catch sxref failures and report as warnings when loading help data

svn: r8063

collects/scribble/xref.ss

@@ -40,7 +40,9 @@
          [ci (send renderer collect null null)])
     (for-each (lambda (src)
                 (parameterize ([current-namespace (namespace-anchor->empty-namespace here)])
-                  (send renderer deserialize-info (src) ci)))
+                  (let ([v (src)])
+                    (when v
+                      (send renderer deserialize-info v ci)))))
               sources)
     (make-xrefs renderer (send renderer resolve null null ci))))
 

collects/scribblings/reference/sandbox.scrbl

@@ -401,12 +401,12 @@ first is a timeout value in seconds, and the second is a memory limit
 in megabytes.  Either one can be @scheme[#f] for disabling the
 corresponding limit; alternately, the parameter can be set to
 @scheme[#f] to disable all limits (in case more are available in
-future versions).
+future versions). The default is @scheme[(list 30 20)].
 
 When limits are set, @scheme[call-with-limits] (see below) is wrapped
 around each use of the evaluator, so consuming too much time or memory
-results in an exception.  You can change the limits of a running
-evaluator using @scheme[set-eval-limits].}
+results in an exception.  Change the limits of a running evaluator
+using @scheme[set-eval-limits].}
 
 @; ----------------------------------------------------------------------
 

collects/scribblings/scribble/xref.scrbl

@@ -27,7 +27,8 @@ by @scheme[load-xref], @scheme[#f] otherwise.}
 
 Creates a cross-reference record given a list of functions that each
 produce a serialized information obtained from @xmethod[render%
-serialize-info].
+serialize-info]. If a @scheme[sources] element produces @scheme[#f],
+its result is ignored.
 
 Since the format of serialized information is specific to a rendering
 class, the optional @scheme[using-render%] argument accepts the

collects/setup/xref.ss

@@ -41,7 +41,14 @@
                                    dirs)))])
           (set! cached-xref (load-xref (map (lambda (dest)
                                               (lambda ()
-                                                (let ([r (with-input-from-file dest read)])
-                                                  (cadr r))))
+                                                (with-handlers ([exn:fail? (lambda (exn)
+                                                                             (fprintf (current-error-port)
+                                                                                      "WARNING: ~a\n"
+                                                                                      (if (exn? exn)
+                                                                                          (exn-message exn)
+                                                                                          (format "~e" exn)))
+                                                                             #f)])
+                                                  (let ([r (with-input-from-file dest read)])
+                                                    (cadr r)))))
                                             dests)))
           cached-xref))))