Flush outputs in main functions (#1066)

Fixes #1064

src/gerbil/compiler/driver.ss

@@ -139,8 +139,13 @@ namespace: gxc
       (write `(define builtin-modules
                 (append (quote ,builtin-modules) libgerbil-builtin-modules)))
       (write `(define (gerbil-main)
-                (gerbil-runtime-init! builtin-modules)
-                (apply ,mod-main (cdr (command-line)))))
+                (with-unwind-protect
+                 (lambda ()
+                   (gerbil-runtime-init! builtin-modules)
+                   (apply ,mod-main (cdr (command-line))))
+                 (lambda ()
+                   (with-catch void (lambda () (force-output (current-output-port))))
+                   (with-catch void (lambda () (force-output (current-error-port))))))))
       (write '(gerbil-main))
       (newline)))
 

src/gerbil/main.ss

@@ -233,14 +233,17 @@ package: gerbil
 
 (def (main)
   (init!)
-  (let* ((cmdline      (command-line))
-         (program      (car cmdline))
-         (program-name (path-strip-directory program))
-         (args         (cdr cmdline)))
-    (if (string-prefix? "gx" program-name)
-      ;; a gerbil tool
-      (tool-main program-name args)
-      ;; our main -- process arguments and dispatch
-      (bach-main program-name args))))
+  (unwind-protect
+    (let* ((cmdline      (command-line))
+           (program      (car cmdline))
+           (program-name (path-strip-directory program))
+           (args         (cdr cmdline)))
+      (if (string-prefix? "gx" program-name)
+        ;; a gerbil tool
+        (tool-main program-name args)
+        ;; our main -- process arguments and dispatch
+        (bach-main program-name args)))
+    (with-catch void (cut force-output (current-output-port)))
+    (with-catch void (cut force-output (current-error-port)))))
 
 (##main-set! main)