(Minibuffer History): Add `history-delete-duplicates'.

2 files changed, 13 insertions, 1 deletions

diff --git a/lispref/minibuf.texi b/lispref/minibuf.texi
index 7b762a654e6..1b076c5837d 100644
--- a/lispref/minibuf.texi
+++ b/lispref/minibuf.texi
@@ -450,7 +450,8 @@ delete old elements if the list gets too long.  The variable
 @code{history-length} specifies the maximum length for most history
 lists.  To specify a different maximum length for a particular history
 list, put the length in the @code{history-length} property of the
-history list symbol.
+history list symbol.  The variable @code{history-delete-duplicates}
+specifies whether to delete duplicates in history.
 
 @defvar history-length
 The value of this variable specifies the maximum length for all
@@ -459,6 +460,11 @@ value is @code{t}, that means there no maximum (don't delete old
 elements).
 @end defvar
 
+@defvar history-delete-duplicates
+If the value of this variable is @code{t}, that means when adding a
+new history element, all previous identical elements are deleted.
+@end defvar
+
   Here are some of the standard minibuffer history list variables:
 
 @defvar minibuffer-history
diff --git a/man/mini.texi b/man/mini.texi
index 040306ba041..ec82c6d4f88 100644
--- a/man/mini.texi
+++ b/man/mini.texi
@@ -511,6 +511,12 @@ is deleted each time an element is added.  If the value of
 @code{history-length} is @code{t}, though, there is no maximum length
 and elements are never deleted.
 
+@vindex history-delete-duplicates
+  The variable @code{history-delete-duplicates} specifies whether to
+delete duplicates in history.  If the value of @code{history-delete-duplicates}
+is @code{t}, that means when adding a new history element, all
+previous identical elements are deleted.
+
 @node Repetition
 @section Repeating Minibuffer Commands
 @cindex command history