vasilito
cb424d7448
verify-patch-sanity.py validates every active recipe .patch has internally- consistent hunk line counts — catching the 'malformed patch at line N' failure at commit/CI/preflight time instead of hours into a cook. This cycle hit that class three times (qtwaylandscanner, sddm, xwayland), each only discovered when cookbook tried to apply the patch. Running it across the repo found 29 latent malformed patches (validated against GNU patch: e.g. relibc/P3-sysv-ipc reproduces 'malformed patch at line 22'). They were harmless only because they sit in vendored recipes (baked, not re- applied) — but would fail on any version-bump re-derivation. --fix recounts the hunk headers (body untouched) and repaired all 29. Wired into build-preflight.sh (Phase 1.0D) and redbear-ci.yml, with a unit test (test-patch-sanity.sh). Skips archived/legacy trees and unvalidatable formats (empty placeholders, bare-@@ git hunks).
78 lines
3.2 KiB
ReStructuredText
78 lines
3.2 KiB
ReStructuredText
.. _implementation-defined-behavior:
|
|
|
|
===============================
|
|
Implementation-defined behavior
|
|
===============================
|
|
|
|
This document contains the implementation details of the implementation-defined behavior in libc++.
|
|
The C++ standard mandates that implementation-defined behavior is documented.
|
|
|
|
.. note:
|
|
This page is far from complete.
|
|
|
|
|
|
Implementation-defined behavior
|
|
===============================
|
|
|
|
Updating the Time Zone Database
|
|
-------------------------------
|
|
|
|
The C++ standard allows implementations to automatically update the
|
|
*remote time zone database*. Libc++ opts not to do that. Instead calling
|
|
|
|
- ``std::chrono::remote_version()`` will update the version information of the
|
|
*remote time zone database*,
|
|
- ``std::chrono::reload_tzdb()``, if needed, will update the entire
|
|
*remote time zone database*.
|
|
|
|
This offers a way for users to update the *remote time zone database* and
|
|
give them full control over the process.
|
|
|
|
|
|
`[ostream.formatted.print]/3 <http://eel.is/c++draft/ostream.formatted.print#3>`_ A terminal capable of displaying Unicode
|
|
--------------------------------------------------------------------------------------------------------------------------
|
|
|
|
The C++ standard specifies that the manner in which a stream is determined to refer
|
|
to a terminal capable of displaying Unicode is implementation-defined. This is
|
|
used for ``std::print`` and similar functions taking an ``ostream&`` argument.
|
|
|
|
Libc++ determines that a stream is Unicode-capable terminal by:
|
|
|
|
* First it determines whether the stream's ``rdbuf()`` has an underlying
|
|
``FILE*``. This is ``true`` in the following cases:
|
|
|
|
* The stream is ``std::cout``, ``std::cerr``, or ``std::clog``.
|
|
|
|
* A ``std::basic_filebuf<CharT, Traits>`` derived from ``std::filebuf``.
|
|
|
|
* The way to determine whether this ``FILE*`` refers to a terminal capable of
|
|
displaying Unicode is the same as specified for `void vprint_unicode(FILE*
|
|
stream, string_view fmt, format_args args);
|
|
<http://eel.is/c++draft/print.fun#7>`_. This function is used for other
|
|
``std::print`` overloads that don't take an ``ostream&`` argument.
|
|
|
|
`[sf.cmath] <https://wg21.link/sf.cmath>`_ Mathematical Special Functions: Large indices
|
|
----------------------------------------------------------------------------------------
|
|
|
|
Most functions within the Mathematical Special Functions section contain integral indices.
|
|
The C++ standard specifies the result for larger indices as implementation-defined.
|
|
Libc++ pursuits reasonable results by choosing the same formulas as for indices below that threshold.
|
|
E.g.,
|
|
|
|
- ``std::hermite(unsigned n, T x)`` for ``n >= 128``
|
|
|
|
|
|
`[stringbuf.cons] <http://eel.is/c++draft/stringbuf.cons>`_ Whether sequence pointers are initialized to null pointers
|
|
----------------------------------------------------------------------------------------------------------------------
|
|
|
|
Libc++ does not initialize the pointers to null pointers. It resizes the buffer
|
|
to its capacity and uses that size. This means the SSO buffer of
|
|
``std::string`` is used as initial output buffer.
|
|
|
|
|
|
Listed in the index of implementation-defined behavior
|
|
======================================================
|
|
|
|
The order of the entries matches the entries in the
|
|
`draft of the Standard <http://eel.is/c++draft/impldefindex>`_.
|