Error if --checkJs is used without --allowJs

Author: mhegazy

src/compiler/program.ts

@@ -1685,6 +1685,10 @@ namespace ts {
                 programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_with_option_1, "allowJs", "declaration"));
             }
 
+            if (options.checkJs && !options.allowJs) {
+                programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1, "checkJs", "allowJs"));
+            }
+
             if (options.emitDecoratorMetadata &&
                 !options.experimentalDecorators) {
                 programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1, "emitDecoratorMetadata", "experimentalDecorators"));

tests/baselines/reference/checkJsFiles6.errors.txt

@@ -0,0 +1,9 @@
+error TS5052: Option 'checkJs' cannot be specified without specifying option 'allowJs'.
+error TS6054: File 'tests/cases/compiler/a.js' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts'.
+
+
+!!! error TS5052: Option 'checkJs' cannot be specified without specifying option 'allowJs'.
+!!! error TS6054: File 'tests/cases/compiler/a.js' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts'.
+==== tests/cases/compiler/a.js (0 errors) ====
+    
+    var x;

tests/cases/compiler/checkJsFiles6.ts

@@ -0,0 +1,6 @@
+// @allowJs: false
+// @checkJs: true
+// @noEmit: true
+
+// @fileName: a.js
+var x;