From 49558a114dd9f9538b6ebc98aa6bfc5234c6d57b Mon Sep 17 00:00:00 2001
From: Jacob Smith <3012099+JakobJingleheimer@users.noreply.github.com>
Date: Sat, 12 Mar 2022 17:34:00 +0100
Subject: [PATCH 1/8] esm: emit experimental warnings in common place

---
 lib/internal/modules/esm/loader.js            | 13 ++++++++
 lib/internal/modules/esm/resolve.js           |  8 -----
 lib/internal/process/esm_loader.js            |  3 --
 .../test-esm-experimental-warnings.mjs        | 31 +++++++++++++++++++
 ...est-esm-specifiers-legacy-flag-warning.mjs | 24 --------------
 5 files changed, 44 insertions(+), 35 deletions(-)
 create mode 100644 test/es-module/test-esm-experimental-warnings.mjs
 delete mode 100644 test/es-module/test-esm-specifiers-legacy-flag-warning.mjs

diff --git a/lib/internal/modules/esm/loader.js b/lib/internal/modules/esm/loader.js
index 16b832527f7c64..f05d7ba5d432fa 100644
--- a/lib/internal/modules/esm/loader.js
+++ b/lib/internal/modules/esm/loader.js
@@ -31,6 +31,7 @@ const {
   ERR_UNKNOWN_MODULE_FORMAT
 } = require('internal/errors').codes;
 const { pathToFileURL, isURLInstance, URL } = require('internal/url');
+const { emitExperimentalWarning } = require('internal/util');
 const {
   isAnyArrayBuffer,
   isArrayBufferView,
@@ -107,6 +108,18 @@ class ESMLoader {
    */
   translators = translators;
 
+  constructor() {
+    if (getOptionValue('--experimental-loader')) {
+      emitExperimentalWarning('Custom ESM Loaders');
+    }
+    if (getOptionValue('--experimental-network-imports')) {
+      emitExperimentalWarning('Network Imports');
+    }
+    if (getOptionValue('--experimental-specifier-resolution') === 'node') {
+      emitExperimentalWarning('Specifier Resolution');
+    }
+  }
+
   static pluckHooks({
     globalPreload,
     resolve,
diff --git a/lib/internal/modules/esm/resolve.js b/lib/internal/modules/esm/resolve.js
index 53085f327469b3..e640947450c973 100644
--- a/lib/internal/modules/esm/resolve.js
+++ b/lib/internal/modules/esm/resolve.js
@@ -364,7 +364,6 @@ function resolveDirectoryEntry(search) {
 }
 
 const encodedSepRegEx = /%2F|%5C/i;
-let experimentalSpecifierResolutionWarned = false;
 /**
  * @param {URL} resolved
  * @param {string | URL | undefined} base
@@ -379,13 +378,6 @@ function finalizeResolution(resolved, base, preserveSymlinks) {
 
   let path = fileURLToPath(resolved);
   if (getOptionValue('--experimental-specifier-resolution') === 'node') {
-    if (!experimentalSpecifierResolutionWarned) {
-      process.emitWarning(
-        'The Node.js specifier resolution flag is experimental. It could change or be removed at any time.',
-        'ExperimentalWarning');
-      experimentalSpecifierResolutionWarned = true;
-    }
-
     let file = resolveExtensionsWithTryExactName(resolved);
 
     // Directory
diff --git a/lib/internal/process/esm_loader.js b/lib/internal/process/esm_loader.js
index 73385a85b4e106..20021134ce40f3 100644
--- a/lib/internal/process/esm_loader.js
+++ b/lib/internal/process/esm_loader.js
@@ -55,9 +55,6 @@ async function initializeLoader() {
 
   if (!customLoaders.length) return;
 
-  const { emitExperimentalWarning } = require('internal/util');
-  emitExperimentalWarning('--experimental-loader');
-
   let cwd;
   try {
     cwd = process.cwd() + '/';
diff --git a/test/es-module/test-esm-experimental-warnings.mjs b/test/es-module/test-esm-experimental-warnings.mjs
new file mode 100644
index 00000000000000..2b8cf9216d4017
--- /dev/null
+++ b/test/es-module/test-esm-experimental-warnings.mjs
@@ -0,0 +1,31 @@
+import { mustCall } from '../common/index.mjs';
+import { fileURL } from '../common/fixtures.mjs';
+import { ok, strictEqual } from 'assert';
+import { spawn } from 'child_process';
+import { execPath } from 'process';
+
+// Verify experimental warnings are printed
+for (
+  const [experiment, arg] of [
+    ['Custom ESM Loaders', `--experimental-loader=${fileURL('es-module-loaders', 'hooks-custom.mjs')}`],
+    ['Network Imports', '--experimental-network-imports'],
+    ['Specifier Resolution', '--experimental-specifier-resolution=node'],
+  ]
+) {
+  const child = spawn(execPath, [
+    arg,
+    '--input-type=module',
+    '--eval',
+    `const foo = 'a'`,
+  ]);
+
+  let stderr = '';
+  child.stderr.setEncoding('utf8');
+  child.stderr.on('data', (data) => { stderr += data });
+  child.on('close', mustCall((code, signal) => {
+    strictEqual(code, 0);
+    strictEqual(signal, null);
+    ok(stderr.includes('ExperimentalWarning:'));
+    ok(stderr.includes(experiment), new Error(`Expected warning to mention ${experiment}`));
+  }));
+}
diff --git a/test/es-module/test-esm-specifiers-legacy-flag-warning.mjs b/test/es-module/test-esm-specifiers-legacy-flag-warning.mjs
deleted file mode 100644
index 244499a3e02093..00000000000000
--- a/test/es-module/test-esm-specifiers-legacy-flag-warning.mjs
+++ /dev/null
@@ -1,24 +0,0 @@
-import { mustCall } from '../common/index.mjs';
-import { fileURL } from '../common/fixtures.mjs';
-import { match, strictEqual } from 'assert';
-import { spawn } from 'child_process';
-import { execPath } from 'process';
-
-// Verify experimental warning is printed
-const child = spawn(execPath, [
-  '--experimental-specifier-resolution=node',
-  '--input-type=module',
-  '--eval',
-  `import ${JSON.stringify(fileURL('es-module-specifiers', 'package-type-module'))}`,
-]);
-
-let stderr = '';
-child.stderr.setEncoding('utf8');
-child.stderr.on('data', (data) => {
-  stderr += data;
-});
-child.on('close', mustCall((code, signal) => {
-  strictEqual(code, 0);
-  strictEqual(signal, null);
-  match(stderr, /ExperimentalWarning: The Node\.js specifier resolution flag is experimental/);
-}));

From 61c0135737d1d3369571c097fc6e8e946e4af631 Mon Sep 17 00:00:00 2001
From: Jacob Smith <3012099+JakobJingleheimer@users.noreply.github.com>
Date: Sat, 12 Mar 2022 22:30:31 +0100
Subject: [PATCH 2/8] fixup: switch test from substring to regex

---
 test/es-module/test-esm-experimental-warnings.mjs | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/test/es-module/test-esm-experimental-warnings.mjs b/test/es-module/test-esm-experimental-warnings.mjs
index 2b8cf9216d4017..30e481f4b30e7f 100644
--- a/test/es-module/test-esm-experimental-warnings.mjs
+++ b/test/es-module/test-esm-experimental-warnings.mjs
@@ -1,15 +1,15 @@
 import { mustCall } from '../common/index.mjs';
 import { fileURL } from '../common/fixtures.mjs';
-import { ok, strictEqual } from 'assert';
+import { match, strictEqual } from 'assert';
 import { spawn } from 'child_process';
 import { execPath } from 'process';
 
 // Verify experimental warnings are printed
 for (
   const [experiment, arg] of [
-    ['Custom ESM Loaders', `--experimental-loader=${fileURL('es-module-loaders', 'hooks-custom.mjs')}`],
-    ['Network Imports', '--experimental-network-imports'],
-    ['Specifier Resolution', '--experimental-specifier-resolution=node'],
+    [/Custom ESM Loaders/, `--experimental-loader=${fileURL('es-module-loaders', 'hooks-custom.mjs')}`],
+    [/Network Imports/, '--experimental-network-imports'],
+    [/Specifier Resolution/, '--experimental-specifier-resolution=node'],
   ]
 ) {
   const child = spawn(execPath, [
@@ -25,7 +25,7 @@ for (
   child.on('close', mustCall((code, signal) => {
     strictEqual(code, 0);
     strictEqual(signal, null);
-    ok(stderr.includes('ExperimentalWarning:'));
-    ok(stderr.includes(experiment), new Error(`Expected warning to mention ${experiment}`));
+    match(stderr, /ExperimentalWarning:/);
+    match(stderr, experiment);
   }));
 }

From 463ae28954ed66b010953ad6cd6496e68fe9c170 Mon Sep 17 00:00:00 2001
From: Jacob Smith <3012099+JakobJingleheimer@users.noreply.github.com>
Date: Sat, 12 Mar 2022 22:34:54 +0100
Subject: [PATCH 3/8] fixup: delint

---
 test/es-module/test-esm-experimental-warnings.mjs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/es-module/test-esm-experimental-warnings.mjs b/test/es-module/test-esm-experimental-warnings.mjs
index 30e481f4b30e7f..3d849b4810968c 100644
--- a/test/es-module/test-esm-experimental-warnings.mjs
+++ b/test/es-module/test-esm-experimental-warnings.mjs
@@ -16,12 +16,12 @@ for (
     arg,
     '--input-type=module',
     '--eval',
-    `const foo = 'a'`,
+    'const foo = "a"',
   ]);
 
   let stderr = '';
   child.stderr.setEncoding('utf8');
-  child.stderr.on('data', (data) => { stderr += data });
+  child.stderr.on('data', (data) => { stderr += data; });
   child.on('close', mustCall((code, signal) => {
     strictEqual(code, 0);
     strictEqual(signal, null);

From 59eff1ff8763a3279e9f0ef8ea0d944e4af603d0 Mon Sep 17 00:00:00 2001
From: Jacob Smith <3012099+JakobJingleheimer@users.noreply.github.com>
Date: Sun, 20 Mar 2022 19:13:47 +0100
Subject: [PATCH 4/8] WIP: switch specifier resolution warning to custom
 message

IRL, both internal and external instances of ESMLoader happen. in the test, only 1 external happens and then the test fails.
---
 lib/internal/modules/esm/loader.js                | 10 ++++++++--
 lib/internal/process/esm_loader.js                |  2 +-
 test/es-module/test-esm-experimental-warnings.mjs | 13 ++++++++++---
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/lib/internal/modules/esm/loader.js b/lib/internal/modules/esm/loader.js
index f05d7ba5d432fa..608c5b1875b7b4 100644
--- a/lib/internal/modules/esm/loader.js
+++ b/lib/internal/modules/esm/loader.js
@@ -108,7 +108,10 @@ class ESMLoader {
    */
   translators = translators;
 
-  constructor() {
+  constructor(isInternal = false) {
+console.log({ isInternal })
+    if (isInternal) return;
+
     if (getOptionValue('--experimental-loader')) {
       emitExperimentalWarning('Custom ESM Loaders');
     }
@@ -116,7 +119,10 @@ class ESMLoader {
       emitExperimentalWarning('Network Imports');
     }
     if (getOptionValue('--experimental-specifier-resolution') === 'node') {
-      emitExperimentalWarning('Specifier Resolution');
+      process.emitWarning(
+        'The Node.js specifier resolution flag is experimental. It could change or be removed at any time.',
+        'ExperimentalWarning'
+      );
     }
   }
 
diff --git a/lib/internal/process/esm_loader.js b/lib/internal/process/esm_loader.js
index 20021134ce40f3..ee20f2badf6621 100644
--- a/lib/internal/process/esm_loader.js
+++ b/lib/internal/process/esm_loader.js
@@ -39,7 +39,7 @@ async function importModuleDynamicallyCallback(wrap, specifier, assertions) {
   throw new ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING();
 };
 
-const esmLoader = new ESMLoader();
+const esmLoader = new ESMLoader(true);
 
 exports.esmLoader = esmLoader;
 
diff --git a/test/es-module/test-esm-experimental-warnings.mjs b/test/es-module/test-esm-experimental-warnings.mjs
index 3d849b4810968c..2d9a976c1896fd 100644
--- a/test/es-module/test-esm-experimental-warnings.mjs
+++ b/test/es-module/test-esm-experimental-warnings.mjs
@@ -9,23 +9,30 @@ for (
   const [experiment, arg] of [
     [/Custom ESM Loaders/, `--experimental-loader=${fileURL('es-module-loaders', 'hooks-custom.mjs')}`],
     [/Network Imports/, '--experimental-network-imports'],
-    [/Specifier Resolution/, '--experimental-specifier-resolution=node'],
+    [/specifier resolution/, '--experimental-specifier-resolution=node'],
   ]
 ) {
+  const input = `import ${JSON.stringify(fileURL('es-module-loaders','module-named-exports.mjs'))}`;
+console.log({ input })
   const child = spawn(execPath, [
     arg,
     '--input-type=module',
     '--eval',
-    'const foo = "a"',
+    input,
   ]);
 
   let stderr = '';
   child.stderr.setEncoding('utf8');
   child.stderr.on('data', (data) => { stderr += data; });
+
+  let stdout = '';
+  child.stdout.setEncoding('utf8');
+  child.stdout.on('data', (data) => { stdout += data; });
   child.on('close', mustCall((code, signal) => {
+console.log({ experiment, code, signal, stderr, stdout })
     strictEqual(code, 0);
     strictEqual(signal, null);
-    match(stderr, /ExperimentalWarning:/);
+    match(stderr, /ExperimentalWarning/);
     match(stderr, experiment);
   }));
 }

From ad57f42f18f01e0249a2e5deac27513cc3310a2d Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webadmin@geoffreybooth.com>
Date: Sun, 27 Mar 2022 19:11:44 -0700
Subject: [PATCH 5/8] fixup: remove log

---
 lib/internal/modules/esm/loader.js                | 1 -
 test/es-module/test-esm-experimental-warnings.mjs | 2 --
 2 files changed, 3 deletions(-)

diff --git a/lib/internal/modules/esm/loader.js b/lib/internal/modules/esm/loader.js
index 608c5b1875b7b4..da7383300972fe 100644
--- a/lib/internal/modules/esm/loader.js
+++ b/lib/internal/modules/esm/loader.js
@@ -109,7 +109,6 @@ class ESMLoader {
   translators = translators;
 
   constructor(isInternal = false) {
-console.log({ isInternal })
     if (isInternal) return;
 
     if (getOptionValue('--experimental-loader')) {
diff --git a/test/es-module/test-esm-experimental-warnings.mjs b/test/es-module/test-esm-experimental-warnings.mjs
index 2d9a976c1896fd..adc6b645f88fbe 100644
--- a/test/es-module/test-esm-experimental-warnings.mjs
+++ b/test/es-module/test-esm-experimental-warnings.mjs
@@ -13,7 +13,6 @@ for (
   ]
 ) {
   const input = `import ${JSON.stringify(fileURL('es-module-loaders','module-named-exports.mjs'))}`;
-console.log({ input })
   const child = spawn(execPath, [
     arg,
     '--input-type=module',
@@ -29,7 +28,6 @@ console.log({ input })
   child.stdout.setEncoding('utf8');
   child.stdout.on('data', (data) => { stdout += data; });
   child.on('close', mustCall((code, signal) => {
-console.log({ experiment, code, signal, stderr, stdout })
     strictEqual(code, 0);
     strictEqual(signal, null);
     match(stderr, /ExperimentalWarning/);

From 592bf88a40b5e642212ca1912bc7c22779f3430f Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webadmin@geoffreybooth.com>
Date: Sun, 27 Mar 2022 19:23:44 -0700
Subject: [PATCH 6/8] fixup: remove isInternal flag for ESMLoader

---
 lib/internal/modules/esm/loader.js | 4 +---
 lib/internal/process/esm_loader.js | 2 +-
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/lib/internal/modules/esm/loader.js b/lib/internal/modules/esm/loader.js
index da7383300972fe..70b6cc5fa24b6e 100644
--- a/lib/internal/modules/esm/loader.js
+++ b/lib/internal/modules/esm/loader.js
@@ -108,9 +108,7 @@ class ESMLoader {
    */
   translators = translators;
 
-  constructor(isInternal = false) {
-    if (isInternal) return;
-
+  constructor() {
     if (getOptionValue('--experimental-loader')) {
       emitExperimentalWarning('Custom ESM Loaders');
     }
diff --git a/lib/internal/process/esm_loader.js b/lib/internal/process/esm_loader.js
index ee20f2badf6621..20021134ce40f3 100644
--- a/lib/internal/process/esm_loader.js
+++ b/lib/internal/process/esm_loader.js
@@ -39,7 +39,7 @@ async function importModuleDynamicallyCallback(wrap, specifier, assertions) {
   throw new ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING();
 };
 
-const esmLoader = new ESMLoader(true);
+const esmLoader = new ESMLoader();
 
 exports.esmLoader = esmLoader;
 

From 35bb8b00cb9c9b70070b9ca02df4ae7fa7a3aea4 Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webadmin@geoffreybooth.com>
Date: Sun, 27 Mar 2022 19:56:16 -0700
Subject: [PATCH 7/8] fixup: lint

---
 test/es-module/test-esm-experimental-warnings.mjs | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/test/es-module/test-esm-experimental-warnings.mjs b/test/es-module/test-esm-experimental-warnings.mjs
index adc6b645f88fbe..bf92b158e485eb 100644
--- a/test/es-module/test-esm-experimental-warnings.mjs
+++ b/test/es-module/test-esm-experimental-warnings.mjs
@@ -12,7 +12,7 @@ for (
     [/specifier resolution/, '--experimental-specifier-resolution=node'],
   ]
 ) {
-  const input = `import ${JSON.stringify(fileURL('es-module-loaders','module-named-exports.mjs'))}`;
+  const input = `import ${JSON.stringify(fileURL('es-module-loaders', 'module-named-exports.mjs'))}`;
   const child = spawn(execPath, [
     arg,
     '--input-type=module',
@@ -23,10 +23,6 @@ for (
   let stderr = '';
   child.stderr.setEncoding('utf8');
   child.stderr.on('data', (data) => { stderr += data; });
-
-  let stdout = '';
-  child.stdout.setEncoding('utf8');
-  child.stdout.on('data', (data) => { stdout += data; });
   child.on('close', mustCall((code, signal) => {
     strictEqual(code, 0);
     strictEqual(signal, null);

From 4c9ecfb95090309f46333f33444821ad526e6aa3 Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webadmin@geoffreybooth.com>
Date: Mon, 28 Mar 2022 11:06:51 -0700
Subject: [PATCH 8/8] fixup: prevent the specifier resolution warning from
 being printed twice

---
 lib/internal/modules/esm/loader.js | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/internal/modules/esm/loader.js b/lib/internal/modules/esm/loader.js
index 70b6cc5fa24b6e..0dccfebbd4f37f 100644
--- a/lib/internal/modules/esm/loader.js
+++ b/lib/internal/modules/esm/loader.js
@@ -54,6 +54,13 @@ const {
   fetchModule,
 } = require('internal/modules/esm/fetch_module');
 
+
+/**
+ * Prevent the specifier resolution warning from being printed twice
+ */
+let emittedSpecifierResolutionWarning = false;
+
+
 /**
  * An ESMLoader instance is used as the main entry point for loading ES modules.
  * Currently, this is a singleton -- there is only one used for loading
@@ -115,11 +122,12 @@ class ESMLoader {
     if (getOptionValue('--experimental-network-imports')) {
       emitExperimentalWarning('Network Imports');
     }
-    if (getOptionValue('--experimental-specifier-resolution') === 'node') {
+    if (getOptionValue('--experimental-specifier-resolution') === 'node' && !emittedSpecifierResolutionWarning) {
       process.emitWarning(
         'The Node.js specifier resolution flag is experimental. It could change or be removed at any time.',
         'ExperimentalWarning'
       );
+      emittedSpecifierResolutionWarning = true;
     }
   }