(Creating Strings): Null strings from concat not unique.

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 282fa19bfa135c074c95a41565e3bc927784cca9..5f52b30d60aec7474b7ed4e3857d391e38fd0d7f 100644 (file)
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,7 @@
+2007-10-31  Richard Stallman  <rms@gnu.org>
+
+       * strings.texi (Creating Strings): Null strings from concat not unique.
+
 2007-10-26  Richard Stallman  <rms@gnu.org>
 
        * objects.texi (Equality Predicates): Null strings are uniquified.

diff --git a/doc/lispref/strings.texi b/doc/lispref/strings.texi
index b2f32ad02d60bb9f2798b84d72528140721b5b30..f119b3ab84b61497942d3e24592239d3d256f5af 100644 (file)
--- a/doc/lispref/strings.texi
+++ b/doc/lispref/strings.texi
@@ -259,7 +259,8 @@ returns an empty string.
 
 @noindent
 The @code{concat} function always constructs a new string that is
-not @code{eq} to any existing string.
+not @code{eq} to any existing string, except when the result is empty
+(since empty strings are canonicalized to save space).
 
 In Emacs versions before 21, when an argument was an integer (not a
 sequence of integers), it was converted to a string of digits making up