Add code fix to remove unused label (#24037)

Andy · web-flow · commit 3eb66da155fc · 2018-05-18T15:25:24.000-07:00
* Add code fix to remove unused label

* Test with trivia and fix indentation with dedented label
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
@@ -4261,5 +4261,13 @@
     "Add missing typeof": {
         "category": "Message",
         "code": 95052
+    },
+    "Remove unused label": {
+        "category": "Message",
+        "code": 95053
+    },
+    "Remove all unused labels": {
+        "category": "Message",
+        "code": 95054
     }
 }
diff --git a/src/harness/tsconfig.json b/src/harness/tsconfig.json
@@ -106,6 +106,7 @@
         "../services/codefixes/fixForgottenThisPropertyAccess.ts",
         "../services/codefixes/fixUnusedIdentifier.ts",
         "../services/codefixes/fixUnreachableCode.ts",
+        "../services/codefixes/fixUnusedLabel.ts",
         "../services/codefixes/fixJSDocTypes.ts",
         "../services/codefixes/fixAwaitInSyncFunction.ts",
         "../services/codefixes/disableJsDiagnostics.ts",
diff --git a/src/server/tsconfig.json b/src/server/tsconfig.json
@@ -102,6 +102,7 @@
         "../services/codefixes/fixForgottenThisPropertyAccess.ts",
         "../services/codefixes/fixUnusedIdentifier.ts",
         "../services/codefixes/fixUnreachableCode.ts",
+        "../services/codefixes/fixUnusedLabel.ts",
         "../services/codefixes/fixJSDocTypes.ts",
         "../services/codefixes/fixAwaitInSyncFunction.ts",
         "../services/codefixes/disableJsDiagnostics.ts",
diff --git a/src/server/tsconfig.library.json b/src/server/tsconfig.library.json
@@ -108,6 +108,7 @@
         "../services/codefixes/fixForgottenThisPropertyAccess.ts",
         "../services/codefixes/fixUnusedIdentifier.ts",
         "../services/codefixes/fixUnreachableCode.ts",
+        "../services/codefixes/fixUnusedLabel.ts",
         "../services/codefixes/fixJSDocTypes.ts",
         "../services/codefixes/fixAwaitInSyncFunction.ts",
         "../services/codefixes/disableJsDiagnostics.ts",
diff --git a/src/services/codefixes/fixUnusedLabel.ts b/src/services/codefixes/fixUnusedLabel.ts
@@ -0,0 +1,25 @@
+/* @internal */
+namespace ts.codefix {
+    const fixId = "fixUnusedLabel";
+    const errorCodes = [Diagnostics.Unused_label.code];
+    registerCodeFix({
+        errorCodes,
+        getCodeActions(context) {
+            const changes = textChanges.ChangeTracker.with(context, t => doChange(t, context.sourceFile, context.span.start));
+            return [createCodeFixAction(fixId, changes, Diagnostics.Remove_unused_label, fixId, Diagnostics.Remove_all_unused_labels)];
+        },
+        fixIds: [fixId],
+        getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => doChange(changes, diag.file, diag.start)),
+    });
+
+    function doChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, start: number): void {
+        const token = getTokenAtPosition(sourceFile, start, /*includeJsDocComment*/ false);
+        const labeledStatement = cast(token.parent, isLabeledStatement);
+        const pos = token.getStart(sourceFile);
+        const statementPos = labeledStatement.statement.getStart(sourceFile);
+        // If label is on a separate line, just delete the rest of that line, but not the indentation of the labeled statement.
+        const end = positionsAreOnSameLine(pos, statementPos, sourceFile) ? statementPos
+            : skipTrivia(sourceFile.text, findChildOfKind(labeledStatement, SyntaxKind.ColonToken, sourceFile)!.end, /*stopAfterLineBreak*/ true);
+        changes.deleteRange(sourceFile, { pos, end });
+    }
+}
diff --git a/src/services/tsconfig.json b/src/services/tsconfig.json
@@ -99,6 +99,7 @@
         "codefixes/fixForgottenThisPropertyAccess.ts",
         "codefixes/fixUnusedIdentifier.ts",
         "codefixes/fixUnreachableCode.ts",
+        "codefixes/fixUnusedLabel.ts",
         "codefixes/fixJSDocTypes.ts",
         "codefixes/fixAwaitInSyncFunction.ts",
         "codefixes/disableJsDiagnostics.ts",
diff --git a/tests/cases/fourslash/codeFixUnusedLabel.ts b/tests/cases/fourslash/codeFixUnusedLabel.ts
@@ -0,0 +1,11 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+
+/////* a */label/* b */:/* c */while (1) {}
+
+verify.codeFix({
+    description: "Remove unused label",
+    newFileContent:
+`/* a */while (1) {}`,
+});
diff --git a/tests/cases/fourslash/codeFixUnusedLabel_all.ts b/tests/cases/fourslash/codeFixUnusedLabel_all.ts
@@ -0,0 +1,21 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+
+////label1: while (1) {}
+////
+////function f() {
+////label2:
+////    while (1) {}
+////}
+
+verify.codeFixAll({
+    fixId: "fixUnusedLabel",
+    fixAllDescription: "Remove all unused labels",
+    newFileContent:
+`while (1) {}
+
+function f() {
+    while (1) {}
+}`,
+});

Original file line number	Diff line number	Diff line change
`@@ -4261,5 +4261,13 @@`
`4261`	`4261`	`"Add missing typeof": {`
`4262`	`4262`	`"category": "Message",`
`4263`	`4263`	`"code": 95052`
	`4264`	`+ },`
	`4265`	`+ "Remove unused label": {`
	`4266`	`+ "category": "Message",`
	`4267`	`+ "code": 95053`
	`4268`	`+ },`
	`4269`	`+ "Remove all unused labels": {`
	`4270`	`+ "category": "Message",`
	`4271`	`+ "code": 95054`
`4264`	`4272`	`}`
`4265`	`4273`	`}`