https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61769
--- Comment #8 from theemathas at hotmail dot com --- (In reply to Jonathan Wakely from comment #7) > If you change it to: > > const int& aa = std::abs(a); > const int& foo=std::max(aa, aa); > > You'll see that the problem goes away because the value returned by std::abs > gets its lifetime extended, then std::max returns a reference to the same > object, which has not gone out of scope. > > Alternatively, avoid the pointless reference: > > int foo = std::max(std::abs(a), std::abs(a)); OK... I think I understand now. By the way, I managed to find the exact text in the standard that states that the code is invalid: http://stackoverflow.com/questions/2784262/does-a-const-reference-prolong-the-life-of-a-temporary "The lifetime extension is not transitive through a function argument. §12.2/5 [class.temporary]: '...A temporary bound to a reference parameter in a function call (§5.2.2 [expr.call]) persists until the completion of the full expression containing the call.' " Thank you for explaining this, though.
