Thanks to visit codestin.com
Credit goes to github.com

Skip to content

bpo-46640: Py_NAN now uses the C99 NAN constant #31134

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Feb 6, 2022
Merged

bpo-46640: Py_NAN now uses the C99 NAN constant #31134

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
b04c630
bpo-46640: Py_NAN now uses the C99 NAN constant
vstinner Feb 4, 2022
4591295
Update Py_NAN comment
vstinner Feb 6, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 6 additions & 0 deletions Doc/whatsnew/3.11.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -604,6 +604,12 @@ Build Changes
``isinf()``, ``isnan()``, ``round()``.
(Contributed by Victor Stinner in :issue:`45440`.)

* Building Python now requires a C99 ``<math.h>`` header file providing
a ``NAN`` constant, or the ``__builtin_nan()`` built-in function. If a
platform does not support Not-a-Number (NaN), the ``Py_NO_NAN`` macro can be
defined in the ``pyconfig.h`` file.
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It turns out that building under Py_NO_NAN doesn't actually work right now. I've opened an issue: https://bugs.python.org/issue46656

(Contributed by Victor Stinner in :issue:`46640`.)

* Freelists for object structs can now be disabled. A new :program:`configure`
option :option:`!--without-freelists` can be used to disable all freelists
except empty tuple singleton.
Expand Down
31 changes: 10 additions & 21 deletions Include/pymath.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -51,29 +51,18 @@
#endif

/* Py_NAN
* A value that evaluates to a NaN. On IEEE 754 platforms INF*0 or
* INF/INF works. Define Py_NO_NAN in pyconfig.h if your platform
* doesn't support NaNs.
* A value that evaluates to a quiet Not-a-Number (NaN).
* Define Py_NO_NAN in pyconfig.h if your platform doesn't support NaNs.
*/
#if !defined(Py_NAN) && !defined(Py_NO_NAN)
# if !defined(__INTEL_COMPILER)
# define Py_NAN (Py_HUGE_VAL * 0.)
# else /* __INTEL_COMPILER */
# if defined(ICC_NAN_STRICT)
#pragma float_control(push)
#pragma float_control(precise, on)
#pragma float_control(except, on)
Py_NO_INLINE static double __icc_nan()
{
return sqrt(-1.0);
}
#pragma float_control (pop)
# define Py_NAN __icc_nan()
# else /* ICC_NAN_RELAXED as default for Intel Compiler */
static const union { unsigned char buf[8]; double __icc_nan; } __nan_store = {0,0,0,0,0,0,0xf8,0x7f};
# define Py_NAN (__nan_store.__icc_nan)
# endif /* ICC_NAN_STRICT */
# endif /* __INTEL_COMPILER */
# if _Py__has_builtin(__builtin_nan)
// Built-in implementation of the ISO C99 function nan(): quiet NaN.
# define Py_NAN (__builtin_nan(""))
#else
// Use C99 NAN constant: quiet Not-A-Number.
// NAN is a float, Py_NAN is a double: cast to double.
# define Py_NAN ((double)NAN)
# endif
#endif

#endif /* Py_PYMATH_H */
4 changes: 4 additions & 0 deletions Misc/NEWS.d/next/Build/2022-02-04-21-26-50.bpo-46640.HXUmQp.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
Building Python now requires a C99 ``<math.h>`` header file providing a ``NAN``
constant, or the ``__builtin_nan()`` built-in function. If a platform does not
support Not-a-Number (NaN), the ``Py_NO_NAN`` macro can be defined in the
``pyconfig.h`` file. Patch by Victor Stinner.