update Linux clang toolchain to support cross compiling

* moves a necessary header file to a new location
* also cleans up the Linux Sysroot workflow

.github/workflows/clang.yml

@@ -143,10 +143,21 @@ jobs:
             unwind \
             builtins
 
+      # Package the toolchain by copying everything listed from the following files:
+      #
+      #  * bin.txt
+      #  * include.txt
+      #  * lib.txt
+      #
+      # Note: There is a header file `__config_site` that gets generated in a platform specific
+      # directory but to support cross compiling we move it into the normal `include` dir. This is
+      # bit hacky, but I've manually confirmed the file is the same for both architectures.
       - name: package toolchain
         run: |
           mkdir package
 
+          mv llvm-project/build/include/$CLANG_TARGET/c++/v1/__config_site llvm-project/build/include/c++/v1/__config_site
+
           for dir in bin include lib; do
             mkdir package/$dir
             cat clang/$dir.txt | while read -r val; do 
@@ -160,12 +171,6 @@ jobs:
           cd package
           tar -cf - * | zstd --ultra -22 -o "../linux_$CLANG_ARCH.tar.zst"
 
-      - name: Upload Toolchain Artifact
-        uses: actions/upload-artifact@v4
-        with:
-          name: toolchains
-          path: "*.tar.zst"
-
       - name: Upload toolchain to release
         uses: svenstaro/upload-release-action@v2
         with:

clang/include.txt

@@ -1,2 +1 @@
 c++
-linux:$CLANG_TARGET

sysroot/Dockerfile

@@ -80,7 +80,6 @@ WORKDIR /downloads/gcc
 RUN curl --fail-early --location "https://ftp.gnu.org/gnu/gcc/gcc-${LIBSTDCXX_VERSION}/gcc-${LIBSTDCXX_VERSION}.tar.xz" \
         | tar --xz --extract --strip-components=1 --file -
 RUN ./contrib/download_prerequisites
-RUN --mount=source=echo_test.sh,target=/usr/bin/echo_test.sh echo_test.sh
 
 FROM base_image AS build_image