From e53ba1220ed299432a7cd792796373bbbeae5779 Mon Sep 17 00:00:00 2001
From: Marco Ippolito <marcoippolito54@gmail.com>
Date: Sat, 31 Jan 2026 15:50:29 +0100
Subject: [PATCH] src: allow empty --experimental-config-file

---
 doc/api/cli.md                                | 11 ++-
 doc/api/test.md                               |  2 +-
 doc/node.1                                    |  9 ++-
 lib/internal/process/pre_execution.js         |  3 +-
 src/node.cc                                   |  2 +-
 src/node_config_file.cc                       | 68 +++++++++++-------
 src/node_config_file.h                        |  2 +-
 src/node_options.cc                           | 10 +--
 src/node_options.h                            |  1 -
 test/parallel/test-cli-node-options-docs.js   |  1 +
 test/parallel/test-config-file.js             | 71 ++++++++++++++++++-
 test/parallel/test-runner-flag-propagation.js |  2 -
 12 files changed, 137 insertions(+), 45 deletions(-)

diff --git a/doc/api/cli.md b/doc/api/cli.md
index 065439a777e5dc..a0526760676220 100644
--- a/doc/api/cli.md
+++ b/doc/api/cli.md
@@ -1014,7 +1014,7 @@ added:
 
 Enable experimental import support for `.node` addons.
 
-### `--experimental-config-file=config`
+### `--experimental-config-file=path`, `--experimental-config-file`
 
 <!-- YAML
 added:
@@ -1025,6 +1025,10 @@ added:
 > Stability: 1.0 - Early development
 
 If present, Node.js will look for a configuration file at the specified path.
+If the path is not specified, Node.js will look for a `node.config.json` file
+in the current working directory.
+The alias `--experimental-default-config-file` is equivalent to
+`--experimental-config-file` without an argument.
 Node.js will read the configuration file and apply the settings. The
 configuration file should be a JSON file with the following structure. `vX.Y.Z`
 in the `$schema` must be replaced with the version of Node.js you are using.
@@ -1131,9 +1135,10 @@ added:
 
 > Stability: 1.0 - Early development
 
-If the `--experimental-default-config-file` flag is present, Node.js will look for a
+This flag is an alias for `--experimental-config-file` without an argument.
+If present, Node.js will look for a
 `node.config.json` file in the current working directory and load it as a
-as configuration file.
+configuration file.
 
 ### `--experimental-eventsource`
 
diff --git a/doc/api/test.md b/doc/api/test.md
index 6daa84d3b32f09..9ccc3e5400a716 100644
--- a/doc/api/test.md
+++ b/doc/api/test.md
@@ -4131,7 +4131,7 @@ Can be used to abort test subtasks when the test has been aborted.
 [`suite()`]: #suitename-options-fn
 [`test()`]: #testname-options-fn
 [code coverage]: #collecting-code-coverage
-[configuration files]: cli.md#--experimental-config-fileconfig
+[configuration files]: cli.md#--experimental-config-filepath---experimental-config-file
 [describe options]: #describename-options-fn
 [it options]: #testname-options-fn
 [running tests from the command line]: #running-tests-from-the-command-line
diff --git a/doc/node.1 b/doc/node.1
index 6d16ef84c45df0..90b21fc1e7bc63 100644
--- a/doc/node.1
+++ b/doc/node.1
@@ -602,8 +602,10 @@ It is possible to run code containing inline types unless the
 .It Fl -experimental-addon-modules
 Enable experimental import support for \fB.node\fR addons.
 .
-.It Fl -experimental-config-file Ns = Ns Ar config
+.It Fl -experimental-config-file= Ns Ar config , Fl -experimental-config-file , Fl -experimental-default-config-file
 If present, Node.js will look for a configuration file at the specified path.
+If the path is not specified, Node.js will look for a \fBnode.config.json\fR file
+in the current working directory.
 Node.js will read the configuration file and apply the settings. The
 configuration file should be a JSON file with the following structure. \fBvX.Y.Z\fR
 in the \fB$schema\fR must be replaced with the version of Node.js you are using.
@@ -689,9 +691,10 @@ Node.js will not sanitize or perform validation on the user-provided configurati
 so \fBNEVER\fR use untrusted configuration files.
 .
 .It Fl -experimental-default-config-file
-If the \fB--experimental-default-config-file\fR flag is present, Node.js will look for a
+This flag is an alias for \fB--experimental-config-file\fR without an argument.
+If present, Node.js will look for a
 \fBnode.config.json\fR file in the current working directory and load it as a
-as configuration file.
+configuration file.
 .
 .It Fl -experimental-eventsource
 Enable exposition of EventSource Web API on the global scope.
diff --git a/lib/internal/process/pre_execution.js b/lib/internal/process/pre_execution.js
index 0902536708bf1d..091bc18bbc3530 100644
--- a/lib/internal/process/pre_execution.js
+++ b/lib/internal/process/pre_execution.js
@@ -382,7 +382,8 @@ function setupSQLite() {
 
 function initializeConfigFileSupport() {
   if (getOptionValue('--experimental-default-config-file') ||
-      getOptionValue('--experimental-config-file')) {
+      getOptionValue('--experimental-config-file') ||
+      getOptionValue('--experimental-config-file=')) {
     emitExperimentalWarning('--experimental-config-file');
   }
 }
diff --git a/src/node.cc b/src/node.cc
index 5f25a5229675e9..164c6dcad27d4f 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -913,7 +913,7 @@ static ExitCode InitializeNodeWithArgsInternal(
   }
 
   std::string node_options_from_config;
-  if (auto path = per_process::config_reader.GetDataFromArgs(*argv)) {
+  if (auto path = per_process::config_reader.GetDataFromArgs(argv)) {
     switch (per_process::config_reader.ParseConfig(*path)) {
       case ParseResult::Valid:
         break;
diff --git a/src/node_config_file.cc b/src/node_config_file.cc
index 4205a3cee7e52a..d52078a4f30a6a 100644
--- a/src/node_config_file.cc
+++ b/src/node_config_file.cc
@@ -2,39 +2,55 @@
 #include "debug_utils-inl.h"
 #include "simdjson.h"
 
-#include <string>
-
 namespace node {
 
+constexpr std::string_view kConfigFileFlag = "--experimental-config-file";
+constexpr std::string_view kDefaultConfigFileFlag =
+    "--experimental-default-config-file";
+constexpr std::string_view kDefaultConfigFileName = "node.config.json";
+
+// Check if "--experimental-config-file=" has path arg
+inline bool HasEqualsPrefix(std::string_view arg, std::string_view flag) {
+  return arg.size() > flag.size() + 1 && arg.starts_with(flag) &&
+         arg[flag.size()] == '=';
+}
+
 std::optional<std::string_view> ConfigReader::GetDataFromArgs(
-    const std::vector<std::string>& args) {
-  constexpr std::string_view flag_path = "--experimental-config-file";
-  constexpr std::string_view default_file =
-      "--experimental-default-config-file";
-
-  bool has_default_config_file = false;
-
-  for (auto it = args.begin(); it != args.end(); ++it) {
-    if (*it == flag_path) {
-      // Case: "--experimental-config-file foo"
-      if (auto next = std::next(it); next != args.end()) {
-        return *next;
-      }
-    } else if (it->starts_with(flag_path)) {
-      // Case: "--experimental-config-file=foo"
-      if (it->size() > flag_path.size() && (*it)[flag_path.size()] == '=') {
-        return std::string_view(*it).substr(flag_path.size() + 1);
+    std::vector<std::string>* args) {
+  std::optional<std::string_view> result;
+
+  for (size_t i = 0; i < args->size(); ++i) {
+    std::string& arg = (*args)[i];
+
+    if (arg == kConfigFileFlag) {
+      // Check if next arg is a path
+      const bool has_next_arg = i + 1 < args->size();
+      const bool next_is_path =
+          has_next_arg && !(*args)[i + 1].starts_with("-");
+
+      if (next_is_path) {
+        // --experimental-config-file path
+        arg = std::string(kConfigFileFlag) + "=" + (*args)[i + 1];
+        args->erase(args->begin() + static_cast<ptrdiff_t>(i + 1));
+        result = std::string_view(arg).substr(kConfigFileFlag.size() + 1);
+      } else {
+        // --experimental-config-file
+        arg = std::string(kConfigFileFlag) + "=" +
+              std::string(kDefaultConfigFileName);
+        result = kDefaultConfigFileName;
       }
-    } else if (*it == default_file || it->starts_with(default_file)) {
-      has_default_config_file = true;
+    } else if (HasEqualsPrefix(arg, kConfigFileFlag)) {
+      // --experimental-config-file=path
+      result = std::string_view(arg).substr(kConfigFileFlag.size() + 1);
+    } else if (arg == kDefaultConfigFileFlag) {
+      // --experimental-default-config-file
+      arg = std::string(kConfigFileFlag) + "=" +
+            std::string(kDefaultConfigFileName);
+      result = kDefaultConfigFileName;
     }
   }
 
-  if (has_default_config_file) {
-    return "node.config.json";
-  }
-
-  return std::nullopt;
+  return result;
 }
 
 ParseResult ConfigReader::ProcessOptionValue(
diff --git a/src/node_config_file.h b/src/node_config_file.h
index 82874cee8b583f..4fb90587f16f0d 100644
--- a/src/node_config_file.h
+++ b/src/node_config_file.h
@@ -30,7 +30,7 @@ class ConfigReader {
   ParseResult ParseConfig(const std::string_view& config_path);
 
   std::optional<std::string_view> GetDataFromArgs(
-      const std::vector<std::string>& args);
+      std::vector<std::string>* args);
 
   std::string GetNodeOptions();
   const std::vector<std::string>& GetNamespaceFlags() const;
diff --git a/src/node_options.cc b/src/node_options.cc
index 22fe0f61da8c69..a04caafbcc888f 100644
--- a/src/node_options.cc
+++ b/src/node_options.cc
@@ -869,11 +869,11 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             &EnvironmentOptions::optional_env_file);
   Implies("--env-file-if-exists", "[has_env_file_string]");
   AddOption("--experimental-config-file",
-            "set config file from supplied file",
-            &EnvironmentOptions::experimental_config_file_path);
-  AddOption("--experimental-default-config-file",
-            "set config file from default config file",
-            &EnvironmentOptions::experimental_default_config_file);
+            "set config file path",
+            &EnvironmentOptions::experimental_config_file_path,
+            kDisallowedInEnvvar);
+  AddAlias("--experimental-config-file=", "--experimental-config-file");
+  AddAlias("--experimental-default-config-file", "--experimental-config-file");
   AddOption("--test",
             "launch test runner on startup",
             &EnvironmentOptions::test_runner,
diff --git a/src/node_options.h b/src/node_options.h
index 21f43946ea8a1e..28c3f924dd8127 100644
--- a/src/node_options.h
+++ b/src/node_options.h
@@ -268,7 +268,6 @@ class EnvironmentOptions : public Options {
   bool report_exclude_env = false;
   bool report_exclude_network = false;
   std::string experimental_config_file_path;
-  bool experimental_default_config_file = false;
 
   inline DebugOptions* get_debug_options() { return &debug_options_; }
   inline const DebugOptions& debug_options() const { return debug_options_; }
diff --git a/test/parallel/test-cli-node-options-docs.js b/test/parallel/test-cli-node-options-docs.js
index 80caa29d4263ef..534c99c04de964 100644
--- a/test/parallel/test-cli-node-options-docs.js
+++ b/test/parallel/test-cli-node-options-docs.js
@@ -122,5 +122,6 @@ for (const [, envVar, config] of nodeOptionsCC.matchAll(addOptionRE)) {
 
 // add alias handling
 manPagesOptions.delete('-trace-events-enabled');
+manPagesOptions.delete('-experimental-default-config-file');
 
 assert.strictEqual(manPagesOptions.size, 0, `Man page options not documented: ${[...manPagesOptions]}`);
diff --git a/test/parallel/test-config-file.js b/test/parallel/test-config-file.js
index c18cc0d45683b6..3bbad91b396faf 100644
--- a/test/parallel/test-config-file.js
+++ b/test/parallel/test-config-file.js
@@ -371,7 +371,34 @@ test('should use node.config.json as default', onlyIfNodeOptionsSupport, async (
   assert.strictEqual(result.code, 0);
 });
 
-test('should override node.config.json when specificied', onlyIfNodeOptionsSupport, async () => {
+test('should use node.config.json when --experimental-config-file has no argument',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-config-file',
+         '-p', 'http.maxHeaderSize',
+       ], {
+         cwd: fixtures.path('rc/default'),
+       });
+       assert.strictEqual(result.stderr, '');
+       assert.strictEqual(result.stdout, '10\n');
+       assert.strictEqual(result.code, 0);
+     });
+
+test('should error when --experimental-config-file= has empty argument',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-config-file=',
+         '-p', 'http.maxHeaderSize',
+       ], {
+         cwd: fixtures.path('rc/default'),
+       });
+       assert.match(result.stderr, /--experimental-config-file= requires an argument/);
+       assert.strictEqual(result.code, 9);
+     });
+
+test('should override node.config.json when specified', onlyIfNodeOptionsSupport, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
     '--experimental-default-config-file',
@@ -385,6 +412,48 @@ test('should override node.config.json when specificied', onlyIfNodeOptionsSuppo
   assert.strictEqual(result.stdout, '20\n');
   assert.strictEqual(result.code, 0);
 });
+
+test('should work with --experimental-config-file=path',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         `--experimental-config-file=${fixtures.path('rc/default/node.config.json')}`,
+         '-p', 'http.maxHeaderSize',
+       ]);
+       assert.strictEqual(result.stderr, '');
+       assert.strictEqual(result.stdout, '10\n');
+       assert.strictEqual(result.code, 0);
+     });
+
+test('should use last config file when multiple are specified',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-config-file',
+         fixtures.path('rc/default/node.config.json'),
+         '--experimental-config-file',
+         fixtures.path('rc/default/override.json'),
+         '-p', 'http.maxHeaderSize',
+       ]);
+       assert.strictEqual(result.stderr, '');
+       assert.strictEqual(result.stdout, '20\n');
+       assert.strictEqual(result.code, 0);
+     });
+
+test('should use default when next argument starts with dash',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-config-file',
+         '-p', 'http.maxHeaderSize',
+       ], {
+         cwd: fixtures.path('rc/default'),
+       });
+       assert.strictEqual(result.stderr, '');
+       assert.strictEqual(result.stdout, '10\n');
+       assert.strictEqual(result.code, 0);
+     });
+
 // Skip on windows because it doesn't support chmod changing read permissions
 // Also skip if user is root because it would have read permissions anyway
 test('should throw an error when the file is non readable', {
diff --git a/test/parallel/test-runner-flag-propagation.js b/test/parallel/test-runner-flag-propagation.js
index f4e9849cce77d0..a48d6b6bfe9938 100644
--- a/test/parallel/test-runner-flag-propagation.js
+++ b/test/parallel/test-runner-flag-propagation.js
@@ -15,8 +15,6 @@ const runner = path.join(fixtureDir, 'runner.mjs');
 describe('test runner flag propagation', () => {
   describe('via command line', () => {
     const flagPropagationTests = [
-      ['--experimental-config-file', 'node.config.json', ''],
-      ['--experimental-default-config-file', '', false],
       ['--env-file', '.env', '.env'],
       ['--env-file-if-exists', '.env', '.env'],
       ['--test-concurrency', '2', '2'],