From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 2 Apr 2018 19:19:00 +0000 (-0700)
Subject: Clarify eq on floats
X-Git-Tag: emacs-27.0.90~5342
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=dfa922dd844c7af966a42b949aee32248ce4e8a2;p=emacs.git

Clarify eq on floats

* doc/lispref/objects.texi (Equality Predicates):
Say that two floats with the same values might or might not be eq.
---

diff --git a/doc/lispref/objects.texi b/doc/lispref/objects.texi
index af740625adb..78a7dccc88d 100644
--- a/doc/lispref/objects.texi
+++ b/doc/lispref/objects.texi
@@ -2083,6 +2083,10 @@ strings), two arguments with the same contents or elements are not
 necessarily @code{eq} to each other: they are @code{eq} only if they
 are the same object, meaning that a change in the contents of one will
 be reflected by the same change in the contents of the other.
+For other types of objects whose contents cannot be changed (e.g.,
+floats), two arguments with the same contents might or might not be
+the same object, and @code{eq} returns @code{t} or @code{nil}
+depending on whether the Lisp interpreter created one object or two.
 
 @example
 @group
@@ -2095,6 +2099,12 @@ be reflected by the same change in the contents of the other.
      @result{} t
 @end group
 
+@group
+(eq 3.0 3.0)
+     @result{} t @r{or} nil
+;; @r{The result is implementation-dependent.}
+@end group
+
 @group
 (eq "asdf" "asdf")
      @result{} nil