Various scripts check the CC environment variable to get the compiler to use. In absence of that variable they do various educated guesses. They guess wrong when running in MSYS (find /usr/bin/gcc instead of /mingw/bin/gcc) and likely also guess wrong when cross-compiling.
Created attachment 250811 [details] Ensure that generator-scripts get CC from configure Various scripts check the CC environment variable to get the compiler to use. In absence of that variable they do various educated guesses. They guess wrong when running in MSYS (find /usr/bin/gcc instead of /mingw/bin/gcc) and likely also guess wrong when cross-compiling. Note that if the version of a "wrong" gcc is close enough to the "right" gcc, things might just work out somehow, but we shouldn't bet on that.
There's an alternative patch for this issue in https://bugs.webkit.org/show_bug.cgi?id=143908 While i believe that the patch from bug 143908 is not entirely correct (for the explanation see https://bugs.webkit.org/show_bug.cgi?id=133028#c38 ), it does fix the immediate problem.
Comment on attachment 250811 [details] Ensure that generator-scripts get CC from configure This patch has been pending review since 2015 with no recent activity. It seems unlikely that it would even still apply to trunk in its current form. Clearing from the review queue. Feel free to update and resubmit if the patch is still relevant.