New issue from Jan Schultke: "§[algorithms.requirements] It is unclear what an algorithm is"

Author: Dani-Hub

xml/issue4277.xml

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+<?xml version='1.0' encoding='utf-8' standalone='no'?>
+<!DOCTYPE issue SYSTEM "lwg-issue.dtd">
+
+<issue num="4277" status="New">
+<title>&sect;[algorithms.requirements] It is unclear what an algorithm is</title>
+<section>
+<sref ref="[algorithms.requirements]"/>
+</section>
+<submitter>Jan Schultke</submitter>
+<date>08 Jun 2025</date>
+<priority>99</priority>
+
+<discussion>
+<p>
+<sref ref="[algorithms.requirements]"/> paragraph 15 states:
+</p>
+<blockquote style="border-left: 3px solid #ccc;padding-left: 15px;">
+<p>
+The well-formedness and behavior of a call to an algorithm with an explicitly-specified 
+template argument list is unspecified, except where explicitly stated otherwise.
+</p>
+</blockquote>
+<p>
+It is unclear what this applies to because "algorithm" is never defined. <sref ref="[algorithms.requirements]"/> 
+paragraph 1 uses the term while mentioning iterators and containers, but <sref ref="[algorithm]"/> specifies 
+function templates such as `std::gcd` which do not accept iterators.
+<p/>
+The <i>Remarks</i> specifications in <sref ref="[alg.min.max]"/> providing exemptions from 
+<sref ref="[algorithms.requirements]"/> paragraph 15 suggest that even function templates not 
+accepting iterators are considered algorithms.
+</p>
+</discussion>
+
+<resolution>
+<p>
+This wording is relative to <paper num="N5008"/>.
+</p>
+
+<ol>
+<li><p>Modify <sref ref="[algorithms.requirements]"/> as indicated:</p>
+
+<blockquote>
+<p>
+-15- The well-formedness and behavior of a call to <del>an algorithm</del><ins>a function template specified in Clause 
+<sref ref="[algorithms]"/> (including call operators of algorithm function objects denoted as algorithms throughout Clause 
+<sref ref="[algorithms.requirements]"/>)</ins> with an explicitly-specified template argument list is unspecified, 
+except where explicitly stated otherwise.
+<p/>
+[<i>Note 3</i>: Consequently, an implementation can declare an algorithm with different template parameters than those
+presented. &mdash; <i>end note</i>]
+</p>
+</blockquote>
+</li>
+
+</ol>
+</resolution>
+
+</issue>