[Python-checkins] bpo-40663: Correctly handle annotations with subscripts in ast_unparse.c (GH-20156)

[Batuhan Taskaya]

https://github.com/python/cpython/commit/2135e10dc717c00d10d899d232bebfc59bb25032
commit: 2135e10dc717c00d10d899d232bebfc59bb25032
branch: master
author: Batuhan Taskaya <batuhanosmantaskaya at gmail.com>
committer: GitHub <noreply at github.com>
date: 2020-05-18T19:23:48+01:00
summary:

bpo-40663: Correctly handle annotations with subscripts in ast_unparse.c (GH-20156)

files:
A Misc/NEWS.d/next/Core and Builtins/2020-05-17-20-38-12.bpo-40663.u2aiZf.rst
M Lib/test/test_future.py
M Python/ast_unparse.c

diff --git a/Lib/test/test_future.py b/Lib/test/test_future.py
index 56b7ac6865559..0f40357b3a731 100644
--- a/Lib/test/test_future.py
+++ b/Lib/test/test_future.py
@@ -275,6 +275,9 @@ def test_annotations(self):
         eq("dict[str, int]")
         eq("set[str,]")
         eq("tuple[str, ...]")
+        eq("tuple[(str, *types)]")
+        eq("tuple[str, int, (str, int)]")
+        eq("tuple[(*int, str, str, (str, int))]")
         eq("tuple[str, int, float, dict[str, int]]")
         eq("slice[0]")
         eq("slice[0:1]")
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-05-17-20-38-12.bpo-40663.u2aiZf.rst b/Misc/NEWS.d/next/Core and Builtins/2020-05-17-20-38-12.bpo-40663.u2aiZf.rst
new file mode 100644
index 0000000000000..5041abc7e3eaa
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-05-17-20-38-12.bpo-40663.u2aiZf.rst	
@@ -0,0 +1,2 @@
+Correctly generate annotations where parentheses are omitted but required
+(e.g: ``Type[(str, int, *other))]``.
diff --git a/Python/ast_unparse.c b/Python/ast_unparse.c
index d1e9d42d33bd4..e699751a05a05 100644
--- a/Python/ast_unparse.c
+++ b/Python/ast_unparse.c
@@ -781,8 +781,19 @@ static int
 append_ast_subscript(_PyUnicodeWriter *writer, expr_ty e)
 {
     APPEND_EXPR(e->v.Subscript.value, PR_ATOM);
+    int level = PR_TUPLE;
+    expr_ty slice = e->v.Subscript.slice;
+    if (slice->kind == Tuple_kind) {
+        for (Py_ssize_t i = 0; i < asdl_seq_LEN(slice->v.Tuple.elts); i++) {
+            expr_ty element = asdl_seq_GET(slice->v.Tuple.elts, i);
+            if (element->kind == Starred_kind) {
+                ++level;
+                break;
+            }
+        }
+    }
     APPEND_STR("[");
-    APPEND_EXPR(e->v.Subscript.slice, PR_TUPLE);
+    APPEND_EXPR(e->v.Subscript.slice, level);
     APPEND_STR_FINISH("]");
 }