Fix CUDA toolchain detection for Arch builds

arch/git/PKGBUILD

@@ -113,10 +113,52 @@ build() {
   FULL_BUILD=true
 
   if [[ "${CARCH}" == "x86_64" ]]; then
-    pacman -Qi cuda &> /dev/null && HAS_CUDA=true || HAS_CUDA=false
+    CUDA_ROOT="${CUDAToolkit_ROOT:-${CUDA_PATH:-${CUDA_HOME:-}}}"
+    CUDA_NVCC=
+    if [[ -n "${CUDACXX:-}" ]] && [[ "${CUDACXX}" != *" "* ]]; then
+      if [[ "${CUDACXX}" == */* ]] && [[ -x "${CUDACXX}" ]]; then
+        CUDA_NVCC="${CUDACXX}"
+      elif [[ "${CUDACXX}" != */* ]]; then
+        CUDA_NVCC="$(command -v "${CUDACXX}" || true)"
+      fi
+    fi
+    if [[ -n "${CUDA_ROOT}" ]] && [[ -x "${CUDA_ROOT}/bin/nvcc" ]]; then
+      CUDA_NVCC="${CUDA_ROOT}/bin/nvcc"
+    fi
+    if [[ -z "${CUDA_NVCC}" ]]; then
+      CUDA_NVCC="$(command -v nvcc || true)"
+    fi
+    if [[ -z "${CUDA_ROOT}" ]] && [[ -n "${CUDA_NVCC}" ]]; then
+      CUDA_ROOT="$(dirname "$(dirname "${CUDA_NVCC}")")"
+    fi
+    if [[ -z "${CUDA_NVCC}" ]] && [[ -x /opt/cuda/bin/nvcc ]]; then
+      CUDA_ROOT=/opt/cuda
+      CUDA_NVCC=/opt/cuda/bin/nvcc
+    fi
+
+    pacman -Qi cuda &> /dev/null && [[ -n "${CUDA_NVCC}" ]] && HAS_CUDA=true || HAS_CUDA=false
 
     if [[ $HAS_CUDA = true ]] && [[ $FULL_BUILD = true ]]; then
-      CMAKE+=" -DBUILD_WHISPERCPP_CUBLAS=ON -DCMAKE_CUDA_ARCHITECTURES=native"
+      export CUDA_PATH="${CUDA_ROOT}"
+      export CUDAToolkit_ROOT="${CUDA_ROOT}"
+      export PATH="$(dirname "${CUDA_NVCC}"):$PATH"
+      CUDA_CMAKE="-DBUILD_WHISPERCPP_CUBLAS=ON \
+        -DCMAKE_CUDA_ARCHITECTURES=native \
+        -DCUDAToolkit_ROOT=${CUDA_ROOT}"
+      if [[ -z "${CUDACXX:-}" ]]; then
+        CUDA_CMAKE+=" -DCMAKE_CUDA_COMPILER=${CUDA_NVCC}"
+      fi
+      if [[ -n "${CUDAHOSTCXX:-}" ]] && [[ -x "${CUDAHOSTCXX}" ]]; then
+        CUDA_CMAKE+=" -DCMAKE_CUDA_HOST_COMPILER=${CUDAHOSTCXX}"
+      elif [[ -n "${NVCC_CCBIN:-}" ]] && [[ -x "${NVCC_CCBIN}" ]]; then
+        export CUDAHOSTCXX="${NVCC_CCBIN}"
+        CUDA_CMAKE+=" -DCMAKE_CUDA_HOST_COMPILER=${NVCC_CCBIN}"
+      elif [[ -x /usr/bin/g++-15 ]]; then
+        export NVCC_CCBIN=/usr/bin/g++-15
+        export CUDAHOSTCXX=/usr/bin/g++-15
+        CUDA_CMAKE+=" -DCMAKE_CUDA_HOST_COMPILER=/usr/bin/g++-15"
+      fi
+      CMAKE+=" ${CUDA_CMAKE}"
       export NVCC_APPEND_FLAGS="-std=c++17 --compress-mode=size --split-compile=0 -Wno-deprecated-gpu-targets"
     fi
   fi

arch/release/PKGBUILD

@@ -111,10 +111,52 @@ build() {
   FULL_BUILD=true
 
   if [[ "${CARCH}" == "x86_64" ]]; then
-    pacman -Qi cuda &> /dev/null && HAS_CUDA=true || HAS_CUDA=false
+    CUDA_ROOT="${CUDAToolkit_ROOT:-${CUDA_PATH:-${CUDA_HOME:-}}}"
+    CUDA_NVCC=
+    if [[ -n "${CUDACXX:-}" ]] && [[ "${CUDACXX}" != *" "* ]]; then
+      if [[ "${CUDACXX}" == */* ]] && [[ -x "${CUDACXX}" ]]; then
+        CUDA_NVCC="${CUDACXX}"
+      elif [[ "${CUDACXX}" != */* ]]; then
+        CUDA_NVCC="$(command -v "${CUDACXX}" || true)"
+      fi
+    fi
+    if [[ -n "${CUDA_ROOT}" ]] && [[ -x "${CUDA_ROOT}/bin/nvcc" ]]; then
+      CUDA_NVCC="${CUDA_ROOT}/bin/nvcc"
+    fi
+    if [[ -z "${CUDA_NVCC}" ]]; then
+      CUDA_NVCC="$(command -v nvcc || true)"
+    fi
+    if [[ -z "${CUDA_ROOT}" ]] && [[ -n "${CUDA_NVCC}" ]]; then
+      CUDA_ROOT="$(dirname "$(dirname "${CUDA_NVCC}")")"
+    fi
+    if [[ -z "${CUDA_NVCC}" ]] && [[ -x /opt/cuda/bin/nvcc ]]; then
+      CUDA_ROOT=/opt/cuda
+      CUDA_NVCC=/opt/cuda/bin/nvcc
+    fi
+
+    pacman -Qi cuda &> /dev/null && [[ -n "${CUDA_NVCC}" ]] && HAS_CUDA=true || HAS_CUDA=false
 
     if [[ $HAS_CUDA = true ]] && [[ $FULL_BUILD = true ]]; then
-      CMAKE+=" -DBUILD_WHISPERCPP_CUBLAS=ON -DCMAKE_CUDA_ARCHITECTURES=native"
+      export CUDA_PATH="${CUDA_ROOT}"
+      export CUDAToolkit_ROOT="${CUDA_ROOT}"
+      export PATH="$(dirname "${CUDA_NVCC}"):$PATH"
+      CUDA_CMAKE="-DBUILD_WHISPERCPP_CUBLAS=ON \
+        -DCMAKE_CUDA_ARCHITECTURES=native \
+        -DCUDAToolkit_ROOT=${CUDA_ROOT}"
+      if [[ -z "${CUDACXX:-}" ]]; then
+        CUDA_CMAKE+=" -DCMAKE_CUDA_COMPILER=${CUDA_NVCC}"
+      fi
+      if [[ -n "${CUDAHOSTCXX:-}" ]] && [[ -x "${CUDAHOSTCXX}" ]]; then
+        CUDA_CMAKE+=" -DCMAKE_CUDA_HOST_COMPILER=${CUDAHOSTCXX}"
+      elif [[ -n "${NVCC_CCBIN:-}" ]] && [[ -x "${NVCC_CCBIN}" ]]; then
+        export CUDAHOSTCXX="${NVCC_CCBIN}"
+        CUDA_CMAKE+=" -DCMAKE_CUDA_HOST_COMPILER=${NVCC_CCBIN}"
+      elif [[ -x /usr/bin/g++-15 ]]; then
+        export NVCC_CCBIN=/usr/bin/g++-15
+        export CUDAHOSTCXX=/usr/bin/g++-15
+        CUDA_CMAKE+=" -DCMAKE_CUDA_HOST_COMPILER=/usr/bin/g++-15"
+      fi
+      CMAKE+=" ${CUDA_CMAKE}"
       export NVCC_APPEND_FLAGS="-std=c++17 --compress-mode=size --split-compile=0 -Wno-deprecated-gpu-targets"
     fi
   fi
@@ -134,4 +176,3 @@ package() {
   cd build
   make DESTDIR="$pkgdir" install
 }
-

cmake/whispercpp.cmake

@@ -95,6 +95,12 @@ if(BUILD_WHISPERCPP_CUBLAS)
     if (NOT DEFINED CMAKE_CUDA_ARCHITECTURES)
         set(CMAKE_CUDA_ARCHITECTURES 50 52 53 60 61 62 70 72 75 80 86 87 89 90 100)
     endif()
+    set(whispercpp_cuda_cmake_args)
+    foreach(cuda_arg CUDAToolkit_ROOT CMAKE_CUDA_COMPILER CMAKE_CUDA_HOST_COMPILER)
+        if(DEFINED ${cuda_arg})
+            list(APPEND whispercpp_cuda_cmake_args -D${cuda_arg}=${${cuda_arg}})
+        endif()
+    endforeach()
     list(JOIN CMAKE_CUDA_ARCHITECTURES "\\\\\\\\\\;" CUDA_ARCHS_STRING)
     ExternalProject_Add(whispercppcublas
         SOURCE_DIR ${external_dir}/whispercppcublas
@@ -113,6 +119,8 @@ if(BUILD_WHISPERCPP_CUBLAS)
             -DCMAKE_INSTALL_LIBDIR=lib
             -DGGML_NATIVE=OFF
             -DGGML_CUDA=ON -DCMAKE_CUDA_ARCHITECTURES:STRING=${CUDA_ARCHS_STRING}
+            ${whispercpp_cuda_cmake_args}
+            -DCMAKE_CUDA_STANDARD=17 -DCMAKE_CUDA_STANDARD_REQUIRED=ON
             -DGGML_AVX=ON -DGGML_AVX2=OFF -DGGML_FMA=OFF -DGGML_F16C=ON
             -DBUILD_SHARED_LIBS=ON
             -DWHISPER_BUILD_TESTS=OFF -DWHISPER_BUILD_EXAMPLES=OFF