[CMake] make GCCROOT optional for clang builds

Author: ajaypanyala

cmake/ga-compiler-options.cmake

@@ -15,25 +15,28 @@ if(CMAKE_C_COMPILER_ID STREQUAL "Clang")
     if(GCCROOT)
       set(__GA_GCC_INSTALL_PREFIX ${GCCROOT})
       set(GA_GCC_TOOLCHAIN_FLAG "--gcc-toolchain=${GCCROOT}")
-    else()
-      get_filename_component(__GA_GCC_INSTALL_PREFIX "${CMAKE_Fortran_COMPILER}/../.." ABSOLUTE)
-      if(CMAKE_Fortran_COMPILER_ID STREQUAL "GNU")
-        set(GA_GCC_TOOLCHAIN_FLAG "--gcc-toolchain=${__GA_GCC_INSTALL_PREFIX}")
-      else()
-        message(FATAL_ERROR "GCCROOT cmake option not set when using clang compilers. \
-                Please set a valid path to the GCC installation.")
-      endif()
+    # else()
+    #   get_filename_component(__GA_GCC_INSTALL_PREFIX "${CMAKE_Fortran_COMPILER}/../.." ABSOLUTE)
+    #   if(CMAKE_Fortran_COMPILER_ID STREQUAL "GNU")
+    #     set(GA_GCC_TOOLCHAIN_FLAG "--gcc-toolchain=${__GA_GCC_INSTALL_PREFIX}")
+    #   else()
+    #     message(FATAL_ERROR "GCCROOT cmake option not set when using clang compilers. \
+    #             Please set a valid path to the GCC installation.")
+    #   endif()
     endif()
     #Check GCC installation
-    if(NOT 
+    if(GCCROOT)
+      if(NOT 
        (EXISTS ${__GA_GCC_INSTALL_PREFIX}/bin AND
         EXISTS ${__GA_GCC_INSTALL_PREFIX}/include AND
         EXISTS ${__GA_GCC_INSTALL_PREFIX}/lib)
       )
       message(FATAL_ERROR "GCC installation path found ${__GA_GCC_INSTALL_PREFIX} seems to be incorrect. \
       Please set the GCCROOT cmake option to the correct GCC installation prefix.")
-    endif()
+      endif()
     message(STATUS "GA_GCC_TOOLCHAIN_FLAG: ${GA_GCC_TOOLCHAIN_FLAG}")
+    endif()
+
     set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} ${GA_GCC_TOOLCHAIN_FLAG}")
     set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} ${GA_GCC_TOOLCHAIN_FLAG}")
     set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} ${GA_GCC_TOOLCHAIN_FLAG}")