change error message for unused parameter property

fix

src/compiler/checker.ts

@@ -14967,7 +14967,7 @@ namespace ts {
                         else if (member.kind === SyntaxKind.Constructor) {
                             for (const parameter of (<ConstructorDeclaration>member).parameters) {
                                 if (!parameter.symbol.isReferenced && parameter.flags & NodeFlags.Private) {
-                                    error(parameter.name, Diagnostics._0_is_declared_but_never_used, parameter.symbol.name);
+                                    error(parameter.name, Diagnostics.Property_0_is_declared_but_never_used, parameter.symbol.name);
                                 }
                             }
                         }

src/compiler/diagnosticMessages.json

@@ -2828,6 +2828,10 @@
         "category": "Message",
         "code": 6137
     },
+    "Property '{0}' is declared but never used.": {
+        "category": "Error",
+        "code": 6138
+    },
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
         "code": 7005

tests/baselines/reference/unusedParameterProperty1.errors.txt

@@ -0,0 +1,14 @@
+tests/cases/compiler/unusedParameterProperty1.ts(3,25): error TS6138: Property 'used' is declared but never used.
+
+
+==== tests/cases/compiler/unusedParameterProperty1.ts (1 errors) ====
+    
+    class A {
+        constructor(private used: string) {
+                            ~~~~
+!!! error TS6138: Property 'used' is declared but never used.
+            let foge = used;
+            foge += "";
+        }
+    }
+    

tests/baselines/reference/unusedParameterProperty1.js

@@ -0,0 +1,19 @@
+//// [unusedParameterProperty1.ts]
+
+class A {
+    constructor(private used: string) {
+        let foge = used;
+        foge += "";
+    }
+}
+
+
+//// [unusedParameterProperty1.js]
+var A = (function () {
+    function A(used) {
+        this.used = used;
+        var foge = used;
+        foge += "";
+    }
+    return A;
+}());

tests/baselines/reference/unusedParameterProperty2.errors.txt

@@ -0,0 +1,14 @@
+tests/cases/compiler/unusedParameterProperty2.ts(3,25): error TS6138: Property 'used' is declared but never used.
+
+
+==== tests/cases/compiler/unusedParameterProperty2.ts (1 errors) ====
+    
+    class A {
+        constructor(private used) {
+                            ~~~~
+!!! error TS6138: Property 'used' is declared but never used.
+            let foge = used;
+            foge += "";
+        }
+    }
+    

tests/baselines/reference/unusedParameterProperty2.js

@@ -0,0 +1,19 @@
+//// [unusedParameterProperty2.ts]
+
+class A {
+    constructor(private used) {
+        let foge = used;
+        foge += "";
+    }
+}
+
+
+//// [unusedParameterProperty2.js]
+var A = (function () {
+    function A(used) {
+        this.used = used;
+        var foge = used;
+        foge += "";
+    }
+    return A;
+}());

tests/cases/compiler/unusedParameterProperty1.ts

@@ -0,0 +1,9 @@
+//@noUnusedLocals:true
+//@noUnusedParameters:true
+
+class A {
+    constructor(private used: string) {
+        let foge = used;
+        foge += "";
+    }
+}

tests/cases/compiler/unusedParameterProperty2.ts

@@ -0,0 +1,9 @@
+//@noUnusedLocals:true
+//@noUnusedParameters:true
+
+class A {
+    constructor(private used) {
+        let foge = used;
+        foge += "";
+    }
+}