Go over "yield" and other precedence

test/simple_source/bug37/04_grammar.py

@@ -0,0 +1,87 @@
+# From test_grammar.py
+# RUNNABLE!
+def check_syntax_error(statement):
+    try:
+        compile(statement, '<test string>', 'exec')
+    except SyntaxError:
+        return
+    assert False
+
+def test_yield():
+    # Requires parentheses as call argument
+    def g():
+        f((yield 1), 1)
+    def g():
+        f((yield from ()))
+    def g():
+        f((yield from ()), 1)
+    def g():
+        f((yield 1))
+
+    # Allowed as standalone statement
+    def g():
+        yield 1
+
+    def g():
+        yield from ()
+
+    # Allowed as RHS of assignment
+    def g():
+        x = yield 1
+
+    def g():
+        x = yield from ()
+
+    # Ordinary yield accepts implicit tuples
+    def g():
+        yield 1, 1
+
+    def g():
+        x = yield 1, 1
+
+    # 'yield from' does not
+    check_syntax_error("def g(): yield from (), 1")
+    check_syntax_error("def g(): x = yield from (), 1")
+    # Requires parentheses as subexpression
+    def g():
+        1, (yield 1)
+
+    def g():
+        1, (yield from ())
+
+    check_syntax_error("def g(): 1, yield 1")
+    check_syntax_error("def g(): 1, yield from ()")
+    # Requires parentheses as call argument
+    def g():
+        f((yield 1))
+
+    def g():
+        f((yield 1), 1)
+
+    def g():
+        f((yield from ()))
+
+    def g():
+        f((yield from ()), 1)
+
+    check_syntax_error("def g(): f(yield 1)")
+    check_syntax_error("def g(): f(yield 1, 1)")
+    check_syntax_error("def g(): f(yield from ())")
+    check_syntax_error("def g(): f(yield from (), 1)")
+    # Not allowed at top level
+    check_syntax_error("yield")
+    check_syntax_error("yield from")
+    # Not allowed at class scope
+    check_syntax_error("class foo:yield 1")
+    check_syntax_error("class foo:yield from ()")
+    # Check annotation refleak on SyntaxError
+    check_syntax_error("def g(a:(yield)): pass")
+
+test_yield()
+
+# From test_types.py
+# Bug was needing parens around (yield 2)
+def gen_func():
+    yield 1
+    return (yield 2)
+gen = gen_func()