One of the good features of the new connection style is that
implicit conversion is performed for the connection arguments.
However, this is also a bad feature when it comes to the old
C remnants in the C++ language: for instance, doubles implicitly
convert to ints, possibly losing precision (and GCC/Clang do not
even warn about those under -Wall, only MSVC does) or even
triggering undefined behavior.
For this reason, when using braced initialization, C++11
disables narrowing conversions or floating/integral conversions.
Use this feature when checking the arguments of a PMF-style
signal/slot connection. Technically this makes the program
ill-formed, however GCC still accepts it (but at least
warns under -Wall).
Hence, add a way to disable these implicit conversions.
This is a opt-in and guarded by a macro, as it's a source
incompatible change.
[ChangeLog][QtCore][QObject] The
QT_NO_NARROWING_CONVERSIONS_IN_CONNECT macro has been added.
When using the new connection syntax (PMF-based) this macro
makes it illegal to narrow the arguments carried by the signal,
and/or to perform floating point to integral implicit
conversions on them. When the macro is defined,
depending on your compiler a QObject::connect() statement
triggering such conversions will now fail to compile.
Change-Id: Ie17eb3e66ce0cd780138e60d8bb7da815a4ada83
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
c0637c0298