Merge 2024-11 LWG Motion 2

P3136R1 Retiring niebloids

Author: tkoeppe

source/algorithms.tex

@@ -38,28 +38,9 @@
 satisfying the assumptions on the algorithms.
 
 \pnum
-The entities defined in the \tcode{std::ranges} namespace in this Clause
-are not found by argument-dependent name lookup\iref{basic.lookup.argdep}.
-When found by unqualified\iref{basic.lookup.unqual} name lookup
-for the \grammarterm{postfix-expression} in a function call\iref{expr.call},
-they inhibit argument-dependent name lookup.
-
-\begin{example}
-\begin{codeblock}
-void foo() {
-  using namespace std::ranges;
-  std::vector<int> vec{1,2,3};
-  find(begin(vec), end(vec), 2);        // \#1
-}
-\end{codeblock}
-The function call expression at \tcode{\#1} invokes \tcode{std::ranges::find},
-not \tcode{std::find}, despite that
-(a) the iterator type returned from \tcode{begin(vec)} and \tcode{end(vec)}
-may be associated with namespace \tcode{std} and
-(b) \tcode{std::find} is more specialized\iref{temp.func.order} than
-\tcode{std::ranges::find} since the former requires
-its first two parameters to have the same type.
-\end{example}
+The entities defined in the \tcode{std::ranges} namespace in this Clause and
+specified as function templates are
+algorithm function objects\iref{alg.func.obj}.
 
 \pnum
 For purposes of determining the existence of data races,

source/iterators.tex

@@ -2933,32 +2933,8 @@
 \end{example}
 
 \pnum
-The function templates defined in \ref{range.iter.ops} are not found by
-argument-dependent name lookup\iref{basic.lookup.argdep}. When found by
-unqualified\iref{basic.lookup.unqual} name lookup for the
-\grammarterm{postfix-expression} in a function call\iref{expr.call}, they
-inhibit argument-dependent name lookup.
-
-\begin{example}
-\begin{codeblock}
-void foo() {
-    using namespace std::ranges;
-    std::vector<int> vec{1,2,3};
-    distance(begin(vec), end(vec));     // \#1
-}
-\end{codeblock}
-The function call expression at \tcode{\#1} invokes \tcode{std::ranges::distance},
-not \tcode{std::distance}, despite that
-(a) the iterator type returned from \tcode{begin(vec)} and \tcode{end(vec)}
-may be associated with namespace \tcode{std} and
-(b) \tcode{std::distance} is more specialized\iref{temp.func.order} than
-\tcode{std::ranges::distance} since the former requires its first two parameters
-to have the same type.
-\end{example}
-
-\pnum
-The number and order of deducible template parameters for the function templates defined
-in \ref{range.iter.ops} is unspecified, except where explicitly stated otherwise.
+The entities defined in \ref{range.iter.ops} are
+algorithm function objects\iref{alg.func.obj}.
 
 \rSec3[range.iter.op.advance]{\tcode{ranges::advance}}
 

source/lib-intro.tex

@@ -856,9 +856,40 @@
 \item \tcode{std::move(as_const(p))(args...)}
 \end{itemize}
 
+\rSec3[alg.func.obj]{Algorithm function objects}
+
+\pnum
+An \defn{algorithm function object} is
+a customization point object\iref{customization.point.object}
+that is specified as one or more overloaded function templates.
+The name of these function templates designates
+the corresponding algorithm function object.
+
 \pnum
-Each customization point object type constrains its return type to model a
-particular concept.
+For an algorithm function object \tcode{o},
+let $S$ be the corresponding set of function templates.
+Then for any sequence of arguments $\tcode{args} \dotsc$,
+$\tcode{o(args} \dotsc \tcode{)}$ is expression-equivalent to
+$\tcode{s(args} \dotsc \tcode{)}$,
+where the result of name lookup for \tcode{s} is the overload set $S$.
+\begin{note}
+Algorithm function objects are not found by
+argument-dependent name lookup\iref{basic.lookup.argdep}.
+When found by unqualified name lookup\iref{basic.lookup.unqual}
+for the \grammarterm{postfix-expression} in a function call\iref{expr.call},
+they inhibit argument-dependent name lookup.
+\begin{example}
+\begin{codeblock}
+void foo() {
+  using namespace std::ranges;
+  std::vector<int> vec{1,2,3};
+  find(begin(vec), end(vec), 2);        // \#1
+}
+\end{codeblock}
+The function call expression at \#1 invokes \tcode{std::ranges::find},
+not \tcode{std::find}.
+\end{example}
+\end{note}
 
 \rSec3[functions.within.classes]{Functions within classes}