convert @babel/helper-module-transforms to typescript (#12928)

Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com>

lib/babel-packages.js.flow

@@ -208,3 +208,7 @@ declare module "@babel/highlight" {
 declare module "@babel/plugin-bugfix-v8-spread-parameters-in-optional-chaining" {
   declare module.exports: any;
 }
+
+declare module "@babel/helper-module-transforms" {
+  declare module.exports: any;
+}

packages/babel-helper-module-transforms/src/get-module-name.ts

@@ -1,9 +1,7 @@
-// @flow
-
 export default function getModuleName(
-  rootOpts: Object,
-  pluginOpts: Object,
-): ?string {
+  rootOpts: any,
+  pluginOpts: any,
+): string | undefined | null {
   const {
     filename,
     filenameRelative = filename,

packages/babel-helper-module-transforms/src/index.ts

@@ -9,9 +9,13 @@ import rewriteLiveReferences from "./rewrite-live-references";
 import normalizeAndLoadModuleMetadata, {
   hasExports,
   isSideEffectImport,
-  type ModuleMetadata,
-  type SourceModuleMetadata,
 } from "./normalize-and-load-metadata";
+import type {
+  InteropType,
+  ModuleMetadata,
+  SourceModuleMetadata,
+} from "./normalize-and-load-metadata";
+import type { NodePath } from "@babel/traverse";
 
 export { default as getModuleName } from "./get-module-name";
 
@@ -24,7 +28,7 @@ export { hasExports, isSideEffectImport, isModule, rewriteThis };
  * and returns a list of statements for use when initializing the module.
  */
 export function rewriteModuleStatementsAndPrepareHeader(
-  path: NodePath,
+  path: NodePath<t.Program>,
   {
     // TODO(Babel 8): Remove this
     loose,
@@ -39,6 +43,17 @@ export function rewriteModuleStatementsAndPrepareHeader(
 
     constantReexports = loose,
     enumerableModuleMeta = loose,
+  }: {
+    exportName?;
+    strict;
+    allowTopLevelThis?;
+    strictMode;
+    loose?;
+    noInterop?;
+    lazy?;
+    esNamespaceOnly?;
+    constantReexports?;
+    enumerableModuleMeta?;
   },
 ) {
   assert(isModule(path), "Cannot process module statements in a script");
@@ -106,9 +121,9 @@ export function ensureStatementsHoisted(statements) {
  */
 export function wrapInterop(
   programPath: NodePath,
-  expr: Node,
+  expr: t.Expression,
   type: InteropType,
-): Node {
+): t.CallExpression {
   if (type === "none") {
     return null;
   }
@@ -138,7 +153,7 @@ export function buildNamespaceInitStatements(
 ) {
   const statements = [];
 
-  let srcNamespace = t.identifier(sourceMetadata.name);
+  let srcNamespace: t.Node = t.identifier(sourceMetadata.name);
   if (sourceMetadata.lazy) srcNamespace = t.callExpression(srcNamespace, []);
 
   for (const localName of sourceMetadata.importsNamespace) {
@@ -329,7 +344,7 @@ function buildExportNameListDeclaration(
       exportedVars[exportName] = true;
     }
 
-    hasReexport = hasReexport || data.reexportAll;
+    hasReexport = hasReexport || !!data.reexportAll;
   }
 
   if (!hasReexport || Object.keys(exportedVars).length === 0) return null;

packages/babel-helper-module-transforms/src/normalize-and-load-metadata.ts

@@ -1,61 +1,52 @@
 import { basename, extname } from "path";
+import type * as t from "@babel/types";
 
 import { isIdentifierName } from "@babel/helper-validator-identifier";
 import splitExportDeclaration from "@babel/helper-split-export-declaration";
+import type { NodePath } from "@babel/traverse";
 
-export type ModuleMetadata = {
-  exportName: string,
-
+export interface ModuleMetadata {
+  exportName: string;
   // The name of the variable that will reference an object containing export names.
-  exportNameListName: null | string,
-
-  hasExports: boolean,
-
+  exportNameListName: null | string;
+  hasExports: boolean;
   // Lookup from local binding to export information.
-  local: Map<string, LocalExportMetadata>,
-
+  local: Map<string, LocalExportMetadata>;
   // Lookup of source file to source file metadata.
-  source: Map<string, SourceModuleMetadata>,
-
+  source: Map<string, SourceModuleMetadata>;
   // List of names that should only be printed as string literals.
   // i.e. `import { "any unicode" as foo } from "some-module"`
   // `stringSpecifiers` is Set(1) ["any unicode"]
   // In most cases `stringSpecifiers` is an empty Set
-  stringSpecifiers: Set<string>,
-};
+  stringSpecifiers: Set<string>;
+}
 
 export type InteropType = "default" | "namespace" | "none";
 
-export type SourceModuleMetadata = {
+export interface SourceModuleMetadata {
   // A unique variable name to use for this namespace object. Centralized for simplicity.
-  name: string,
-
-  loc: ?BabelNodeSourceLocation,
-
-  interop: InteropType,
-
+  name: string;
+  loc: t.SourceLocation | undefined | null;
+  interop: InteropType;
   // Local binding to reference from this source namespace. Key: Local name, value: Import name
-  imports: Map<string, string>,
-
+  imports: Map<string, string>;
   // Local names that reference namespace object.
-  importsNamespace: Set<string>,
-
+  importsNamespace: Set<string>;
   // Reexports to create for namespace. Key: Export name, value: Import name
-  reexports: Map<string, string>,
-
+  reexports: Map<string, string>;
   // List of names to re-export namespace as.
-  reexportNamespace: Set<string>,
-
+  reexportNamespace: Set<string>;
   // Tracks if the source should be re-exported.
   reexportAll: null | {
-    loc: ?BabelNodeSourceLocation,
-  },
+    loc: t.SourceLocation | undefined | null;
   };
+  lazy?;
+}
 
-export type LocalExportMetadata = {
-  name: Array<string>, // names of exports
-  kind: "import" | "hoisted" | "block" | "var",
-};
+export interface LocalExportMetadata {
+  names: Array<string>; // names of exports,
+  kind: "import" | "hoisted" | "block" | "var";
+}
 
 /**
  * Check if the module has any exports that need handling.
@@ -82,7 +73,7 @@ export function isSideEffectImport(source: SourceModuleMetadata) {
  * needed to reconstruct the module's behavior.
  */
 export default function normalizeModuleAndLoadMetadata(
-  programPath: NodePath,
+  programPath: NodePath<t.Program>,
   exportName?: string,
   {
     noInterop = false,
@@ -94,7 +85,7 @@ export default function normalizeModuleAndLoadMetadata(
   if (!exportName) {
     exportName = programPath.scope.generateUidIdentifier("exports").name;
   }
-  const stringSpecifiers = new Set();
+  const stringSpecifiers = new Set<string>();
 
   nameAnonymousExports(programPath);
 
@@ -166,11 +157,15 @@ function getExportSpecifierName(
  * Get metadata about the imports and exports present in this module.
  */
 function getModuleMetadata(
-  programPath: NodePath,
+  programPath: NodePath<t.Program>,
   {
     lazy,
     initializeReexports,
-  }: { lazy: boolean, initializeReexports: boolean },
+  }: {
+    // todo(flow-ts) changed from boolean, to match expected usage inside the function
+    lazy: boolean | string[] | Function;
+    initializeReexports: boolean;
+  },
   stringSpecifiers: Set<string>,
 ) {
   const localData = getLocalExportMetadata(
@@ -289,7 +284,9 @@ function getModuleMetadata(
         data.reexports.set(exportName, importName);
 
         if (exportName === "__esModule") {
-          throw exportName.buildCodeFrameError('Illegal export "__esModule".');
+          throw spec
+            .get("exported")
+            .buildCodeFrameError('Illegal export "__esModule".');
         }
       });
     } else if (
@@ -360,13 +357,13 @@ function getModuleMetadata(
  * Get metadata about local variables that are exported.
  */
 function getLocalExportMetadata(
-  programPath: NodePath,
+  programPath: NodePath<t.Program>,
   initializeReexports: boolean,
   stringSpecifiers: Set<string>,
 ): Map<string, LocalExportMetadata> {
   const bindingKindLookup = new Map();
 
-  programPath.get("body").forEach(child => {
+  programPath.get("body").forEach((child: any) => {
     let kind;
     if (child.isImportDeclaration()) {
       kind = "import";
@@ -434,7 +431,8 @@ function getLocalExportMetadata(
       (initializeReexports || !child.node.source)
     ) {
       if (child.node.declaration) {
-        const declaration = child.get("declaration");
+        // todo: flow->ts babel-types node field types
+        const declaration = child.get("declaration") as NodePath;
         const ids = declaration.getOuterBindingIdentifierPaths();
         Object.keys(ids).forEach(name => {
           if (name === "__esModule") {
@@ -463,6 +461,7 @@ function getLocalExportMetadata(
         declaration.isFunctionDeclaration() ||
         declaration.isClassDeclaration()
       ) {
+        // @ts-expect-error todo(flow->ts): improve babel-types
         getLocalMetadata(declaration.get("id")).names.push("default");
       } else {
         // These should have been removed by the nameAnonymousExports() call.
@@ -478,7 +477,7 @@ function getLocalExportMetadata(
 /**
  * Ensure that all exported values have local binding names.
  */
-function nameAnonymousExports(programPath: NodePath) {
+function nameAnonymousExports(programPath: NodePath<t.Program>) {
   // Name anonymous exported locals.
   programPath.get("body").forEach(child => {
     if (!child.isExportDefaultDeclaration()) return;
@@ -486,12 +485,13 @@ function nameAnonymousExports(programPath: NodePath) {
   });
 }
 
-function removeModuleDeclarations(programPath: NodePath) {
+function removeModuleDeclarations(programPath: NodePath<t.Program>) {
   programPath.get("body").forEach(child => {
     if (child.isImportDeclaration()) {
       child.remove();
     } else if (child.isExportNamedDeclaration()) {
       if (child.node.declaration) {
+        // @ts-expect-error todo(flow->ts): avoid mutations
         child.node.declaration._blockHoist = child.node._blockHoist;
         child.replaceWith(child.node.declaration);
       } else {
@@ -504,6 +504,7 @@ function removeModuleDeclarations(programPath: NodePath) {
         declaration.isFunctionDeclaration() ||
         declaration.isClassDeclaration()
       ) {
+        // @ts-expect-error todo(flow->ts): avoid mutations
         declaration._blockHoist = child.node._blockHoist;
         child.replaceWith(declaration);
       } else {

packages/babel-helper-module-transforms/src/rewrite-live-references.ts

@@ -1,12 +1,33 @@
 import assert from "assert";
 import * as t from "@babel/types";
 import template from "@babel/template";
+import type { NodePath, Visitor, Scope } from "@babel/traverse";
 import simplifyAccess from "@babel/helper-simple-access";
 
 import type { ModuleMetadata } from "./normalize-and-load-metadata";
 
+interface RewriteReferencesVisitorState {
+  exported: Map<any, any>;
+  metadata: ModuleMetadata;
+  requeueInParent: (path) => void;
+  scope: Scope;
+  imported: Map<any, any>;
+  buildImportReference: (
+    [source, importName, localName]: readonly [any, any, any],
+    identNode,
+  ) => any;
+  seen: WeakSet<object>;
+}
+
+interface RewriteBindingInitVisitorState {
+  exported: Map<any, any>;
+  metadata: ModuleMetadata;
+  requeueInParent: (path) => void;
+  scope: Scope;
+}
+
 export default function rewriteLiveReferences(
-  programPath: NodePath,
+  programPath: NodePath<t.Program>,
   metadata: ModuleMetadata,
 ) {
   const imported = new Map();
@@ -39,12 +60,16 @@ export default function rewriteLiveReferences(
   }
 
   // Rewrite initialization of bindings to update exports.
-  programPath.traverse(rewriteBindingInitVisitor, {
+  const rewriteBindingInitVisitorState: RewriteBindingInitVisitorState = {
     metadata,
     requeueInParent,
     scope: programPath.scope,
     exported, // local name => exported name list
-  });
+  };
+  programPath.traverse(
+    rewriteBindingInitVisitor,
+    rewriteBindingInitVisitorState,
+  );
 
   simplifyAccess(
     programPath,
@@ -53,7 +78,7 @@ export default function rewriteLiveReferences(
   );
 
   // Rewrite reads/writes from imports and exports to have the correct behavior.
-  programPath.traverse(rewriteReferencesVisitor, {
+  const rewriteReferencesVisitorState: RewriteReferencesVisitorState = {
     seen: new WeakSet(),
     metadata,
     requeueInParent,
@@ -68,7 +93,7 @@ export default function rewriteLiveReferences(
         return identNode;
       }
 
-      let namespace = t.identifier(meta.name);
+      let namespace: t.Expression = t.identifier(meta.name);
       if (meta.lazy) namespace = t.callExpression(namespace, []);
 
       const computed = metadata.stringSpecifiers.has(importName);
@@ -79,13 +104,14 @@ export default function rewriteLiveReferences(
         computed,
       );
     },
-  });
+  };
+  programPath.traverse(rewriteReferencesVisitor, rewriteReferencesVisitorState);
 }
 
 /**
  * A visitor to inject export update statements during binding initialization.
  */
-const rewriteBindingInitVisitor = {
+const rewriteBindingInitVisitor: Visitor<RewriteBindingInitVisitorState> = {
   Scope(path) {
     path.skip();
   },
@@ -105,6 +131,7 @@ const rewriteBindingInitVisitor = {
           t.identifier(localName),
         ),
       );
+      // @ts-expect-error todo(flow->ts): avoid mutations
       statement._blockHoist = path.node._blockHoist;
 
       requeueInParent(path.insertAfter(statement)[0]);
@@ -124,6 +151,7 @@ const rewriteBindingInitVisitor = {
             t.identifier(localName),
           ),
         );
+        // @ts-expect-error todo(flow->ts): avoid mutations
         statement._blockHoist = path.node._blockHoist;
 
         requeueInParent(path.insertAfter(statement)[0]);
@@ -163,7 +191,7 @@ const buildImportThrow = localName => {
   `;
 };
 
-const rewriteReferencesVisitor = {
+const rewriteReferencesVisitor: Visitor<RewriteReferencesVisitorState> = {
   ReferencedIdentifier(path) {
     const {
       seen,
@@ -200,9 +228,11 @@ const rewriteReferencesVisitor = {
       } else if (path.isJSXIdentifier() && t.isMemberExpression(ref)) {
         const { object, property } = ref;
         path.replaceWith(
-          t.JSXMemberExpression(
-            t.JSXIdentifier(object.name),
-            t.JSXIdentifier(property.name),
+          t.jsxMemberExpression(
+            // @ts-expect-error todo(flow->ts): possible bug `object` might not have a name
+            t.jsxIdentifier(object.name),
+            // @ts-expect-error todo(flow->ts): possible bug `property` might not have a name
+            t.jsxIdentifier(property.name),
           ),
         );
       } else {
@@ -303,9 +333,10 @@ const rewriteReferencesVisitor = {
         });
 
         if (items.length > 0) {
-          let node = t.sequenceExpression(items);
+          let node: t.Node = t.sequenceExpression(items);
           if (path.parentPath.isExpressionStatement()) {
             node = t.expressionStatement(node);
+            // @ts-expect-error todo(flow->ts): avoid mutations
             node._blockHoist = path.parentPath.node._blockHoist;
           }
 
@@ -315,7 +346,9 @@ const rewriteReferencesVisitor = {
       }
     },
   },
-  "ForOfStatement|ForInStatement"(path) {
+  "ForOfStatement|ForInStatement"(
+    path: NodePath<t.ForOfStatement | t.ForInStatement>,
+  ) {
     const { scope, node } = path;
     const { left } = node;
     const { exported, scope: programScope } = this;

packages/babel-helper-module-transforms/src/rewrite-this.ts

@@ -2,6 +2,7 @@ import { environmentVisitor } from "@babel/helper-replace-supers";
 import traverse from "@babel/traverse";
 import * as t from "@babel/types";
 
+import type { NodePath, Visitor } from "@babel/traverse";
 export default function rewriteThis(programPath: NodePath) {
   // Rewrite "this" to be "undefined".
   traverse(programPath.node, { ...rewriteThisVisitor, noScope: true });
@@ -11,10 +12,10 @@ export default function rewriteThis(programPath: NodePath) {
  * A visitor to walk the tree, rewriting all `this` references in the top-level scope to be
  * `void 0` (undefined).
  */
-const rewriteThisVisitor = traverse.visitors.merge([
+const rewriteThisVisitor: Visitor = traverse.visitors.merge([
   environmentVisitor,
   {
-    ThisExpression(path) {
+    ThisExpression(path: NodePath<t.ThisExpression>) {
       path.replaceWith(t.unaryExpression("void", t.numericLiteral(0), true));
     },
   },