CJS & ESM static analysis

Author: laverdet

Diff for: packages/cli/src/problemUtils.ts

@@ -9,7 +9,7 @@ export const problemFlags = {
   CJSResolvesToESM: "cjs-resolves-to-esm",
   FallbackCondition: "fallback-condition",
   CJSOnlyExportsDefault: "cjs-only-exports-default",
-  CJSNamedExports: "cjs-named-exports",
+  NamedExports: "named-exports",
   FalseExportDefault: "false-export-default",
   MissingExportEquals: "missing-export-equals",
   UnexpectedModuleSyntax: "unexpected-module-syntax",

Diff for: packages/core/package.json

@@ -25,7 +25,7 @@
   },
   "type": "module",
   "imports": {
-    "#internal/*": "./dist/internal/*"
+    "#*": "./dist/*"
   },
   "exports": {
     ".": {
@@ -51,6 +51,7 @@
   },
   "dependencies": {
     "@andrewbranch/untar.js": "^1.0.3",
+    "acorn": "^8.11.3",
     "cjs-module-lexer": "^1.2.3",
     "fflate": "^0.8.2",
     "semver": "^7.5.4",

Diff for: packages/core/src/internal/checks/cjsNamedExports.ts

@@ -1,5 +1,5 @@
 import cjsOnlyExportsDefault from "./cjsOnlyExportsDefault.js";
-import cjsNamedExports from "./cjsNamedExports.js";
+import namedExports from "./namedExports.js";
 import entrypointResolutions from "./entrypointResolutions.js";
 import exportDefaultDisagreement from "./exportDefaultDisagreement.js";
 import internalResolutionError from "./internalResolutionError.js";
@@ -10,7 +10,7 @@ export default [
   entrypointResolutions,
   moduleKindDisagreement,
   exportDefaultDisagreement,
-  cjsNamedExports,
+  namedExports,
   cjsOnlyExportsDefault,
   unexpectedModuleSyntax,
   internalResolutionError,

Diff for: packages/core/src/internal/checks/index.ts

@@ -0,0 +1,41 @@
+import ts from "typescript";
+import { defineCheck } from "../defineCheck.js";
+import { getEsmModuleNamespace } from "../esm/esmNamespace.js";
+
+export default defineCheck({
+  name: "NamedExports",
+  dependencies: ({ entrypoints, subpath, resolutionKind }) => {
+    const entrypoint = entrypoints[subpath].resolutions[resolutionKind];
+    const typesFileName = entrypoint.resolution?.fileName;
+    const implementationFileName = entrypoint.implementationResolution?.fileName;
+    return [implementationFileName, typesFileName, resolutionKind];
+  },
+  execute: ([implementationFileName, typesFileName, resolutionKind], context) => {
+    if (!implementationFileName || !typesFileName || resolutionKind !== "node16-esm") {
+      return;
+    }
+
+    // Get declared exported names from TypeScript
+    const host = context.hosts.findHostForFiles([typesFileName])!;
+    const typesSourceFile = host.getSourceFile(typesFileName)!;
+    const typeChecker = host.createAuxiliaryProgram([typesFileName]).getTypeChecker();
+    const typesExports = typeChecker.getExportsAndPropertiesOfModule(typesSourceFile.symbol);
+    const expectedNames = typesExports
+      .flatMap((node) => [...(node.declarations?.values() ?? [])])
+      .filter((node) => !ts.isTypeAlias(node) && !ts.isTypeDeclaration(node) && !ts.isNamespaceBody(node))
+      .map((declaration) => declaration.symbol.escapedName);
+
+    // Get actual exported names as seen by nodejs
+    const exports = getEsmModuleNamespace(context.pkg, implementationFileName);
+    const missing = expectedNames.filter((name) => !exports.includes(String(name))).map(String);
+    if (missing.length > 0) {
+      console.log("🚨", implementationFileName, missing);
+      return {
+        kind: "NamedExports",
+        implementationFileName,
+        typesFileName,
+        missing,
+      };
+    }
+  },
+});

Diff for: packages/core/src/internal/checks/namedExports.ts

@@ -0,0 +1,8 @@
+import type { Exports } from "cjs-module-lexer";
+import { init, parse as cjsParse } from "cjs-module-lexer";
+
+await init();
+
+export function getCjsModuleBindings(sourceText: string): Exports {
+  return cjsParse(sourceText);
+}

Diff for: packages/core/src/internal/esm/cjsBindings.ts

@@ -0,0 +1,32 @@
+import { Package } from "../../createPackage.js";
+import { getCjsModuleBindings } from "./cjsBindings.js";
+import { cjsResolve } from "./cjsResolve.js";
+
+export function getCjsModuleNamespace(fs: Package, file: URL, seen = new Set<string>()) {
+  seen.add(file.pathname);
+  const { exports, reexports } = getCjsModuleBindings(fs.readFile(file.pathname));
+
+  // CJS always exports `default`
+  if (!exports.includes("default")) {
+    exports.push("default");
+  }
+
+  // Additionally, resolve facade reexports
+  const lastResolvableReexport = (() => {
+    for (const source of reexports.reverse()) {
+      try {
+        return cjsResolve(fs, source, file);
+      } catch {}
+    }
+  })();
+  if (
+    lastResolvableReexport &&
+    lastResolvableReexport.format === "commonjs" &&
+    !seen.has(lastResolvableReexport.resolved.pathname)
+  ) {
+    const extra = getCjsModuleNamespace(fs, lastResolvableReexport.resolved, seen);
+    exports.push(...extra.filter((name) => !exports.includes(name)));
+  }
+
+  return exports;
+}