Merge pull request RustPython#4358 from harupy/fix-slice-location

Fix `Slice` location

Author: youknowone

compiler/parser/python.lalrpop

@@ -1024,7 +1024,7 @@ SubscriptList: ast::Expr = {
 
 Subscript: ast::Expr = {
     Test<"all">,
-    <e1:Test<"all">?> <location:@L> ":" <e2:Test<"all">?> <e3:SliceOp?> <end_location:@R> => {
+    <location:@L> <e1:Test<"all">?> ":" <e2:Test<"all">?> <e3:SliceOp?> <end_location:@R> => {
         let lower = e1.map(Box::new);
         let upper = e2.map(Box::new);
         let step = e3.flatten().map(Box::new);

compiler/parser/src/parser.rs

@@ -233,4 +233,11 @@ class Foo(A, B):
         let parse_ast = parse_expression(&source, "<test>").unwrap();
         insta::assert_debug_snapshot!(parse_ast);
     }
+
+    #[test]
+    fn test_slice() {
+        let source = String::from("x[1:2:3]");
+        let parse_ast = parse_expression(&source, "<test>").unwrap();
+        insta::assert_debug_snapshot!(parse_ast);
+    }
 }