https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90655
Bug ID: 90655 Summary: make install fails with empty DESTDIR on cygwin Product: gcc Version: 8.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: other Assignee: unassigned at gcc dot gnu.org Reporter: helmut.grohne at intenta dot de Target Milestone: --- Host: x86_64-w64-mingw32 Build: x86_64-pc-cygwinng Created attachment 46425 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46425&action=edit patch for trunk When running make install with an empty DESTDIR, a small number of install invocations will attempt to install to $(DESTDIR)/$(something) where something typically is one of libdir, includedir or plugin_resourcesdir. All of these typically start with ${prefix} which starts with a slash. When DESTDIR is empty, the whole path starts with two forward slashes. Cygwin has a special handling for paths that start with two forward slashes and interprets them as network shares (see https://unix.stackexchange.com/a/12291/259352). The relevant install invocations fail. This affects a small number of install invocations in c, cp, jit and lto. The majority of install invocations use $(DESTDIR)$(something), which works fine on cygwin.