fix uncaught-exception-handler handling of non-escaping escape handler

and change the emergency error display handler to log and error
 Closes PR 11630

collects/scribblings/reference/exns.scrbl

@@ -275,17 +275,18 @@ handler that reports both the original and newly raised exception).
 
 The default uncaught-exception handler prints an error message using
 the current @tech{error display handler} (see @racket[error-display-handler])
-and then escapes by calling the current error escape handler (see
+and then escapes by calling the current @tech{error escape handler} (see
 @racket[error-escape-handler]). The call to each handler is
 @racket[parameterize]d to set @racket[error-display-handler] to the
 default @tech{error display handler}, and it is @racket[parameterize-break]ed
-to disable breaks. The call to the error escape handler is further
+to disable breaks. The call to the @tech{error escape handler} is further
 parameterized to set @racket[error-escape-handler] to the default
-error escape handler.
+@tech{error escape handler}; if the @tech{error escape handler} returns, then
+the default @tech{error escape handler} is called.
 
 When the current @tech{error display handler} is the default handler, then the
 error-display call is parameterized to install an emergency error
-display handler that attempts to print directly to a console and never
+display handler that logs an error (see @racket[log-error]) and never
 fails.}
 
 @defform[(with-handlers ([pred-expr handler-expr] ...)

collects/tests/racket/thread.rktl

@@ -1349,4 +1349,36 @@
 
 ; --------------------
 
+;; Check that the default uncaught-exception handler falls
+;; back to the default error escape handler if the current
+;; one doesn't escape.
+(test 'done
+      'error-non-escape-handler
+      (begin
+        (call-with-continuation-prompt
+         (lambda ()
+           (parameterize ([error-escape-handler void]
+                          [error-display-handler void])
+             (raise 'oops))))
+        'done))
+
+;; Check that if the current error port is broken,
+;; so that the default error display handler fails,
+;; then check that an error is logged.
+(test #t
+      regexp-match? 
+      #rx"output port is closed" 
+      (let* ([p (open-output-bytes)]
+             [l (make-logger)]
+             [r (make-log-receiver l 'error)])
+        (close-output-port p)
+        (call-with-continuation-prompt
+         (lambda ()
+           (parameterize ([current-error-port p]
+                          [current-logger l])
+             (raise 'ack))))
+        (vector-ref (sync r) 1)))
+      
+; --------------------
+
 (report-errs)

src/racket/src/error.c

@@ -661,23 +661,6 @@ void scheme_init_logger_config() {
   scheme_set_root_param(MZCONFIG_LOGGER, (Scheme_Object *)scheme_main_logger);
 }
 
-static void
-scheme_inescapeable_error(const char *a, const char *b)
-{
-  int al, bl;
-  char *t;
-
-  al = strlen(a);
-  bl = strlen(b);
-  t = scheme_malloc_atomic(al + bl + 2);
-  memcpy(t, a, al);
-  memcpy(t + al, b, bl);
-  t[al + bl] = '\n';
-  t[al + bl + 1] = 0;
-
-  scheme_console_output(t, al + bl + 1);
-}
-
 static void
 call_error(char *buffer, int len, Scheme_Object *exn)
 {
@@ -763,9 +746,8 @@ call_error(char *buffer, int len, Scheme_Object *exn)
     scheme_pop_break_enable(&cframe2, 0);
     scheme_pop_continuation_frame(&cframe);
 
-    /* Uh-oh; record the error and fall back to the default escaper */
-    scheme_inescapeable_error("error escape handler did not escape; calling the default error escape handler", "");
-    scheme_longjmp(savebuf, 1); /* force an exit */
+    /* Didn't escape, so fall back to the default escaper: */
+    def_error_escape_proc(0, NULL);
   }
 }
 
@@ -2418,9 +2400,9 @@ emergency_error_display_proc(int argc, Scheme_Object *argv[])
 
   s = scheme_char_string_to_byte_string(argv[0]);
 
-  scheme_console_output(SCHEME_BYTE_STR_VAL(s),
-			SCHEME_BYTE_STRTAG_VAL(s));
-  scheme_console_output("\n", 1);
+  scheme_log_message(NULL, SCHEME_LOG_ERROR, 
+                     SCHEME_BYTE_STR_VAL(s), SCHEME_BYTE_STRTAG_VAL(s), 
+                     scheme_false);
 
   return scheme_void;
 }