current-filename canonicalizes path, remove add-to-path

* module/ice-9/boot-9.scm (current-filename): Canonicalize the path, so
  that the result is independent of the current directory, and so
  that `dirname' can traverse up the file system, as in the
  add-to-load-path example.
  (add-to-path): Remove.  The eval-when semantics make this macro too
  tricky to explain -- people will start using it on other path-like
  things, in lexical contours, whereas it only really makes sense with
  load-like paths at the toplevel.

* doc/ref/api-evaluation.texi (Loading): Fix link to load-with-path
  docs, and remove add-to-path docs.

doc/ref/api-evaluation.texi

@@ -781,7 +781,7 @@ change occurs at the right time.
 A procedure to be called @code{(%load-hook @var{filename})} whenever a
 file is loaded, or @code{#f} for no such call.  @code{%load-hook} is
 used by all of the loading functions (@code{load} and
-@code{primitive-load}, and @code{load-path} and
+@code{primitive-load}, and @code{load-from-path} and
 @code{primitive-load-path} documented in the next section).
 
 For example an application can set this to show what's loaded,
@@ -832,13 +832,6 @@ It's better to use @code{add-to-load-path} than to modify
 @code{%load-path} directly, because @code{add-to-load-path} takes care
 of modifying the path both at compile-time and at run-time.
 
-There is a more general version for use with other paths, like
-@code{%load-compiled-path}:
-
-@deffn {Scheme Syntax} add-to-path path dir
-Add @var{dir} to @var{path}.
-@end deffn
-
 @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

module/ice-9/boot-9.scm

@@ -521,8 +521,8 @@ If there is no handler at all, Guile prints an error and then exits."
     "A macro that expands to the current filename: the filename that
 the (current-filename) form appears in.  Expands to #f if this
 information is unavailable."
-    (and=> (syntax-source x)
+    (false-if-exception
-           (lambda (s) (assq-ref s 'filename)))))
+     (canonicalize-path (assq-ref (syntax-source x) 'filename)))))
 
 (define-syntax-rule (define-once sym val)
   (define sym
@@ -1402,14 +1402,10 @@ VALUE."
   (start-stack 'load-stack
                (primitive-load-path name)))
 
-(define-syntax-rule (add-to-path path elt)
-  "Add ELT to PATH, at compile-time and at run-time."
-  (eval-when (compile load eval)
-    (set! path (cons elt path))))
-
 (define-syntax-rule (add-to-load-path elt)
   "Add ELT to Guile's load path, at compile-time and at run-time."
-  (add-to-path %load-path elt))
+  (eval-when (compile load eval)
+    (set! %load-path (cons elt %load-path))))
 
 (define %load-verbosely #f)
 (define (assert-load-verbosity v) (set! %load-verbosely v))