fix(41621): fixUnusedIdentifier - allow deleting prefix/postfix unary operators (#41624)

Author: a-tarasyuk

src/services/codefixes/fixUnusedIdentifier.ts

@@ -225,7 +225,7 @@ namespace ts.codefix {
         if (isIdentifier(token)) {
             FindAllReferences.Core.eachSymbolReferenceInFile(token, checker, sourceFile, (ref: Node) => {
                 if (isPropertyAccessExpression(ref.parent) && ref.parent.name === ref) ref = ref.parent;
-                if (!isFixAll && isBinaryExpression(ref.parent) && isExpressionStatement(ref.parent.parent) && ref.parent.left === ref) {
+                if (!isFixAll && mayDeleteExpression(ref)) {
                     changes.delete(sourceFile, ref.parent.parent);
                 }
             });
@@ -332,4 +332,9 @@ namespace ts.codefix {
             parameters.slice(index + 1).every(p => isIdentifier(p.name) && !p.symbol.isReferenced) :
             index === parameters.length - 1;
     }
+
+    function mayDeleteExpression(node: Node) {
+        return ((isBinaryExpression(node.parent) && node.parent.left === node) ||
+            ((isPostfixUnaryExpression(node.parent) || isPrefixUnaryExpression(node.parent)) && node.parent.operand === node)) && isExpressionStatement(node.parent.parent);
+    }
 }

tests/cases/fourslash/codeFixUnusedIdentifier_postfix_operator1.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+////function fn() {
+////   let x = 1;
+////   x++;
+////}
+
+verify.codeFix({
+    description: "Remove unused declaration for: 'x'",
+    newFileContent:
+`function fn() {
+}`
+});

tests/cases/fourslash/codeFixUnusedIdentifier_postfix_operator2.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+////function fn() {
+////   let x = 1;
+////   x--;
+////}
+
+verify.codeFix({
+    description: "Remove unused declaration for: 'x'",
+    newFileContent:
+`function fn() {
+}`
+});

tests/cases/fourslash/codeFixUnusedIdentifier_prefix_operator1.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+////function fn() {
+////   let x = 1;
+////   ++x;
+////}
+
+verify.codeFix({
+    description: "Remove unused declaration for: 'x'",
+    newFileContent:
+`function fn() {
+}`
+});

tests/cases/fourslash/codeFixUnusedIdentifier_prefix_operator2.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+////function fn() {
+////   let x = 1;
+////   --x;
+////}
+
+verify.codeFix({
+    description: "Remove unused declaration for: 'x'",
+    newFileContent:
+`function fn() {
+}`
+});