LWG3662 basic_string::append/assign(NTBS, pos, n) suboptimal

burblebee · tkoeppe · commit 9d7581a8195e · 2026-04-12T21:19:48.000+01:00
Fixes NB RU 268 (C++26 CD).
diff --git a/source/strings.tex b/source/strings.tex
@@ -2153,6 +2153,7 @@
       constexpr basic_string& append(const T& t, size_type pos, size_type n = npos);
     constexpr basic_string& append(const charT* s, size_type n);
     constexpr basic_string& append(const charT* s);
+    constexpr basic_string& append(const charT* s, size_type pos, size_type n);
     constexpr basic_string& append(size_type n, charT c);
     template<class InputIterator>
       constexpr basic_string& append(InputIterator first, InputIterator last);
@@ -2173,6 +2174,7 @@
       constexpr basic_string& assign(const T& t, size_type pos, size_type n = npos);
     constexpr basic_string& assign(const charT* s, size_type n);
     constexpr basic_string& assign(const charT* s);
+    constexpr basic_string& assign(const charT* s, size_type pos, size_type n);
     constexpr basic_string& assign(size_type n, charT c);
     template<class InputIterator>
       constexpr basic_string& assign(InputIterator first, InputIterator last);
@@ -3353,6 +3355,18 @@
 Equivalent to: \tcode{return append(s, traits::length(s));}
 \end{itemdescr}
 
+\indexlibrarymember{append}{basic_string}%
+\begin{itemdecl}
+constexpr basic_string& append(const charT* s, size_type pos, size_type n);
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to:
+\tcode{return append(basic_string_view<charT, traits>(s).substr(pos, n));}
+\end{itemdescr}
+
 \indexlibrarymember{append}{basic_string}%
 \begin{itemdecl}
 constexpr basic_string& append(size_type n, charT c);
@@ -3546,6 +3560,18 @@
 Equivalent to: \tcode{return assign(s, traits::length(s));}
 \end{itemdescr}
 
+\indexlibrarymember{assign}{basic_string}%
+\begin{itemdecl}
+constexpr basic_string& assign(const charT* s, size_type pos, size_type n);
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to:
+\tcode{return assign(basic_string_view<charT, traits>(s).substr(pos, n));}
+\end{itemdescr}
+
 \indexlibrarymember{assign}{basic_string}%
 \begin{itemdecl}
 constexpr basic_string& assign(initializer_list<charT> il);
