Do not use 'with-continuation-barrier'.

It turns out that 'with-continuation-barrier' allows delimited
continuations (i.e., prompts) to get through.

* gash/shell.scm (%subshell): Replace 'with-continuation-barrier' with
'dynamic-wind', making sure to preserve exit statuses that were leaked
through before.
* tests/unit/shell.scm (call-with-temporary-directory): Replace
'with-continuation-barrier' with 'dynamic-wind'.
* tests/spec/oil.scm: Enable previously failing tests.

gash/shell.scm

@@ -247,13 +247,20 @@ process."
   ;; duplicate output.
   (flush-all-ports)
   (match (primitive-fork)
-    (0 (with-continuation-barrier
-        (lambda ()
-          (restore-signals)
-          (set-atexit! #f)
-          (thunk)
-          (primitive-exit (get-status))))
-       (primitive-exit 1))
+    (0 (dynamic-wind
+         (lambda () #t)
+         (lambda ()
+           (restore-signals)
+           (set-atexit! #f)
+           ;; We need to preserve the status given to 'exit', so we
+           ;; catch the 'quit' key here.
+           (catch 'quit
+             thunk
+             (lambda (_ status)
+               (primitive-exit status)))
+           (primitive-exit (get-status)))
+         (lambda ()
+           (primitive-exit 1))))
     (pid pid)))
 
 (define (sh:subshell thunk)

tests/spec/oil.scm

@@ -158,9 +158,6 @@
                        ("\\$\\(\\(i\\+1\\)\\)" "$(expr $i + 1)"))
                       ("while in pipe with subshell"
                        ("\\$\\(\\(i\\+1\\)\\)" "$(expr $i + 1)"))
-                      ;; Gash needs to be fixed to pass these tests.
-                      ("continue in subshell")
-                      ("continue in subshell aborts with errexit")
                       ;; The Oil shell handles this statically.  We
                       ;; will treat it as a fatal run-time error (for
                       ;; now).

tests/unit/shell.scm

@@ -58,12 +58,13 @@
   (file-system-fold enter? leaf down up skip error #f path))
 
 (define (call-with-temporary-directory proc)
-  (let* ((directory (make-temporary-directory))
-         (result (with-continuation-barrier
-                  (lambda ()
-                    (proc directory)))))
-    (delete-recursively directory)
-    result))
+  (let* ((directory (make-temporary-directory)))
+    (dynamic-wind
+      (lambda () #t)
+      (lambda ()
+        (proc directory))
+      (lambda ()
+        (delete-recursively directory)))))
 
 (define (%make-script object . forms)
   (define (write-script port)