cmake: Fix cross-compiling zig on alpine (#15400)

Co-authored-by: Electroid <Electroid@users.noreply.github.com>

.buildkite/ci.mjs

@@ -307,14 +307,16 @@ function getPipeline(options) {
   const getZigAgent = platform => {
     const { arch } = platform;
     const instanceType = arch === "aarch64" ? "c8g.large" : "c7i.large";
-    const zigPlatform = {
+    return {
+      robobun: true,
+      robobun2: true,
       os: "linux",
       arch,
-      abi: "musl",
-      distro: "alpine",
-      release: "3.20"
+      distro: "debian",
+      release: "11",
+      "image-name": `linux-${arch}-debian-11-v5`, // v5 is not on main yet
+      "instance-type": instanceType,
     };
-    return getEmphemeralAgent("v2", zigPlatform, instanceType);
     // TODO: Temporarily disable due to configuration
     // return {
     //   queue: "build-zig",

cmake/Globals.cmake

@@ -136,16 +136,6 @@ else()
   set(WARNING WARNING)
 endif()
 
-if(LINUX)
-  if(EXISTS "/etc/alpine-release")
-    set(DEFAULT_ABI "musl")
-  else()
-    set(DEFAULT_ABI "gnu")
-  endif()
-
-  optionx(ABI "musl|gnu" "The ABI to use (e.g. musl, gnu)" DEFAULT ${DEFAULT_ABI})
-endif()
-
 # TODO: This causes flaky zig builds in CI, so temporarily disable it.
 # if(CI)
 #   set(DEFAULT_VENDOR_PATH ${CACHE_PATH}/vendor)

cmake/Options.cmake

@@ -48,6 +48,16 @@ else()
   message(FATAL_ERROR "Unsupported architecture: ${CMAKE_SYSTEM_PROCESSOR}")
 endif()
 
+if(LINUX)
+  if(EXISTS "/etc/alpine-release")
+    set(DEFAULT_ABI "musl")
+  else()
+    set(DEFAULT_ABI "gnu")
+  endif()
+
+  optionx(ABI "musl|gnu" "The ABI to use (e.g. musl, gnu)" DEFAULT ${DEFAULT_ABI})
+endif()
+
 if(ARCH STREQUAL "x64")
   optionx(ENABLE_BASELINE BOOL "If baseline features should be used for older CPUs (e.g. disables AVX, AVX2)" DEFAULT OFF)
 endif()

cmake/targets/BuildBun.cmake

@@ -1163,7 +1163,7 @@ if(NOT BUN_CPP_ONLY)
 
   if(CI)
     set(bunTriplet bun-${OS}-${ARCH})
-    if(ABI STREQUAL "musl")
+    if(LINUX AND ABI STREQUAL "musl")
       set(bunTriplet ${bunTriplet}-musl)
     endif()
     if(ENABLE_BASELINE)

cmake/tools/SetupLLVM.cmake

@@ -4,7 +4,7 @@ if(NOT ENABLE_LLVM)
   return()
 endif()
 
-if(CMAKE_HOST_WIN32 OR CMAKE_HOST_APPLE OR ABI STREQUAL "musl")
+if(CMAKE_HOST_WIN32 OR CMAKE_HOST_APPLE OR EXISTS "/etc/alpine-release")
   set(DEFAULT_LLVM_VERSION "18.1.8")
 else()
   set(DEFAULT_LLVM_VERSION "16.0.6")

cmake/tools/SetupWebKit.cmake

@@ -63,7 +63,7 @@ else()
   message(FATAL_ERROR "Unsupported architecture: ${CMAKE_SYSTEM_PROCESSOR}")
 endif()
 
-if(ABI STREQUAL "musl")
+if(LINUX AND ABI STREQUAL "musl")
   set(WEBKIT_SUFFIX "-musl")
 endif()