For JavaScript files, we report semantic errors for using TypeScript-only constructs

src/compiler/program.ts

@@ -725,6 +725,12 @@ namespace ts {
         }
 
         function getSyntacticDiagnosticsForFile(sourceFile: SourceFile): Diagnostic[] {
+            // For JavaScript files, we report semantic errors for using TypeScript-only
+            // constructs from within a JavaScript file as syntactic errors.
+            if (isSourceFileJavaScript(sourceFile) && !sourceFile.parseJavaScriptDiagnostics) {
+                sourceFile.parseJavaScriptDiagnostics = getJavaScriptSemanticDiagnosticsForFile(sourceFile);
+                sourceFile.parseDiagnostics = sourceFile.parseDiagnostics.concat(sourceFile.parseJavaScriptDiagnostics);
+            }
             return sourceFile.parseDiagnostics;
         }
 
@@ -757,12 +763,10 @@ namespace ts {
 
                 Debug.assert(!!sourceFile.bindDiagnostics);
                 const bindDiagnostics = sourceFile.bindDiagnostics;
-                // For JavaScript files, we don't want to report the normal typescript semantic errors.
-                // Instead, we just report errors for using TypeScript-only constructs from within a
-                // JavaScript file.
-                const checkDiagnostics = isSourceFileJavaScript(sourceFile) ?
-                    getJavaScriptSemanticDiagnosticsForFile(sourceFile) :
-                    typeChecker.getDiagnostics(sourceFile, cancellationToken);
+                // For JavaScript files, we don't want to report semantic errors.
+                // Instead, we'll report errors for using TypeScript-only constructs from within a
+                // JavaScript file when we get syntactic diagnostics for the file.
+                const checkDiagnostics = isSourceFileJavaScript(sourceFile) ? [] : typeChecker.getDiagnostics(sourceFile, cancellationToken);
                 const fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 const programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
 

src/compiler/types.ts

@@ -2024,6 +2024,9 @@ namespace ts {
         // as well as code diagnostics).
         /* @internal */ parseDiagnostics: Diagnostic[];
 
+        // Stores file level JavaScript diagnostics reported by the program
+        /* @internal */ parseJavaScriptDiagnostics?: Diagnostic[];
+
         // File level diagnostics reported by the binder.
         /* @internal */ bindDiagnostics: Diagnostic[];
 

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics1.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// import a = b;
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'import ... =' can only be used in a .ts file.",
     "start": 0,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics10.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// function F<T>() { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'type parameter declarations' can only be used in a .ts file.",
     "start": 11,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics11.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// function F(): number { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'types' can only be used in a .ts file.",
     "start": 14,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics12.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// declare var v;
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'declare' can only be used in a .ts file.",
     "start": 0,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics13.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// var v: () => number;
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'types' can only be used in a .ts file.",
     "start": 7,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics14.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// Foo<number>();
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'type arguments' can only be used in a .ts file.",
     "start": 4,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics15.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// function F(public p) { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'parameter modifiers' can only be used in a .ts file.",
     "start": 11,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics16.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// function F(p?) { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'?' can only be used in a .ts file.",
     "start": 12,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics17.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// function F(a: number) { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'types' can only be used in a .ts file.",
     "start": 14,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics18.ts

@@ -9,7 +9,7 @@
 ////}
 
 goTo.file("a.js");
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "\'public\' can only be used in a .ts file.",
     "start": 93,
@@ -25,7 +25,7 @@ verify.getSemanticDiagnostics(`[
 ////}
 
 goTo.file("b.js");
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'types' can only be used in a .ts file.",
     "start": 17,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics19.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// enum E { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'enum declarations' can only be used in a .ts file.",
     "start": 5,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics2.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// export = b;
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'export=' can only be used in a .ts file.",
     "start": 0,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics3.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// class C<T> { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'type parameter declarations' can only be used in a .ts file.",
     "start": 8,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics4.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// public class C { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'public' can only be used in a .ts file.",
     "start": 0,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics5.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// class C implements D { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'implements clauses' can only be used in a .ts file.",
     "start": 8,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics6.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// interface I { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'interface declarations' can only be used in a .ts file.",
     "start": 10,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics7.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// module M { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'module declarations' can only be used in a .ts file.",
     "start": 7,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics8.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// type a = b;
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'type aliases' can only be used in a .ts file.",
     "start": 5,

tests/cases/fourslash/getJavaScriptSyntacticDiagnostics9.ts

@@ -4,7 +4,7 @@
 // @Filename: a.js
 //// public function F() { }
 
-verify.getSemanticDiagnostics(`[
+verify.getSyntacticDiagnostics(`[
   {
     "message": "'public' can only be used in a .ts file.",
     "start": 0,

tests/cases/fourslash/server/getJavaScriptSyntacticDiagnostics02.ts

@@ -0,0 +1,40 @@
+/// <reference path="../fourslash.ts" />
+
+// @allowJs: true
+// @Filename: b.js
+//// var a = "a";
+//// var b: boolean = true;
+//// function foo(): string { }
+//// var var = "c";
+
+verify.getSyntacticDiagnostics(`[
+  {
+    "message": "Variable declaration expected.",
+    "start": 67,
+    "length": 3,
+    "category": "error",
+    "code": 1134
+  },
+  {
+    "message": "Variable declaration expected.",
+    "start": 71,
+    "length": 1,
+    "category": "error",
+    "code": 1134
+  },
+  {
+    "message": "Variable declaration expected.",
+    "start": 73,
+    "length": 3,
+    "category": "error",
+    "code": 1134
+  },
+  {
+    "message": "\'types\' can only be used in a .ts file.",
+    "start": 20,
+    "length": 7,
+    "category": "error",
+    "code": 8010
+  }
+]`);
+verify.getSemanticDiagnostics(`[]`);