Throw error if TypeScript class has empty implements (#9292)

packages/babel-parser/src/plugins/typescript.js

@@ -905,11 +905,21 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       return this.finishNode(node, "TSTypeAssertion");
     }
 
-    tsParseHeritageClause(): $ReadOnlyArray<N.TsExpressionWithTypeArguments> {
+    tsParseHeritageClause(
-      return this.tsParseDelimitedList(
+      descriptor: string,
+    ): $ReadOnlyArray<N.TsExpressionWithTypeArguments> {
+      const originalStart = this.state.start;
+
+      const delimitedList = this.tsParseDelimitedList(
         "HeritageClauseElement",
         this.tsParseExpressionWithTypeArguments.bind(this),
       );
+
+      if (!delimitedList.length) {
+        this.raise(originalStart, `'${descriptor}' list cannot be empty.`);
+      }
+
+      return delimitedList;
     }
 
     tsParseExpressionWithTypeArguments(): N.TsExpressionWithTypeArguments {
@@ -930,7 +940,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       node.id = this.parseIdentifier();
       node.typeParameters = this.tsTryParseTypeParameters();
       if (this.eat(tt._extends)) {
-        node.extends = this.tsParseHeritageClause();
+        node.extends = this.tsParseHeritageClause("extends");
       }
       const body: N.TSInterfaceBody = this.startNode();
       body.body = this.tsInType(this.tsParseObjectTypeMembers.bind(this));
@@ -1879,7 +1889,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         node.superTypeParameters = this.tsParseTypeArguments();
       }
       if (this.eatContextual("implements")) {
-        node.implements = this.tsParseHeritageClause();
+        node.implements = this.tsParseHeritageClause("implements");
       }
     }
 

packages/babel-parser/test/fixtures/typescript/class/extends-empty/input.js

@@ -0,0 +1,2 @@
+interface foo extends {
+}

packages/babel-parser/test/fixtures/typescript/class/extends-empty/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "'extends' list cannot be empty. (1:22)"
+}

packages/babel-parser/test/fixtures/typescript/class/extends-implements-empty/input.js

@@ -0,0 +1,2 @@
+class Foo extends Bar implements {
+}

packages/babel-parser/test/fixtures/typescript/class/extends-implements-empty/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "'implements' list cannot be empty. (1:33)"
+}

packages/babel-parser/test/fixtures/typescript/class/implements-empty/input.js

@@ -0,0 +1,2 @@
+class Foo implements {
+}

packages/babel-parser/test/fixtures/typescript/class/implements-empty/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "'implements' list cannot be empty. (1:21)"
+}

packages/babel-parser/test/fixtures/typescript/type-arguments/empty/input.js

@@ -0,0 +1 @@
+foo<>()

packages/babel-parser/test/fixtures/typescript/type-arguments/empty/output.json

@@ -0,0 +1,99 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 7,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 7
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 7,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 7
+      }
+    },
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 7,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 7
+          }
+        },
+        "expression": {
+          "type": "CallExpression",
+          "start": 0,
+          "end": 7,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 0
+            },
+            "end": {
+              "line": 1,
+              "column": 7
+            }
+          },
+          "callee": {
+            "type": "Identifier",
+            "start": 0,
+            "end": 3,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 0
+              },
+              "end": {
+                "line": 1,
+                "column": 3
+              },
+              "identifierName": "foo"
+            },
+            "name": "foo"
+          },
+          "arguments": [],
+          "typeParameters": {
+            "type": "TSTypeParameterInstantiation",
+            "start": 3,
+            "end": 5,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 3
+              },
+              "end": {
+                "line": 1,
+                "column": 5
+              }
+            },
+            "params": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}