Fix top-level 'break', 'continue', and 'return'.

* gash/environment.scm (sh:break, sh:continue, sh:return): Wrap
'abort-to-prompt' with 'false-if-exception'.
* gash/built-ins/break.scm (main): Print warning and continue if
'sh:break' returns.
* gash/built-ins/continue.scm (main): Likewise, but for 'sh:continue'.
* gash/built-ins/return.scm (main): Likewise, but for 'sh:return'.
* tests/functions.org (Top-level return): New test.
* tests/spec/oil.scm: Enable previously failing test.

gash/built-ins/break.scm

@@ -37,7 +37,10 @@
                    "gash: break: argument must be a positive integer~%")
            EXIT_FAILURE)
        (n (set-status! 0)
-          (sh:break (1- n)))))
+          (sh:break (1- n))
+          (format (current-error-port)
+                  "gash: break: no loop to break from~%")
+          EXIT_SUCCESS)))
     (_ (format (current-error-port)
                "gash: break: too many arguments~%")
        EXIT_FAILURE)))

gash/built-ins/continue.scm

@@ -37,7 +37,10 @@
                    "gash: continue: argument must be a positive integer~%")
            EXIT_FAILURE)
        (n (set-status! 0)
-          (sh:continue (1- n)))))
+          (sh:continue (1- n))
+          (format (current-error-port)
+                  "gash: continue: no loop to continue from~%")
+          EXIT_SUCCESS)))
     (_ (format (current-error-port)
                "gash: continue: too many arguments~%")
        EXIT_FAILURE)))

gash/built-ins/return.scm

@@ -36,7 +36,11 @@
        (#f (format (current-error-port)
                    "gash: return: argument must be a number from 0 to 255~%")
            EXIT_FAILURE)
-       (n (sh:return n))))
+       (n (sh:return n)
+          (format (current-error-port)
+                  (string-append "gash: return: no function "
+                                 "or sourced script to return from~%"))
+          EXIT_SUCCESS)))
     (_ (format (current-error-port)
                "gash: return: too many arguments~%")
        EXIT_FAILURE)))

gash/environment.scm

@@ -334,8 +334,9 @@ exit the dynamic extent of @var{thunk}."
 
 (define* (sh:continue #:optional (n 0))
   "Exit to the closest invocation of @code{call-with-continue}.  If
-@var{n} is set, exit to the @math{n + 1}th closest invocation."
+@var{n} is set, exit to the @math{n + 1}th closest invocation.  If not
-  (abort-to-prompt *continue-tag* n))
+called from within @code{call-with-continue}, return @code{#f}."
+  (false-if-exception (abort-to-prompt *continue-tag* n)))
 
 (define *break-tag* (make-prompt-tag))
 
@@ -351,8 +352,9 @@ exit the dynamic extent of @var{thunk}."
 
 (define* (sh:break #:optional (n 0))
   "Exit to the closest invocation of @code{call-with-break}.  If
-@var{n} is set, exit to the @math{n + 1}th closest invocation."
+@var{n} is set, exit to the @math{n + 1}th closest invocation.  If not
-  (abort-to-prompt *break-tag* n))
+called from within @code{call-with-break}, return @code{#f}."
+  (false-if-exception (abort-to-prompt *break-tag* n)))
 
 (define *return-tag* (make-prompt-tag))
 
@@ -367,8 +369,9 @@ exit the dynamic extent of @var{thunk}."
 (define* (sh:return #:optional (status (get-status)))
   "Exit to the closest invocation of @code{call-with-return} setting
 status to @var{status}.  If @var{status} is not set, keep the current
-status."
+status.  If not called from within @code{call-with-return}, return
-  (abort-to-prompt *return-tag* status))
+@code{#f}."
+  (false-if-exception (abort-to-prompt *return-tag* status)))
 
 (define *atexit* #f)
 (define *exiting?* #f)

tests/functions.org

@@ -83,3 +83,10 @@
   foo
 #+end_src
 :status: 1
+
+* Top-level return
+:script:
+#+begin_src sh
+  return
+#+end_src
+:status: 0

tests/spec/oil.scm

@@ -159,7 +159,6 @@
                       ("while in pipe with subshell"
                        ("\\$\\(\\(i\\+1\\)\\)" "$(expr $i + 1)"))
                       ;; Gash needs to be fixed to pass these tests.
-                      ("continue at top level")
                       ("continue in subshell")
                       ("continue in subshell aborts with errexit")
                       ;; The Oil shell handles this statically.  We