As an example, consider the following input: ``` # CMakeLists.txt cmake_minimum_required(VERSION 3.8) project(test LANGUAGES Fortran) enable_language(ASM) add_executable(main main.f90) # main.f90 end ``` Configuring with `-DCMAKE_C_COMPILER=gcc` results in ``` -- The Fortran compiler identification is GNU 8.2.1 -- Check for working Fortran compiler: /bin/f95 -- Check for working Fortran compiler: /bin/f95 -- works -- Detecting Fortran compiler ABI info -- Detecting Fortran compiler ABI info - done -- Checking whether /bin/f95 supports Fortran 90 -- Checking whether /bin/f95 supports Fortran 90 -- yes -- The ASM compiler identification is GNU -- Found assembler: gcc CMake Error at CMakeLists.txt:8 (enable_language): The CMAKE_ASM_COMPILER: gcc is not a full path and was not found in the PATH. Tell CMake where to find the compiler by setting either the environment variable "ASM" or the CMake cache entry CMAKE_ASM_COMPILER to the full path to the compiler, or to the compiler name if it is in the PATH. ``` even though `gcc` is in the PATH. I'm opening this issue following !2418.