# Test if compile errors are produced where necessary. include(CheckCXXSourceCompiles) set(CMAKE_REQUIRED_INCLUDES ${CMAKE_CURRENT_SOURCE_DIR}/..) function (expect_compile_error code) check_cxx_source_compiles(" #include \"format.cc\" int main() { ${code} } " compiles) if (compiles) error("No compile error for: ${code}") endif () endfunction () # Writing a wide character to a character stream Writer is forbidden. expect_compile_error("fmt::Writer() << L'a';")