Created attachment 8877663 [details] [diff] [review] compiler-error-mingw-debug.patch Compiling Firefox with --enable-debug crashes the MinGW compiler. The attached patch fixes the crash, but undoubtedly the real fix is fixing MinGW.
I can't reproduce it with GCC 7.1.
That got fixed in GCC 5.2.0 by https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65727. WORKSFORME then.