bpo-37053: handle strings like u"bar" correctly in Tools/parser/unparse.py (GH-13583)

Constant.kind is added in https://bugs.python.org/issue36280.
Current possible values for Constant.kind are "u" or None.

For r'bar' and b'bar', Constant.kind value is None, so there's no need
for special handling.


https://bugs.python.org/issue37053

Lib/test/test_tools/test_unparse.py

@@ -139,6 +139,11 @@ class UnparseTestCase(ASTTestCase):
         self.check_roundtrip(r"""f'{f"{0}"*3}'""")
         self.check_roundtrip(r"""f'{f"{y}"*3}'""")
 
+    def test_strings(self):
+        self.check_roundtrip("u'foo'")
+        self.check_roundtrip("r'foo'")
+        self.check_roundtrip("b'foo'")
+
     def test_del_statement(self):
         self.check_roundtrip("del x, y, z")
 

Misc/NEWS.d/next/Tools-Demos/2019-05-26-16-47-06.bpo-37053.-EYRuz.rst

@@ -0,0 +1 @@
+Handle strings like u"bar" correctly in Tools/parser/unparse.py. Patch by Chih-Hsuan Yen.

Tools/parser/unparse.py

@@ -399,6 +399,8 @@ class Unparser:
         elif value is ...:
             self.write("...")
         else:
+            if t.kind == "u":
+                self.write("u")
             self._write_constant(t.value)
 
     def _List(self, t):