Fix parameter decorator review feedback

Author: jtenner

src/extra/ast.ts

@@ -1568,12 +1568,12 @@ export class ASTBuilder {
   serializeParameterDecorators(decorators: DecoratorNode[] | null): void {
     if (decorators) {
       for (let i = 0, k = decorators.length; i < k; ++i) {
-        this.serializeParameterDecorator(decorators[i]);
+        this.visitParameterDecorator(decorators[i]);
       }
     }
   }
 
-  private serializeParameterDecorator(node: DecoratorNode): void {
+  private visitParameterDecorator(node: DecoratorNode): void {
     let sb = this.sb;
     sb.push("@");
     this.visitNode(node.name);

src/parser.ts

@@ -752,6 +752,7 @@ export class Parser extends DiagnosticEmitter {
               this.tryParseSignatureIsSignature = true;
               return null;
             }
+            this.reportInvalidParameterDecorators(tn);
             thisType = <NamedTypeNode>type;
             thisDecorators = decorators;
           } else {
@@ -782,10 +783,12 @@ export class Parser extends DiagnosticEmitter {
               this.tryParseSignatureIsSignature = isSignature;
               return null;
             }
+            this.reportInvalidParameterDecorators(tn);
             let param = Node.createParameter(kind, name, type, null, tn.range(paramStart, tn.pos), decorators);
             if (!parameters) parameters = [ param ];
             else parameters.push(param);
           } else {
+            this.reportInvalidParameterDecorators(tn);
             if (!isSignature) {
               if (tn.peek() == Token.Comma) {
                 isSignature = true;
@@ -949,6 +952,17 @@ export class Parser extends DiagnosticEmitter {
     return decorators;
   }
 
+  /** Consumes decorators that appear after a parameter has already started. */
+  private reportInvalidParameterDecorators(tn: Tokenizer): void {
+    let decorators = this.parseParameterDecorators(tn);
+    if (decorators) {
+      this.error(
+        DiagnosticCode.Decorators_are_not_valid_here,
+        Range.join(decorators[0].range, decorators[decorators.length - 1].range)
+      );
+    }
+  }
+
   parseVariable(
     tn: Tokenizer,
     flags: CommonFlags,
@@ -1292,6 +1306,7 @@ export class Parser extends DiagnosticEmitter {
               thisType.range
             );
           }
+          this.reportInvalidParameterDecorators(tn);
         } else {
           this.error(
             DiagnosticCode._0_expected,
@@ -1420,12 +1435,14 @@ export class Parser extends DiagnosticEmitter {
           );
         }
       }
+      this.reportInvalidParameterDecorators(tn);
       if (tn.skip(Token.Colon)) {
         type = this.parseType(tn);
         if (!type) return null;
       } else {
         type = Node.createOmittedType(tn.range(tn.pos));
       }
+      this.reportInvalidParameterDecorators(tn);
       let initializer: Expression | null = null;
       if (tn.skip(Token.Equals)) {
         if (isRest) {

tests/compiler/parameter-decorators-errors.json

@@ -0,0 +1,22 @@
+{
+  "asc_flags": [
+  ],
+  "stderr": [
+    "TS1003: Identifier expected.",
+    "function regularEmpty(@first): void {}",
+    "TS1003: Identifier expected.",
+    "function firstEmpty(@first, value: i32): void {}",
+    "TS1206: Decorators are not valid here.",
+    "function regularWrongPos(value @first: i32): void {}",
+    "TS1206: Decorators are not valid here.",
+    "function regularWrongPos2(value: i32 @first): void {}",
+    "TS1206: Decorators are not valid here.",
+    "function restWrongPos(...values @rest: i32[]): void {}",
+    "TS1206: Decorators are not valid here.",
+    "function selfWrongPos(this: i32 @self): void {}",
+    "TS1003: Identifier expected.",
+    "function noLits(@123 value: i32): void {}",
+    "TS1003: Identifier expected.",
+    "function noExprs(@(a + b) value: i32): void {}"
+  ]
+}

tests/compiler/parameter-decorators-errors.ts

@@ -0,0 +1,8 @@
+function regularEmpty(@first): void {}
+function firstEmpty(@first, value: i32): void {}
+function regularWrongPos(value @first: i32): void {}
+function regularWrongPos2(value: i32 @first): void {}
+function restWrongPos(...values @rest: i32[]): void {}
+function selfWrongPos(this: i32 @self): void {}
+function noLits(@123 value: i32): void {}
+function noExprs(@(a + b) value: i32): void {}