bpo-29137: Remove fpectl module (#4789)

This module has never been enabled by default, never worked correctly
on x86-64, and caused ABI problems that caused C extension
compatibility. See bpo-29137 for details/discussion.

3 files changed, 1 insertions, 126 deletions

diff --git a/Doc/library/exceptions.rst b/Doc/library/exceptions.rst
index a6b20a5..c8d32cf 100644
--- a/Doc/library/exceptions.rst
+++ b/Doc/library/exceptions.rst
@@ -154,10 +154,7 @@ The following exceptions are the exceptions that are usually raised.
 
 .. exception:: FloatingPointError
 
-   Raised when a floating point operation fails.  This exception is always defined,
-   but can only be raised when Python is configured with the
-   ``--with-fpectl`` option, or the :const:`WANT_SIGFPE_HANDLER` symbol is
-   defined in the :file:`pyconfig.h` file.
+   Not currently used.
 
 
 .. exception:: GeneratorExit
diff --git a/Doc/library/fpectl.rst b/Doc/library/fpectl.rst
deleted file mode 100644
index 9660716..0000000
--- a/Doc/library/fpectl.rst
+++ /dev/null
@@ -1,121 +0,0 @@
-:mod:`fpectl` --- Floating point exception control
-==================================================
-
-.. module:: fpectl
-   :platform: Unix
-   :synopsis: Provide control for floating point exception handling.
-
-.. moduleauthor:: Lee Busby <busby1@llnl.gov>
-.. sectionauthor:: Lee Busby <busby1@llnl.gov>
-
-.. note::
-
-   The :mod:`fpectl` module is not built by default, and its usage is discouraged
-   and may be dangerous except in the hands of experts.  See also the section
-   :ref:`fpectl-limitations` on limitations for more details.
-
-.. index:: single: IEEE-754
-
---------------
-
-Most computers carry out floating point operations in conformance with the
-so-called IEEE-754 standard. On any real computer, some floating point
-operations produce results that cannot be expressed as a normal floating point
-value. For example, try ::
-
-   >>> import math
-   >>> math.exp(1000)
-   inf
-   >>> math.exp(1000) / math.exp(1000)
-   nan
-
-(The example above will work on many platforms. DEC Alpha may be one exception.)
-"Inf" is a special, non-numeric value in IEEE-754 that stands for "infinity",
-and "nan" means "not a number." Note that, other than the non-numeric results,
-nothing special happened when you asked Python to carry out those calculations.
-That is in fact the default behaviour prescribed in the IEEE-754 standard, and
-if it works for you, stop reading now.
-
-In some circumstances, it would be better to raise an exception and stop
-processing at the point where the faulty operation was attempted. The
-:mod:`fpectl` module is for use in that situation. It provides control over
-floating point units from several hardware manufacturers, allowing the user to
-turn on the generation of :const:`SIGFPE` whenever any of the IEEE-754
-exceptions Division by Zero, Overflow, or Invalid Operation occurs. In tandem
-with a pair of wrapper macros that are inserted into the C code comprising your
-python system, :const:`SIGFPE` is trapped and converted into the Python
-:exc:`FloatingPointError` exception.
-
-The :mod:`fpectl` module defines the following functions and may raise the given
-exception:
-
-
-.. function:: turnon_sigfpe()
-
-   Turn on the generation of :const:`SIGFPE`, and set up an appropriate signal
-   handler.
-
-
-.. function:: turnoff_sigfpe()
-
-   Reset default handling of floating point exceptions.
-
-
-.. exception:: FloatingPointError
-
-   After :func:`turnon_sigfpe` has been executed, a floating point operation that
-   raises one of the IEEE-754 exceptions Division by Zero, Overflow, or Invalid
-   operation will in turn raise this standard Python exception.
-
-
-.. _fpectl-example:
-
-Example
--------
-
-The following example demonstrates how to start up and test operation of the
-:mod:`fpectl` module. ::
-
-   >>> import fpectl
-   >>> import fpetest
-   >>> fpectl.turnon_sigfpe()
-   >>> fpetest.test()
-   overflow        PASS
-   FloatingPointError: Overflow
-
-   div by 0        PASS
-   FloatingPointError: Division by zero
-     [ more output from test elided ]
-   >>> import math
-   >>> math.exp(1000)
-   Traceback (most recent call last):
-     File "<stdin>", line 1, in <module>
-   FloatingPointError: in math_1
-
-
-.. _fpectl-limitations:
-
-Limitations and other considerations
-------------------------------------
-
-Setting up a given processor to trap IEEE-754 floating point errors currently
-requires custom code on a per-architecture basis. You may have to modify
-:mod:`fpectl` to control your particular hardware.
-
-Conversion of an IEEE-754 exception to a Python exception requires that the
-wrapper macros ``PyFPE_START_PROTECT`` and ``PyFPE_END_PROTECT`` be inserted
-into your code in an appropriate fashion.  Python itself has been modified to
-support the :mod:`fpectl` module, but many other codes of interest to numerical
-analysts have not.
-
-The :mod:`fpectl` module is not thread-safe.
-
-
-.. seealso::
-
-   Some files in the source distribution may be interesting in learning more about
-   how this module operates. The include file :file:`Include/pyfpe.h` discusses the
-   implementation of this module at some length. :file:`Modules/fpetestmodule.c`
-   gives several examples of use. Many additional examples can be found in
-   :file:`Objects/floatobject.c`.
-
diff --git a/Doc/library/python.rst b/Doc/library/python.rst
index f307d7d..440dc66 100644
--- a/Doc/library/python.rst
+++ b/Doc/library/python.rst
@@ -24,4 +24,3 @@ overview:
    gc.rst
    inspect.rst
    site.rst
-   fpectl.rst