LWG3878 import std; should guarantee initialization of standard iostreams objects

Author: burblebee

source/iostreams.tex

@@ -506,6 +506,17 @@
 The results of including \libheader{iostream} in a translation unit shall be as if
 \libheader{iostream} defined an instance of \tcode{ios_base::Init} with static
 storage duration.
+Each \Cpp{} library module\iref{std.modules} in a hosted implementation
+shall behave as if it contains an interface unit that
+defines an unexported \tcode{ios_base::Init} variable with
+ordered initialization\iref{basic.start.dynamic}.
+
+\begin{note}
+As a result, the definition of that variable is appearance-ordered before
+any declaration following the point of importation of a \Cpp{} library module.
+Whether such a definition exists is unobservable by a program that
+does not reference any of the standard iostream objects.
+\end{note}
 
 \pnum
 Mixing operations on corresponding wide- and narrow-character streams