From 31c7b24aa5f57fbe8258c9e9845c8d630af4aec1 Mon Sep 17 00:00:00 2001 From: Marc Mutz Date: Fri, 1 Apr 2016 23:55:25 +0200 Subject: Silence MSVC warnings when using certain std algorithms The MSVC STL warns when passing naked pointers as non-bounded iterators to algorithms such as std::equal and std::copy, in an attempt to inform users that the range specified by that iterator has an implicit minimum size that the caller of the algorithm must ensure is met: warning C4996: 'std::_Equal1': Function call with parameters that may be unsafe - \ this call relies on the caller to check that the passed values are correct. To \ disable this warning, use -D_SCL_SECURE_NO_WARNINGS. See documentation on how to \ use Visual C++ 'Checked Iterators' When building Qt, as well as when building user projects with qmake (cf. 0a76b6bc7f98900ea884cd10ccca1a332e5bdba5), we globally disable this warning (with -D_SCL_SECURE_NO_WARNINGS), but since we started using STL algorithms in public headers (e.g. in qvector.h), users get this warning in their own projects now, unless they, too, define said macro. But such a requirement is against the Qt policy to have headers that are warning-free as much as possible. The suggested way of fixing this warning is to wrap the naked pointer in a stdext::unchecked_array_iterator before passing it to the algorithm, cf. examples in https://msdn.microsoft.com/en-us/library/ttcz0bys%28v=vs.120%29.aspx or, together with the capacity-made-explicit, in a stdext::checked_array_iterator. To avoid ifdefs for platforms that don't have these extensions (which, incidentally, for the unchecked case, includes MSVC 2012), wrap the calls in macros. The end game here is to drop -D_SCL_SECURE_NO_WARNINGS, at least for public headers, even though this commit also adds the wrapper to implementation and private header files. An alternative to the wrapper would have been the version of std::equal that takes four iterators. However, that is a C++14 library feature, while this version of Qt still needs to compile with a C++98 compiler, and, more importantly, there isn't, and never will be, a corresponding 4-iterator version of std::copy. Task-number: QTBUG-47948 Done-with: Stephen Kelly Change-Id: I1bbab257fb5f1c5042939c382a412b596112ff26 Reviewed-by: Stephen Kelly --- src/corelib/tools/qlist.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/corelib/tools/qlist.h') diff --git a/src/corelib/tools/qlist.h b/src/corelib/tools/qlist.h index 9a57a2c6a5..e04a6be1ab 100644 --- a/src/corelib/tools/qlist.h +++ b/src/corelib/tools/qlist.h @@ -846,7 +846,7 @@ inline bool QList::op_eq_impl(const QList &l, QListData::ArrayCompatibleLayou const T *lb = reinterpret_cast(l.p.begin()); const T *b = reinterpret_cast(p.begin()); const T *e = reinterpret_cast(p.end()); - return std::equal(b, e, lb); + return std::equal(b, e, QT_MAKE_CHECKED_ARRAY_ITERATOR(lb, l.p.size())); } template -- cgit v1.2.3