Although CMAKE_C_COMPILER_FRONTEND_VARIANT is defined, it's not always set to some...

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 130d82753b2ed39e075c05ca88db7808812bd466..501540882bd47c9358111e19e3f290d5547164c0 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -276,7 +276,7 @@ message(STATUS "Wrote ${PROJECT_BINARY_DIR}/config.h")
 configure_file(${PROJECT_SOURCE_DIR}/cmake/json_config.h.in   ${PROJECT_BINARY_DIR}/json_config.h)
 message(STATUS "Wrote ${PROJECT_BINARY_DIR}/json_config.h")
 
-if (NOT DEFINED CMAKE_C_COMPILER_FRONTEND_VARIANT)  # only available in cmake 3.14+
+if (NOT DEFINED CMAKE_C_COMPILER_FRONTEND_VARIANT OR "${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "")  # only available in cmake 3.14+
        if ("${CMAKE_C_COMPILER_ID}" STREQUAL "MSVC")
                set(CMAKE_C_COMPILER_FRONTEND_VARIANT "MSVC")
        elseif ("${CMAKE_C_COMPILER_ID}" STREQUAL "GNU")