[osh-language] Make 'eval break', 'source return.sh', etc. work

Addresses issue #774.

Also fix unit test and lint error.

osh/builtin_meta.py

@@ -15,6 +15,7 @@
 from frontend import flag_spec
 from frontend import consts
 from frontend import reader
+from osh import cmd_eval
 
 from typing import Dict, List, Tuple, Optional, TYPE_CHECKING
 if TYPE_CHECKING:
@@ -58,7 +59,8 @@ def Run(self, cmd_val):
     src = source.EvalArg(eval_spid)
     self.arena.PushSource(src)
     try:
-      return main_loop.Batch(self.cmd_ev, c_parser, self.arena)
+      return main_loop.Batch(self.cmd_ev, c_parser, self.arena,
+                             cmd_flags=cmd_eval.IsEvalSource)
     finally:
       self.arena.PopSource()
 
@@ -111,7 +113,8 @@ def Run(self, cmd_val):
       src = source.SourcedFile(path, call_spid)
       self.arena.PushSource(src)
       try:
-        status = main_loop.Batch(self.cmd_ev, c_parser, self.arena)
+        status = main_loop.Batch(self.cmd_ev, c_parser, self.arena,
+                                 cmd_flags=cmd_eval.IsEvalSource)
       finally:
         self.arena.PopSource()
         self.mem.PopSource(source_argv)

osh/cmd_eval.py

@@ -102,9 +102,12 @@
   from osh import word_eval
   from osh import builtin_process
 
-# flags for main_loop.Batch, ExecuteAndCatch
-IsMainProgram = 1 << 0  # the main shell program, not eval/source
-Optimize = 1 << 1
+# flags for main_loop.Batch, ExecuteAndCatch.  TODO: Should probably in
+# ExecuteAndCatch, along with SetVar() flags.
+IsMainProgram = 1 << 0  # the main shell program, not eval/source/subshell
+IsEvalSource = 1 << 1  # eval/source builtins
+Optimize = 1 << 2
+
 
 
 # Python type name -> Oil type name
@@ -1457,24 +1460,27 @@ def ExecuteAndCatch(self, node, cmd_flags=0):
     try:
       status = self._Execute(node)
     except _ControlFlow as e:
-      # Return at top level is OK, unlike in bash.
-      if e.IsReturn():
-        is_return = True
-        status = e.StatusCode()
+      if cmd_flags & IsEvalSource:
+        raise  # 'eval break' and 'source return.sh', etc.
       else:
-        #raise  # break and continue in eval
-        is_eval = False
-        # TODO: This error message is invalid.  Can also happen in eval.
-        # We need a flag.
-
-        # Invalid control flow
-        self.errfmt.Print_(
-            "Loop and control flow can't be in 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
+        # Return at top level is OK, unlike in bash.
+        if e.IsReturn():
+          is_return = True
+          status = e.StatusCode()
+        else:
+          #raise  # break and continue in eval
+          is_eval = False
+          # TODO: This error message is invalid.  Can also happen in eval.
+          # We need a flag.
+
+          # Invalid control flow
+          self.errfmt.Print_(
+              "Loop and control flow can't be in 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 error.Parse as e:
       self.dumper.MaybeCollect(self, e)  # Do this before unwinding stack
       raise

osh/string_ops_test.py

@@ -62,12 +62,12 @@ def test_PreviousUtf8Char(self):
     ]
     for expected_indexes, input_str in CASES:
       print()
-      print('_PreviousUtf8Char case %r %r' % (expected_indexes, input_str))
+      print('PreviousUtf8Char case %r %r' % (expected_indexes, input_str))
       i = len(input_str)
       actual_indexes = []
       while True:
         try:
-          i = string_ops._PreviousUtf8Char(input_str, i)
+          i = string_ops.PreviousUtf8Char(input_str, i)
           actual_indexes.append(i)
           if i == 0:
             break

osh/word_eval.py

@@ -31,7 +31,7 @@
 from core import passwd
 from core import pyutil
 from qsn_ import qsn
-from core.util import log, e_die, e_strict
+from core.util import log, e_die
 from frontend import consts
 from frontend import match
 from mycpp.mylib import tagswitch