Index: texinfo.tex
===================================================================
--- texinfo.tex	(revision 6352)
+++ texinfo.tex	(working copy)
@@ -7429,6 +7429,17 @@
   \usembodybackslash
 }
 
+% \sometimesescape - backslash behaviour - expand \\ as \, otherwise 
+% keep \ as it is
+{
address@hidden @address@hidden@other
address@hidden@[=1 @address@hidden
address@hidden@sometimesescape#1[%
+% we need noexpand because \ is active
address@hidden @noexpand address@hidden #1 @normalbackslash%
address@hidden @normalbackslash#1%
address@hidden
+
 \def\macroargctxt{% used when scanning invocations
   \scanctxt
   \catcode`\\=0
@@ -7828,8 +7839,8 @@
         \noexpand\scanmacro{\temp}\egroup}%
     \or % 1
       \expandafter\xdef\csname\the\macname\endcsname{%
-         \bgroup\noexpand\macroargctxt
-         \noexpand\braceorline
+         \bgroup\noexpand\scanctxt
+         \noexpand\oneargbraceorline
          \expandafter\noexpand\csname\the\macname xxx\endcsname}%
       \expandafter\xdef\csname\the\macname xxx\endcsname##1{%
         \egroup
@@ -7875,7 +7886,24 @@
     \expandafter\parsearg
   \fi \macnamexxx}
 
+\def\oneargbraceorline#1{%
+  \let\macnamexxx=#1\futurelet\nchar\oneargbraceorlinexxx}
 
+% \oneargbraceorlinexxx
+% We need to set \ as active so the @let works
address@hidden @address@hidden
address@hidden@oneargbraceorlinexxx{%
+  @address@hidden@bgroup
+  @macroargctxt
+  @message{argument in braces,}
+  @else
+  @message{argument on line,}
+  @scanctxt
+  @address@hidden@sometimesescape
+    @address@hidden
+  @fi @macnamexxx}}
+
+
 % @alias.
 % We need some trickery to remove the optional spaces around the equal
 % sign.  Make them active and then expand them all to nothing.