module: bring back support for exports: false

Refs: nodejs#31625
Refs: nodejs#32107
Refs: babel/babel#11216

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))

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);

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) {