Better reference usage detection

Author: KnisterPeter

src/services/codefixes/fixUnusedIdentifier.ts

@@ -181,8 +181,8 @@ namespace ts.codefix {
 
     function deleteAssignments(changes: textChanges.ChangeTracker, sourceFile: SourceFile, token: Identifier, checker: TypeChecker) {
         FindAllReferences.Core.eachSymbolReferenceInFile(token, checker, sourceFile, (ref: Node) => {
-            if (ref.parent.kind === SyntaxKind.PropertyAccessExpression) ref = ref.parent;
-            if (ref.parent.kind === SyntaxKind.BinaryExpression && ref.parent.parent.kind === SyntaxKind.ExpressionStatement) {
+            if (isPropertyAccessExpression(ref.parent) && ref.parent.name === ref) ref = ref.parent;
+            if (isBinaryExpression(ref.parent) && isExpressionStatement(ref.parent.parent) && ref.parent.left === ref) {
                 changes.delete(sourceFile, ref.parent.parent);
             }
         });
@@ -201,7 +201,7 @@ namespace ts.codefix {
     function tryDeleteParameter(changes: textChanges.ChangeTracker, sourceFile: SourceFile, p: ParameterDeclaration, checker: TypeChecker, sourceFiles: ReadonlyArray<SourceFile>, isFixAll: boolean): void {
         if (mayDeleteParameter(p, checker, isFixAll)) {
             if (p.modifiers && p.modifiers.length > 0
-                && (!isIdentifier(p.name) || FindAllReferences.Core.isSymbolReferencedInFile(p.name, checker, sourceFile))) {
+                    && (!isIdentifier(p.name) || FindAllReferences.Core.isSymbolReferencedInFile(p.name, checker, sourceFile))) {
                 p.modifiers.forEach(modifier => {
                     changes.deleteModifier(sourceFile, modifier);
                 });

src/services/findAllReferences.ts

@@ -839,7 +839,9 @@ namespace ts.FindAllReferences.Core {
     }
 
     export function eachSymbolReferenceInFile<T>(definition: Identifier, checker: TypeChecker, sourceFile: SourceFile, cb: (token: Identifier) => T): T | undefined {
-        const symbol = checker.getSymbolAtLocation(definition);
+        const symbol = isParameterPropertyDeclaration(definition.parent)
+            ? first(checker.getSymbolsOfParameterPropertyDeclaration(definition.parent, definition.text))
+            : checker.getSymbolAtLocation(definition);
         if (!symbol) return undefined;
         for (const token of getPossibleSymbolReferenceNodes(sourceFile, symbol.name)) {
             if (!isIdentifier(token) || token === definition || token.escapedText !== definition.escapedText) continue;