teach 2to3 about 'yield from'

3 files changed, 11 insertions, 1 deletions

diff --git a/Lib/lib2to3/Grammar.txt b/Lib/lib2to3/Grammar.txt
index bc084e9..e667bcd 100644
--- a/Lib/lib2to3/Grammar.txt
+++ b/Lib/lib2to3/Grammar.txt
@@ -155,4 +155,5 @@ testlist1: test (',' test)*
 # not used in grammar, but may appear in "node" passed from Parser to Compiler
 encoding_decl: NAME
 
-yield_expr: 'yield' [testlist]
+yield_expr: 'yield' [yield_arg]
+yield_arg: 'from' test | testlist
diff --git a/Lib/lib2to3/tests/test_parser.py b/Lib/lib2to3/tests/test_parser.py
index 83682b7..b64469c 100644
--- a/Lib/lib2to3/tests/test_parser.py
+++ b/Lib/lib2to3/tests/test_parser.py
@@ -54,6 +54,13 @@ class TestMatrixMultiplication(GrammarTest):
         self.validate("a @= b")
 
 
+class TestYieldFrom(GrammarTest):
+    def test_matrix_multiplication_operator(self):
+        self.validate("yield from x")
+        self.validate("(yield from x) + y")
+        self.invalid_syntax("yield from")
+
+
 class TestRaiseChanges(GrammarTest):
     def test_2x_style_1(self):
         self.validate("raise")
diff --git a/Misc/NEWS b/Misc/NEWS
index 9e49e06..d5b281e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -168,6 +168,8 @@ Tests
 Tools/Demos
 -----------
 
+- Add support for ``yield from`` to 2to3.
+
 - Add support for the PEP 465 matrix multiplication operator to 2to3.
 
 - Issue #16047: Fix module exception list and __file__ handling in freeze.