
 
         return g_error_free && g_free && g_hash_table_new && g_hash_table_destroy && g_hash_table_lookup && g_hash_table_insert && g_list_free && secret_password_store_sync && secret_password_lookup_sync && secret_password_clear_sync && secret_password_free;
     }

src/bun.js/bindings/TextCodecCJK.cpp

@@ -890,7 +890,7 @@ static const GB18030EncodeIndex& gb18030EncodeIndex()
 // https://unicode-org.atlassian.net/browse/ICU-22357
 // The 2-byte values are handled correctly by values from gb18030()
 // but these need to be exceptions from gb18030Ranges().
-static std::optional<uint16_t> gb18030AsymmetricEncode(char16_t codePoint)
+static std::optional<uint16_t> gb18030AsymmetricEncode(char32_t codePoint)
 {
     switch (codePoint) {
     case 0xE81E:

src/bun.js/bindings/TextCodecSingleByte.cpp

@@ -262,7 +262,7 @@ static Vector<uint8_t> encode(const SingleByteEncodeTable& table, StringView str
     result.reserveInitialCapacity(string.length());
     for (auto codePoint : string.codePoints()) {
         if (isASCII(codePoint)) {
-            result.append(codePoint);
+            result.append(static_cast<uint8_t>(codePoint));
             continue;
         }
         auto byte = findFirstInSortedPairs(table, codePoint);

src/bun.js/bindings/TextCodecUserDefined.cpp

@@ -70,9 +70,9 @@ static Vector<uint8_t> encodeComplexUserDefined(StringView string, UnencodableHa
     Vector<uint8_t> result;
 
     for (auto character : string.codePoints()) {
-        int8_t signedByte = character;
-        if ((signedByte & 0xF7FF) == character)
-            result.append(signedByte);
+        auto signedByte = static_cast<int8_t>(character);
+        if (static_cast<char32_t>(signedByte & 0xF7FF) == character)
+            result.append(static_cast<uint8_t>(signedByte));
         else {
             // No way to encode this character with x-user-defined.
             UnencodableReplacementArray replacement;

src/bun.js/bindings/highway_strings.cpp

@@ -81,10 +81,16 @@ size_t IndexOfAnyCharImpl(const uint8_t* HWY_RESTRICT text, size_t text_len, con
     } else {
         ASSERT(chars_len <= 16);
         constexpr size_t kMaxPreloadedChars = 16;
-        hn::Vec<D8> char_vecs[kMaxPreloadedChars];
+
+        // Use FixedTag to get a fixed-size vector type that can be stored in arrays.
+        // This avoids the "sizeless type" issue with scalable vectors (SVE).
+        // FixedTag<T, N> gives us exactly N lanes with a known compile-time size.
+        const hn::FixedTag<uint8_t, 16> d_fixed;
+        using VecFixed = hn::Vec<decltype(d_fixed)>;
+        VecFixed char_vecs[kMaxPreloadedChars];
         const size_t num_chars_to_preload = std::min(chars_len, kMaxPreloadedChars);
         for (size_t c = 0; c < num_chars_to_preload; ++c) {
-            char_vecs[c] = hn::Set(d, chars[c]);
+            char_vecs[c] = hn::Set(d_fixed, chars[c]);
         }
 
         const size_t simd_text_len = text_len - (text_len % N);
@@ -95,7 +101,8 @@ size_t IndexOfAnyCharImpl(const uint8_t* HWY_RESTRICT text, size_t text_len, con
             auto found_mask = hn::MaskFalse(d);
 
             for (size_t c = 0; c < num_chars_to_preload; ++c) {
-                found_mask = hn::Or(found_mask, hn::Eq(text_vec, char_vecs[c]));
+                // ResizeBitCast converts the fixed-size vector to the scalable vector type
+                found_mask = hn::Or(found_mask, hn::Eq(text_vec, hn::ResizeBitCast(d, char_vecs[c])));
             }
             if (chars_len > num_chars_to_preload) {
                 for (size_t c = num_chars_to_preload; c < chars_len; ++c) {

src/bun.js/bindings/webcore/EventTarget.cpp

@@ -105,7 +105,7 @@ bool EventTarget::addEventListener(const AtomString& eventType, Ref<EventListene
     if (options.signal) {
         options.signal->addAlgorithm([weakThis = WeakPtr { *this }, eventType, listener = WeakPtr { listener }, capture = options.capture](JSC::JSValue) {
             if (weakThis && listener)
-                Ref { *weakThis } -> removeEventListener(eventType, *listener, capture);
+                Ref { *weakThis }->removeEventListener(eventType, *listener, capture);
         });
     }
 

src/bun.js/bindings/webcore/URLPatternCanonical.cpp

@@ -37,10 +37,9 @@ namespace WebCore {
 
 static constexpr auto dummyURLCharacters { "https://w/"_s };
 
-static bool isValidIPv6HostCodePoint(auto codepoint)
+static bool isValidIPv6HostCodePoint(char32_t codepoint)
 {
-    static constexpr std::array validSpecialCodepoints { '[', ']', ':' };
-    return isASCIIHexDigit(codepoint) || std::find(validSpecialCodepoints.begin(), validSpecialCodepoints.end(), codepoint) != validSpecialCodepoints.end();
+    return isASCIIHexDigit(codepoint) || codepoint == '[' || codepoint == ']' || codepoint == ':';
 }
 
 // https://urlpattern.spec.whatwg.org/#is-an-absolute-pathname

src/bun.js/bindings/webcore/URLPatternParser.cpp

@@ -541,7 +541,7 @@ String escapePatternString(StringView input)
 }
 
 // https://urlpattern.spec.whatwg.org/#is-a-valid-name-code-point
-bool isValidNameCodepoint(char16_t codepoint, URLPatternUtilities::IsFirst first)
+bool isValidNameCodepoint(char32_t codepoint, URLPatternUtilities::IsFirst first)
 {
     if (first == URLPatternUtilities::IsFirst::Yes)
         return u_hasBinaryProperty(codepoint, UCHAR_ID_START) || codepoint == '_' || codepoint == '$';

src/bun.js/bindings/webcore/URLPatternParser.h

@@ -104,7 +104,7 @@ ASCIILiteral convertModifierToString(Modifier);
 std::pair<String, Vector<String>> generateRegexAndNameList(const Vector<Part>& partList, const URLPatternStringOptions&);
 String generatePatternString(const Vector<Part>& partList, const URLPatternStringOptions&);
 String escapePatternString(StringView input);
-bool isValidNameCodepoint(char16_t codepoint, URLPatternUtilities::IsFirst);
+bool isValidNameCodepoint(char32_t codepoint, URLPatternUtilities::IsFirst);
 
 } // namespace URLPatternUtilities
 } // namespace WebCore

src/crash_handler.zig

@@ -1699,8 +1699,8 @@ pub fn dumpStackTrace(trace: std.builtin.StackTrace, limits: WriteStackTraceLimi
 
     const programs: []const [:0]const u8 = switch (bun.Environment.os) {
         .windows => &.{"pdb-addr2line"},
-        // if `llvm-symbolizer` doesn't work, also try `llvm-symbolizer-19`
-        else => &.{ "llvm-symbolizer", "llvm-symbolizer-19" },
+        // if `llvm-symbolizer` doesn't work, also try `llvm-symbolizer-21`
+        else => &.{ "llvm-symbolizer", "llvm-symbolizer-21" },
     };
     for (programs) |program| {
         var arena = bun.ArenaAllocator.init(bun.default_allocator);

test/napi/node-napi-tests/harness.ts

@@ -20,8 +20,8 @@ export async function build(dir: string) {
       // so we make it use clang instead
       ...(process.platform == "linux" && isCI
         ? {
-            CC: !isMusl ? "/usr/lib/llvm-19/bin/clang" : "/usr/lib/llvm19/bin/clang",
-            CXX: !isMusl ? "/usr/lib/llvm-19/bin/clang++" : "/usr/lib/llvm19/bin/clang++",
+            CC: !isMusl ? "/usr/lib/llvm-21/bin/clang" : "/usr/lib/llvm21/bin/clang",
+            CXX: !isMusl ? "/usr/lib/llvm-21/bin/clang++" : "/usr/lib/llvm21/bin/clang++",
           }
         : {}),
     },