diff --git a/contrib/guix/libexec/build_linux.sh b/contrib/guix/libexec/build_linux.sh
index 492890ecc1c..212b86c23dc 100755
--- a/contrib/guix/libexec/build_linux.sh
+++ b/contrib/guix/libexec/build_linux.sh
@@ -8,32 +8,8 @@ set -o errexit -o pipefail
 # shellcheck source=setup.sh
 source "$(dirname "${BASH_SOURCE[0]}")/setup.sh"
 
-# Set environment variables to point the NATIVE toolchain to the right
-# includes/libs
-NATIVE_GCC="$(store_path gcc-toolchain)"
-
-# Set native toolchain
-build_CC="${NATIVE_GCC}/bin/gcc -isystem ${NATIVE_GCC}/include"
-build_CXX="${NATIVE_GCC}/bin/g++ -isystem ${NATIVE_GCC}/include/c++ -isystem ${NATIVE_GCC}/include"
-
-NATIVE_GCC_STATIC="$(store_path gcc-toolchain static)"
-export LIBRARY_PATH="${NATIVE_GCC}/lib:${NATIVE_GCC_STATIC}/lib"
-
-# Set environment variables to point the CROSS toolchain to the right
-# includes/libs for $HOST
-CROSS_GLIBC="$(store_path "glibc-cross-${HOST}")"
-CROSS_GLIBC_STATIC="$(store_path "glibc-cross-${HOST}" static)"
-CROSS_KERNEL="$(store_path "linux-libre-headers-cross-${HOST}")"
-CROSS_GCC="$(store_path "gcc-cross-${HOST}")"
-CROSS_GCC_LIB_STORE="$(store_path "gcc-cross-${HOST}" lib)"
-CROSS_GCC_LIBS=( "${CROSS_GCC_LIB_STORE}/lib/gcc/${HOST}"/* ) # This expands to an array of directories...
-CROSS_GCC_LIB="${CROSS_GCC_LIBS[0]}" # ...we just want the first one (there should only be one)
-
-export CROSS_C_INCLUDE_PATH="${CROSS_GCC_LIB}/include:${CROSS_GCC_LIB}/include-fixed:${CROSS_GLIBC}/include:${CROSS_KERNEL}/include"
-export CROSS_CPLUS_INCLUDE_PATH="${CROSS_GCC}/include/c++:${CROSS_GCC}/include/c++/${HOST}:${CROSS_GCC}/include/c++/backward:${CROSS_C_INCLUDE_PATH}"
-export CROSS_LIBRARY_PATH="${CROSS_GCC_LIB_STORE}/lib:${CROSS_GCC_LIB}:${CROSS_GLIBC}/lib:${CROSS_GLIBC_STATIC}/lib"
-
-check_cross_paths "${CROSS_C_INCLUDE_PATH}:${CROSS_CPLUS_INCLUDE_PATH}:${CROSS_LIBRARY_PATH}"
+# setup gcc toolchain
+gcc_toolchain
 
 # Build the depends tree, overriding variables that assume multilib gcc
 make -C depends --jobs="$JOBS" HOST="$HOST" \
@@ -65,6 +41,12 @@ esac
 # LDFLAGS
 HOST_LDFLAGS="-Wl,--as-needed -Wl,--dynamic-linker=$(glibc_dynamic_linker "$HOST") -Wl,-O2"
 
+# Use LINK_WARNING_AS_ERROR when using CMake 4.x
+case "$HOST" in
+    riscv64-linux-gnu) ;; # https://github.com/boostorg/test/issues/345
+    *) HOST_LDFLAGS="${HOST_LDFLAGS} -Wl,--fatal-warnings" ;;
+esac
+
 mkdir -p "$DISTSRC"
 (
     cd "$DISTSRC"
@@ -76,15 +58,16 @@ mkdir -p "$DISTSRC"
     env CFLAGS="${HOST_CFLAGS}" CXXFLAGS="${HOST_CXXFLAGS}" LDFLAGS="${HOST_LDFLAGS}" \
     cmake -S . -B build \
           --toolchain "${BASEPREFIX}/${HOST}/toolchain.cmake" \
-          -Werror=dev \
           -DBUILD_BENCH=OFF \
           -DBUILD_FUZZ_BINARY=OFF \
           -DBUILD_GUI=OFF \
+          -DBUILD_GUI_TESTS=OFF \
+          -DCMAKE_EXE_LINKER_FLAGS="${HOST_LDFLAGS} -static-libstdc++ -static-libgcc" \
           -DCMAKE_INSTALL_PREFIX="${INSTALLPATH}" \
           -DCMAKE_SKIP_RPATH=TRUE \
           -DREDUCE_EXPORTS=ON \
-          -DCMAKE_EXE_LINKER_FLAGS="${HOST_LDFLAGS} -static-libstdc++ -static-libgcc" \
-          -DWITH_CCACHE=OFF
+          -DWITH_CCACHE=OFF \
+          -Werror=dev
 
     # Build Bitcoin Core
     cmake --build build -j "$JOBS"
diff --git a/contrib/guix/libexec/build_linux_gui.sh b/contrib/guix/libexec/build_linux_gui.sh
index 218bc0a952c..f069d4b4f1b 100755
--- a/contrib/guix/libexec/build_linux_gui.sh
+++ b/contrib/guix/libexec/build_linux_gui.sh
@@ -8,32 +8,8 @@ set -o errexit -o pipefail
 # shellcheck source=setup.sh
 source "$(dirname "${BASH_SOURCE[0]}")/setup.sh"
 
-# Set environment variables to point the NATIVE toolchain to the right
-# includes/libs
-NATIVE_GCC="$(store_path gcc-toolchain)"
-
-# Set native toolchain
-build_CC="${NATIVE_GCC}/bin/gcc -isystem ${NATIVE_GCC}/include"
-build_CXX="${NATIVE_GCC}/bin/g++ -isystem ${NATIVE_GCC}/include/c++ -isystem ${NATIVE_GCC}/include"
-
-NATIVE_GCC_STATIC="$(store_path gcc-toolchain static)"
-export LIBRARY_PATH="${NATIVE_GCC}/lib:${NATIVE_GCC_STATIC}/lib"
-
-# Set environment variables to point the CROSS toolchain to the right
-# includes/libs for $HOST
-CROSS_GLIBC="$(store_path "glibc-cross-${HOST}")"
-CROSS_GLIBC_STATIC="$(store_path "glibc-cross-${HOST}" static)"
-CROSS_KERNEL="$(store_path "linux-libre-headers-cross-${HOST}")"
-CROSS_GCC="$(store_path "gcc-cross-${HOST}")"
-CROSS_GCC_LIB_STORE="$(store_path "gcc-cross-${HOST}" lib)"
-CROSS_GCC_LIBS=( "${CROSS_GCC_LIB_STORE}/lib/gcc/${HOST}"/* ) # This expands to an array of directories...
-CROSS_GCC_LIB="${CROSS_GCC_LIBS[0]}" # ...we just want the first one (there should only be one)
-
-export CROSS_C_INCLUDE_PATH="${CROSS_GCC_LIB}/include:${CROSS_GCC_LIB}/include-fixed:${CROSS_GLIBC}/include:${CROSS_KERNEL}/include"
-export CROSS_CPLUS_INCLUDE_PATH="${CROSS_GCC}/include/c++:${CROSS_GCC}/include/c++/${HOST}:${CROSS_GCC}/include/c++/backward:${CROSS_C_INCLUDE_PATH}"
-export CROSS_LIBRARY_PATH="${CROSS_GCC_LIB_STORE}/lib:${CROSS_GCC_LIB}:${CROSS_GLIBC}/lib:${CROSS_GLIBC_STATIC}/lib"
-
-check_cross_paths "${CROSS_C_INCLUDE_PATH}:${CROSS_CPLUS_INCLUDE_PATH}:${CROSS_LIBRARY_PATH}"
+# setup gcc toolchain
+gcc_toolchain
 
 # Build the depends tree, overriding variables that assume multilib gcc
 make -C depends --jobs="$JOBS" HOST="$HOST" \
@@ -75,8 +51,8 @@ mkdir -p "$DISTSRC"
     env CFLAGS="${HOST_CFLAGS}" CXXFLAGS="${HOST_CXXFLAGS}" LDFLAGS="${HOST_LDFLAGS}" \
     cmake -S . -B build \
           --toolchain "${BASEPREFIX}/${HOST}/toolchain.cmake" \
-          -Werror=dev \
           -DBUILD_BENCH=OFF \
+          -DBUILD_BITCOIN_BIN=OFF \
           -DBUILD_CLI=OFF \
           -DBUILD_DAEMON=OFF \
           -DBUILD_FUZZ_BINARY=OFF \
@@ -89,7 +65,8 @@ mkdir -p "$DISTSRC"
           -DCMAKE_INSTALL_PREFIX="${INSTALLPATH}" \
           -DCMAKE_SKIP_RPATH=TRUE \
           -DREDUCE_EXPORTS=ON \
-          -DWITH_CCACHE=OFF
+          -DWITH_CCACHE=OFF \
+          -Werror=dev
 
     # Build Bitcoin Core
     cmake --build build -j "$JOBS" --target bitcoin-gui bitcoin-qt
diff --git a/contrib/guix/libexec/build_macos.sh b/contrib/guix/libexec/build_macos.sh
index b8dc2500994..08298d3513c 100755
--- a/contrib/guix/libexec/build_macos.sh
+++ b/contrib/guix/libexec/build_macos.sh
@@ -8,21 +8,8 @@ set -o errexit -o pipefail
 # shellcheck source=setup.sh
 source "$(dirname "${BASH_SOURCE[0]}")/setup.sh"
 
-# Set toolchain
-CLANG_TOOLCHAIN="$(store_path clang-toolchain)"
-LIBCXX="$(store_path libcxx)"
-build_CC="${CLANG_TOOLCHAIN}/bin/clang \
-    -isystem ${CLANG_TOOLCHAIN}/include"
-build_CXX="${CLANG_TOOLCHAIN}/bin/clang++ \
-    -stdlib=libc++ \
-    -isystem ${LIBCXX}/include/c++/v1 \
-    -isystem ${CLANG_TOOLCHAIN}/include"
-build_LDFLAGS="-fuse-ld=lld -rtlib=compiler-rt -unwindlib=libunwind -L${LIBCXX}/lib -Wl,-rpath,${LIBCXX}/lib"
-build_AR="${CLANG_TOOLCHAIN}/bin/llvm-ar"
-build_RANLIB="${CLANG_TOOLCHAIN}/bin/llvm-ranlib"
-build_OBJDUMP="${CLANG_TOOLCHAIN}/bin/llvm-objdump"
-build_NM="${CLANG_TOOLCHAIN}/bin/llvm-nm"
-build_STRIP="${CLANG_TOOLCHAIN}/bin/llvm-strip"
+# Setup toolchain
+llvm_toolchain
 
 # Build the depends tree
 make -C depends --jobs="$JOBS" HOST="$HOST" \
@@ -50,7 +37,6 @@ mkdir -p "$DISTSRC"
     # Configure this DISTSRC for $HOST
     env cmake -S . -B build \
           --toolchain "${BASEPREFIX}/${HOST}/toolchain.cmake" \
-          -Werror=dev \
           -DBUILD_BENCH=OFF \
           -DBUILD_FUZZ_BINARY=OFF \
           -DBUILD_GUI=OFF \
@@ -58,7 +44,8 @@ mkdir -p "$DISTSRC"
           -DCMAKE_INSTALL_PREFIX="${INSTALLPATH}" \
           -DCMAKE_SKIP_RPATH=TRUE \
           -DREDUCE_EXPORTS=ON \
-          -DWITH_CCACHE=OFF
+          -DWITH_CCACHE=OFF \
+          -Werror=dev
 
     # Build Bitcoin Core
     cmake --build build -j "$JOBS"
diff --git a/contrib/guix/libexec/build_macos_gui.sh b/contrib/guix/libexec/build_macos_gui.sh
index 3db1cfac643..1f2dbc6468d 100755
--- a/contrib/guix/libexec/build_macos_gui.sh
+++ b/contrib/guix/libexec/build_macos_gui.sh
@@ -8,21 +8,8 @@ set -o errexit -o pipefail
 # shellcheck source=setup.sh
 source "$(dirname "${BASH_SOURCE[0]}")/setup.sh"
 
-# Set toolchain
-CLANG_TOOLCHAIN="$(store_path clang-toolchain)"
-LIBCXX="$(store_path libcxx)"
-build_CC="${CLANG_TOOLCHAIN}/bin/clang \
-    -isystem ${CLANG_TOOLCHAIN}/include"
-build_CXX="${CLANG_TOOLCHAIN}/bin/clang++ \
-    -stdlib=libc++ \
-    -isystem ${LIBCXX}/include/c++/v1 \
-    -isystem ${CLANG_TOOLCHAIN}/include"
-build_LDFLAGS="-fuse-ld=lld -rtlib=compiler-rt -unwindlib=libunwind -L${LIBCXX}/lib -Wl,-rpath,${LIBCXX}/lib"
-build_AR="${CLANG_TOOLCHAIN}/bin/llvm-ar"
-build_RANLIB="${CLANG_TOOLCHAIN}/bin/llvm-ranlib"
-build_OBJDUMP="${CLANG_TOOLCHAIN}/bin/llvm-objdump"
-build_NM="${CLANG_TOOLCHAIN}/bin/llvm-nm"
-build_STRIP="${CLANG_TOOLCHAIN}/bin/llvm-strip"
+# Setup toolchain
+llvm_toolchain
 
 # Build the depends tree
 make -C depends --jobs="$JOBS" HOST="$HOST" \
@@ -49,8 +36,6 @@ mkdir -p "$DISTSRC"
     # Configure this DISTSRC for $HOST
     env cmake -S . -B build \
           --toolchain "${BASEPREFIX}/${HOST}/toolchain.cmake" \
-          -DWITH_CCACHE=OFF \
-          -Werror=dev \
           -DBUILD_BENCH=OFF \
           -DBUILD_BITCOIN_BIN=OFF \
           -DBUILD_CLI=OFF \
@@ -63,7 +48,9 @@ mkdir -p "$DISTSRC"
           -DBUILD_WALLET_TOOL=OFF \
           -DCMAKE_INSTALL_PREFIX="${INSTALLPATH}" \
           -DCMAKE_SKIP_RPATH=TRUE \
-          -DREDUCE_EXPORTS=ON
+          -DREDUCE_EXPORTS=ON \
+          -DWITH_CCACHE=OFF \
+          -Werror=dev
 
     # Build Bitcoin Core
     cmake --build build -j "$JOBS" --target bitcoin-gui bitcoin-qt
diff --git a/contrib/guix/libexec/build_win.sh b/contrib/guix/libexec/build_win.sh
index ce1f7fd4d03..3b4554e963d 100755
--- a/contrib/guix/libexec/build_win.sh
+++ b/contrib/guix/libexec/build_win.sh
@@ -8,32 +8,8 @@ set -o errexit -o pipefail
 # shellcheck source=setup.sh
 source "$(dirname "${BASH_SOURCE[0]}")/setup.sh"
 
-# Set environment variables to point the NATIVE toolchain to the right
-# includes/libs
-NATIVE_GCC="$(store_path gcc-toolchain)"
-
-# Set native toolchain
-build_CC="${NATIVE_GCC}/bin/gcc -isystem ${NATIVE_GCC}/include"
-build_CXX="${NATIVE_GCC}/bin/g++ -isystem ${NATIVE_GCC}/include/c++ -isystem ${NATIVE_GCC}/include"
-
-# Set environment variables to point the CROSS toolchain to the right
-# includes/libs for $HOST
-# Determine output paths to use in CROSS_* environment variables
-CROSS_GLIBC="$(store_path "mingw-w64-x86_64-winpthreads")"
-CROSS_GCC="$(store_path "gcc-cross-${HOST}")"
-CROSS_GCC_LIB_STORE="$(store_path "gcc-cross-${HOST}" lib)"
-CROSS_GCC_LIBS=( "${CROSS_GCC_LIB_STORE}/lib/gcc/${HOST}"/* ) # This expands to an array of directories...
-CROSS_GCC_LIB="${CROSS_GCC_LIBS[0]}" # ...we just want the first one (there should only be one)
-
-# The search path ordering is generally:
-#    1. gcc-related search paths
-#    2. libc-related search paths
-#    2. kernel-header-related search paths (not applicable to mingw-w64 hosts)
-export CROSS_C_INCLUDE_PATH="${CROSS_GCC_LIB}/include:${CROSS_GCC_LIB}/include-fixed:${CROSS_GLIBC}/include"
-export CROSS_CPLUS_INCLUDE_PATH="${CROSS_GCC}/include/c++:${CROSS_GCC}/include/c++/${HOST}:${CROSS_GCC}/include/c++/backward:${CROSS_C_INCLUDE_PATH}"
-export CROSS_LIBRARY_PATH="${CROSS_GCC_LIB_STORE}/lib:${CROSS_GCC_LIB}:${CROSS_GLIBC}/lib"
-
-check_cross_paths "${CROSS_C_INCLUDE_PATH}:${CROSS_CPLUS_INCLUDE_PATH}:${CROSS_LIBRARY_PATH}"
+# setup mingw-w64 toolchain
+mingw_w64_toolchain
 
 # Build the depends tree
 make -C depends --jobs="$JOBS" HOST="$HOST" \
@@ -54,7 +30,7 @@ HOST_CFLAGS+=" -fno-ident"
 HOST_CXXFLAGS="$HOST_CFLAGS"
 
 # LDFLAGS
-HOST_LDFLAGS="-Wl,--no-insert-timestamp"
+HOST_LDFLAGS="-Wl,--no-insert-timestamp -Wl,--fatal-warnings"
 
 mkdir -p "$DISTSRC"
 (
@@ -67,14 +43,14 @@ mkdir -p "$DISTSRC"
     env CFLAGS="${HOST_CFLAGS}" CXXFLAGS="${HOST_CXXFLAGS}" LDFLAGS="${HOST_LDFLAGS}" \
     cmake -S . -B build \
           --toolchain "${BASEPREFIX}/${HOST}/toolchain.cmake" \
-          -Werror=dev \
           -DBUILD_BENCH=OFF \
           -DBUILD_FUZZ_BINARY=OFF \
           -DBUILD_GUI=OFF \
           -DBUILD_GUI_TESTS=OFF \
           -DCMAKE_INSTALL_PREFIX="${INSTALLPATH}" \
           -DREDUCE_EXPORTS=ON \
-          -DWITH_CCACHE=OFF
+          -DWITH_CCACHE=OFF \
+          -Werror=dev
 
     # Build Bitcoin Core
     cmake --build build -j "$JOBS"
diff --git a/contrib/guix/libexec/build_win_gui.sh b/contrib/guix/libexec/build_win_gui.sh
index 94f21166392..65696a2fb43 100755
--- a/contrib/guix/libexec/build_win_gui.sh
+++ b/contrib/guix/libexec/build_win_gui.sh
@@ -8,32 +8,8 @@ set -o errexit -o pipefail
 # shellcheck source=setup.sh
 source "$(dirname "${BASH_SOURCE[0]}")/setup.sh"
 
-# Set environment variables to point the NATIVE toolchain to the right
-# includes/libs
-NATIVE_GCC="$(store_path gcc-toolchain)"
-
-# Set native toolchain
-build_CC="${NATIVE_GCC}/bin/gcc -isystem ${NATIVE_GCC}/include"
-build_CXX="${NATIVE_GCC}/bin/g++ -isystem ${NATIVE_GCC}/include/c++ -isystem ${NATIVE_GCC}/include"
-
-# Set environment variables to point the CROSS toolchain to the right
-# includes/libs for $HOST
-# Determine output paths to use in CROSS_* environment variables
-CROSS_GLIBC="$(store_path "mingw-w64-x86_64-winpthreads")"
-CROSS_GCC="$(store_path "gcc-cross-${HOST}")"
-CROSS_GCC_LIB_STORE="$(store_path "gcc-cross-${HOST}" lib)"
-CROSS_GCC_LIBS=( "${CROSS_GCC_LIB_STORE}/lib/gcc/${HOST}"/* ) # This expands to an array of directories...
-CROSS_GCC_LIB="${CROSS_GCC_LIBS[0]}" # ...we just want the first one (there should only be one)
-
-# The search path ordering is generally:
-#    1. gcc-related search paths
-#    2. libc-related search paths
-#    2. kernel-header-related search paths (not applicable to mingw-w64 hosts)
-export CROSS_C_INCLUDE_PATH="${CROSS_GCC_LIB}/include:${CROSS_GCC_LIB}/include-fixed:${CROSS_GLIBC}/include"
-export CROSS_CPLUS_INCLUDE_PATH="${CROSS_GCC}/include/c++:${CROSS_GCC}/include/c++/${HOST}:${CROSS_GCC}/include/c++/backward:${CROSS_C_INCLUDE_PATH}"
-export CROSS_LIBRARY_PATH="${CROSS_GCC_LIB_STORE}/lib:${CROSS_GCC_LIB}:${CROSS_GLIBC}/lib"
-
-check_cross_paths "${CROSS_C_INCLUDE_PATH}:${CROSS_CPLUS_INCLUDE_PATH}:${CROSS_LIBRARY_PATH}"
+# setup mingw-w64 toolchain
+mingw_w64_toolchain
 
 # Build the depends tree
 make -C depends --jobs="$JOBS" HOST="$HOST" \
@@ -53,7 +29,7 @@ HOST_CFLAGS+=" -fno-ident"
 HOST_CXXFLAGS="$HOST_CFLAGS"
 
 # LDFLAGS
-HOST_LDFLAGS="-Wl,--no-insert-timestamp"
+HOST_LDFLAGS="-Wl,--no-insert-timestamp -Wl,--fatal-warnings"
 
 mkdir -p "$DISTSRC"
 (
@@ -66,7 +42,6 @@ mkdir -p "$DISTSRC"
     env CFLAGS="${HOST_CFLAGS}" CXXFLAGS="${HOST_CXXFLAGS}" LDFLAGS="${HOST_LDFLAGS}" \
     cmake -S . -B build \
           --toolchain "${BASEPREFIX}/${HOST}/toolchain.cmake" \
-          -Werror=dev \
           -DBUILD_BENCH=OFF \
           -DBUILD_BITCOIN_BIN=OFF \
           -DBUILD_CLI=OFF \
@@ -79,7 +54,8 @@ mkdir -p "$DISTSRC"
           -DBUILD_WALLET_TOOL=OFF \
           -DCMAKE_INSTALL_PREFIX="${INSTALLPATH}" \
           -DREDUCE_EXPORTS=ON \
-          -DWITH_CCACHE=OFF
+          -DWITH_CCACHE=OFF \
+          -Werror=dev
 
     # Build Bitcoin Core
     cmake --build build -j "$JOBS" --target bitcoin-qt
diff --git a/contrib/guix/libexec/setup.sh b/contrib/guix/libexec/setup.sh
index c6858c9862d..2e3eb159838 100755
--- a/contrib/guix/libexec/setup.sh
+++ b/contrib/guix/libexec/setup.sh
@@ -86,6 +86,84 @@ glibc_dynamic_linker() {
     esac
 }
 
+gcc_toolchain() {
+    # Set environment variables to point the NATIVE toolchain to the right
+    # includes/libs
+    local NATIVE_GCC NATIVE_GCC_STATIC CROSS_GLIBC CROSS_GLIBC_STATIC CROSS_KERNEL CROSS_GCC CROSS_GCC_LIB_STORE CROSS_GCC_LIBS CROSS_GCC_LIB
+
+    NATIVE_GCC="$(store_path gcc-toolchain)"
+
+    # Set native toolchain
+    export build_CC="${NATIVE_GCC}/bin/gcc -isystem ${NATIVE_GCC}/include"
+    export build_CXX="${NATIVE_GCC}/bin/g++ -isystem ${NATIVE_GCC}/include/c++ -isystem ${NATIVE_GCC}/include"
+
+    NATIVE_GCC_STATIC="$(store_path gcc-toolchain static)"
+    export LIBRARY_PATH="${NATIVE_GCC}/lib:${NATIVE_GCC_STATIC}/lib"
+
+    # Set environment variables to point the CROSS toolchain to the right
+    # includes/libs for $HOST
+    CROSS_GLIBC="$(store_path "glibc-cross-${HOST}")"
+    CROSS_GLIBC_STATIC="$(store_path "glibc-cross-${HOST}" static)"
+    CROSS_KERNEL="$(store_path "linux-libre-headers-cross-${HOST}")"
+    CROSS_GCC="$(store_path "gcc-cross-${HOST}")"
+    CROSS_GCC_LIB_STORE="$(store_path "gcc-cross-${HOST}" lib)"
+    CROSS_GCC_LIBS=( "${CROSS_GCC_LIB_STORE}/lib/gcc/${HOST}"/* ) # This expands to an array of directories...
+    CROSS_GCC_LIB="${CROSS_GCC_LIBS[0]}" # ...we just want the first one (there should only be one)
+
+    export CROSS_C_INCLUDE_PATH="${CROSS_GCC_LIB}/include:${CROSS_GCC_LIB}/include-fixed:${CROSS_GLIBC}/include:${CROSS_KERNEL}/include"
+    export CROSS_CPLUS_INCLUDE_PATH="${CROSS_GCC}/include/c++:${CROSS_GCC}/include/c++/${HOST}:${CROSS_GCC}/include/c++/backward:${CROSS_C_INCLUDE_PATH}"
+    export CROSS_LIBRARY_PATH="${CROSS_GCC_LIB_STORE}/lib:${CROSS_GCC_LIB}:${CROSS_GLIBC}/lib:${CROSS_GLIBC_STATIC}/lib"
+
+    check_cross_paths "${CROSS_C_INCLUDE_PATH}:${CROSS_CPLUS_INCLUDE_PATH}:${CROSS_LIBRARY_PATH}"
+}
+
+llvm_toolchain() {
+    local CLANG_TOOLCHAIN LIB_CXX
+
+    CLANG_TOOLCHAIN="$(store_path clang-toolchain)"
+    LIB_CXX="$(store_path libcxx)"
+
+    export build_CC="${CLANG_TOOLCHAIN}/bin/clang -isystem ${CLANG_TOOLCHAIN}/include"
+    export build_CXX="${CLANG_TOOLCHAIN}/bin/clang++ -stdlib=libc++ -isystem ${LIB_CXX}/include/c++/v1 -isystem ${CLANG_TOOLCHAIN}/include"
+    export build_LDFLAGS="-fuse-ld=lld -rtlib=compiler-rt -unwindlib=libunwind -L${LIB_CXX}/lib -Wl,-rpath,${LIB_CXX}/lib"
+    export build_AR="${CLANG_TOOLCHAIN}/bin/llvm-ar"
+    export build_RANLIB="${CLANG_TOOLCHAIN}/bin/llvm-ranlib"
+    export build_OBJDUMP="${CLANG_TOOLCHAIN}/bin/llvm-objdump"
+    export build_NM="${CLANG_TOOLCHAIN}/bin/llvm-nm"
+    export build_STRIP="${CLANG_TOOLCHAIN}/bin/llvm-strip"
+}
+
+mingw_w64_toolchain() {
+    # Set environment variables to point the NATIVE toolchain to the right
+    # includes/libs
+    local NATIVE_GCC CROSS_GLIBC CROSS_GCC CROSS_GCC_LIB_STORE CROSS_GCC_LIBS CROSS_GCC_LIB
+
+    NATIVE_GCC="$(store_path gcc-toolchain)"
+
+    # Set native toolchain
+    export build_CC="${NATIVE_GCC}/bin/gcc -isystem ${NATIVE_GCC}/include"
+    export build_CXX="${NATIVE_GCC}/bin/g++ -isystem ${NATIVE_GCC}/include/c++ -isystem ${NATIVE_GCC}/include"
+
+    # Set environment variables to point the CROSS toolchain to the right
+    # includes/libs for $HOST
+    # Determine output paths to use in CROSS_* environment variables
+    CROSS_GLIBC="$(store_path "mingw-w64-x86_64-winpthreads")"
+    CROSS_GCC="$(store_path "gcc-cross-${HOST}")"
+    CROSS_GCC_LIB_STORE="$(store_path "gcc-cross-${HOST}" lib)"
+    CROSS_GCC_LIBS=( "${CROSS_GCC_LIB_STORE}/lib/gcc/${HOST}"/* ) # This expands to an array of directories...
+    CROSS_GCC_LIB="${CROSS_GCC_LIBS[0]}" # ...we just want the first one (there should only be one)
+
+    # The search path ordering is generally:
+    #    1. gcc-related search paths
+    #    2. libc-related search paths
+    #    2. kernel-header-related search paths (not applicable to mingw-w64 hosts)
+    export CROSS_C_INCLUDE_PATH="${CROSS_GCC_LIB}/include:${CROSS_GCC_LIB}/include-fixed:${CROSS_GLIBC}/include"
+    export CROSS_CPLUS_INCLUDE_PATH="${CROSS_GCC}/include/c++:${CROSS_GCC}/include/c++/${HOST}:${CROSS_GCC}/include/c++/backward:${CROSS_C_INCLUDE_PATH}"
+    export CROSS_LIBRARY_PATH="${CROSS_GCC_LIB_STORE}/lib:${CROSS_GCC_LIB}:${CROSS_GLIBC}/lib"
+
+    check_cross_paths "${CROSS_C_INCLUDE_PATH}:${CROSS_CPLUS_INCLUDE_PATH}:${CROSS_LIBRARY_PATH}"
+}
+
 # Disable Guix ld auto-rpath behavior
 export GUIX_LD_WRAPPER_DISABLE_RPATH=yes