[Python-checkins] [3.7] bpo-40663: Correctly handle annotations with subscripts in ast_unparse.c (GH-20156). (GH-20192)

[Batuhan Taskaya]

https://github.com/python/cpython/commit/43300148c5f30317ebf767aa8853a957ee5c87fb
commit: 43300148c5f30317ebf767aa8853a957ee5c87fb
branch: 3.7
author: Batuhan Taskaya <isidentical at gmail.com>
committer: GitHub <noreply at github.com>
date: 2020-05-22T23:32:34+01:00
summary:

[3.7] bpo-40663: Correctly handle annotations with subscripts in ast_unparse.c (GH-20156). (GH-20192)

(cherry picked from commit 2135e10dc717c00d10d899d232bebfc59bb25032)

Co-authored-by: Batuhan Taskaya <batuhanosmantaskaya at gmail.com>

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 2aed01095aa7e..13a4f6f3cc6a3 100644
--- a/Lib/test/test_future.py
+++ b/Lib/test/test_future.py
@@ -237,6 +237,10 @@ def test_annotations(self):
         eq("dict[str, int]")
         eq("set[str,]")
         eq("tuple[str, ...]")
+        eq("tuple[(str, *types)]")
+        eq("tuple[xx:yy, (*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 93b3ecffb017e..7ed4b4f180823 100644
--- a/Python/ast_unparse.c
+++ b/Python/ast_unparse.c
@@ -743,6 +743,24 @@ append_ast_ext_slice(_PyUnicodeWriter *writer, slice_ty slice)
     return 0;
 }
 
+static int
+append_ast_index_slice(_PyUnicodeWriter *writer, slice_ty slice)
+{
+    int level = PR_TUPLE;
+    expr_ty value = slice->v.Index.value;
+    if (value->kind == Tuple_kind) {
+        for (Py_ssize_t i = 0; i < asdl_seq_LEN(value->v.Tuple.elts); i++) {
+            expr_ty element = asdl_seq_GET(value->v.Tuple.elts, i);
+            if (element->kind == Starred_kind) {
+                ++level;
+                break;
+            }
+        }
+    }
+    APPEND_EXPR(value, level);
+    return 0;
+}
+
 static int
 append_ast_slice(_PyUnicodeWriter *writer, slice_ty slice)
 {
@@ -752,8 +770,7 @@ append_ast_slice(_PyUnicodeWriter *writer, slice_ty slice)
     case ExtSlice_kind:
         return append_ast_ext_slice(writer, slice);
     case Index_kind:
-        APPEND_EXPR(slice->v.Index.value, PR_TUPLE);
-        return 0;
+        return append_ast_index_slice(writer, slice);
     default:
         PyErr_SetString(PyExc_SystemError,
                         "unexpected slice kind");