Restore signature of `scm_primitive_load_path ()' as found in 1.8.

The incompatibility was introduced by
0fb81f95b0 ("add exception_on_error
optional arg to primitive-load-path").

* libguile/load.c (scm_primitive_load_path): Change to take 1 rest
  argument.  Interpret the argument as either a file name (C-level
  backward compatibility with 1.8) or an actual argument list.
  (scm_c_primitive_load_path): Update caller.

* libguile/load.h (scm_primitive_load_path): Update accordingly.

* doc/ref/api-evaluation.texi (Loading): Update documentation of
  `primitive-load-path' and `scm_primitive_load_path ()'.

doc/ref/api-evaluation.texi

@@ -1,6 +1,6 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Guile Reference Manual.
-@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006
+@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2009
 @c   Free Software Foundation, Inc.
 @c See the file guile.texi for copying conditions.
 
@@ -538,13 +538,20 @@ documentation for @code{%load-hook} later in this section.
 @code{SCM}.
 @end deftypefn
 
-@deffn {Scheme Procedure} primitive-load-path filename
+@deffn {Scheme Procedure} primitive-load-path filename [exception-on-not-found]
 @deffnx {C Function} scm_primitive_load_path (filename)
 Search @code{%load-path} for the file named @var{filename} and
 load it into the top-level environment.  If @var{filename} is a
 relative pathname and is not found in the list of search paths,
 an error is signalled. Preferentially loads a compiled version of the
 file, if it is available and up-to-date.
+
+By default or if @var{exception-on-not-found} is true, an exception is
+raised if @var{filename} is not found.  If @var{exception-on-not-found}
+is @code{#f} and @var{filename} is not found, no exception is raised and
+@code{#f} is returned.  For compatibility with Guile 1.8 and earlier,
+the C function takes only one argument, which can be either a string
+(the file name) or an argument list.
 @end deffn
 
 @deffn {Scheme Procedure} %search-load-path filename

libguile/load.c

@@ -685,8 +685,8 @@ scm_try_autocompile (SCM source)
                       NULL, NULL);
 }
 
-SCM_DEFINE (scm_primitive_load_path, "primitive-load-path", 1, 1, 0, 
-	    (SCM filename, SCM exception_on_not_found),
+SCM_DEFINE (scm_primitive_load_path, "primitive-load-path", 0, 0, 1,
+	    (SCM args),
 	    "Search @var{%load-path} for the file named @var{filename} and\n"
 	    "load it into the top-level environment.  If @var{filename} is a\n"
 	    "relative pathname and is not found in the list of search paths,\n"
@@ -695,9 +695,33 @@ SCM_DEFINE (scm_primitive_load_path, "primitive-load-path", 1, 1, 0,
             "@code{#f} is returned instead.")
 #define FUNC_NAME s_scm_primitive_load_path
 {
+  SCM filename, exception_on_not_found;
   SCM full_filename, compiled_filename;
   int compiled_is_fallback = 0;
 
+  if (scm_is_string (args))
+    {
+      /* C code written for 1.8 and earlier expects this function to take a
+	 single argument (the file name).  */
+      filename = args;
+      exception_on_not_found = SCM_UNDEFINED;
+    }
+  else
+    {
+      /* Starting from 1.9, this function takes 1 required and 1 optional
+	 argument.  */
+      long len;
+
+      SCM_VALIDATE_LIST_COPYLEN (SCM_ARG1, args, len);
+      if (len < 1 || len > 2)
+	scm_error_num_args_subr (FUNC_NAME);
+
+      filename = SCM_CAR (args);
+      SCM_VALIDATE_STRING (SCM_ARG1, filename);
+
+      exception_on_not_found = len > 1 ? SCM_CADR (args) : SCM_UNDEFINED;
+    }
+
   if (SCM_UNBNDP (exception_on_not_found))
     exception_on_not_found = SCM_BOOL_T;
 
@@ -775,8 +799,7 @@ SCM_DEFINE (scm_primitive_load_path, "primitive-load-path", 1, 1, 0,
 SCM
 scm_c_primitive_load_path (const char *filename)
 {
-  return scm_primitive_load_path (scm_from_locale_string (filename),
-                                  SCM_BOOL_T);
+  return scm_primitive_load_path (scm_from_locale_string (filename));
 }
 
 

libguile/load.h

@@ -3,7 +3,7 @@
 #ifndef SCM_LOAD_H
 #define SCM_LOAD_H
 
-/* Copyright (C) 1995,1996,1998,2000,2001, 2006, 2008 Free Software Foundation, Inc.
+/* Copyright (C) 1995,1996,1998,2000,2001, 2006, 2008, 2009 Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -34,7 +34,7 @@ SCM_API SCM scm_sys_library_dir (void);
 SCM_API SCM scm_sys_site_dir (void);
 SCM_API SCM scm_search_path (SCM path, SCM filename, SCM exts, SCM require_exts);
 SCM_API SCM scm_sys_search_load_path (SCM filename);
-SCM_API SCM scm_primitive_load_path (SCM filename, SCM exception_on_not_found);
+SCM_API SCM scm_primitive_load_path (SCM filename_and_exception_on_not_found);
 SCM_API SCM scm_c_primitive_load_path (const char *filename);
 SCM_INTERNAL SCM scm_sys_warn_autocompilation_enabled (void);
 SCM_INTERNAL void scm_init_load_path (void);