When using qmake to build a user project on macOS, the Qt headers are
included with the -I option, rather than the -isystem option. This
means that the compiler will not silence warnings that are generated
while parsing Qt headers.
If the user project compiles their code with the
-Wzero-as-null-pointer-constant compiler option, this leads to
warnings like:
/QtCore.framework/Headers/qcompare.h:226:78:
warning: zero as null pointer constant
[-Wzero-as-null-pointer-constant]
friend constexpr bool is_eq (partial_ordering o) noexcept
{ return o == 0; }
^
nullptr
Fixing qmake to use -isystem instead of -I is not trivial.
We already silence these warnings for gcc in the header file.
Do it for clang as well.
Amends bdd41f491c
Fixes: QTBUG-132581
Change-Id: I7883248b7be548580a03333e76620ac10f57733a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
(cherry picked from commit 0711eb60716b53dc86cacb2fc19b72aa4ffee3d0)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit fa8effc7da2417f6ccaca923bd1b2c376f63ac38)
957ce6868b