unrecognized command line option -fself-test

[J.W. Jagersma]

I'm trying to build gcc-7.1.0 on mingw64, and it fails with the following error:

make[2]: Entering directory '/home/JW/build-gcc-msys/gcc'
x86_64-w64-mingw32-gcc -nostdinc -x c /dev/null -S -o /dev/null
-fself-test=../../gcc-7.1.0/gcc/testsuite/selftests
x86_64-w64-mingw32-gcc: error: unrecognized command line option
‘-fself-test=../../gcc-7.1.0/gcc/testsuite/selftests’
make[2]: *** [Makefile:1933: s-selftest] Error 1
make[2]: Leaving directory '/home/JW/build-gcc-msys/gcc'
make[1]: *** [Makefile:4246: all-gcc] Error 2
make[1]: Leaving directory '/home/JW/build-gcc-msys'
make: *** [Makefile:909: all] Error 2

That seems like an odd error message. Am I doing something wrong here?