anchor.diff:  
   assert cloog != null -> stdenv.lib.versionOlder version "5";
   assert langJava -> stdenv.lib.versionOlder version "7";
  +
  +# Note [Windows Exception Handling]
  +# sjlj (short jump long jump) exception handling makes no sense on x86_64,
  +# it's forcably slowing programs down as it produces a constant overhead.
  +# On x86_64 we have SEH (Structured Exception Handling) and we should use
  +# that. On i686, we do not have SEH, and have to use sjlj with dwarf2.
  +# Hence it's now conditional on x86_32 (i686 is 32bit).
  +#
  +# ref: https://stackoverflow.com/questions/15670169/what-is-difference-between-sjlj-vs-dwarf-vs-seh
  +
   
   let
     inherit (stdenv)
  
positive.code:       "--disable-nls"
        # To keep ABI compatibility with upstream mingw-w64
        "--enable-fully-dynamic-string"
      ] ++ lib.optionals (crossMingw && targetPlatform.isx86_32) [
        "--enable-sjlj-exceptions"
        "--with-dwarf2"
      ] ++ lib.optional (targetPlatform.libc == "newlib") "--with-newlib"
        ++ lib.optional (targetPlatform.libc == "avrlibc") "--with-avrlibc"
      );
  
negative.code:       "--disable-debug"
        "--disable-win32-registry"
      ] ++ lib.optionals (crossMingw && targetPlatform.isx86_32) [
        # See Note [Windows Exception Handling]
        "--enable-sjlj-exceptions"
        "--with-dwarf2"
      ] else [
        (if crossDarwin then "--with-sysroot=${lib.getLib libcCross}/share/sysroot"
         else                "--with-headers=${lib.getDev libcCross}${libcCross.incdir or "/include"}")
  