Make engine startup failure non-fatal in WinBoard

Unlike XBoard, which forks first, the parent process WinBoard has direct
knowledge of a failure to execute the engine command, and used it to
trigger a fatal error. The code doing this has now been disabled. Only
in case of a first engine we switch back to -ncp mode in stead, but no
action is taken to 'bury' the deceased engine process. Like in XBoard,
errors in writing or reading the pipes will trigger this.

diff --git a/backend.c b/backend.c
index e56bbb1..508ddf7 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -9477,9 +9477,14 @@ StartChessProgram(cps)
 
     if (err != 0) {
       snprintf(buf, MSG_SIZ, _("Startup failure on '%s'"), cps->program);
-       DisplayFatalError(buf, err, 1);
-       cps->pr = NoProc;
-       cps->isr = NULL;
+       DisplayError(buf, err); // [HGM] bit of a rough kludge: ignore failure, (which XBoard would do anyway), and let I/O discover it
+       if(cps != &first) return;
+       appData.noChessProgram = TRUE;
+       ThawUI();
+       SetNCPMode();
+//     DisplayFatalError(buf, err, 1);
+//     cps->pr = NoProc;
+//     cps->isr = NULL;
        return;
     }