babel-parser(ts): Raise recoverable error for abstract interface (#12771)

* Support parsing abstract interface

* Address review

Address reviews

Address reviews

* Fix types

* Add hasFollowingLineBreak

packages/babel-parser/src/parser/util.js

@@ -96,6 +96,12 @@ export default class UtilParser extends Tokenizer {
     );
   }
 
+  hasFollowingLineBreak(): boolean {
+    return lineBreak.test(
+      this.input.slice(this.state.end, this.nextTokenStart()),
+    );
+  }
+
   // TODO
 
   isLineTerminator(): boolean {

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

@@ -89,6 +89,8 @@ const TSErrors = Object.freeze({
     "Tuple members must all have names or all not have names.",
   NonAbstractClassHasAbstractMethod:
     "Abstract methods can only appear within an abstract class.",
+  NonClassMethodPropertyHasAbstractModifer:
+    "'abstract' modifier can only appear on a class, method, or property declaration.",
   OptionalTypeBeforeRequired:
     "A required element cannot follow an optional element.",
   PatternIsOptional:
@@ -1585,20 +1587,13 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     ): ?N.Declaration {
       switch (value) {
         case "abstract":
-          if (this.tsCheckLineTerminatorAndMatch(tt._class, next)) {
-            const cls: N.ClassDeclaration = node;
-            cls.abstract = true;
-            if (next) {
-              this.next();
-              if (!this.match(tt._class)) {
-                this.unexpected(null, tt._class);
-              }
-            }
-            return this.parseClass(
-              cls,
-              /* isStatement */ true,
-              /* optionalId */ false,
-            );
+          if (
+            this.tsCheckLineTerminatorAndMatch(tt._class, next) ||
+            // for interface
+            this.tsCheckLineTerminatorAndMatch(tt.name, next)
+          ) {
+            if (next) this.next();
+            return this.tsParseAbstractDeclaration(node);
           }
           break;
 
@@ -2849,4 +2844,36 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         this.state.inAbstractClass = oldInAbstractClass;
       }
     }
+
+    tsParseAbstractDeclaration(
+      node: any,
+    ): N.ClassDeclaration | N.TsInterfaceDeclaration | typeof undefined {
+      if (this.match(tt._class)) {
+        node.abstract = true;
+        return this.parseClass<N.ClassDeclaration>(
+          (node: N.ClassDeclaration),
+          /* isStatement */ true,
+          /* optionalId */ false,
+        );
+      } else if (this.isContextual("interface")) {
+        // for invalid abstract interface
+
+        // To avoid
+        //   abstract interface
+        //   Foo {}
+        if (!this.hasFollowingLineBreak()) {
+          node.abstract = true;
+          this.raise(
+            node.start,
+            TSErrors.NonClassMethodPropertyHasAbstractModifer,
+          );
+          this.next();
+          return this.tsParseInterfaceDeclaration(
+            (node: N.TsInterfaceDeclaration),
+          );
+        }
+      } else {
+        this.unexpected(null, tt._class);
+      }
+    }
   };

packages/babel-parser/test/fixtures/typescript/interface/abstract/input.ts

@@ -0,0 +1,3 @@
+abstract interface Foo {
+  foo: string;
+}

packages/babel-parser/test/fixtures/typescript/interface/abstract/output.json

@@ -0,0 +1,50 @@
+{
+  "type": "File",
+  "start":0,"end":41,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+  "errors": [
+    "SyntaxError: 'abstract' modifier can only appear on a class, method, or property declaration. (1:0)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":41,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TSInterfaceDeclaration",
+        "start":0,"end":41,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+        "abstract": true,
+        "id": {
+          "type": "Identifier",
+          "start":19,"end":22,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":22},"identifierName":"Foo"},
+          "name": "Foo"
+        },
+        "body": {
+          "type": "TSInterfaceBody",
+          "start":23,"end":41,"loc":{"start":{"line":1,"column":23},"end":{"line":3,"column":1}},
+          "body": [
+            {
+              "type": "TSPropertySignature",
+              "start":27,"end":39,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":14}},
+              "key": {
+                "type": "Identifier",
+                "start":27,"end":30,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":5},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "computed": false,
+              "typeAnnotation": {
+                "type": "TSTypeAnnotation",
+                "start":30,"end":38,"loc":{"start":{"line":2,"column":5},"end":{"line":2,"column":13}},
+                "typeAnnotation": {
+                  "type": "TSStringKeyword",
+                  "start":32,"end":38,"loc":{"start":{"line":2,"column":7},"end":{"line":2,"column":13}}
+                }
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/typescript/interface/export-abstract-interface/options.json

@@ -1,3 +0,0 @@
-{
-  "throws": "Unexpected token, expected \"class\" (1:16)"
-}

packages/babel-parser/test/fixtures/typescript/interface/export-abstract-interface/output.json

@@ -0,0 +1,38 @@
+{
+  "type": "File",
+  "start":0,"end":32,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+  "errors": [
+    "SyntaxError: 'abstract' modifier can only appear on a class, method, or property declaration. (1:7)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":32,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExportNamedDeclaration",
+        "start":0,"end":32,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+        "exportKind": "type",
+        "specifiers": [],
+        "source": null,
+        "declaration": {
+          "type": "TSInterfaceDeclaration",
+          "start":7,"end":32,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
+          "abstract": true,
+          "id": {
+            "type": "Identifier",
+            "start":26,"end":27,"loc":{"start":{"line":1,"column":26},"end":{"line":1,"column":27},"identifierName":"I"},
+            "name": "I"
+          },
+          "body": {
+            "type": "TSInterfaceBody",
+            "start":28,"end":32,"loc":{"start":{"line":1,"column":28},"end":{"line":3,"column":1}},
+            "body": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/typescript/interface/invalid-abstract-interface/input.ts

@@ -0,0 +1,2 @@
+abstract interface
+Foo {}

packages/babel-parser/test/fixtures/typescript/interface/invalid-abstract-interface/output.json

@@ -0,0 +1,50 @@
+{
+  "type": "File",
+  "start":0,"end":25,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":6}},
+  "errors": [
+    "SyntaxError: Missing semicolon (1:8)",
+    "SyntaxError: Missing semicolon (2:3)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":25,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":6}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+        "expression": {
+          "type": "Identifier",
+          "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8},"identifierName":"abstract"},
+          "name": "abstract"
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":9,"end":18,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":18}},
+        "expression": {
+          "type": "Identifier",
+          "start":9,"end":18,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":18},"identifierName":"interface"},
+          "name": "interface"
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":19,"end":22,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":3}},
+        "expression": {
+          "type": "Identifier",
+          "start":19,"end":22,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":3},"identifierName":"Foo"},
+          "name": "Foo"
+        }
+      },
+      {
+        "type": "BlockStatement",
+        "start":23,"end":25,"loc":{"start":{"line":2,"column":4},"end":{"line":2,"column":6}},
+        "body": [],
+        "directives": []
+      }
+    ],
+    "directives": []
+  }
+}