Allow new.target in class properties (#759)

src/parser/expression.js

@@ -1049,11 +1049,14 @@ export default class ExpressionParser extends LValParser {
     if (this.eat(tt.dot)) {
       const metaProp = this.parseMetaProperty(node, meta, "target");
 
-      if (!this.state.inFunction) {
-        this.raise(
-          metaProp.property.start,
-          "new.target can only be used in functions",
-        );
+      if (!this.state.inFunction && !this.state.inClassProperty) {
+        let error = "new.target can only be used in functions";
+
+        if (this.hasPlugin("classProperties")) {
+          error += " or class properties";
+        }
+
+        this.raise(metaProp.start, error);
       }
 
       return metaProp;

test/fixtures/es2015/meta-properties/new-target-invalid/options.json

@@ -1,3 +1,3 @@
 {
-  "throws": "new.target can only be used in functions (1:4)"
+  "throws": "new.target can only be used in functions (1:0)"
 }

test/fixtures/esprima/es2015-meta-property/invalid-new-target/options.json

@@ -1,3 +1,3 @@
 {
-  "throws": "new.target can only be used in functions (1:12)"
+  "throws": "new.target can only be used in functions (1:8)"
 }

test/fixtures/experimental/class-properties/new-target-invalid/actual.js

@@ -0,0 +1 @@
+var x = new.target;

test/fixtures/experimental/class-properties/new-target-invalid/options.json

@@ -0,0 +1,4 @@
+{
+  "plugins": ["classProperties"],
+  "throws": "new.target can only be used in functions or class properties (1:8)"
+}

test/fixtures/experimental/class-properties/new-target-with-flow/actual.js

@@ -0,0 +1,10 @@
+class X {
+  static a = new.target;
+  static b = (foo = 1 + bar(new.target));
+  static c = () => new.target;
+  static d = (foo = new.target) => {};
+  e = new.target;
+  f = (foo = 1 + bar(new.target));
+  g = () => new.target;
+  h = (foo = new.target) => {};
+}

test/fixtures/experimental/class-properties/new-target-with-flow/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["classProperties", "flow"]
+}

test/fixtures/experimental/class-properties/new-target/actual.js

@@ -0,0 +1,10 @@
+class X {
+  static a = new.target;
+  static b = (foo = 1 + bar(new.target));
+  static c = () => new.target;
+  static d = (foo = new.target) => {};
+  e = new.target;
+  f = (foo = 1 + bar(new.target));
+  g = () => new.target;
+  h = (foo = new.target) => {};
+}

test/fixtures/experimental/class-properties/new-target/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["classProperties"]
+}