Merge 2019-02 CWG Motion 5

P1381R1 Reference capture of structured bindings

Fixes #2685.

Author: zygoloid

source/expressions.tex

@@ -2296,7 +2296,7 @@
 static_assert([](int n) { return [&n] { return ++n; }(); }(3) == 4);
 \end{codeblock}
 \end{example}
-A bit-field, a structured binding, or a member of an anonymous union
+A bit-field or a member of an anonymous union
 shall not be captured by reference.
 
 \pnum