From bf4f0183f0b6148d1610a4a8eb158979d72eabe5 Mon Sep 17 00:00:00 2001
From: Guy Bedford <guybedford@gmail.com>
Date: Sun, 26 Apr 2020 21:40:01 -0700
Subject: [PATCH] module: no type module resolver side effects

---
 doc/api/esm.md                                    | 7 -------
 lib/internal/modules/esm/resolve.js               | 9 +--------
 test/es-module/test-esm-type-main.mjs             | 9 +++++++++
 test/fixtures/node_modules/type-main/index.js     | 1 +
 test/fixtures/node_modules/type-main/package.json | 4 ++++
 5 files changed, 15 insertions(+), 15 deletions(-)
 create mode 100644 test/es-module/test-esm-type-main.mjs
 create mode 100644 test/fixtures/node_modules/type-main/index.js
 create mode 100644 test/fixtures/node_modules/type-main/package.json

diff --git a/doc/api/esm.md b/doc/api/esm.md
index 49c467effbc3cd..5047600f988f66 100644
--- a/doc/api/esm.md
+++ b/doc/api/esm.md
@@ -1601,13 +1601,6 @@ The resolver can throw the following errors:
 >       1. Return **PACKAGE_EXPORTS_TARGET_RESOLVE**(_packageURL_,
 >          _mainExport_, _""_).
 >    1. Throw a _Package Path Not Exported_ error.
-> 1. If _pjson.main_ is a String, then
->    1. Let _resolvedMain_ be the URL resolution of _packageURL_, "/", and
->       _pjson.main_.
->    1. If the file at _resolvedMain_ exists, then
->       1. Return _resolvedMain_.
-> 1. If _pjson.type_ is equal to _"module"_, then
->    1. Throw a _Module Not Found_ error.
 > 1. Let _legacyMainURL_ be the result applying the legacy
 >    **LOAD_AS_DIRECTORY** CommonJS resolver to _packageURL_, throwing a
 >    _Module Not Found_ error for no resolution.
diff --git a/lib/internal/modules/esm/resolve.js b/lib/internal/modules/esm/resolve.js
index 5bb2f37e53eeb5..8b8582544494a5 100644
--- a/lib/internal/modules/esm/resolve.js
+++ b/lib/internal/modules/esm/resolve.js
@@ -439,11 +439,6 @@ function packageMainResolve(packageJSONUrl, packageConfig, base, conditions) {
 
       throw new ERR_PACKAGE_PATH_NOT_EXPORTED(packageJSONUrl, '.');
     }
-    if (packageConfig.main !== undefined) {
-      const resolved = new URL(packageConfig.main, packageJSONUrl);
-      const path = fileURLToPath(resolved);
-      if (tryStatSync(path).isFile()) return resolved;
-    }
     if (getOptionValue('--experimental-specifier-resolution') === 'node') {
       if (packageConfig.main !== undefined) {
         return finalizeResolution(
@@ -453,9 +448,7 @@ function packageMainResolve(packageJSONUrl, packageConfig, base, conditions) {
           new URL('index', packageJSONUrl), base);
       }
     }
-    if (packageConfig.type !== 'module') {
-      return legacyMainResolve(packageJSONUrl, packageConfig);
-    }
+    return legacyMainResolve(packageJSONUrl, packageConfig);
   }
 
   throw new ERR_MODULE_NOT_FOUND(
diff --git a/test/es-module/test-esm-type-main.mjs b/test/es-module/test-esm-type-main.mjs
new file mode 100644
index 00000000000000..012cf4f35fc959
--- /dev/null
+++ b/test/es-module/test-esm-type-main.mjs
@@ -0,0 +1,9 @@
+import { mustNotCall } from '../common/index.mjs';
+import assert from 'assert';
+import { importFixture } from '../fixtures/pkgexports.mjs';
+
+(async () => {
+  const m = await importFixture('type-main');
+  assert.strictEqual(m.default, 'asdf');
+})()
+.catch(mustNotCall);
diff --git a/test/fixtures/node_modules/type-main/index.js b/test/fixtures/node_modules/type-main/index.js
new file mode 100644
index 00000000000000..a4cb53964349f5
--- /dev/null
+++ b/test/fixtures/node_modules/type-main/index.js
@@ -0,0 +1 @@
+export default 'asdf';
diff --git a/test/fixtures/node_modules/type-main/package.json b/test/fixtures/node_modules/type-main/package.json
new file mode 100644
index 00000000000000..7665d7a8037428
--- /dev/null
+++ b/test/fixtures/node_modules/type-main/package.json
@@ -0,0 +1,4 @@
+{
+  "main": "index",
+  "type": "module"
+}