fix: Preserve imports for types used in typeof generic (#348)

Author: dayongkr

src/transform/DeclarationScope.ts

@@ -39,6 +39,7 @@ export class DeclarationScope {
   declaration: ESTree.FunctionDeclaration;
   iife?: ESTree.ExpressionStatement;
   private returnExpr: ESTree.ArrayExpression;
+  private valueReferences: Set<string> = new Set();
 
   constructor({ id, range }: DeclarationScopeOptions) {
     if (id) {
@@ -72,6 +73,14 @@ export class DeclarationScope {
     this.scopes[this.scopes.length - 1]?.add(name);
   }
 
+  markAsValue(name: string) {
+    this.valueReferences.add(name);
+  }
+
+  getValueReferences(): Set<string> {
+    return this.valueReferences;
+  }
+
   pushReference(id: ESTree.Expression) {
     let name: string | undefined;
     // We convert references from TS AST to ESTree
@@ -302,7 +311,17 @@ export class DeclarationScope {
       return;
     }
     if (ts.isTypeQueryNode(node)) {
-      this.pushReference(this.convertEntityName(node.exprName));
+      const reference = this.convertEntityName(node.exprName);
+      this.pushReference(reference);
+
+      if (reference.type === "Identifier") {
+        this.markAsValue(reference.name);
+      } else if (reference.type === "MemberExpression" && reference.object.type === "Identifier") {
+        this.markAsValue(reference.object.name);
+      }
+
+      this.convertTypeArguments(node);
+
       return;
     }
     if (ts.isRestTypeNode(node)) {

src/transform/Transformer.ts

@@ -12,6 +12,7 @@ interface ConvertInput {
 
 interface ConvertOutput {
   ast: ESTree.Program;
+  valueReferences: Set<string>;
 }
 
 export function convert({ sourceFile }: ConvertInput): ConvertOutput {
@@ -21,6 +22,7 @@ export function convert({ sourceFile }: ConvertInput): ConvertOutput {
 
 class Transformer {
   ast: ESTree.Program;
+  allTypeReferences: Set<string> = new Set();
 
   declarations = new Map<string, DeclarationScope>();
 
@@ -29,11 +31,18 @@ class Transformer {
     for (const stmt of sourceFile.statements) {
       this.convertStatement(stmt);
     }
+
+    for (const scope of this.declarations.values()) {
+      for (const valueRef of scope.getValueReferences()) {
+        this.allTypeReferences.add(valueRef);
+      }
+    }
   }
 
   transform(): ConvertOutput {
     return {
       ast: this.ast,
+      valueReferences: this.allTypeReferences,
     };
   }
 

src/transform/TypeOnlyFixer.ts

@@ -17,6 +17,7 @@ export class TypeOnlyFixer {
   private values: Set<string> = new Set();
   private typeHints: Map<string, number> = new Map();
   private reExportTypeHints: Map<string, number> = new Map();
+  private typeofValueReferences: Set<string> = new Set();
 
   private importNodes: ImportDeclarationWithClause[] = [];
   private exportNodes: ExportDeclarationWithClause[] = [];
@@ -27,6 +28,10 @@ export class TypeOnlyFixer {
     this.code = new MagicString(rawCode);
   }
 
+  setValueReferences(valueReferences: Set<string>) {
+    this.typeofValueReferences = valueReferences;
+  }
+
   fix() {
     this.analyze(this.source.statements);
 
@@ -274,6 +279,9 @@ export class TypeOnlyFixer {
   }
 
   private isTypeOnly(name: string) {
+    if(this.typeofValueReferences.has(name)) {
+      return false;
+    }
     return this.typeHints.has(name)
       || (this.types.has(name) && !this.values.has(name));
   }

src/transform/index.ts

@@ -27,6 +27,7 @@ import { parse, trimExtension, JSON_EXTENSIONS } from "../helpers.js";
 export const transform = () => {
   const allTypeReferences = new Map<string, Set<string>>();
   const allFileReferences = new Map<string, Set<string>>();
+  const allValueReferences = new Map<string, Set<string>>();
 
   return {
     name: "dts-transform",
@@ -88,6 +89,8 @@ export const transform = () => {
       sourceFile = parse(fileName, code);
       const converted = convert({ sourceFile });
 
+      allValueReferences.set(sourceFile.fileName, converted.valueReferences);
+
       if (process.env.DTS_DUMP_AST) {
         console.log(fileName);
         console.log(code);
@@ -103,10 +106,14 @@ export const transform = () => {
 
       const typeReferences = new Set<string>();
       const fileReferences = new Set<string>();
+      const valueReferences = new Set<string>();
       for (const fileName of Object.keys(chunk.modules)) {
         for (const ref of allTypeReferences.get(fileName.split("\\").join("/")) || []) {
           typeReferences.add(ref);
         }
+        for (const ref of allValueReferences.get(fileName.split("\\").join("/")) || []) {
+          valueReferences.add(ref);
+        }
         for (const ref of allFileReferences.get(fileName.split("\\").join("/")) || []) {
           if (ref.startsWith(".")) {
             // Need absolute path of the target file here
@@ -135,6 +142,7 @@ export const transform = () => {
       }
 
       const typeOnlyFixer = new TypeOnlyFixer(chunk.fileName, code, !!options.sourcemap);
+      typeOnlyFixer.setValueReferences(typeReferences);
 
       return typeOnlyFixer.fix();
     },

tests/testcases/typeof-generic-type-parameter/expected.d.ts

@@ -0,0 +1,4 @@
+import { Test } from './models';
+import { test } from './test';
+declare const b: ReturnType<typeof test<Test>>;
+export { b };

tests/testcases/typeof-generic-type-parameter/index.d.ts

@@ -0,0 +1,4 @@
+import { Test } from './models';
+import { test } from './test';
+
+export const b: ReturnType<typeof test<Test>>;

tests/testcases/typeof-generic-type-parameter/meta.js

@@ -0,0 +1,14 @@
+// @ts-check
+/** @type {import('../../testcases').Meta} */
+export default {
+  tsVersion: "4.8",
+  options: {
+    respectExternal: true,
+  },
+  rollupOptions: {
+    input: {
+      index: "index.d.ts",
+    },
+    external: ["./models", "./test"],
+  },
+};

tests/testcases/typeof-generic-type-parameter/models.d.ts

@@ -0,0 +1,3 @@
+export type Test = {
+  a: string;
+};

tests/testcases/typeof-generic-type-parameter/test.d.ts

@@ -0,0 +1,3 @@
+import { Test } from './models';
+
+export function test<T extends Test>(input: T): () => T;