Allowing comma separated fields

- Fixes babel#540
- Fixes location for publicFields (should not contain semi-colon)
- Allow decorators for comma separated fields
- Added tests

src/parser/statement.js

@@ -859,6 +859,9 @@ export default class StatementParser extends ExpressionParser {
 
     while (!this.eat(tt.braceR)) {
       if (this.eat(tt.semi)) {
+        if (this.state.inCommaSeparatedFields) {
+          this.unexpected();
+        }
         if (decorators.length > 0) {
           this.raise(
             this.state.lastTokEnd,
@@ -881,10 +884,26 @@ export default class StatementParser extends ExpressionParser {
         if (this.hasPlugin("decorators2")) {
           this.resetStartLocationFromNode(member, decorators[0]);
         }
-        decorators = [];
       }
 
       this.parseClassMember(classBody, member, state);
+      const isClassField = member.kind == null;
+
+      if (isClassField) {
+        if (this.eat(tt.comma)) {
+          this.state.inCommaSeparatedFields = true;
+          // Copy decorators for cases like `@foo x, y;`
+          if (decorators.length) {
+            member.decorators = decorators;
+          }
+        } else {
+          decorators = [];
+          this.state.inCommaSeparatedFields = false;
+          this.semicolon();
+        }
+      } else {
+        decorators = [];
+      }
 
       if (
         this.hasPlugin("decorators2") &&
@@ -899,7 +918,7 @@ export default class StatementParser extends ExpressionParser {
       }
     }
 
-    if (decorators.length) {
+    if (!this.state.inCommaSeparatedFields && decorators.length) {
       this.raise(
         this.state.start,
         "You have trailing decorators with no method",
@@ -1071,7 +1090,7 @@ export default class StatementParser extends ExpressionParser {
         /* isConstructor */ false,
       );
       this.checkGetterSetterParamCount(method);
-    } else if (this.isLineTerminator()) {
+    } else if (this.isLineTerminator() || this.match(tt.comma)) {
       // an uninitialized class property (due to ASI, since we don't otherwise recognize the next token)
       if (this.isNonstaticConstructor(prop)) {
         this.raise(
@@ -1135,7 +1154,7 @@ export default class StatementParser extends ExpressionParser {
     } else {
       node.value = null;
     }
-    this.semicolon();
+
     this.state.inClassProperty = false;
     return this.finishNode(node, "ClassPrivateProperty");
   }
@@ -1158,7 +1177,7 @@ export default class StatementParser extends ExpressionParser {
     } else {
       node.value = null;
     }
-    this.semicolon();
+
     this.state.inClassProperty = false;
     return this.finishNode(node, "ClassProperty");
   }

src/tokenizer/state.js

@@ -80,6 +80,7 @@ export default class State {
 
   // Check whether we are in a (nested) class or not.
   classLevel: number;
+  inCommaSeparatedFields: boolean;
 
   // Labels in scope.
   labels: Array<{ kind: ?("loop" | "switch"), statementStart?: number }>;

test/fixtures/experimental/class-private-properties/comma-separated/actual.js

@@ -0,0 +1,5 @@
+class C {
+  #p1,#p2;
+  #p3 = 1, #p4 = 1;
+  #p5 = 1, #p6, #p7;
+}