Raise error on encountering bad indentation during Autograph parsing.

PiperOrigin-RevId: 213324570

2 files changed, 30 insertions, 1 deletions

diff --git a/tensorflow/python/autograph/pyct/parser.py b/tensorflow/python/autograph/pyct/parser.py
index 112ed46a1e..63686350d5 100644
--- a/tensorflow/python/autograph/pyct/parser.py
+++ b/tensorflow/python/autograph/pyct/parser.py
@@ -31,8 +31,21 @@ from tensorflow.python.util import tf_inspect
 def parse_entity(entity):
   """Returns the AST of given entity."""
   source = tf_inspect.getsource(entity)
+  # Comments and multiline strings can appear at arbitrary indentation levels,
+  # causing textwrap.dedent to not correctly dedent source code.
+  # TODO(b/115884650): Automatic handling of comments/multiline strings.
   source = textwrap.dedent(source)
-  return parse_str(source), source
+  try:
+    return parse_str(source), source
+  except IndentationError:
+    # Because we are parsing the source code of entities that have already
+    # successfully parsed once, any IndentationErrors are guaranteed to be
+    # caused by insufficient dedenting.
+    raise ValueError(
+        'Failed to dedent prior to parsing source code. If you have comments '
+        'or multiline strings in your code, try indenting them. '
+        'Multiline strings can be rewritten using textwrap.dedent.\n'
+        'Offending source code: \n %s' % source)
 
 
 def parse_str(src):
diff --git a/tensorflow/python/autograph/pyct/parser_test.py b/tensorflow/python/autograph/pyct/parser_test.py
index d0b465eb73..d3a7b7a014 100644
--- a/tensorflow/python/autograph/pyct/parser_test.py
+++ b/tensorflow/python/autograph/pyct/parser_test.py
@@ -42,6 +42,22 @@ class ParserTest(test.TestCase):
     """))
     self.assertEqual('f', mod.body[0].name)
 
+  def test_parse_comments(self):
+    def f():
+# unindented comment
+      pass
+    with self.assertRaises(ValueError):
+      parser.parse_entity(f)
+
+  def test_parse_multiline_strings(self):
+    def f():
+      print("""
+some
+multiline
+string""")
+    with self.assertRaises(ValueError):
+      parser.parse_entity(f)
+
   def test_parse_expression(self):
     node = parser.parse_expression('a.b')
     self.assertEqual('a', node.value.id)