https://lists.gnu.org/archive/html/automake-patches/2018-03/msg00006.html
+ # For Cygwin compatibility. + if [ -x "$src".exe ]; then + src=${src}.exe + fi I think this change is too dangerous. It would make it impossible to install foo if foo.exe exists, regardless of what was intended. I think Cygwin support has to be handled at a different level, like EXEEXT in Autoconf. (I remember writing this before, but can't find any record that I sent it. Sorry if duplicate.) -k