Speed up parsing when detecting input file change.

* m4/input.c (next_char): Clear input_change flag.  Bug introduced
2006-10-25.

Signed-off-by: Eric Blake <ebb9@byu.net>

2 files changed, 9 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index a0802edd..6717a8a3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2009-02-13  Eric Blake  <ebb9@byu.net>
+
+	Speed up parsing when detecting input file change.
+	* m4/input.c (next_char): Clear input_change flag.  Bug introduced
+	2006-10-25.
+
 2009-02-12  Eric Blake  <ebb9@byu.net>
 
 	Avoid quadratic code when walking definition stack.
diff --git a/m4/input.c b/m4/input.c
index c3c47d09..26723867 100644
--- a/m4/input.c
+++ b/m4/input.c
@@ -1,6 +1,6 @@
 /* GNU m4 -- A simple macro processor
-   Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 2006, 2007, 2008
-   Free Software Foundation, Inc.
+   Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 2006, 2007, 2008,
+   2009 Free Software Foundation, Inc.
 
    This file is part of GNU M4.
 
@@ -1287,6 +1287,7 @@ next_char (m4 *context, bool allow_quote, bool allow_argv, bool allow_unget)
 	{
 	  m4_set_current_file (context, isp->file);
 	  m4_set_current_line (context, isp->line);
+	  input_change = false;
 	}
 
       assert (isp->funcs->read_func);