[Bug c++/82899] *this in constructors could not alias with reference input parameters of the same type

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82899

--- Comment #13 from Marc Glisse <glisse at gcc dot gnu.org> ---
Explicitly marking the constructor with __restrict lets it optimize also the
testcase in comment #12. I have no idea what was changed in gcc-8 that helped
the original testcase, but it wasn't equivalent to marking constructors with
__restrict :-(