bpo-35814: Allow same r.h.s. in annotated assignments as in normal ones (GH-11667)

ilevkivskyi · web-flow · commit 62c35a8a8ff5 · 2019-01-25T01:39:19.000Z
diff --git a/Grammar/Grammar b/Grammar/Grammar
@@ -40,7 +40,7 @@ small_stmt: (expr_stmt | del_stmt | pass_stmt | flow_stmt |
              import_stmt | global_stmt | nonlocal_stmt | assert_stmt)
 expr_stmt: testlist_star_expr (annassign | augassign (yield_expr|testlist) |
                      ('=' (yield_expr|testlist_star_expr))*)
-annassign: ':' test ['=' test]
+annassign: ':' test ['=' (yield_expr|testlist)]
 testlist_star_expr: (test|star_expr) (',' (test|star_expr))* [',']
 augassign: ('+=' | '-=' | '*=' | '@=' | '/=' | '%=' | '&=' | '|=' | '^=' |
             '<<=' | '>>=' | '**=' | '//=')
diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py
@@ -445,6 +445,15 @@ def __getitem__(self, item):
         exec('X: str', {}, CNS2())
         self.assertEqual(nonloc_ns['__annotations__']['x'], str)
 
+    def test_var_annot_rhs(self):
+        ns = {}
+        exec('x: tuple = 1, 2', ns)
+        self.assertEqual(ns['x'], (1, 2))
+        stmt = ('def f():\n'
+                '    x: int = yield')
+        exec(stmt, ns)
+        self.assertEqual(list(ns['f']()), [None])
+
     def test_funcdef(self):
         ### [decorators] 'def' NAME parameters ['->' test] ':' suite
         ### decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
diff --git a/Lib/test/test_parser.py b/Lib/test/test_parser.py
@@ -166,7 +166,7 @@ def test_var_annot(self):
         with self.assertRaises(SyntaxError):
             exec("x, *y, z: int = range(5)", {}, {})
         with self.assertRaises(SyntaxError):
-            exec("t: tuple = 1, 2", {}, {})
+            exec("x: int = 1, y = 2", {}, {})
         with self.assertRaises(SyntaxError):
             exec("u = v: int", {}, {})
         with self.assertRaises(SyntaxError):
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-01-24-13-25-21.bpo-35814.r_MjA6.rst b/Misc/NEWS.d/next/Core and Builtins/2019-01-24-13-25-21.bpo-35814.r_MjA6.rst
@@ -0,0 +1,2 @@
+Allow same right hand side expressions in annotated assignments as in normal ones.
+In particular, ``x: Tuple[int, int] = 1, 2`` (without parentheses on the right) is now allowed.
diff --git a/Python/ast.c b/Python/ast.c
@@ -3163,7 +3163,12 @@ ast_for_expr_stmt(struct compiling *c, const node *n)
         }
         else {
             ch = CHILD(ann, 3);
-            expr3 = ast_for_expr(c, ch);
+            if (TYPE(ch) == testlist) {
+                expr3 = ast_for_testlist(c, ch);
+            }
+            else {
+                expr3 = ast_for_expr(c, ch);
+            }
             if (!expr3) {
                 return NULL;
             }
diff --git a/Python/graminit.c b/Python/graminit.c
@@ -498,8 +498,9 @@ static arc arcs_17_2[2] = {
     {31, 3},
     {0, 2},
 };
-static arc arcs_17_3[1] = {
-    {26, 4},
+static arc arcs_17_3[2] = {
+    {50, 4},
+    {9, 4},
 };
 static arc arcs_17_4[1] = {
     {0, 4},
@@ -508,7 +509,7 @@ static state states_17[5] = {
     {1, arcs_17_0},
     {1, arcs_17_1},
     {2, arcs_17_2},
-    {1, arcs_17_3},
+    {2, arcs_17_3},
     {1, arcs_17_4},
 };
 static arc arcs_18_0[2] = {

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+Allow same right hand side expressions in annotated assignments as in normal ones.`
	`2`	+In particular, ``x: Tuple[int, int] = 1, 2`` (without parentheses on the right) is now allowed.
Original file line number	Diff line number	Diff line change
`@@ -3163,7 +3163,12 @@ ast_for_expr_stmt(struct compiling c, const node n)`
`3163`	`3163`	`}`
`3164`	`3164`	`else {`
`3165`	`3165`	`ch = CHILD(ann, 3);`
`3166`		`- expr3 = ast_for_expr(c, ch);`
	`3166`	`+ if (TYPE(ch) == testlist) {`
	`3167`	`+ expr3 = ast_for_testlist(c, ch);`
	`3168`	`+ }`
	`3169`	`+ else {`
	`3170`	`+ expr3 = ast_for_expr(c, ch);`
	`3171`	`+ }`
`3167`	`3172`	`if (!expr3) {`
`3168`	`3173`	`return NULL;`
`3169`	`3174`	`}`