This also affects our software. I agree with Dan (danmbox): I don't understand; so many people depend on it and yet an out-of-the-box solution doesn't work.

I don't want to break the distutils package of our users because we use mingw. Within one Python script, I managed to fix it using this before the setup call:

if isWindows():
	"""
	Fix bug in cygwinccompiler: removed -mno-cygwin. This is fixed in cygwinccompiler_new.
	We hacked the distutils.ccompiler : def new_compiler : It uses sys.modules to fetch the compiler
	By modifying the sys.modules, we can choose our own compiler version.
	(this is a bug that's out there for quite some time)
	"""
	import cygwinccompiler_new
	import distutils.cygwinccompiler
	import sys
	sys.modules["distutils.cygwinccompiler"] = cygwinccompiler_new

..if I then later run setup(...), it will use my new cygwinccompiler_new, that has the '-mno-cygwin' line removed.

However, when you want to install new packages using pip from the command-line, I cannot find a suitable fix (except if I would replace the distutils.cygwinccompiler before pip'ing, then put it back). For afaik, distutils cannot be virtualenv'ed, right? So we cannot even fix the issue in a virtual environment.

If it is not possible to find out what version of gcc implemented it first; can't you simply use a pragmatic solution and run
"gcc -mno-cygwin": if it gives an error, then remove the option. That would need the least testing and would fix the issue.