Make `warnings.catch_warnings()` use a context variable for holding
the warning filtering state if the `sys.flags.context_aware_warnings`
flag is set to true. This makes using the context manager thread-safe in
multi-threaded programs.
Add the `sys.flags.thread_inherit_context` flag. If true, starting a new
thread with `threading.Thread` will use a copy of the context
from the caller of `Thread.start()`.
Both these flags are set to true by default for the free-threaded build
and false for the default build.
Move the Python implementation of warnings.py into _py_warnings.py.
Make _contextvars a builtin module.
Co-authored-by: Kumar Aditya <kumaraditya@python.org>
Move pycore_obmalloc.h include from pycore_interp_structs.h to
pycore_runtime_structs.h.
Add also comment explaining the purpose of each include in
pycore_interp_structs.h, pycore_runtime_structs.h and
pycore_structs.h.
Remove <stdbool.h> and <stddef.h> from pycore_structs.h.
