component/headless-chromium: use external llvm compiler

When using internal llvm compiler, we got this error on Debian 12

2023-07-12 00:48:42 slapos[2468769] INFO FAILED: brotli
2023-07-12 00:48:42 slapos[2468769] INFO python3 "../../build/toolchain/gcc_link_wrapper.py" --output="./brotli" -- "/srv/slapgrid/slappart0/t/dvl/i/0/tmp/soft/8db55dc3d35b55b9f773dc4e56fb2801/parts/chromium-source/src/third_party/llvm-build/Release+Asserts/bin/clang++" -fuse-ld=lld -Wl,--fatal-warnings -Wl,--build-id -fPIC -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -Wl,--icf=all -Wl,--color-diagnostics -Wl,--no-call-graph-profile-sort -m64 -no-canonical-prefixes -Werror -Wl,-O2 -Wl,--gc-sections -rdynamic -nostdlib++ --sysroot=../../build/linux/debian_sid_amd64-sysroot -Wl,-z,defs -Wl,--as-needed -pie -Wl,--disable-new-dtags "-Wl,-rpath=/srv/slapgrid/slappart0/t/dvl/i/0/tmp/soft/8db55dc3d35b55b9f773dc4e56fb2801/parts/nss/lib,-rpath=/srv/slapgrid/slappart0/t/dvl/i/0/tmp/soft/8db55dc3d35b55b9f773dc4e56fb2801/parts/nspr/lib" -o "./brotli" -Wl,--start-group @"./brotli.rsp"  -Wl,--end-group  -ldl -lpthread -lrt
2023-07-12 00:48:42 slapos[2468769] INFO /srv/slapgrid/slappart0/t/dvl/i/0/tmp/soft/8db55dc3d35b55b9f773dc4e56fb2801/parts/chromium-source/src/third_party/llvm-build/Release+Asserts/bin/ld.lld: /srv/slapgrid/slappart0/t/dvl/i/0/tmp/soft/8db55dc3d35b55b9f773dc4e56fb2801/parts/chromium-source/src/third_party/llvm-build/Release+Asserts/bin/../lib/libstdc++.so.6: version `GLIBCXX_3.4.30' not found (required by /lib/x86_64-linux-gnu/libicuuc.so.72)

component/headless-chromium/buildout.cfg

@@ -6,6 +6,7 @@ extends =
   ../depot_tools/buildout.cfg
   ../git/buildout.cfg
   ../gperf/buildout.cfg
+  ../llvm/buildout.cfg
   ../pkgconfig/buildout.cfg
 # Runtime dependencies:
   ../nspr/buildout.cfg
@@ -75,16 +76,16 @@ build-config-options =
   is_debug = false
   symbol_level = 0
   blink_symbol_level = 0
+  clang_use_chrome_plugins = false
 
-  # We need to unbundle the build toolchain in order to set our own
-  # LDFLAGS.
-  custom_toolchain = "//build/toolchain/linux/unbundle:default"
-  host_toolchain = "//build/toolchain/linux/unbundle:default"
+  clang_base_path = "${llvm:location}"
   current_os = "linux"
   current_cpu = "x64"
+  treat_warnings_as_errors = false
 
-# Chromium bundles its own LLVM toolchain, so we might as well use it.
-llvm-toolchain = ${:path}/third_party/llvm-build/Release+Asserts/bin
+# Don't use internal llvm toolchain to better control the library linking
+llvm-toolchain = ${llvm:location}/bin
+#${:path}/third_party/llvm-build/Release+Asserts/bin
 
 configure-command =
 # Sync build dependencies---this is a little finnicky.
@@ -104,7 +105,7 @@ make-binary =
 # compatibility. The build is quite cheap compared to Chromium, anyway.
   autoninja -C ${:fake-location} chromedriver
 environment =
-  PATH=${depot_tools:location}:${gperf:location}/bin:${pkgconfig:location}/bin:${coreutils:location}/bin:${git:location}/bin:${curl:location}/bin:%(PATH)s
+  PATH=${depot_tools:location}:${gperf:location}/bin:${pkgconfig:location}/bin:${coreutils:location}/bin:${git:location}/bin:${curl:location}/bin:${llvm:location}/bin%(PATH)s
   LDFLAGS="-Wl,-rpath=${nss:location}/lib,-rpath=${nspr:location}/lib"
   CC="${:llvm-toolchain}/clang"
   CXX="${:llvm-toolchain}/clang++"

component/llvm/buildout.cfg

@@ -6,23 +6,60 @@ extends =
 
 parts = llvm
 
+[llvm-version]
+version = 15.0.0
+
 [llvm-cmake]
 recipe = slapos.recipe.build:download-unpacked
 shared = true
-url = https://github.com/llvm/llvm-project/releases/download/llvmorg-${:version}/cmake-${:version}.src.tar.xz
-version = 15.0.0
+url = https://github.com/llvm/llvm-project/releases/download/llvmorg-${llvm-version:version}/cmake-${llvm-version:version}.src.tar.xz
 md5sum = e2e69ec36e163293f0b558e0382660cb
 environment =
   PATH=${xz-utils:location}/bin:%(PATH)s
 
+[llvm-clang]
+recipe = slapos.recipe.build:download-unpacked
+shared = true
+url = https://github.com/llvm/llvm-project/releases/download/llvmorg-${llvm-version:version}/clang-${llvm-version:version}.src.tar.xz
+md5sum = ff48dab9de875ca48736a97fdde60ced
+environment =
+  PATH=${xz-utils:location}/bin:%(PATH)s
+
+[llvm-lld]
+recipe = slapos.recipe.build:download-unpacked
+shared = true
+url = https://github.com/llvm/llvm-project/releases/download/llvmorg-${llvm-version:version}/lld-${llvm-version:version}.src.tar.xz
+md5sum = 5293c1ea3bb76cb0586ae01fb53231a6
+environment =
+  PATH=${xz-utils:location}/bin:%(PATH)s
+
+[llvm-libunwind]
+recipe = slapos.recipe.build:download-unpacked
+shared = true
+url = https://github.com/llvm/llvm-project/releases/download/llvmorg-${llvm-version:version}/libunwind-${llvm-version:version}.src.tar.xz
+md5sum = 9b94d6cb031792b14cbfb58386e68ac2
+environment =
+  PATH=${xz-utils:location}/bin:%(PATH)s
+
 [llvm]
 recipe = slapos.recipe.cmmi
 shared = true
-url = https://github.com/llvm/llvm-project/releases/download/llvmorg-${:version}/llvm-${:version}.src.tar.xz
-version = 15.0.0
+url = https://github.com/llvm/llvm-project/releases/download/llvmorg-${llvm-version:version}/llvm-${llvm-version:version}.src.tar.xz
 md5sum = 7b406c97f87b94cda4224aa53968c9d5
 pre-configure =
   cp ${llvm-cmake:location}/Modules/* ./cmake/modules/
+  mkdir ../clang
+  cp -r ${llvm-clang:location}/* ../clang/
+  # we need to give permission so that at the end of cmmi, we can delete it
+  chmod -R u+rw ../clang
+  mkdir ../lld
+  cp -r ${llvm-lld:location}/* ../lld/
+  # we need to give permission so that at the end of cmmi, we can delete it
+  chmod -R u+rw ../lld
+  mkdir ../libunwind
+  cp -r ${llvm-libunwind:location}/* ../libunwind/
+  # we need to give permission so that at the end of cmmi, we can delete it
+  chmod -R u+rw ../libunwind
 configure-command = ${cmake:location}/bin/cmake
 configure-options =
     -Bbuild
@@ -32,6 +69,7 @@ configure-options =
     -DLLVM_INCLUDE_BENCHMARKS=OFF
     -DCMAKE_C_FLAGS="${:CMAKE_CFLAGS}"
     -DCMAKE_CXX_FLAGS="${:CMAKE_CFLAGS}"
+    -DLLVM_ENABLE_PROJECTS="clang;libunwind;lld"
 make-options = -C build
 CMAKE_CFLAGS = -I${libxml2:location}/include/libxml2 -I${ncurses:location}/include -I${zlib:location}/include
 environment =