Cygwin problem caused by config.hpp defining BOOST_USE_UCONTEXT

[pdimov]

https://github.com/boostorg/context/blob/fb0f3eab4d14ce2de4cf3a5446c8a0f735a9282d/include/boost/context/detail/config.hpp#L33-L35

defines BOOST_USE_UCONTEXT on Cygwin. This causes Fiber to fail to build, because it tries to use ucontext, but Context is built with fcontext.

If Context is built with ucontext instead, Fiber builds, but then Coroutine fails, because it needs fcontext:

https://github.com/boostorg/coroutine/blob/4e47f98d44ad0d5d487788ed6eb4d347489e5483/src/detail/coroutine_context.cpp#L68

Should config.hpp be defining BOOST_USE_UCONTEXT on Cygwin?

[pdimov]

Ah, that's https://github.com/boostorg/context/pull/155. Well it breaks one of Fiber or Coroutine, then.

[olk]

boost.coroutine is deprecated

[pdimov]

ASIO depends on Coroutine, so whether it's "deprecated" or not is of no relevance. It must work.

[olk]

ASIO should switch to boost.context instead of using deprecated boost.coroutine.

Peter Dimov @.***> schrieb am Do., 3. Juni 2021, 21:00:

ASIO depends on Coroutine, so whether it's "deprecated" or not is of no relevance. It must work.

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[pdimov]

That's not my department. I'm just seeing that Fiber fails to build on Cygwin, and am telling you that it does, and why.

[pdimov]

New Fiber failure after the latest changes:

[ 21%] Building CXX object libs/fiber/CMakeFiles/boost_fiber.dir/src/algo/algorithm.cpp.o
In file included from /home/travis/build/boostorg/boost-root/libs/fiber/src/algo/algorithm.cpp:9:0:
/home/travis/build/boostorg/boost-root/libs/fiber/include/boost/fiber/context.hpp:26:42: fatal error: boost/context/detail/apply.hpp: No such file or directory
compilation terminated.

[olk]

New Fiber failure after the latest changes

fixed

[pdimov]

fixed

Indeed, thanks.

ASIO should switch to boost.context instead of using deprecated boost.coroutine.

I've looked at your PR https://github.com/boostorg/asio/pull/55 that does exactly that, but it seems to me that even if accepted, it won't solve the issue here. It would just move the dependency on fcontext from Coroutine to Asio, but building Context with ucontext will still break asio::spawn.

[corngood]

I've been able to get fcontext working in cygwin as described here:

https://cygwin.com/pipermail/cygwin-developers/2020-September/011970.html

It also seems the ucontext is broken for the same reason that fcontext was:

https://cygwin.com/pipermail/cygwin-developers/2021-December/012536.html

[olk]

I've been able to get fcontext working in cygwin as described here:

https://cygwin.com/pipermail/cygwin-developers/2020-September/011970.html

It also seems the ucontext is broken for the same reason that fcontext was:

https://cygwin.com/pipermail/cygwin-developers/2021-December/012536.html

This means that some fixes have to be done in the cygwin?!