/// Returns a list of flags to pass to the C++ compiler for the target

    /// specified.

    fn cxxflags(&self, target: &str) -> Vec<String> {

        // Filter out -O and /O (the optimization flags) that we picked up from

        // gcc-rs because the build scripts will determine that for themselves.

        let mut base = self.cxx[target].args().iter()

                           .map(|s| s.to_string_lossy().into_owned())

                           .filter(|s| !s.starts_with("-O") && !s.starts_with("/O"))

                           .collect::<Vec<_>>();

        // If we're compiling on macOS then we add a few unconditional flags

        // indicating that we want libc++ (more filled out than libstdc++) and

        // we want to compile for 10.7. This way we can ensure that

        // LLVM/jemalloc/etc are all properly compiled.

        if target.contains("apple-darwin") {

            base.push("-stdlib=libc++".into());

        }

        // Work around an apparently bad MinGW / GCC optimization,

        // See: http://lists.llvm.org/pipermail/cfe-dev/2016-December/051980.html

        // See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78936

        if target == "i686-pc-windows-gnu" {

            base.push("-fno-omit-frame-pointer".into());

        }

        return base

    }