C++17 adopts P0021R1[1], which makes noexcept be part of the function
pointer's type and thus be overloadable. It contains some provisions for
allowing a noexcept function pointer to cast implicitly to a non-
noexcept function pointer, but that fails in the presence of templates
and additional overloads that could match the type in question.
Fortunately, the paper proposed a test macro, so we can change our
sources now and be compatible with both C++14 and C++17 rules.
This first failed with Clang 4.0 trunk. This source incompatibility is
not our fault, it's the language's doing.
[1] http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0012r1.html
Task-number: QTBUG-58054
Change-Id: I2bc52f3c7a574209b213fffd14988cf0b875be63
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
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