Daily bit(e) of C++ | default-constructible lambdas
Daily bit(e) of C++ #478, C++20 default-constructible and copy-assignable support for non-capturing lambdas.
C++20 introduced a significant change to lambdas without capture. The autogenerated unique type is now default-constructible and copy (and move) assignable.
While the previous behaviour made sense for lambdas with captures and conceptually (each lambda is inherently an instance of its autogenerated type), it also made lambdas awkward to use as arguments to generic code.
