Is there a reason on not allowing lambdas to deduce the return type if it contains more than one statement?

Question

Taken from the C++0x FDIS (n3290):

If a lambda-expression does not include a lambda-declarator, it is as if the lambda-declarator were (). If a lambda

Answer 1

There's no technical reason for this. IIRC it was already implemented by the GCC C++ maintainer and he said it's trivial to implement.

The committee is very conservative about accepting features into the Standard so they went with this simple form of deduction and will later hopefully accept a more powerful form. See the reason for rejection on US 30 comment.

DR 975 is already marked "ready" so chances are good it will be accepted.