Add quickfix for labeled tuple syntax mistakes

Author: weswigham

src/compiler/diagnosticMessages.json

@@ -5693,6 +5693,10 @@
         "category": "Message",
         "code": 95116
     },
+    "Move labeled tuple element modifiers to labels": {
+        "category": "Message",
+        "code": 95117
+    },
 
     "No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer.": {
         "category": "Error",

src/services/codefixes/fixIncorrectNamedTupleSyntax.ts

@@ -0,0 +1,52 @@
+/* @internal */
+namespace ts.codefix {
+    const fixId = "fixIncorrectNamedTupleSyntax";
+    const errorCodes = [
+        Diagnostics.A_labeled_tuple_element_is_declared_as_optional_with_a_question_mark_after_the_name_and_before_the_colon_rather_than_after_the_type.code,
+        Diagnostics.A_labeled_tuple_element_is_declared_as_rest_with_a_before_the_name_rather_than_before_the_type.code
+    ];
+
+    registerCodeFix({
+        errorCodes,
+        getCodeActions: context => {
+            const { sourceFile, span } = context;
+            const namedTupleMember = getNamedTupleMember(sourceFile, span.start);
+            const changes = textChanges.ChangeTracker.with(context, t => doChange(t, sourceFile, namedTupleMember));
+            return [createCodeFixAction(fixId, changes, Diagnostics.Move_labeled_tuple_element_modifiers_to_labels, fixId, Diagnostics.Move_labeled_tuple_element_modifiers_to_labels)];
+        },
+        fixIds: [fixId]
+    });
+
+    function getNamedTupleMember(sourceFile: SourceFile, pos: number) {
+        const token = getTokenAtPosition(sourceFile, pos);
+        return findAncestor(token, t => t.kind === SyntaxKind.NamedTupleMember) as NamedTupleMember | undefined;
+    }
+    function doChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, namedTupleMember?: NamedTupleMember) {
+        if (!namedTupleMember) {
+            return;
+        }
+        let unwrappedType = namedTupleMember.type;
+        let sawOptional = false;
+        let sawRest = false;
+        while (unwrappedType.kind === SyntaxKind.OptionalType || unwrappedType.kind === SyntaxKind.RestType || unwrappedType.kind === SyntaxKind.ParenthesizedType) {
+            if (unwrappedType.kind === SyntaxKind.OptionalType) {
+                sawOptional = true;
+            }
+            else if (unwrappedType.kind === SyntaxKind.RestType) {
+                sawRest = true;
+            }
+            unwrappedType = (unwrappedType as OptionalTypeNode | RestTypeNode | ParenthesizedTypeNode).type;
+        }
+        const updated = updateNamedTupleMember(
+            namedTupleMember,
+            namedTupleMember.dotDotDotToken || (sawRest ? createToken(SyntaxKind.DotDotDotToken) : undefined),
+            namedTupleMember.name,
+            namedTupleMember.questionToken || (sawOptional ? createToken(SyntaxKind.QuestionToken) : undefined),
+            unwrappedType
+        );
+        if (updated === namedTupleMember) {
+            return;
+        }
+        changes.replaceNode(sourceFile, namedTupleMember, updated);
+    }
+}

src/services/tsconfig.json

@@ -64,6 +64,7 @@
         "codefixes/fixClassIncorrectlyImplementsInterface.ts",
         "codefixes/importFixes.ts",
         "codefixes/fixImplicitThis.ts",
+        "codefixes/fixIncorrectNamedTupleSyntax.ts",
         "codefixes/fixSpelling.ts",
         "codefixes/returnValueCorrect.ts",
         "codefixes/fixAddMissingMember.ts",

tests/cases/fourslash/codeFixIncorrectNamedTupleSyntax1.ts

@@ -0,0 +1,10 @@
+/// <reference path='fourslash.ts' />
+
+////type Tup = [first: string, elem: ...any[]];
+
+verify.codeFix({
+    description: "Move labeled tuple element modifiers to labels",
+    index: 0,
+    newFileContent: 
+  `type Tup = [first: string, ...elem: any[]];`
+});

tests/cases/fourslash/codeFixIncorrectNamedTupleSyntax2.ts

@@ -0,0 +1,10 @@
+/// <reference path='fourslash.ts' />
+
+////type Tup = [first: string, elem: any[]?];
+
+verify.codeFix({
+    description: "Move labeled tuple element modifiers to labels",
+    index: 0,
+    newFileContent: 
+  `type Tup = [first: string, elem?: any[]];`
+});