Merge pull request microsoft#11998 from Microsoft/unusedProperty

 Mark property referenced in the destructuring as referenced

Author: sheetalkamat

src/compiler/checker.ts

@@ -11534,6 +11534,21 @@ namespace ts {
             diagnostics.add(createDiagnosticForNodeFromMessageChain(propNode, errorInfo));
         }
 
+        function markPropertyAsReferenced(prop: Symbol) {
+            if (prop &&
+                noUnusedIdentifiers &&
+                (prop.flags & SymbolFlags.ClassMember) &&
+                prop.valueDeclaration && (getModifierFlags(prop.valueDeclaration) & ModifierFlags.Private)) {
+                if (prop.flags & SymbolFlags.Instantiated) {
+                    getSymbolLinks(prop).target.isReferenced = true;
+
+                }
+                else {
+                    prop.isReferenced = true;
+                }
+            }
+        }
+
         function checkPropertyAccessExpressionOrQualifiedName(node: PropertyAccessExpression | QualifiedName, left: Expression | QualifiedName, right: Identifier) {
             const type = checkNonNullExpression(left);
             if (isTypeAny(type) || type === silentNeverType) {
@@ -11553,17 +11568,7 @@ namespace ts {
                 return unknownType;
             }
 
-            if (noUnusedIdentifiers &&
-                (prop.flags & SymbolFlags.ClassMember) &&
-                prop.valueDeclaration && (getModifierFlags(prop.valueDeclaration) & ModifierFlags.Private)) {
-                if (prop.flags & SymbolFlags.Instantiated) {
-                    getSymbolLinks(prop).target.isReferenced = true;
-
-                }
-                else {
-                    prop.isReferenced = true;
-                }
-            }
+            markPropertyAsReferenced(prop);
 
             getNodeLinks(node).resolvedSymbol = prop;
 
@@ -16353,6 +16358,7 @@ namespace ts {
                 const parentType = getTypeForBindingElementParent(parent);
                 const name = node.propertyName || <Identifier>node.name;
                 const property = getPropertyOfType(parentType, getTextOfPropertyName(name));
+                markPropertyAsReferenced(property);
                 if (parent.initializer && property && getParentOfSymbol(property)) {
                     checkClassPropertyAccess(parent, parent.initializer, parentType, property);
                 }

tests/baselines/reference/unusedLocalProperty.js

@@ -0,0 +1,25 @@
+//// [unusedLocalProperty.ts]
+declare var console: { log(msg: any): void; }
+class Animal {
+    constructor(private species: string) {
+    }
+
+    printSpecies() {
+        let { species } = this;
+        console.log(species);
+    }
+}
+
+
+
+//// [unusedLocalProperty.js]
+var Animal = (function () {
+    function Animal(species) {
+        this.species = species;
+    }
+    Animal.prototype.printSpecies = function () {
+        var species = this.species;
+        console.log(species);
+    };
+    return Animal;
+}());

tests/baselines/reference/unusedLocalProperty.symbols

@@ -0,0 +1,29 @@
+=== tests/cases/compiler/unusedLocalProperty.ts ===
+declare var console: { log(msg: any): void; }
+>console : Symbol(console, Decl(unusedLocalProperty.ts, 0, 11))
+>log : Symbol(log, Decl(unusedLocalProperty.ts, 0, 22))
+>msg : Symbol(msg, Decl(unusedLocalProperty.ts, 0, 27))
+
+class Animal {
+>Animal : Symbol(Animal, Decl(unusedLocalProperty.ts, 0, 45))
+
+    constructor(private species: string) {
+>species : Symbol(Animal.species, Decl(unusedLocalProperty.ts, 2, 16))
+    }
+
+    printSpecies() {
+>printSpecies : Symbol(Animal.printSpecies, Decl(unusedLocalProperty.ts, 3, 5))
+
+        let { species } = this;
+>species : Symbol(species, Decl(unusedLocalProperty.ts, 6, 13))
+>this : Symbol(Animal, Decl(unusedLocalProperty.ts, 0, 45))
+
+        console.log(species);
+>console.log : Symbol(log, Decl(unusedLocalProperty.ts, 0, 22))
+>console : Symbol(console, Decl(unusedLocalProperty.ts, 0, 11))
+>log : Symbol(log, Decl(unusedLocalProperty.ts, 0, 22))
+>species : Symbol(species, Decl(unusedLocalProperty.ts, 6, 13))
+    }
+}
+
+

tests/baselines/reference/unusedLocalProperty.types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/unusedLocalProperty.ts ===
+declare var console: { log(msg: any): void; }
+>console : { log(msg: any): void; }
+>log : (msg: any) => void
+>msg : any
+
+class Animal {
+>Animal : Animal
+
+    constructor(private species: string) {
+>species : string
+    }
+
+    printSpecies() {
+>printSpecies : () => void
+
+        let { species } = this;
+>species : string
+>this : this
+
+        console.log(species);
+>console.log(species) : void
+>console.log : (msg: any) => void
+>console : { log(msg: any): void; }
+>log : (msg: any) => void
+>species : string
+    }
+}
+
+

tests/cases/compiler/unusedLocalProperty.ts

@@ -0,0 +1,12 @@
+//@noUnusedLocals:true
+declare var console: { log(msg: any): void; }
+class Animal {
+    constructor(private species: string) {
+    }
+
+    printSpecies() {
+        let { species } = this;
+        console.log(species);
+    }
+}
+