clang 4.0.0 or newer can not compile 1.4.0 release because it uses

add_cflag_if_supported("-Wall")
add_cflag_if_supported("-Wextra")
add_cflag_if_supported("-Werror")

in CFlags.cmake, and later add integer to string literal (in logging code), which is warning for clang. Build log is attached,

build.txt