Acquire the GIL in nogil functions only when strictly needed on function exit, e.g. for cleaning up temp variables from with-gil blocks or adding tracebacks.

Closes GH-3554
Closes GH-4637

Unconditionally adding `/D_USE_MATH_DEFINES` via cmdline triggers `-Wmacro-redefined` in cython-generated code.

Make the pickle test actually test that auto-pickling uses the right checksum (and not a user implemented reduce method that uses no checksums at all).

Make error message more readable by using hex integer values for all presented checksums, not just the compile time ones.

For the auto-pickle checksum, allow SHA-1 and SHA-256 which are used by Cython 3.x pickles now. Otherwise stick to MD5 since that was used before.

Closes https://github.com/cython/cython/issues/4680

In https://github.com/python/cpython/pull/31530
https://bugs.python.org/issue46836

the `_frame` struct was moved to an internal header, however the public API is
primarily read-only, and Cython needs to build PyFrameObjects so still import
the internal headers.

Also sets the Py_BUILD_CORE define for py311a6, trying to restrict it to the frame header.

This creates two copies of the function, one for the exception
case and one for the non-exception case. It's probably inefficient
but the simplest solution.

Fixes https://github.com/cython/cython/issues/4651.

runtests: Print shard number also for each command in the EndToEnd test error output to make it easy to find in the logs.

runtests: print the shard number in front of the test name to show which was the last test in case it hangs.

Partially reverts https://github.com/cython/cython/commit/1027db04fb7c5bbfea2b9bcdfce0b1f384e26a93

By disabling "CYTHON_FAST_THREAD_STATE" and "CYTHON_USE_EXC_INFO_STACK"

I think this still leaves some breakage in Coroutines.c but it's enough of a fix that Cython succeeds in building itself. Therefore I think it's worth doing now even if it doesn't fix everything.

Related to https://github.com/cython/cython/issues/4500

Fix division-by-zero crash in tests when the C ompiler discards the computational body of a Cython coroutine.

Add a new command line option so that
$ cythonize -M foo.pyx
produces a file `foo.c.dep` with the dependencies of foo.pyx, in addition to `foo.c`.
Try to write relative paths as much as possible.

Backport of https://github.com/cython/cython/pull/4563

Make the test files that depend on "cythonarrayutil.pxi" compilable by themselves, without the search directory setup of the test runner.

Use "Py_ssize_t" instead of "int" for a node counter variable to avoid uselessly limiting its value range.

Disable parallel builds in the 0.29.x branch since they currently misbehave and fail in CI, trying to rebuild everything multiple times in parallel.

Cython incorrectly generated (optimised) range code for "for i in range(1,2,3,4)" as if it saw "for i in range(1,2,3)".
This PR deactivates this optimization when too many arguments are provided, to match the behavior of Python.
Original patch by Max Bachmann.

Closes https://github.com/cython/cython/pull/4550

Remove outdated warning about OpenMP < 3.0. Even the now-EOL Docker images for manylinux2010 had that.

Closes https://github.com/cython/cython/issues/4574

For PyPy3.8 (the current release is 7.3.7)

* PyPy<7.3.8 declares a struct with the last fields tp_finalize, tp_print, tp_pypy_flags
* PyPy>=7.3.8 will declare a struct with the last fields tp_finalize, tp_vectorcall, tp_print

PyPy3.9 (not yet released) will declare a struct with the last fields tp_finalize, tp_vectorcall, tp_pypy_flags

See https://foss.heptapod.net/pypy/pypy/-/issues/3618