Merge 2018-03 LWG Motion 16

Author: zygoloid

source/containers.tex

@@ -3149,6 +3149,10 @@
 one of these tables and
 for operations where there is additional semantic information.
 
+\pnum
+The types \tcode{iterator} and \tcode{const_iterator} satisfy
+the constexpr iterator requirements\iref{iterator.requirements.general}.
+
 \indexlibrary{\idxcode{array}}%
 \indexlibrarymember{array}{begin}%
 \indexlibrarymember{array}{end}%

source/iterators.tex

@@ -222,6 +222,21 @@
 is undefined.
 }
 
+\pnum
+\indextext{iterator!constexpr}
+Iterators are called \defn{constexpr iterators}
+if all operations provided to satisfy iterator category operations
+are constexpr functions, except for
+\begin{itemize}
+\item \tcode{swap},
+\item a pseudo-destructor call\iref{expr.pseudo}, and
+\item the construction of an iterator with a singular value.
+\end{itemize}
+\begin{note}
+For example, the types ``pointer to \tcode{int}'' and
+\tcode{reverse_iterator<int*>} are constexpr iterators.
+\end{note}
+
 \pnum
 In the following sections,
 \tcode{a}

source/strings.tex

@@ -4973,6 +4973,10 @@
 In every specialization \tcode{basic_string_view<charT, traits>}, the type \tcode{traits} shall satisfy the character traits requirements\iref{char.traits},
 and the type \tcode{traits::char_type} shall name the same type as \tcode{charT}.
 
+\pnum
+The type \tcode{iterator} satisfies
+the constexpr iterator requirements\iref{iterator.requirements.general}.
+
 \rSec3[string.view.cons]{Construction and assignment}
 
 \indexlibrary{\idxcode{basic_string_view}!constructor}%