While I am reading page93 $5.1.2 of the C++11 standard, during which it said it is ellegal for you to use the braced-init-list in this case:
auto x=[]{return {1,2}}; //error: a braced-init-list is not an expression
And I have found these two topics, one from the standard and the other from N3681 proposal.
Page397 $14.8.2.5:an initializer list argument causes the parameter to be considered a non-deduced context. and $7.6.1.4:replacing the occurrences of auto with either a new invented type template parameter U or, if the initializer is a braced-init-list (8.5.4), with std::initializer_list.
While the N3691 proposal suggested "to change a brace-initialized auto to not deduce to an initializer list, and to ban brace-initialized auto for cases where the braced-initializer has more than one element. " and it said "returning a braced-list won't work as it's not an expression" http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3681.html
However, I failed to find "Why is a braced-init-list not an expression？" It may have the same meaning of this topic: Why can't we have automatically deduced return types? but there's a little differences while he was trying to understand why the C++ commitee concluded this kind of grammar was worthless. So there must be a particular reason for this?Thank you very much.