[osh/cmd_exec] Fix bug with break/continue and subshell.

OSH used to print the wrong result, but it's now more strict than any
shell.

The subshell exits 1 when the control flow isn't wrapped in a loop.
Then 'set -o errexit' will cause the program to exit early, which you
want for this programming error.

Fixes issue #302.

core/process.py

@@ -476,7 +476,10 @@ def Run(self):
     # NOTE: may NOT return due to exec().
     if self.disable_errexit:
       self.ex.exec_opts.errexit.Disable()
+
     self.ex.ExecuteAndCatch(self.node, fork_external=False)
+    # NOTE: We ignore the is_fatal return value.  The user should set -o
+    # errexit so failures in subprocesses cause failures in the parent.
 
     # Raises SystemExit, so we still have time to write a crash dump.
     sys.exit(self.ex.LastStatus())

osh/cmd_exec.py

@@ -1192,7 +1192,14 @@ def ExecuteAndCatch(self, node, fork_external=True):
         is_control_flow = True
         status = e.StatusCode()
       else:
-        raise  # Invalid
+        # Invalid control flow
+        self.errfmt.Print(
+            "Loop and control flow can't be in a different processes",
+            span_id=e.token.span_id)
+        is_fatal = True
+        # All shells exit 0 here.  It could be hidden behind
+        # strict-control-flow if the incompatibility causes problems.
+        status = 1
     except util.ParseError as e:
       self.dumper.MaybeCollect(self, e)  # Do this before unwinding stack
       raise

spec/loop.test.sh

@@ -178,30 +178,73 @@ one
 ## END
 
 #### continue in subshell
-for i in $(seq 3); do
+for i in $(seq 2); do
   echo "> $i"
   ( if true; then continue; fi; echo "Should not print" )
+  echo subshell status=$?
   echo ". $i"
 done
 ## STDOUT:
+# osh lets you fail
 > 1
+subshell status=1
 . 1
 > 2
+subshell status=1
+. 2
+## END
+## OK dash/bash/zsh STDOUT:
+> 1
+subshell status=0
+. 1
+> 2
+subshell status=0
 . 2
-> 3
-. 3
 ## END
 ## BUG mksh STDOUT:
 > 1
 Should not print
+subshell status=0
 . 1
 > 2
 Should not print
+subshell status=0
+. 2
+## END
+
+#### continue in subshell aborts with errexit
+# The other shells don't let you recover from this programming error!
+set -o errexit
+for i in $(seq 2); do
+  echo "> $i"
+  ( if true; then continue; fi; echo "Should not print" )
+  echo 'should fail after subshell'
+  echo ". $i"
+done
+## STDOUT:
+> 1
+## END
+## status: 1
+## BUG dash/bash/zsh STDOUT:
+> 1
+should fail after subshell
+. 1
+> 2
+should fail after subshell
 . 2
-> 3
+## END
+## BUG dash/bash/zsh status: 0
+## BUG mksh STDOUT:
+> 1
+Should not print
+should fail after subshell
+. 1
+> 2
 Should not print
-. 3
+should fail after subshell
+. 2
 ## END
+## BUG mksh status: 0
 
 #### bad arg to break
 x=oops

test/runtime-errors.sh

@@ -585,6 +585,14 @@ strict_control_flow_warnings() {
   break
 }
 
+control_flow_subshell() {
+  set -o errexit
+  for i in $(seq 2); do
+    echo $i
+    ( break; echo 'oops')
+  done
+}
+
 #
 # TEST DRIVER
 #
@@ -622,7 +630,7 @@ all() {
     builtin_popd builtin_unset builtin_alias_unalias builtin_help \
     builtin_trap builtin_getopts builtin_wait \
     strict_word_eval_warnings strict_arith_warnings \
-    strict_control_flow_warnings; do
+    strict_control_flow_warnings control_flow_subshell; do
     _run_test $t
   done
 }

test/spec.sh

@@ -287,7 +287,7 @@ quote() {
 }
 
 loop() {
-  sh-spec spec/loop.test.sh --osh-failures-allowed 1 \
+  sh-spec spec/loop.test.sh \
     ${REF_SHELLS[@]} $ZSH $OSH_LIST "$@"
 }