[osh-language] Fix default value of 'exit' and 'return'.

Addresses issue #423.

osh/cmd_exec.py

@@ -878,6 +878,8 @@ def _Dispatch(self, node, fork_external):
         # false; echo $?; local f=x; echo $?
 
     elif node.tag == command_e.ControlFlow:
+      tok = node.token
+
       if node.arg_word:  # Evaluate the argument
         val = self.word_ev.EvalWordToString(node.arg_word)
         assert val.tag == value_e.Str
@@ -887,12 +889,14 @@ def _Dispatch(self, node, fork_external):
           e_die('%r expected a number, got %r',
               node.token.val, val.s, word=node.arg_word)
       else:
-        arg = 0  # return 0, exit 0, break 0 levels, etc.
+        if tok.id in (Id.ControlFlow_Exit, Id.ControlFlow_Return):
+          arg = self.mem.LastStatus()
+        else:
+          arg = 0  # break 0 levels, nothing for continue
 
       # NOTE: A top-level 'return' is OK, unlike in bash.  If you can return
       # from a sourced script, it makes sense to return from a main script.
       ok = True
-      tok = node.token
       if (tok.id in (Id.ControlFlow_Break, Id.ControlFlow_Continue) and
           self.loop_level == 0):
         ok = False

spec/func.test.sh

@@ -70,3 +70,14 @@ f
 echo "[$mylocal $myglobal]"
 ## stdout-json: "[L G]\n[ G]\n"
 ## status: 0
+
+#### Return without args gives previous
+f() {
+  ( exit 42 )
+  return
+}
+f
+echo status=$?
+## STDOUT:
+status=42
+## END

spec/sh-options.test.sh

@@ -27,39 +27,6 @@ $SH -i -c 'echo $-' | grep -q i && echo TRUE
 FALSE
 TRUE
 ## END
-
-#### sh -c
-$SH -c 'echo hi'
-## stdout: hi
-## status: 0
-
-#### empty -c input
-# had a bug here
-$SH -c ''
-## stdout-json: ""
-## status: 0
-
-#### empty stdin
-# had a bug here
-echo -n '' | $SH
-## stdout-json: ""
-## status: 0
-
-#### args are passed
-$SH -c 'argv.py "$@"' dummy a b
-## stdout: ['a', 'b']
-
-#### args that look like flags are passed after script
-script=$TMP/sh1.sh
-echo 'argv.py "$@"' > $script
-chmod +x $script
-$SH $script --help --help -h
-## stdout: ['--help', '--help', '-h']
-
-#### args that look like flags are passed after -c
-$SH -c 'argv.py "$@"' --help --help -h
-## stdout: ['--help', '-h']
-
 #### pass short options on command line
 $SH -e -c 'false; echo status=$?'
 ## stdout-json: ""

test/spec.sh

@@ -507,6 +507,11 @@ var-sub-quote() {
     ${REF_SHELLS[@]} $OSH_LIST "$@"
 }
 
+sh-usage() {
+  sh-spec spec/sh-usage.test.sh \
+    ${REF_SHELLS[@]} $OSH_LIST "$@"
+}
+
 sh-options() {
   sh-spec spec/sh-options.test.sh --osh-failures-allowed 2 \
     ${REF_SHELLS[@]} $OSH_LIST "$@"