If the signal passed to QtFuture::connect() takes multiple arguments,
we need to wrap the arguments in a std::tuple when reporting the result.
To detect this case we were checking if the result type of a QFuture
returned by QtFuture::connect() is a std::tuple, but this was not
correct: the result type could be a std::tuple also if the passed
signal takes a single std::tuple argument. Instead, check if the signal
takes more than one argument.
As a drive-by modified the tst_QFuture::signalConnect to use const
values for tuples used in multiple test-cases, to avoid repetition.
Fixes: QTBUG-100071
Pick-to: 6.2 6.3
Change-Id: I1ce39cf87028f36ef94a9d1a4423b0c51473afd4
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
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