This is a stylistic difference, as there are some places where the leading return type is invalid, but a trailing return type using the -> is valid. For exampl

This is a stylistic difference, as there are some places where the leading return type is invalid, but a trailing return type using the -> is valid. For example, an immediately invoked lambda expression in which some of the returned values require type conversions. For this reason, some prefer a “auto almost everywhere” style, in which you preferentially use trailing return types.