Is my book's discussion of lambda return types wrong?

Question

My book says this:

Lambdas with function bodies that contain anything other than a single return statement that do not specify a return type return vo

Answer 1

The book accurately reflects the rules in draft n3290 of the Standard. Perhaps your compiler implemented a different draft.

In section 5.1.2p4, the draft reads

If a lambda-expression does not include a trailing-return-type, it is as if the trailing-return-type denotes the following type:

• if the compound-statement is of the form { attribute-specifier-seq_opt return expression ; } the type of the returned expression after lvalue-to-rvalue conversion, array-to-pointer conversion, and function-to-pointer conversion;
• otherwise, void.

The syntactic construct attribute-specifier-seq may be alignas or the double-bracketed attributes. Not variable declarations.

Draft n3485, which followed publication of C++11 (i.e. it is work in progress toward C++1y), contains the same wording. I don't know if there was a different rule in some draft earlier than n3290.