The mingw-w64-shims is responsible for exposing GCC and binutils from Cygwin into the switch. There's a potential race condition when mingw-w64-shims reinstalls because of a recompilation. Fault tracked in dra27/mingw-w64-shims#1
(int)' collect2.exe: error: ld returned 1 exit status = note: some `extern` functions couldn't be found; some native libraries may need to be installed or have their path specified = note: use the `-l` flag to specify native libraries to link = note: use the `cargo:rustc-link-...