Fix: load .env value also if entry target is specified with source value in package.json

packages/core/core/src/resolveOptions.js

@@ -50,7 +50,18 @@ export default async function resolveOptions(
     entries = [path.resolve(inputCwd, initialOptions.entries)];
   }
 
-  let entryRoot = getRootDir(entries);
+  let entryRoot = getRootDir(
+    await Promise.all(
+      entries.map(async entry =>
+        // getRootDir treats the input as files, so getRootDir(["/home/user/myproject"]) returns "/home/user".
+        // Instead we need to make the entries refer to some file inside the specified folders.
+        (await inputFS.stat(entry)).isFile()
+          ? entry
+          : path.join(entry, 'index'),
+      ),
+    ),
+  );
+
   let projectRootFile =
     (await resolveConfig(
       inputFS,

packages/core/integration-tests/test/integration/env-file-with-package-source/.env

@@ -0,0 +1,2 @@
+FOO=bar
+BAR=test

packages/core/integration-tests/test/integration/env-file-with-package-source/index.js

@@ -0,0 +1 @@
+module.exports = process.env.FOO + process.env.BAR;

packages/core/integration-tests/test/integration/env-file-with-package-source/package.json

@@ -0,0 +1,4 @@
+{
+    "name": "env-file-with-package-source",
+    "source": "index.js"
+}

packages/core/integration-tests/test/javascript.js

@@ -2978,6 +2978,15 @@ describe('javascript', function () {
     assert.equal(output, 'barbaz');
   });
 
+  it('should insert environment variables from a file even if entry file is specified with source value in package.json', async function () {
+    let b = await bundle(
+      path.join(__dirname, '/integration/env-file-with-package-source'),
+    );
+
+    let output = await run(b);
+    assert.equal(output, 'bartest');
+  });
+
   it('should error on process.env mutations', async function () {
     let filePath = path.join(__dirname, '/integration/env-mutate/index.js');
     await assert.rejects(bundle(filePath), {