Support TypeScript 5.7, drop TS <5.0

Also fix readonly index signatures.

CHANGELOG.md

@@ -6,6 +6,7 @@ title: Changelog
 
 ## Breaking Changes
 
+-   Drop support for TypeScript <5.0, no longer supported by DefinitelyTyped
 -   Relaxed requirements for file names and generated url fragments. This may
     result in a different file name structure, #2714.
 -   Anchors to document headings and reflections within a HTML generated pages
@@ -30,6 +31,7 @@ title: Changelog
 
 ## Features
 
+-   Add support for TypeScript 5.7
 -   TypeDoc will now discover entry points from `package.json` exports if they
     are not provided manually, #1937.
 -   Relative links to markdown files may now include `#anchor` links to
@@ -79,6 +81,7 @@ title: Changelog
 
 ## Bug Fixes
 
+-   TypeDoc now properly flags `readonly` index signatures.
 -   TypeDoc will now use the first signature's comment for later signatures in
     overloads if present, #2718.
 -   Fixed handling of `@enum` if the type was declared before the variable, #2719.

eslint.config.mjs

@@ -8,6 +8,9 @@ const config = {
         parserOptions: {
             project: true,
             tsconfigRootDir: import.meta.dirname,
+            // We're fairly frequently on a later version of the TS compiler than
+            // is officially supported. So far this has never been a real problem.
+            warnOnUnsupportedTypeScriptVersion: false,
         },
     },
     rules: {

package.json

@@ -33,7 +33,7 @@
     "yaml": "^2.6.0"
   },
   "peerDependencies": {
-    "typescript": "4.6.x || 4.7.x || 4.8.x || 4.9.x || 5.0.x || 5.1.x || 5.2.x || 5.3.x || 5.4.x || 5.5.x || 5.6.x"
+    "typescript": "5.0.x || 5.1.x || 5.2.x || 5.3.x || 5.4.x || 5.5.x || 5.6.x || 5.7.x"
   },
   "devDependencies": {
     "@types/lunr": "^2.3.7",
@@ -49,7 +49,7 @@
     "puppeteer": "^23.6.1",
     "semver": "^7.6.3",
     "tsx": "^4.19.2",
-    "typescript": "5.6.3",
+    "typescript": "5.7.1-rc",
     "typescript-eslint": "^8.12.2"
   },
   "files": [

site/overview.md

@@ -18,7 +18,7 @@ support more versions of TypeScript.
 
 | TypeDoc Version | TypeScript Version |
 | --------------- | ------------------ |
-| 0.27            | 4.6 through 5.7    |
+| 0.27            | 5.0 through 5.7    |
 | 0.26            | 4.6 through 5.6    |
 | 0.25            | 4.6 through 5.4    |
 | 0.24            | 4.6 through 5.1    |

src/lib/converter/factories/index-signature.ts

@@ -1,56 +1,97 @@
 import assert from "assert";
-import ts from "typescript";
+import type ts from "typescript";
 import {
     DeclarationReflection,
     ParameterReflection,
+    ReflectionFlag,
     ReflectionKind,
     SignatureReflection,
+    UnionType,
 } from "../../models/index.js";
 import type { Context } from "../context.js";
 import { ConverterEvents } from "../converter-events.js";
 
-export function convertIndexSignatures(context: Context, symbol: ts.Symbol) {
+export function convertIndexSignatures(context: Context, type: ts.Type) {
     assert(context.scope instanceof DeclarationReflection);
 
-    const indexSymbol = symbol.members?.get("__index" as ts.__String);
-    if (!indexSymbol) return;
+    // Each declaration should have one SignatureReflection
+    // If we don't have a declaration, the index signature was inferred by TS
+    // and we should make a separate SignatureReflection for each index signature.
+    const seenByDeclaration = new Map<ts.Declaration, SignatureReflection>();
+    const createdSignatures: [
+        ts.IndexSignatureDeclaration | undefined,
+        SignatureReflection,
+    ][] = [];
 
-    for (const indexDeclaration of indexSymbol.getDeclarations() || []) {
-        assert(ts.isIndexSignatureDeclaration(indexDeclaration));
-        const param = indexDeclaration.parameters[0] as
-            | ts.ParameterDeclaration
-            | undefined;
-        assert(param && ts.isParameter(param));
+    for (const indexInfo of context.checker.getIndexInfosOfType(type)) {
+        // Check if we've already created an index signature for this type
+        if (
+            indexInfo.declaration &&
+            seenByDeclaration.has(indexInfo.declaration)
+        ) {
+            const createdSig = seenByDeclaration.get(indexInfo.declaration)!;
+            if (createdSig.parameters![0].type?.type !== "union") {
+                createdSig.parameters![0].type = new UnionType([
+                    createdSig.parameters![0].type!,
+                ]);
+            }
+            createdSig.parameters![0].type.types.push(
+                context.converter.convertType(
+                    context.withScope(createdSig),
+                    indexInfo.keyType,
+                ),
+            );
+            // No need to update the return type as it will be the same for all members.
+            continue;
+        }
+
+        // Otherwise create a new one
         const index = new SignatureReflection(
             "__index",
             ReflectionKind.IndexSignature,
             context.scope,
         );
-        index.comment = context.getNodeComment(indexDeclaration, false);
+        if (indexInfo.isReadonly) {
+            index.setFlag(ReflectionFlag.Readonly);
+        }
+
+        createdSignatures.push([indexInfo.declaration, index]);
+        if (indexInfo.declaration) {
+            seenByDeclaration.set(indexInfo.declaration, index);
+            index.comment = context.getNodeComment(
+                indexInfo.declaration,
+                /* moduleComment */ false,
+            );
+        }
+
         index.parameters = [
             new ParameterReflection(
-                param.name.getText(),
+                indexInfo.declaration?.parameters[0].name.getText() ?? "key",
                 ReflectionKind.Parameter,
                 index,
             ),
         ];
         index.parameters[0].type = context.converter.convertType(
             context.withScope(index.parameters[0]),
-            param.type,
+            indexInfo.keyType,
         );
         index.type = context.converter.convertType(
             context.withScope(index),
-            indexDeclaration.type,
+            indexInfo.type,
         );
-        context.registerReflection(index, indexSymbol);
+
+        context.registerReflection(index, indexInfo.declaration?.symbol);
         context.scope.indexSignatures ||= [];
         context.scope.indexSignatures.push(index);
+    }
 
+    // Now that we've created everything, trigger events for them.
+    for (const [declaration, index] of createdSignatures) {
         context.converter.trigger(
             ConverterEvents.CREATE_SIGNATURE,
             context,
             index,
-            indexDeclaration,
+            declaration,
         );
     }
 }

src/lib/converter/symbols.ts

@@ -459,7 +459,7 @@ function convertTypeAliasAsInterface(
     convertConstructSignatures(rc, symbol);
 
     // And finally, index signatures
-    convertIndexSignatures(rc, symbol);
+    convertIndexSignatures(rc, type);
 }
 
 function convertFunctionOrMethod(
@@ -674,7 +674,7 @@ function convertClassOrInterface(
     convertConstructSignatures(reflectionContext, symbol);
 
     // And finally, index signatures
-    convertIndexSignatures(reflectionContext, symbol);
+    convertIndexSignatures(reflectionContext, instanceType);
 
     // Normally this shouldn't matter, unless someone did something with skipLibCheck on.
     return ts.SymbolFlags.Alias;

src/lib/converter/types.ts

@@ -631,7 +631,7 @@ const typeLiteralConverter: TypeConverter<ts.TypeLiteralNode> = {
             );
         }
 
-        convertIndexSignatures(rc, symbol);
+        convertIndexSignatures(rc, type);
 
         return new ReflectionType(reflection);
     },
@@ -670,7 +670,7 @@ const typeLiteralConverter: TypeConverter<ts.TypeLiteralNode> = {
         }
 
         if (symbol) {
-            convertIndexSignatures(context.withScope(reflection), symbol);
+            convertIndexSignatures(context.withScope(reflection), type);
         }
 
         return new ReflectionType(reflection);

src/lib/output/formatter.tsx

@@ -724,6 +724,16 @@ export class FormattedCodeBuilder {
             for (const index of reflection.indexSignatures) {
                 members.push(
                     nodes(
+                        ...(index.flags.isReadonly
+                            ? [
+                                  simpleElement(
+                                      <span class="tsd-signature-keyword">
+                                          readonly
+                                      </span>,
+                                  ),
+                                  space(),
+                              ]
+                            : []),
                         simpleElement(
                             <span class="tsd-signature-symbol">[</span>,
                         ),

src/lib/output/themes/default/partials/typeDetails.tsx

@@ -309,6 +309,7 @@ function renderIndexSignature(context: DefaultThemeRenderContext, index: Signatu
     return (
         <li class="tsd-parameter-index-signature">
             <h5>
+                {index.flags.isReadonly && <span class="tsd-signature-keyword">readonly </span>}
                 <span class="tsd-signature-symbol">[</span>
                 {index.parameters!.map((item) => (
                     <>

src/lib/output/themes/default/templates/reflection.tsx

@@ -84,6 +84,7 @@ function renderIndexSignature(context: DefaultThemeRenderContext, index: Signatu
     return (
         <li class="tsd-index-signature">
             <div class="tsd-signature">
+                {index.flags.isReadonly && <span class="tsd-signature-keyword">readonly </span>}
                 <span class="tsd-signature-symbol">[</span>
                 {index.parameters!.map((item) => (
                     <>

src/lib/utils/jsx.elements.ts

@@ -127,7 +127,9 @@ export interface IntrinsicElements {
     text: JsxTextElementProps;
 }
 
-export const JsxFragment: unique symbol = Symbol();
+export function JsxFragment(): never {
+    throw new Error("Should never be called");
+}
 
 export type JsxComponent<P> = (props: P) => JsxElement | null | undefined;