sbuild cross compile broken

sbuild cross compile fails with:

[ 2%] Performing configure step for 'GMock'
cd /«PKGBUILDDIR»/obj-arm-linux-gnueabihf/gmock/libs && /usr/bin/cmake -DCMAKE_CXX_FLAGS=-fPIC -DCMAKE_CXX_COMPILER=/usr/bin/arm-linux-gnueabihf-g++ -DCMAKE_C_COMPILER=/usr/bin/arm-linux-gnueabihf-gcc -DCMAKE_TOOLCHAIN_FILE=/«PKGBUILDDIR»/cmake/LinuxCrossCompile.cmake "-GUnix Makefiles" /usr/src/gmock
-- The CXX compiler identification is unknown
/«PKGBUILDDIR»/3rd_party/xcursor/xcursor.c: In function '_XcursorBuildFullname':
/«PKGBUILDDIR»/3rd_party/xcursor/xcursor.c:720:5: warning: ISO C90 forbids mixed declarations and code [-Wpedantic]
     size_t padding = 4;
     ^
-- The C compiler identification is unknown
CMake Error at CMakeLists.txt:40 (project):
  The CMAKE_CXX_COMPILER:

    /usr/bin/-g++

  is not a full path to an existing compiler tool.

  Tell CMake where to find the compiler by setting either the environment
  variable "CXX" or the CMake cache entry CMAKE_CXX_COMPILER to the full path
  to the compiler, or to the compiler name if it is in the PATH.

CMake Error at CMakeLists.txt:40 (project):
  The CMAKE_C_COMPILER:

    /usr/bin/-gcc

  is not a full path to an existing compiler tool.

  Tell CMake where to find the compiler by setting either the environment
  variable "CC" or the CMake cache entry CMAKE_C_COMPILER to the full path to
  the compiler, or to the compiler name if it is in the PATH.

-- Configuring incomplete, errors occurred!
See also "/«PKGBUILDDIR»/obj-arm-linux-gnueabihf/gmock/libs/CMakeFiles/CMakeOutput.log".
See also "/«PKGBUILDDIR»/obj-arm-linux-gnueabihf/gmock/libs/CMakeFiles/CMakeError.log".
make[3]: *** [gmock/src/GMock-stamp/GMock-configure] Error 1
CMakeFiles/GMock.dir/build.make:101: recipe for target 'gmock/src/GMock-stamp/GMock-configure' failed
make[3]: Leaving directory '/«PKGBUILDDIR»/obj-arm-linux-gnueabihf'
make[2]: *** [CMakeFiles/GMock.dir/all] Error 2
make[2]: *** Waiting for unfinished jobs....
CMakeFiles/Makefile2:63: recipe for target 'CMakeFiles/GMock.dir/all' failed