On more than one occasion, we have had reports about not being able to build on Windows due to Visual Studio being installed with a different language. This causes the check in toolchain.m4 to fail as it assumes the compiler greeting is in english. The latest failure gave this message:

configure: The C compiler (located as
/cygdrive/c/progra~3/micros~1.0/vc/bin/cl) does not seem to be the required
microsoft compiler.
configure: The result from running it was: "Compilador de optimizaci▒n de
C/C++ de Microsoft (R) versi▒n 19.00.24234.1 para x86"

(from http://mail.openjdk.java.net/pipermail/build-dev/2018-October/023663.html)

The check looks for "Microsoft.*Compiler". I think that to be language neutral we can only really look for "Microsoft". If the tool is also named cl.exe, then I think that's enough due diligence from us in trying to fail early.