Annex C (informative) Compatibility [diff]

Change: The lifetime of temporary objects in the for-range-initializer is extended until the end of the loop ([class.temporary]).

Rationale: Improve usability of the range-based for statement.

Effect on original feature: Destructors of some temporary objects are invoked later.

For example: void f() { std::vector<int> v = { 42, 17, 13 }; std::mutex m; for (int x : static_cast<void>(std::lock_guard<std::mutex>(m)), v) { // lock released in C++ 2020 std::lock_guard<std::mutex> guard(m); // OK in C++ 2020, now deadlocks } }