Add deprecation warning for computed property names in enums

This adds a suggestion diagnostic for using computed property names with
literal expressions in enum members (e.g., `["key"]`).

This syntax is rarely used, not supported by Babel/typescript-eslint/SWC,
and will be disallowed in a future version (typescript-go).

Changes:
- Add suggestion diagnostic (code 1550) for computed property names
- Add quick fix to convert `["key"]` to `"key"`
- Add "Fix All" support for batch conversion

Author: magic-akari

src/compiler/checker.ts

@@ -47833,6 +47833,13 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 error(member.name, Diagnostics.An_enum_member_cannot_have_a_numeric_name);
             }
         }
+        if (isComputedPropertyName(member.name)) {
+            // Computed property name with a literal expression (e.g., ['key'] or [`key`])
+            // This is deprecated and will be disallowed in a future version
+            suggestionDiagnostics.add(
+                createDiagnosticForNode(member.name, Diagnostics.Using_a_string_literal_as_an_enum_member_name_via_a_computed_property_is_deprecated_Use_a_simple_string_literal_instead),
+            );
+        }
         if (member.initializer) {
             return computeConstantEnumMemberValue(member);
         }

src/compiler/diagnosticMessages.json

@@ -1861,7 +1861,11 @@
         "category": "Message",
         "code": 1549
     },
-
+    "Using a string literal as an enum member name via a computed property is deprecated. Use a simple string literal instead.": {
+        "category": "Suggestion",
+        "code": 1550,
+        "reportsDeprecated": true
+    },
     "The types of '{0}' are incompatible between these types.": {
         "category": "Error",
         "code": 2200
@@ -8348,7 +8352,14 @@
         "category": "Message",
         "code": 95197
     },
-
+    "Remove unnecessary computed property name syntax": {
+        "category": "Message",
+        "code": 95198
+    },
+    "Remove all unnecessary computed property name syntax": {
+        "category": "Message",
+        "code": 95199
+    },
     "No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer.": {
         "category": "Error",
         "code": 18004

src/services/_namespaces/ts.codefix.ts

@@ -74,3 +74,4 @@ export * from "../codefixes/splitTypeOnlyImport.js";
 export * from "../codefixes/convertConstToLet.js";
 export * from "../codefixes/fixExpectedComma.js";
 export * from "../codefixes/fixAddVoidToPromise.js";
+export * from "../codefixes/convertComputedEnumMemberName.js";

src/services/codefixes/convertComputedEnumMemberName.ts

@@ -0,0 +1,83 @@
+import {
+    createCodeFixActionMaybeFixAll,
+    createCombinedCodeActions,
+    eachDiagnostic,
+    registerCodeFix,
+} from "../_namespaces/ts.codefix.js";
+import {
+    ComputedPropertyName,
+    Diagnostics,
+    factory,
+    getTokenAtPosition,
+    isComputedPropertyName,
+    isEnumMember,
+    isNoSubstitutionTemplateLiteral,
+    isStringLiteral,
+    SourceFile,
+    textChanges,
+} from "../_namespaces/ts.js";
+
+const fixId = "convertComputedEnumMemberName";
+const errorCodes = [Diagnostics.Using_a_string_literal_as_an_enum_member_name_via_a_computed_property_is_deprecated_Use_a_simple_string_literal_instead.code];
+
+registerCodeFix({
+    errorCodes,
+    getCodeActions(context) {
+        const { sourceFile, span } = context;
+        const info = getInfo(sourceFile, span.start);
+        if (info === undefined) return;
+
+        const changes = textChanges.ChangeTracker.with(context, t => doChange(t, sourceFile, info));
+        return [createCodeFixActionMaybeFixAll(fixId, changes, Diagnostics.Remove_unnecessary_computed_property_name_syntax, fixId, Diagnostics.Remove_all_unnecessary_computed_property_name_syntax)];
+    },
+    getAllCodeActions(context) {
+        return createCombinedCodeActions(textChanges.ChangeTracker.with(context, changes => {
+            eachDiagnostic(context, errorCodes, diag => {
+                const info = getInfo(diag.file, diag.start);
+                if (info) {
+                    return doChange(changes, diag.file, info);
+                }
+                return undefined;
+            });
+        }));
+    },
+    fixIds: [fixId],
+});
+
+interface Info {
+    computedName: ComputedPropertyName;
+    literalText: string;
+}
+
+function getInfo(sourceFile: SourceFile, pos: number): Info | undefined {
+    const token = getTokenAtPosition(sourceFile, pos);
+
+    // Navigate to find the computed property name
+    let node = token;
+    while (node && !isComputedPropertyName(node)) {
+        node = node.parent;
+    }
+
+    if (!node || !isComputedPropertyName(node)) return undefined;
+    if (!isEnumMember(node.parent)) return undefined;
+
+    const expression = node.expression;
+    let literalText: string;
+
+    if (isStringLiteral(expression)) {
+        literalText = expression.text;
+    }
+    else if (isNoSubstitutionTemplateLiteral(expression)) {
+        literalText = expression.text;
+    }
+    else {
+        return undefined;
+    }
+
+    return { computedName: node, literalText };
+}
+
+function doChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, info: Info) {
+    // Replace ['\t'] with '\t' (or ["key"] with "key")
+    changes.replaceNode(sourceFile, info.computedName, factory.createStringLiteral(info.literalText));
+}

tests/cases/fourslash/codeFixEnumComputedPropertyName.ts

@@ -0,0 +1,17 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: test.ts
+////enum CHAR {
+////    [|['\t']|] = 0x09,
+////    ['\n'] = 0x0A,
+////}
+
+goTo.file("test.ts");
+verify.codeFix({
+    description: "Remove unnecessary computed property name syntax",
+    newFileContent: `enum CHAR {
+    "\\t" = 0x09,
+    ['\\n'] = 0x0A,
+}`,
+    index: 0,
+});

tests/cases/fourslash/codeFixEnumComputedPropertyNameAll.ts

@@ -0,0 +1,19 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: test.ts
+////enum CHAR {
+////    ['\t'] = 0x09,
+////    ['\n'] = 0x0A,
+////    [`\r`] = 0x0D,
+////}
+
+goTo.file("test.ts");
+verify.codeFixAll({
+    fixId: "convertComputedEnumMemberName",
+    fixAllDescription: "Remove all unnecessary computed property name syntax",
+    newFileContent: `enum CHAR {
+    "\\t" = 0x09,
+    "\\n" = 0x0A,
+    "\\r" = 0x0D,
+}`,
+});

tests/cases/fourslash/enumComputedPropertyNameDeprecated.ts

@@ -0,0 +1,23 @@
+///<reference path="fourslash.ts" />
+// @Filename: a.ts
+////enum CHAR {
+////    [|['\t']|] = 0x09,
+////    [|['\n']|] = 0x0A,
+////    [|[`\r`]|] = 0x0D,
+////    'space' = 0x20,  // no warning for simple string literal
+////}
+////
+////enum NoWarning {
+////    A = 1,
+////    B = 2,
+////    "quoted" = 3,
+////}
+
+goTo.file("a.ts")
+const diagnostics = test.ranges().map(range => ({
+    code: 1550,
+    message: "Using a string literal as an enum member name via a computed property is deprecated. Use a simple string literal instead.",
+    reportsDeprecated: true,
+    range,
+}));
+verify.getSuggestionDiagnostics(diagnostics)

tests/cases/fourslash/enumComputedPropertyNameError.ts

@@ -0,0 +1,15 @@
+///<reference path="fourslash.ts" />
+// @Filename: a.ts
+////const key = "dynamic";
+////enum Test {
+////    [|[key]|] = 1,           // error: non-literal computed property name
+////    [|["a" + "b"]|] = 2,     // error: binary expression
+////}
+
+goTo.file("a.ts")
+const diagnostics = test.ranges().map(range => ({
+    code: 1164,
+    message: "Computed property names are not allowed in enums.",
+    range,
+}));
+verify.getSemanticDiagnostics(diagnostics)