The `--disable-gil` builds occasionally need to pause all but one thread. Some
examples include:
* Cyclic garbage collection, where this is often called a "stop the world event"
* Before calling `fork()`, to ensure a consistent state for internal data structures
* During interpreter shutdown, to ensure that daemon threads aren't accessing Python objects
This adds the following functions to implement global and per-interpreter pauses:
* `_PyEval_StopTheWorldAll()` and `_PyEval_StartTheWorldAll()` (for the global runtime)
* `_PyEval_StopTheWorld()` and `_PyEval_StartTheWorld()` (per-interpreter)
(The function names may change.)
These functions are no-ops outside of the `--disable-gil` build.
Fix warnings C4100 in Py_UNUSED() when Python is built with "cl /W4".
Example with this function included by Python.h:
static inline unsigned int
PyUnicode_IS_READY(PyObject* Py_UNUSED(op))
{ return 1; }
Without this change, building a C program with "cl /W4" which just
includes Python.h emits the warning:
Include\cpython/unicodeobject.h(199):
warning C4100: '_unused_op': unreferenced formal parameter
This change fix this warning.
Several platforms don't define the static_assert macro despite having
compiler support for the _Static_assert keyword. The macro needs to be
defined since it is used unconditionally in the Python code. So it
should always be safe to define it if undefined and not in C++11 (or
later) mode.
Hence, remove the checks for particular platforms or libc versions,
and just define static_assert anytime it needs to be defined but isn't.
That way, all platforms that need the fix will get it, regardless of
whether someone specifically thought of them.
Also document that certain macOS versions are among the platforms that
need this.
The C2x draft (currently expected to become C23) makes static_assert
a keyword to match C++. So only define the macro for up to C17.
Co-authored-by: Victor Stinner <vstinner@python.org>
Add a new _Py_RVALUE() macro to prevent using an expression as an
l-value.
Replace a "(void)" cast with the _Py_RVALUE() macro in the following
macros:
* PyCell_SET()
* PyList_SET_ITEM()
* PyTuple_SET_ITEM()
* _PyGCHead_SET_FINALIZED()
* _PyGCHead_SET_NEXT()
* asdl_seq_SET()
* asdl_seq_SET_UNTYPED()
Add also parentheses around macro arguments in PyCell_SET() and
PyTuple_SET_ITEM() macros.
* Add Py_UNREACHABLE() as an alias to abort().
* Use Py_UNREACHABLE() instead of assert(0)
* Convert more unreachable code to use Py_UNREACHABLE()
* Document Py_UNREACHABLE() and a few other macros.
Sam Gross
Victor Stinner
Joshua Root
Pablo Galindo Salgado
Dong-hee Na
Serhiy Storchaka
Victor Stinner
Zachary Ware
Inada Naoki
Barry Warsaw
Niklas Fiekas
Victor Stinner
Benjamin Peterson
Larry Hastings
Christian Heimes
Antoine Pitrou
Victor Stinner
Victor Stinner