Dockerfile: Add MinGW-w64 toolchain

This commit adds a script that builds MinGW-w64 toolchains with `win32`
and `posix` thread models and updates the Dockerfile to invoke it.

The MinGW-w64 toolchains are installed in the Docker image as follows:

* /opt/mingw-w64-win32: x86_64-w64-mingw32 toolchain, win32 thread model
* /opt/mingw-w64-posix: x86_64-w64-mingw32 toolchain, posix thread model

The toolchain build scripts cleans up after itself so that no
intermediate build artifacts end up in the final Docker image.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

Dockerfile

@@ -64,6 +64,10 @@ RUN pip3 install awscli
 # Install meson to allow building picolibc
 RUN pip3 install meson
 
+# Install MinGW-w64 toolchain
+COPY mingw-build.sh /mingw-build.sh
+RUN /mingw-build.sh && rm -f /mingw-build.sh
+
 # Install QEMU
 RUN wget https://download.qemu.org/qemu-${QEMU_VERSION}.tar.xz && \
 	tar Jxf qemu-${QEMU_VERSION}.tar.xz && \

mingw-build.sh

@@ -0,0 +1,107 @@
+#!/bin/bash
+
+BINUTILS_VERSION=2.42
+GCC_VERSION=13.2.0
+MINGW_VERSION=12.0.0
+
+mkdir mingw
+pushd mingw
+
+# Download source code
+echo "@@@ Downloading source code"
+mkdir src
+pushd src
+## Binutils
+wget https://ftp.gnu.org/gnu/binutils/binutils-${BINUTILS_VERSION}.tar.xz
+tar Jxf binutils-${BINUTILS_VERSION}.tar.xz
+## GCC
+wget https://ftp.gnu.org/gnu/gcc/gcc-${GCC_VERSION}/gcc-${GCC_VERSION}.tar.xz
+tar Jxf gcc-${GCC_VERSION}.tar.xz
+pushd gcc-${GCC_VERSION}
+contrib/download_prerequisites
+popd
+## MinGW-w64
+wget https://sourceforge.net/projects/mingw-w64/files/mingw-w64/mingw-w64-release/mingw-w64-v${MINGW_VERSION}.tar.bz2
+tar jxf mingw-w64-v${MINGW_VERSION}.tar.bz2
+popd
+
+build_mingw_toolchain() {
+  local old_path=$PATH
+  local thread_model=$1
+  local prefix=/opt/mingw-w64-${thread_model}
+
+  echo "@@@ Building MinGW-w64 toolchain with '${thread_model}' thread model"
+
+  # Add prefix bin directory to PATH to aid toolchain discovery
+  export PATH="${prefix}/bin:${PATH}"
+
+  # Create build directory
+  mkdir build-${thread_model}
+  pushd build-${thread_model}
+
+  # Build Binutils
+  mkdir binutils
+  pushd binutils
+  ../../src/binutils-${BINUTILS_VERSION}/configure \
+    --prefix=${prefix} \
+    --target=x86_64-w64-mingw32 \
+    --disable-multilib
+  make -j$(nproc)
+  make install
+  popd
+
+  # Install MinGW headers
+  mkdir mingw-headers
+  pushd mingw-headers
+  ../../src/mingw-w64-v${MINGW_VERSION}/mingw-w64-headers/configure \
+    --prefix=${prefix}/x86_64-w64-mingw32 \
+    --host=x86_64-w64-mingw32 \
+    --with-default-msvcrt=ucrt
+  make install
+  popd
+
+  # Build core GCC
+  mkdir gcc
+  pushd gcc
+  ../../src/gcc-${GCC_VERSION}/configure \
+    --prefix=${prefix} \
+    --target=x86_64-w64-mingw32 \
+    --disable-multilib \
+    --enable-languages=c,c++ \
+    --enable-threads=win32 \
+    --with-headers
+  make -j$(nproc) all-gcc
+  make install-gcc
+  popd
+
+  # Build MinGW
+  mkdir mingw
+  pushd mingw
+  ../../src/mingw-w64-v${MINGW_VERSION}/configure \
+    --prefix=${prefix}/x86_64-w64-mingw32 \
+    --host=x86_64-w64-mingw32 \
+    --with-default-msvcrt=ucrt
+  make -j$(nproc)
+  make install -j$(nproc)
+  popd
+
+  # Build final GCC
+  pushd gcc
+  make -j$(nproc)
+  make install
+  popd
+
+  # Restore environment
+  popd
+  export PATH=${old_path}
+}
+
+# Build MinGW toolchain with 'win32' thread model
+build_mingw_toolchain win32
+
+# Build MinGW toolchain with 'posix' thread model
+build_mingw_toolchain posix
+
+# Clean up build directories
+popd
+rm -rf mingw