The parser does not recognize auto return declarations with contracts:
auto foo()in{}body{}
function declaration without return type. (Note that constructors are\
always named 'this')
no identifier for declarator foo()
Comment #1 by k.hara.pg — 2011-12-03T10:04:26Z
I have already posted a pull request to allow it.
But it is not yet merged.
*** This issue has been marked as a duplicate of issue 4785 ***