printf %qd is nonstandard

[hfuru]

BPO	10320
Nosy	@amauryfa, @abalkin, @ezio-melotti, @meadori, @serhiy-storchaka, @ZackerySpytz, @miss-islington
PRs	bpo-10320: Replace nonstandard sprintf() length modifier in ctypes' PyCArg_repr() #10853 [3.7] bpo-10320: Replace nonstandard sprintf() length modifier in ctypes' PyCArg_repr(). (GH-10853) #10856 [3.6] bpo-10320: Replace nonstandard sprintf() length modifier in ctypes' PyCArg_repr(). (GH-10853) #10857 [2.7] bpo-10320: Replace nonstandard sprintf() length modifier in ctypes' PyCArg_repr(). (GH-10853) #10858 [2.7] bpo-10320: Replace nonstandard sprintf() length modifier in ctypes' PyCArg_repr(). (GH-10853) #11228 [2.7] bpo-10320: Use PY_FORMAT_LONG_LONG in ctypes' PyCArg_repr() #11230

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2018-12-19.09:18:08.941>
created_at = <Date 2010-11-05.08:38:07.039>
labels = ['3.8', 'ctypes', 'type-bug', '3.7']
title = 'printf %qd is nonstandard'
updated_at = <Date 2018-12-19.09:18:08.940>
user = 'https://bugs.python.org/hfuru'

bugs.python.org fields:

activity = <Date 2018-12-19.09:18:08.940>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2018-12-19.09:18:08.941>
closer = 'serhiy.storchaka'
components = ['ctypes']
creation = <Date 2010-11-05.08:38:07.039>
creator = 'hfuru'
dependencies = []
files = []
hgrepos = []
issue_num = 10320
keywords = ['patch']
message_count = 11.0
messages = ['120473', '142299', '145773', '235566', '235567', '330905', '330911', '330919', '330920', '332102', '332109']
nosy_count = 10.0
nosy_names = ['amaury.forgeotdarc', 'belopolsky', 'hfuru', 'ezio.melotti', 'meador.inge', 'bugs-python@vendor.thewrittenword.com', 'serhiy.storchaka', 'John.Malmberg', 'ZackerySpytz', 'miss-islington']
pr_nums = ['10853', '10856', '10857', '10858', '11228', '11230']
priority = 'low'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue10320'
versions = ['Python 2.7', 'Python 3.6', 'Python 3.7', 'Python 3.8']

[hfuru]

Modules/_ctypes/callproc.c:PyCArg_repr() uses sprintf(%qd, long long),
which is a GNU (and more?) extension. ISO C99 says %lld.

Instead, use "%" PY_FORMAT_LONG_LONG "d" from pyconfig.h/pyport.h.
Kills off #ifdef MS_WIN32 too. If Python must support C libraries
that handle %qd but not %lld, configure.in seems the right place.

Index: ./Modules/_ctypes/callproc.c
@@ -468,8 +468,3 @@ PyCArg_repr(PyCArgObject *self)
     case 'Q':
-        sprintf(buffer,
-#ifdef MS_WIN32
-            "<cparam '%c' (%I64d)>",
-#else
-            "<cparam '%c' (%qd)>",
-#endif
+        sprintf(buffer, "<cparam '%c' (%" PY_FORMAT_LONG_LONG "d)>",
             self->tag, self->value.q);

pyport.h tests (defined(MS_WIN64) || defined(MS_WINDOWS)) instead of
#ifdef MS_WIN32 for when to use %I64d. I assume that's more up to date.

[meadori]

I agree that this violates C99, but is this actually causing any real world problems with the platforms Python supports? If so, then we need a test case. This seems low priority

[bugs-pythonvendorthewrittenwordcom]

Objects/stringobject.c already does something similar:
else if (longlongflag)
sprintf(s, "%" PY_FORMAT_LONG_LONG "d",
va_arg(vargs, PY_LONG_LONG));
so it makes sense to do the same in Modules/_ctypes/callproc.c.

[JohnMalmberg]

OpenVMS needs %lld or "%" PY_FORMAT_LONG_LONG "d" in order to build the _ctypes module.

[BreamoreBoy]

As VMS is not supported I doubt that people here are too bothered about what is needed to build the _ctypes module on it.

[ZackerySpytz]

I've created a PR for this issue.

[serhiy-storchaka]

New changeset 062cbb6 by Serhiy Storchaka (Zackery Spytz) in branch 'master':
bpo-10320: Replace nonstandard sprintf() length modifier in ctypes' PyCArg_repr(). (GH-10853)
062cbb6

[miss-islington]

New changeset a9f435e by Miss Islington (bot) in branch '3.7':
bpo-10320: Replace nonstandard sprintf() length modifier in ctypes' PyCArg_repr(). (GH-10853)
a9f435e

[miss-islington]

New changeset f65ede3 by Miss Islington (bot) in branch '3.6':
bpo-10320: Replace nonstandard sprintf() length modifier in ctypes' PyCArg_repr(). (GH-10853)
f65ede3