process: add CLI opt to hide experimental warnings

Adds a command line option to supress experimental warnings. Currently
this cannot be accomplished without supressing all warnings (by using
the --no-warnings option). However, once this option is enabled, a user
can miss out on essential warnings as this supresses all warnings.
This commit adds the --no-experimental-warnings command line option to
allow users to ignore warnings they will expect while still being able
to monitor unexpected warnings.

Fixes: nodejs#30810

doc/api/cli.md

@@ -455,6 +455,14 @@ added: v0.8.0
 
 Silence deprecation warnings.
 
+### `--no-experimental-warnings`
+<!-- YAML
+added: REPLACEME
+-->
+
+Silence all experimental process warnings. These are emitted when using
+features which are considered experimental.
+
 ### `--no-force-async-hooks-checks`
 <!-- YAML
 added: v9.0.0
@@ -1111,6 +1119,7 @@ Node.js options that are allowed are:
 * `--max-http-header-size`
 * `--napi-modules`
 * `--no-deprecation`
+* `--no-experimental-warnings`
 * `--no-force-async-hooks-checks`
 * `--no-warnings`
 * `--openssl-config`

lib/internal/util.js

@@ -173,6 +173,8 @@ function slowCases(enc) {
 }
 
 function emitExperimentalWarning(feature) {
+  const { getOptionValue } = require('internal/options');
+  if (getOptionValue('--no-experimental-warnings')) return;
   if (experimentalWarnings.has(feature)) return;
   const msg = `${feature} is an experimental feature. This feature could ` +
        'change at any time';

src/node_options.cc

@@ -409,6 +409,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "silence all process warnings",
             &EnvironmentOptions::no_warnings,
             kAllowedInEnvironment);
+AddOption("--no-experimental-warnings",
+            "silence all experimental process warnings",
+            &EnvironmentOptions::no_experimental_warnings,
+            kAllowedInEnvironment);
   AddOption("--force-context-aware",
             "disable loading non-context-aware addons",
             &EnvironmentOptions::force_context_aware,

src/node_options.h

@@ -120,6 +120,7 @@ class EnvironmentOptions : public Options {
   bool no_deprecation = false;
   bool no_force_async_hooks_checks = false;
   bool no_warnings = false;
+  bool no_experimental_warnings = false;
   bool force_context_aware = false;
   bool pending_deprecation = false;
   bool preserve_symlinks = false;

test/parallel/test-process-no-emit-experimental-warnings.js

@@ -0,0 +1,16 @@
+// Flags: --no-experimental-warnings --expose-internals
+'use strict';
+// Test supressing experimental warnings.
+const common = require('../common');
+const { hijackStderr,
+        restoreStderr
+} = require('../common/hijackstdio');
+const { emitExperimentalWarning } = require('internal/util');
+
+function test() {
+  hijackStderr(common.mustNotCall('stderr.write must not be called'));
+  emitExperimentalWarning('testExperimentalWarning');
+  restoreStderr();
+}
+
+test();