Merge pull request #9189 from Microsoft/js_property_declaration

Allow property declarations in .js files

src/compiler/diagnosticMessages.json

@@ -2921,10 +2921,6 @@
         "category": "Error",
         "code": 8012
     },
-    "'property declarations' can only be used in a .ts file.": {
-        "category": "Error",
-        "code": 8014
-    },
     "'enum declarations' can only be used in a .ts file.": {
         "category": "Error",
         "code": 8015

src/compiler/program.ts

@@ -1601,8 +1601,19 @@ namespace ts {
                             }
                             break;
                         case SyntaxKind.PropertyDeclaration:
-                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.property_declarations_can_only_be_used_in_a_ts_file));
-                            return true;
+                            const propertyDeclaration = <PropertyDeclaration>node;
+                            if (propertyDeclaration.modifiers) {
+                                for (const modifier of propertyDeclaration.modifiers) {
+                                    if (modifier.kind !== SyntaxKind.StaticKeyword) {
+                                        diagnostics.push(createDiagnosticForNode(modifier, Diagnostics._0_can_only_be_used_in_a_ts_file, tokenToString(modifier.kind)));
+                                        return true;
+                                    }
+                                }
+                            }
+                            if (checkTypeAnnotation((<PropertyDeclaration>node).type)) {
+                                return true;
+                            }
+                            break;
                         case SyntaxKind.EnumDeclaration:
                             diagnostics.push(createDiagnosticForNode(node, Diagnostics.enum_declarations_can_only_be_used_in_a_ts_file));
                             return true;

tests/baselines/reference/jsFileCompilationPropertySyntaxOfClass.errors.txt

@@ -1,9 +0,0 @@
-error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
-tests/cases/compiler/a.js(1,11): error TS8014: 'property declarations' can only be used in a .ts file.
-
-
-!!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
-==== tests/cases/compiler/a.js (1 errors) ====
-    class C { v }
-              ~
-!!! error TS8014: 'property declarations' can only be used in a .ts file.

tests/cases/compiler/jsFileCompilationPropertySyntaxOfClass.ts

@@ -1,3 +0,0 @@
-// @allowJs: true
-// @filename: a.js
-class C { v }

tests/cases/fourslash/getJavaScriptSemanticDiagnostics18.ts

@@ -2,14 +2,35 @@
 
 // @allowJs: true
 // @Filename: a.js
-//// class C { v }
+////class C {
+////    x; // Regular property declaration allowed
+////    static y; // static allowed
+////    public z; // public not allowed
+////}
 
+goTo.file("a.js");
 verify.getSemanticDiagnostics(`[
   {
-    "message": "'property declarations' can only be used in a .ts file.",
-    "start": 10,
-    "length": 1,
+    "message": "\'public\' can only be used in a .ts file.",
+    "start": 93,
+    "length": 6,
     "category": "error",
-    "code": 8014
+    "code": 8009
   }
-]`);
+]`);
+
+// @Filename: b.js
+////class C {
+////    x: number; // Types not allowed
+////}
+
+goTo.file("b.js");
+verify.getSemanticDiagnostics(`[
+  {
+    "message": "'types' can only be used in a .ts file.",
+    "start": 17,
+    "length": 6,
+    "category": "error",
+    "code": 8010
+  }
+]`);