P3923R0: Re NB US 225-341 (C++26 CD)

Fixes NB US 225-341 (C++26 CD).

Author: eisenwave

source/utilities.tex

@@ -1662,9 +1662,9 @@
   public:
     // \ref{tuple.cnstr}, \tcode{tuple} construction
     constexpr explicit(@\seebelow@) tuple();
-    constexpr explicit(@\seebelow@) tuple(const Types&...);         // only if \tcode{sizeof...(Types) >= 1}
+    constexpr explicit(@\seebelow@) tuple(const Types&...) noexcept(@\seebelow@);    // only if \tcode{sizeof...(Types) >= 1}
     template<class... UTypes>
-      constexpr explicit(@\seebelow@) tuple(UTypes&&...);           // only if \tcode{sizeof...(Types) >= 1}
+      constexpr explicit(@\seebelow@) tuple(UTypes&&...) noexcept(@\seebelow@);      // only if \tcode{sizeof...(Types) >= 1}
 
     tuple(const tuple&) = default;
     tuple(tuple&&) = default;
@@ -1840,7 +1840,8 @@
 
 \indexlibraryctor{tuple}%
 \begin{itemdecl}
-constexpr explicit(@\seebelow@) tuple(const Types&...);
+constexpr explicit(@\seebelow@) tuple(const Types&...)
+  noexcept((is_nothrow_copy_constructible_v<Types> && ...));
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -1864,7 +1865,8 @@
 
 \indexlibraryctor{tuple}%
 \begin{itemdecl}
-template<class... UTypes> constexpr explicit(@\seebelow@) tuple(UTypes&&... u);
+template<class... UTypes> constexpr explicit(@\seebelow@) tuple(UTypes&&... u)
+  noexcept((is_nothrow_constructible_v<Types, UTypes> && ...));
 \end{itemdecl}
 
 \begin{itemdescr}