From b66496d5fe449813690580ad3d8c2e1cbe463368 Mon Sep 17 00:00:00 2001
From: Myles Borins <myles.borins@gmail.com>
Date: Fri, 6 Mar 2020 02:11:13 -0500
Subject: [PATCH] module: bring back support for exports: false

Refs: https://github.com/nodejs/node/pull/31625
Refs: https://github.com/nodejs/node/issues/32107
Refs: https://github.com/babel/babel/issues/11216
---
 lib/internal/modules/cjs/loader.js            |  2 +-
 src/module_wrap.cc                            | 36 ++++++++++---------
 test/es-module/test-esm-exports.mjs           |  8 +++++
 .../pkgexports-false-cjs/main.cjs             |  1 +
 .../pkgexports-false-cjs/package.json         |  4 +++
 .../pkgexports-false-mjs/main.mjs             |  1 +
 .../pkgexports-false-mjs/package.json         |  4 +++
 7 files changed, 38 insertions(+), 18 deletions(-)
 create mode 100644 test/fixtures/node_modules/pkgexports-false-cjs/main.cjs
 create mode 100644 test/fixtures/node_modules/pkgexports-false-cjs/package.json
 create mode 100644 test/fixtures/node_modules/pkgexports-false-mjs/main.mjs
 create mode 100644 test/fixtures/node_modules/pkgexports-false-mjs/package.json

diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index a73101aa1feaf1..752cf46e8cbfdc 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -495,7 +495,7 @@ function applyExports(basePath, expansion) {
   const mappingKey = `.${expansion}`;
 
   let pkgExports = readPackageExports(basePath);
-  if (pkgExports === undefined || pkgExports === null)
+  if (pkgExports === undefined || pkgExports === null || pkgExports === false)
     return path.resolve(basePath, mappingKey);
 
   if (isConditionalDotExportSugar(pkgExports, basePath))
diff --git a/src/module_wrap.cc b/src/module_wrap.cc
index 2b1708088bf449..839864f71cb05b 100644
--- a/src/module_wrap.cc
+++ b/src/module_wrap.cc
@@ -1145,25 +1145,27 @@ Maybe<URL> PackageMainResolve(Environment* env,
 
     if (!pcfg.exports.IsEmpty()) {
       Local<Value> exports = pcfg.exports.Get(isolate);
-      Maybe<bool> isConditionalExportsMainSugar =
-          IsConditionalExportsMainSugar(env, exports, pjson_url, base);
-      if (isConditionalExportsMainSugar.IsNothing())
-        return Nothing<URL>();
-      if (isConditionalExportsMainSugar.FromJust()) {
-        return ResolveExportsTarget(env, pjson_url, exports, "", "", base);
-      } else if (exports->IsObject()) {
-        Local<Object> exports_obj = exports.As<Object>();
-        if (exports_obj->HasOwnProperty(env->context(), env->dot_string())
-            .FromJust()) {
-          Local<Value> target =
-              exports_obj->Get(env->context(), env->dot_string())
-              .ToLocalChecked();
-          return ResolveExportsTarget(env, pjson_url, target, "", "", base);
+      if (!exports->IsFalse()) {
+        Maybe<bool> isConditionalExportsMainSugar =
+            IsConditionalExportsMainSugar(env, exports, pjson_url, base);
+        if (isConditionalExportsMainSugar.IsNothing())
+          return Nothing<URL>();
+        if (isConditionalExportsMainSugar.FromJust()) {
+          return ResolveExportsTarget(env, pjson_url, exports, "", "", base);
+        } else if (exports->IsObject()) {
+          Local<Object> exports_obj = exports.As<Object>();
+          if (exports_obj->HasOwnProperty(env->context(), env->dot_string())
+              .FromJust()) {
+            Local<Value> target =
+                exports_obj->Get(env->context(), env->dot_string())
+                .ToLocalChecked();
+            return ResolveExportsTarget(env, pjson_url, target, "", "", base);
+          }
         }
+        std::string msg = "No \"exports\" main resolved in " +
+            pjson_url.ToFilePath();
+        node::THROW_ERR_PACKAGE_PATH_NOT_EXPORTED(env, msg.c_str());
       }
-      std::string msg = "No \"exports\" main resolved in " +
-          pjson_url.ToFilePath();
-      node::THROW_ERR_PACKAGE_PATH_NOT_EXPORTED(env, msg.c_str());
     }
     if (pcfg.has_main == HasMain::Yes) {
       URL resolved(pcfg.main, pjson_url);
diff --git a/test/es-module/test-esm-exports.mjs b/test/es-module/test-esm-exports.mjs
index 7dbc963502824e..a1163452c6932e 100644
--- a/test/es-module/test-esm-exports.mjs
+++ b/test/es-module/test-esm-exports.mjs
@@ -33,6 +33,14 @@ import fromInside from '../fixtures/node_modules/pkgexports/lib/hole.js';
       { default: 'self-cjs' } : { default: 'self-mjs' }],
     // Resolve self sugar
     ['pkgexports-sugar', { default: 'main' }],
+    // Resolve exports false
+    isRequire ? [
+      'pkgexports-false-cjs',
+      { default: 'false-exports-cjs'
+    }] : [
+      'pkgexports-false-mjs',
+      { default: 'false-exports-mjs'
+    }],
   ]);
 
   for (const [validSpecifier, expected] of validSpecifiers) {
diff --git a/test/fixtures/node_modules/pkgexports-false-cjs/main.cjs b/test/fixtures/node_modules/pkgexports-false-cjs/main.cjs
new file mode 100644
index 00000000000000..48ff9c2b91f860
--- /dev/null
+++ b/test/fixtures/node_modules/pkgexports-false-cjs/main.cjs
@@ -0,0 +1 @@
+module.exports = 'false-exports-cjs';
diff --git a/test/fixtures/node_modules/pkgexports-false-cjs/package.json b/test/fixtures/node_modules/pkgexports-false-cjs/package.json
new file mode 100644
index 00000000000000..2b5d92a21e56b8
--- /dev/null
+++ b/test/fixtures/node_modules/pkgexports-false-cjs/package.json
@@ -0,0 +1,4 @@
+{
+  "main": "./main.cjs",
+  "exports": false
+}
diff --git a/test/fixtures/node_modules/pkgexports-false-mjs/main.mjs b/test/fixtures/node_modules/pkgexports-false-mjs/main.mjs
new file mode 100644
index 00000000000000..9495fea4907216
--- /dev/null
+++ b/test/fixtures/node_modules/pkgexports-false-mjs/main.mjs
@@ -0,0 +1 @@
+export default 'false-exports-mjs';
diff --git a/test/fixtures/node_modules/pkgexports-false-mjs/package.json b/test/fixtures/node_modules/pkgexports-false-mjs/package.json
new file mode 100644
index 00000000000000..aa78413bdad28d
--- /dev/null
+++ b/test/fixtures/node_modules/pkgexports-false-mjs/package.json
@@ -0,0 +1,4 @@
+{
+  "main": "./main.mjs",
+  "exports": false
+}