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Value Categories, Move and Perfect Forwarding · 3:33
Where Forwarding Fails
Perfect forwarding promises that wrapping a call changes nothing, yet four kinds of argument break it: braced lists, a literal 0 used as a null pointer, overloaded function names and bit-fields. We see clang's real error for each and the one-line fix, then count what pass-by-value and emplace_back actually cost.
You will learn
- State what perfect forwarding promises and why deduction is where it breaks
- Recognise and fix the four failure cases: braced lists, 0/NULL, overloaded names, bit-fields
- Compare pass-by-value with a pair of overloads in copies and moves
- Explain why emplace_back can construct in place while push_back makes a temporary