[builtin/complete] Add syntax error when no args, but flags

- 'complete' is an alias for 'complete -p'
- 'complete -F f' with no args is a syntax error

osh/builtin_comp.py

@@ -108,7 +108,6 @@ def __init__(
 
         self.errfmt = errfmt
 
-
     def Build(self, argv, attrs, base_opts):
         # type: (List[str], _Attributes, Dict[str, bool]) -> UserSpec
         """Given flags to complete/compgen, return a UserSpec."""
@@ -280,21 +279,29 @@ def Run(self, cmd_val):
         commands = arg_r.Rest()
 
         if arg.D:
-            commands.append(
-                '__fallback')  # if the command doesn't match anything
+            # if the command doesn't match anything
+            commands.append('__fallback')
         if arg.E:
             commands.append('__first')  # empty line
 
         if len(commands) == 0:
-            self.comp_lookup.PrintSpecs()
-            return 0
+            if len(cmd_val.argv) == 1:  # nothing passed at all
+                assert cmd_val.argv[0] == 'complete'
+
+                # TODO: crashes in C++
+                self.comp_lookup.PrintSpecs()
+                return 0
+            else:
+                # complete -F f is an error
+                raise error.Usage('expected 1 or more commands', loc.Missing)
 
         base_opts = dict(attrs.opt_changes)
         try:
             user_spec = self.spec_builder.Build(cmd_val.argv, attrs, base_opts)
         except error.Parse as e:
             # error printed above
             return 2
+
         for command in commands:
             self.comp_lookup.RegisterName(command, base_opts, user_spec)
 

spec/builtin-completion.test.sh

@@ -1,4 +1,56 @@
 
+## oils_failures_allowed: 2
+## compare_shells: bash
+
+#### complete with no args and complete -p both print completion spec
+
+set -e
+
+complete
+
+complete -W 'foo bar' mycommand
+
+complete
+
+complete -F myfunc other
+
+complete -p
+
+## STDOUT:
+complete -W 'foo bar' mycommand
+complete -W 'foo bar' mycommand
+complete -F myfunc other
+## END
+
+#### complete -F f is usage error
+
+#complete -F f cmd
+
+# Alias for complete -p
+complete > /dev/null  # ignore OSH output for now
+echo status=$?
+
+# But this is an error
+complete -F f
+echo status=$?
+
+## STDOUT:
+status=0
+status=2
+## END
+
+#### complete with nonexistent function
+complete -F invalidZZ -D
+echo status=$?
+## stdout: status=2
+## BUG bash stdout: status=0
+
+#### complete with no action
+complete foo
+echo status=$?
+## stdout: status=2
+## BUG bash stdout: status=0
+
 #### -A function prints functions
 add () { expr 4 + 4; }
 div () { expr 6 / 2; }
@@ -218,18 +270,6 @@ while
 status=0
 ## END
 
-#### complete with nonexistent function
-complete -F invalidZZ -D
-echo status=$?
-## stdout: status=2
-## BUG bash stdout: status=0
-
-#### complete with no action
-complete foo
-echo status=$?
-## stdout: status=2
-## BUG bash stdout: status=0
-
 #### -o filenames and -o nospace have no effect with compgen 
 # they are POSTPROCESSING.
 compgen -o filenames -o nospace -W 'bin build'

test/spec.sh

@@ -265,10 +265,8 @@ vars-special() {
     ${REF_SHELLS[@]} $ZSH $OSH_LIST "$@"
 }
 
-# This is bash/OSH only
 builtin-completion() {
-  sh-spec spec/builtin-completion.test.sh --oils-failures-allowed 1 \
-    $BASH $OSH_LIST "$@"
+  run-file builtin-completion "$@"
 }
 
 builtin-special() {