I like overall approach and think it really should be rule of a
thumb for designing D features - defining simple bullet-proof
semantics and making conclusions from it. As opposed to
syntax-based special case coverage.
What I do find lacking in this DIP:
1) "Optional parentheses" part needs detailed description why
exactly those cases have special handling and how are they
different from others. Also looks like example code has errors
there, for example, function that has no return statement and
uint return type.
2) If you want to prohibit functions having an address, you need
a section explaining communication with C in details in regard to
passing function pointers.
3) It really needs a broad overview of semantic changes in common
use cases and code breakage list.
