Merge pull request RustPython#4551 from charliermarsh/charlie/trailing

Allow trailing commas in MappingPattern

Author: DimitrisJim

compiler/parser/python.lalrpop

@@ -801,7 +801,7 @@ MappingPattern: ast::PatternKind = {
             rest: None,
         };
     },
-    <location:@L> "{" <e:OneOrMore<MatchMappingEntry>> "}" <end_location:@R> => {
+    <location:@L> "{" <e:OneOrMore<MatchMappingEntry>> ","? "}" <end_location:@R> => {
         let (keys, patterns) = e
             .into_iter()
             .unzip();
@@ -811,14 +811,14 @@ MappingPattern: ast::PatternKind = {
             rest: None,
         };
     },
-    <location:@L> "{" "**" <rest:Identifier> "}" <end_location:@R> => {
+    <location:@L> "{" "**" <rest:Identifier> ","? "}" <end_location:@R> => {
         return ast::PatternKind::MatchMapping {
             keys: vec![],
             patterns: vec![],
             rest: Some(rest),
         };
     },
-    <location:@L> "{" <e:OneOrMore<MatchMappingEntry>> ","  "**" <rest:Identifier> "}" <end_location:@R> => {
+    <location:@L> "{" <e:OneOrMore<MatchMappingEntry>> ","  "**" <rest:Identifier> ","? "}" <end_location:@R> => {
         let (keys, patterns) = e
             .into_iter()
             .unzip();

compiler/parser/src/parser.rs

@@ -497,7 +497,7 @@ match match:
     }
 
     #[test]
-    fn test_match_complex() {
+    fn test_patma() {
         let source = r#"# Cases sampled from Lib/test/test_patma.py
 
 # case test_patma_098
@@ -666,4 +666,34 @@ match w := x,:
         let parse_ast = parse_program(source, "<test>").unwrap();
         insta::assert_debug_snapshot!(parse_ast);
     }
+
+    #[test]
+    fn test_match() {
+        let parse_ast = parse_program(
+            r#"
+match {"test": 1}:
+    case {
+        **rest,
+    }:
+        print(rest)
+match {"label": "test"}:
+    case {
+        "label": str() | None as label,
+    }:
+        print(label)
+match x:
+    case [0, 1,]:
+        y = 0
+match x:
+    case (0, 1,):
+        y = 0
+match x:
+    case (0,):
+        y = 0
+"#,
+            "<test>",
+        )
+        .unwrap();
+        insta::assert_debug_snapshot!(parse_ast);
+    }
 }