https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66672
--- Comment #4 from Anders Schau Knatten <anders at knatten dot org> --- Update: There's a related issue with Clang, in which Richard Smith makes a good argument: https://bugs.llvm.org/show_bug.cgi?id=35423#c2 He refers to http://eel.is/c++draft/expr.prim.id.unqual#2.sentence-2, of which I was previously unaware, which seems to cover what was previously covered by §5.1.2¶18 in C++11. It says: "If the entity is a local entity and naming it from outside of an unevaluated operand within the declarative region where the unqualified-id appears would result in some intervening lambda-expression capturing it by copy ([expr.prim.lambda.capture]), the type of the expression is the type of a class member access expression ([expr.ref]) naming the non-static data member that would be declared for such a capture in the closure object of the innermost such intervening lambda-expression." If I read that passage correctly, it says that "even if decltype doesn't odr-use the identifier, and thus it isn't actually captured, the type of the expression is still as if it had been captured." So I now believe my previous comment was wrong, and that gcc is wrong both according to C++11 and the current draft.
