From 4ff0f452db37e3658b5b974727c88cdb1e1a8282 Mon Sep 17 00:00:00 2001
From: hauntsaninja <>
Date: Mon, 20 Apr 2020 22:09:26 -0700
Subject: [PATCH 1/2] fastparse: add line and column information for extended
 slices

---
 mypy/fastparse.py         |  7 +++++--
 test-data/unit/parse.test | 44 +++++++++++++++++++--------------------
 2 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/mypy/fastparse.py b/mypy/fastparse.py
index 4b963c74f223..3b4ad8fb66b6 100644
--- a/mypy/fastparse.py
+++ b/mypy/fastparse.py
@@ -1205,7 +1205,10 @@ def visit_Attribute(self, n: Attribute) -> Union[MemberExpr, SuperExpr]:
     def visit_Subscript(self, n: ast3.Subscript) -> IndexExpr:
         e = IndexExpr(self.visit(n.value), self.visit(n.slice))
         self.set_line(e, n)
-        if isinstance(e.index, SliceExpr):
+        if (
+            isinstance(e.index, SliceExpr) or
+            (sys.version_info <= (3, 9) and isinstance(e.index, TupleExpr))
+        ):
             # Slice has no line/column in the raw ast.
             e.index.line = e.line
             e.index.column = e.column
@@ -1233,7 +1236,7 @@ def visit_List(self, n: ast3.List) -> Union[ListExpr, TupleExpr]:
 
     # Tuple(expr* elts, expr_context ctx)
     def visit_Tuple(self, n: ast3.Tuple) -> TupleExpr:
-        e = TupleExpr([self.visit(e) for e in n.elts])
+        e = TupleExpr(self.translate_expr_list(n.elts))
         return self.set_line(e, n)
 
     # --- slice ---
diff --git a/test-data/unit/parse.test b/test-data/unit/parse.test
index 8940d211e219..3b1d1198c269 100644
--- a/test-data/unit/parse.test
+++ b/test-data/unit/parse.test
@@ -3151,7 +3151,7 @@ MypyFile:1(
   ExpressionStmt:1(
     IndexExpr:1(
       NameExpr(a)
-      TupleExpr:-1(
+      TupleExpr:1(
         SliceExpr:-1(
           <empty>
           <empty>)
@@ -3166,7 +3166,7 @@ MypyFile:1(
   ExpressionStmt:1(
     IndexExpr:1(
       NameExpr(a)
-      TupleExpr:-1(
+      TupleExpr:1(
         SliceExpr:-1(
           IntExpr(1)
           IntExpr(2))
@@ -3181,7 +3181,7 @@ MypyFile:1(
   ExpressionStmt:1(
     IndexExpr:1(
       NameExpr(a)
-      TupleExpr:-1(
+      TupleExpr:1(
         SliceExpr:-1(
           IntExpr(1)
           IntExpr(2)
@@ -3426,25 +3426,25 @@ y = 30
 f'Hello {x!s:<{y+y}}'
 [out]
 MypyFile:1(
-  AssignmentStmt:1(             
-    NameExpr(x)                 
-    StrExpr(mypy))              
-  AssignmentStmt:2(             
-    NameExpr(y)                 
-    IntExpr(30))                
-  ExpressionStmt:3(             
-    CallExpr:3(                 
-      MemberExpr:3(             
-        StrExpr()               
-        join)                   
-      Args(                     
-        ListExpr:3(             
-          StrExpr(Hello )       
-          CallExpr:3(           
-            MemberExpr:3(       
-              StrExpr({!s:{}})  
-              format)           
-            Args(               
+  AssignmentStmt:1(
+    NameExpr(x)
+    StrExpr(mypy))
+  AssignmentStmt:2(
+    NameExpr(y)
+    IntExpr(30))
+  ExpressionStmt:3(
+    CallExpr:3(
+      MemberExpr:3(
+        StrExpr()
+        join)
+      Args(
+        ListExpr:3(
+          StrExpr(Hello )
+          CallExpr:3(
+            MemberExpr:3(
+              StrExpr({!s:{}})
+              format)
+            Args(
               NameExpr(x)
               CallExpr:3(
                 MemberExpr:3(

From d616fd5e2013d6813efb640b9f4542bf5fd1ff98 Mon Sep 17 00:00:00 2001
From: hauntsaninja <>
Date: Thu, 30 Apr 2020 11:11:45 -0700
Subject: [PATCH 2/2] fastparse: fix comparison, clarify

Comparison using the ast3 nodes makes things a little clearer, as does
commenting the code.
---
 mypy/fastparse.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/mypy/fastparse.py b/mypy/fastparse.py
index 3b4ad8fb66b6..2aac8412f657 100644
--- a/mypy/fastparse.py
+++ b/mypy/fastparse.py
@@ -1206,10 +1206,13 @@ def visit_Subscript(self, n: ast3.Subscript) -> IndexExpr:
         e = IndexExpr(self.visit(n.value), self.visit(n.slice))
         self.set_line(e, n)
         if (
-            isinstance(e.index, SliceExpr) or
-            (sys.version_info <= (3, 9) and isinstance(e.index, TupleExpr))
+            isinstance(n.slice, ast3.Slice) or
+            (sys.version_info < (3, 9) and isinstance(n.slice, ast3.ExtSlice))
         ):
-            # Slice has no line/column in the raw ast.
+            # Before Python 3.9, Slice has no line/column in the raw ast. To avoid incompatibility
+            # visit_Slice doesn't set_line, even in Python 3.9 on.
+            # ExtSlice also has no line/column info. In Python 3.9 on, line/column is set for
+            # e.index when visiting n.slice.
             e.index.line = e.line
             e.index.column = e.column
         return e