Such a Little Thing: The Semicolon in Rust
Is that really some "special behavior"? As far as i understand the semicolon is just an expression separator like in Erlang and Pascal. In contrast, the semicolon is a statement terminator in C. C uses the comma for expression separation. Practically everything is an expression in Rust, even blocks, so  foo()       => evaluates to the return value of foo
  { foo() }   => evaluates to the return value of foo
  { foo(); }  => evaluates to nil

The last case is not a special case. The last expression in the block determines the returned value. There is an expression separator in there, so there must be two expressions which are separated by it. The first one is foo() and second one is ... wait for it ... the empty expression. Which value should EmptyExpression have? Of course: nil, which would be called void in C-land.