RE: Regression in Cygwin 3.2.0

[David Allsopp <David.Allsopp@cl.cam.ac.uk>]

Thomas Wolff wrote:
> Am 16.04.2021 um 16:07 schrieb David Allsopp via Cygwin:
> > Thomas Wolff wrote:
> >> Am 16.04.2021 um 12:17 schrieb David Allsopp via Cygwin:
> >>> I'm unable to build OCaml using the mingw-w64 compilers with Cygwin
> >>> 3.2.0. Windows 10.0.19042.928 (and tried on three different machines
> >>> so far)
> >>>
> >>> Repro:
> >>>
> >>>    - Fresh Cygwin64 installation with make, libiconv,
> >>> mingw64-x86_64-gcc-core and git added; fire up mintty
> >>>    - git clone --depth 1 --recursive https://github.com/ocaml/ocaml
> >>>    - cd ocaml && ./configure --host=x86_64-w64-mingw32 && make -j8
> >>> flexdll && make -j8 world.opt
> >>>
> >>> This is consistently hanging with Cygwin 3.2.0 and seems possibly to
> >>> have something to do with linking (the creation of
> >>> runtime/ocamlrun.exe and stdlib/camlheader, which is also an
> >>> executable, seem to be part of the problem).
> >>>
> >>> It can be immediately fixed by downgrading to Cygwin 3.1.7, cleaning
> >>> the tree and repeating the build.
> >>>
> >>> I'm of course very happy to try to reduce this to a smaller repro
> >>> case, but is there an obvious culprit in Cygwin 3.2.0 to check
> >>> before I do?
> >> The build fails for me with error messages but it does not hang.
> > Thanks for confirming!
> >
> >> You could have tried at least building without -j option, and running
> >> the build steps separately for better diagnostics.
> > Indeed - the repro case above was intended to be small and fast. I was
> > still at the "is this just me/us", stage. Suggesting a non-parallel
> > build of OCaml would have been mean, as it takes about an hour if it
> > doesn't crash...!
> >
> > That said, the non-parallel build I think reveals the Cygwin problem:
> > there are console windows constantly flashing up (it renders the
> > workstation unusable for the duration of the build). The first stage
> > of the build compiles ocamlrun.exe which is non-Cygwin in this case
> > and then it uses that throughout the build, so I guess it's the conpty
> > changes which are biting.
> >
> > However, the build did succeed when run without -j, however this
> > (which will take about 20 mins or so):
> >
> > ./configure --build=x86_64-w64-mingw32 --disable-native-compiler make
> > flexdll runtop
> >
> > causes a new console Window to pop up with an OCaml prompt (which can
> > be quit by taking #quit;;) rather than the same prompt being connected
> > to mintty.
> >
> > With make -j, it doesn't appear to flash up all the console Windows,
> > but it's also reliably failing. I tried with the cygwin1.dll snapshot
> > from this morning which seems to be doing the same.
> Maybe a non-cygwin tool is injected in your build process?
> What if you strip your PATH from all non-cygwin directories?

There always has been a non-Cygwin tool - it's calling an ocamlrun.exe it us built at the start of the process with x86_64-w64-mingw32. Is that no longer permitted?!

However, I'm not sure how the environment has anything to do with this: everything goes back to working just by downgrading cygwin1.dll to 3.1.7.


David