[utility.requirements] Add front matter on exception propagation under [exception.propagation]

Author: JohelEGP

source/lib-intro.tex

@@ -1427,6 +1427,8 @@
 \ref{hash.requirements} describes the requirements on hash function objects.
 \ref{allocator.requirements} describes the requirements on storage
 allocators.
+\ref{exception.propagation}
+describes additional requirements and guarantees when propagating exceptions.
 
 \rSec3[utility.arg.requirements]{Template argument requirements}
 
@@ -2218,6 +2220,24 @@
   other than \tcode{value_type} are complete types.
 \end{itemize}
 
+\rSec3[exception.propagation]{Exception propagation requirements}
+
+\pnum
+Some functions defined in the \Cpp{} standard library
+impose requirements and guarantees when an exception is thrown from a described evaluation.
+Unless stated otherwise,
+exceptions thrown due to evaluating the subexpression
+that implements the described evaluation
+up to the complete evaluation of its enclosing full-expression
+also have those requirements and guarantees imposed.
+\begin{note}
+This includes exceptions thrown as part of
+initializing parameters,
+evaluating default arguments, and
+destroying temporaries (including discarded-value expressions)
+\iref{expr.call}.
+\end{note}
+
 \rSec2[constraints]{Constraints on programs}
 
 \rSec3[constraints.overview]{Overview}