From ca9520a9786c781d302c41df2d7d9d704aa123b8 Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna@addaleax.net>
Date: Sun, 12 Apr 2020 18:11:14 +0200
Subject: [PATCH 1/3] process: suggest --trace-warnings when printing warning

Suggest using `--trace-warnings` or `--trace-deprecation` the first
time a warning is emitted without a stack trace, similar to how
we suggest `--trace-uncaught` when printing uncaught exceptions
without a stack trace.
---
 lib/internal/process/warning.js                         | 7 +++++++
 test/message/async_error_sync_esm.out                   | 1 +
 test/message/esm_display_syntax_error.out               | 1 +
 test/message/esm_display_syntax_error_import.out        | 1 +
 test/message/esm_display_syntax_error_import_module.out | 1 +
 test/message/esm_display_syntax_error_module.out        | 3 ++-
 test/message/esm_loader_not_found.out                   | 1 +
 test/message/esm_loader_syntax_error.out                | 1 +
 test/message/v8_warning.out                             | 1 +
 test/parallel/test-debugger-pid.js                      | 7 +++++--
 test/parallel/test-env-var-no-warnings.js               | 2 +-
 test/pseudo-tty/test-tty-color-support-warning-2.out    | 1 +
 test/pseudo-tty/test-tty-color-support-warning.out      | 1 +
 test/pseudo-tty/test-tty-color-support.out              | 1 +
 14 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/lib/internal/process/warning.js b/lib/internal/process/warning.js
index 4a2ce2d6b203c8..490de2f0caeec1 100644
--- a/lib/internal/process/warning.js
+++ b/lib/internal/process/warning.js
@@ -58,6 +58,7 @@ function doEmitWarning(warning) {
   return () => process.emit('warning', warning);
 }
 
+let traceWarningHelperShown = false;
 function onWarning(warning) {
   if (!(warning instanceof Error)) return;
   const isDeprecation = warning.name === 'DeprecationWarning';
@@ -78,6 +79,12 @@ function onWarning(warning) {
   if (typeof warning.detail === 'string') {
     msg += `\n${warning.detail}`;
   }
+  if (!trace && !traceWarningHelperShown) {
+    const flag = isDeprecation ? '--trace-deprecation' : '--trace-warnings';
+    msg += `\n(Use \`node ${flag} ...\` to show where the warning ` +
+           'was created)';
+    traceWarningHelperShown = true;
+  }
   const warningFile = lazyOption();
   if (warningFile) {
     return writeToFile(msg);
diff --git a/test/message/async_error_sync_esm.out b/test/message/async_error_sync_esm.out
index 6577fff6944723..abaa2524cff3b8 100644
--- a/test/message/async_error_sync_esm.out
+++ b/test/message/async_error_sync_esm.out
@@ -1,4 +1,5 @@
 (node:*) ExperimentalWarning: The ESM module loader is experimental.
+(Use `node --trace-warnings ...` to show where the warning was created)
 Error: test
     at one (*fixtures*async-error.js:4:9)
     at two (*fixtures*async-error.js:17:9)
diff --git a/test/message/esm_display_syntax_error.out b/test/message/esm_display_syntax_error.out
index 778d901129fa95..382d459c2e67dd 100644
--- a/test/message/esm_display_syntax_error.out
+++ b/test/message/esm_display_syntax_error.out
@@ -1,4 +1,5 @@
 (node:*) ExperimentalWarning: The ESM module loader is experimental.
+(Use `node --trace-warnings ...` to show where the warning was created)
 file:///*/test/message/esm_display_syntax_error.mjs:2
 await async () => 0;
 ^^^^^
diff --git a/test/message/esm_display_syntax_error_import.out b/test/message/esm_display_syntax_error_import.out
index e39744a049b59b..d24891bd2c0df0 100644
--- a/test/message/esm_display_syntax_error_import.out
+++ b/test/message/esm_display_syntax_error_import.out
@@ -1,4 +1,5 @@
 (node:*) ExperimentalWarning: The ESM module loader is experimental.
+(Use `node --trace-warnings ...` to show where the warning was created)
 file:///*/test/message/esm_display_syntax_error_import.mjs:5
   notfound
   ^^^^^^^^
diff --git a/test/message/esm_display_syntax_error_import_module.out b/test/message/esm_display_syntax_error_import_module.out
index 0daaeff5b95daf..aaf65069bc4f18 100644
--- a/test/message/esm_display_syntax_error_import_module.out
+++ b/test/message/esm_display_syntax_error_import_module.out
@@ -1,4 +1,5 @@
 (node:*) ExperimentalWarning: The ESM module loader is experimental.
+(Use `node --trace-warnings ...` to show where the warning was created)
 file:///*/test/fixtures/es-module-loaders/syntax-error-import.mjs:1
 import { foo, notfound } from './module-named-exports.mjs';
               ^^^^^^^^
diff --git a/test/message/esm_display_syntax_error_module.out b/test/message/esm_display_syntax_error_module.out
index a1498f72c94d57..c22bf0437c56a7 100644
--- a/test/message/esm_display_syntax_error_module.out
+++ b/test/message/esm_display_syntax_error_module.out
@@ -1,7 +1,8 @@
 (node:*) ExperimentalWarning: The ESM module loader is experimental.
+(Use `node --trace-warnings ...` to show where the warning was created)
 file:///*/test/fixtures/es-module-loaders/syntax-error.mjs:2
 await async () => 0;
 ^^^^^
 
 SyntaxError: Unexpected reserved word
-    at Loader.moduleStrategy (internal/modules/esm/translators.js:*:*)
\ No newline at end of file
+    at Loader.moduleStrategy (internal/modules/esm/translators.js:*:*)
diff --git a/test/message/esm_loader_not_found.out b/test/message/esm_loader_not_found.out
index a054dacf2f930a..0949c4d0e3ace6 100644
--- a/test/message/esm_loader_not_found.out
+++ b/test/message/esm_loader_not_found.out
@@ -1,4 +1,5 @@
 (node:*) ExperimentalWarning: The ESM module loader is experimental.
+(Use `node --trace-warnings ...` to show where the warning was created)
 (node:*) ExperimentalWarning: --experimental-loader is an experimental feature. This feature could change at any time
 internal/modules/run_main.js:*
     internalBinding('errors').triggerUncaughtException(
diff --git a/test/message/esm_loader_syntax_error.out b/test/message/esm_loader_syntax_error.out
index 9767a9c86c6bc2..cde6bd0aa811f8 100644
--- a/test/message/esm_loader_syntax_error.out
+++ b/test/message/esm_loader_syntax_error.out
@@ -1,4 +1,5 @@
 (node:*) ExperimentalWarning: The ESM module loader is experimental.
+(Use `node --trace-warnings ...` to show where the warning was created)
 (node:*) ExperimentalWarning: --experimental-loader is an experimental feature. This feature could change at any time
 file://*/test/fixtures/es-module-loaders/syntax-error.mjs:2
 await async () => 0;
diff --git a/test/message/v8_warning.out b/test/message/v8_warning.out
index 7943d0e9d64dfe..b006af0518f0f4 100644
--- a/test/message/v8_warning.out
+++ b/test/message/v8_warning.out
@@ -1 +1,2 @@
 (node:*) V8: *v8_warning.js:* Invalid asm.js: Invalid return type
+(Use `node --trace-warnings ...` to show where the warning was created)
diff --git a/test/parallel/test-debugger-pid.js b/test/parallel/test-debugger-pid.js
index f269ff310b145c..00f14b2cf5bb61 100644
--- a/test/parallel/test-debugger-pid.js
+++ b/test/parallel/test-debugger-pid.js
@@ -29,9 +29,12 @@ interfacer.on('line', function(line) {
     case 1:
       expected =
         new RegExp(`^\\(node:${pid}\\) \\[DEP0068\\] DeprecationWarning: `);
-      assert.ok(expected.test(line), `expected regexp match for ${line}`);
+      assert.match(line, expected);
       break;
     case 2:
+      assert.match(line, /Use `node --trace-deprecation \.\.\.` to show where /);
+      break;
+    case 3:
       // Doesn't currently work on Windows.
       if (!common.isWindows) {
         expected = "Target process: 655555 doesn't exist.";
@@ -48,6 +51,6 @@ interfacer.on('line', function(line) {
 interfacer.on('exit', function(code, signal) {
   assert.strictEqual(code, 1, `Got unexpected code: ${code}`);
   if (!common.isWindows) {
-    assert.strictEqual(lineCount, 2);
+    assert.strictEqual(lineCount, 3);
   }
 });
diff --git a/test/parallel/test-env-var-no-warnings.js b/test/parallel/test-env-var-no-warnings.js
index cf90c2759d9ad7..b6164da1039a55 100644
--- a/test/parallel/test-env-var-no-warnings.js
+++ b/test/parallel/test-env-var-no-warnings.js
@@ -17,7 +17,7 @@ if (process.argv[2] === 'child') {
       if (env.NODE_NO_WARNINGS === '1')
         assert.strictEqual(stderr, '');
       else
-        assert(/Warning: foo$/.test(stderr.trim()));
+        assert.match(stderr.trim(), /Warning: foo\n/);
     }));
   }
 
diff --git a/test/pseudo-tty/test-tty-color-support-warning-2.out b/test/pseudo-tty/test-tty-color-support-warning-2.out
index cd57b3f9f69672..d17fa99b96974a 100644
--- a/test/pseudo-tty/test-tty-color-support-warning-2.out
+++ b/test/pseudo-tty/test-tty-color-support-warning-2.out
@@ -1,2 +1,3 @@
 
 (node:*) Warning: The 'NODE_DISABLE_COLORS' env is ignored due to the 'FORCE_COLOR' env being set.
+(Use `node --trace-warnings ...` to show where the warning was created)
diff --git a/test/pseudo-tty/test-tty-color-support-warning.out b/test/pseudo-tty/test-tty-color-support-warning.out
index 9360ae1328b2cd..7a9df4725486d2 100644
--- a/test/pseudo-tty/test-tty-color-support-warning.out
+++ b/test/pseudo-tty/test-tty-color-support-warning.out
@@ -1,2 +1,3 @@
 
 (node:*) Warning: The 'NODE_DISABLE_COLORS' and 'NO_COLOR' env is ignored due to the 'FORCE_COLOR' env being set.
+(Use `node --trace-warnings ...` to show where the warning was created)
diff --git a/test/pseudo-tty/test-tty-color-support.out b/test/pseudo-tty/test-tty-color-support.out
index e6904d10b8a7b8..86ed488ee8c1b2 100644
--- a/test/pseudo-tty/test-tty-color-support.out
+++ b/test/pseudo-tty/test-tty-color-support.out
@@ -1 +1,2 @@
 (node:*) Warning: The 'NO_COLOR' env is ignored due to the 'FORCE_COLOR' env being set.
+(Use `node --trace-warnings ...` to show where the warning was created)

From 2ca8186afd81ebf24b0a944d08856592533aaa45 Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna@addaleax.net>
Date: Sun, 12 Apr 2020 19:08:22 +0200
Subject: [PATCH 2/3] fixup! process: suggest --trace-warnings when printing
 warning

---
 lib/internal/process/warning.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/internal/process/warning.js b/lib/internal/process/warning.js
index 490de2f0caeec1..4434b715d508fc 100644
--- a/lib/internal/process/warning.js
+++ b/lib/internal/process/warning.js
@@ -81,7 +81,8 @@ function onWarning(warning) {
   }
   if (!trace && !traceWarningHelperShown) {
     const flag = isDeprecation ? '--trace-deprecation' : '--trace-warnings';
-    msg += `\n(Use \`node ${flag} ...\` to show where the warning ` +
+    const argv0 = require('path').basename(process.argv0 || 'node');
+    msg += `\n(Use \`${argv0} ${flag} ...\` to show where the warning ` +
            'was created)';
     traceWarningHelperShown = true;
   }

From 6405a9a766f8de1183e2783949d5ab6c82b607f7 Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna@addaleax.net>
Date: Sun, 12 Apr 2020 22:37:10 +0200
Subject: [PATCH 3/3] fixup! process: suggest --trace-warnings when printing
 warning

---
 lib/internal/process/warning.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/internal/process/warning.js b/lib/internal/process/warning.js
index 4434b715d508fc..383bbd7e0fe79f 100644
--- a/lib/internal/process/warning.js
+++ b/lib/internal/process/warning.js
@@ -81,7 +81,7 @@ function onWarning(warning) {
   }
   if (!trace && !traceWarningHelperShown) {
     const flag = isDeprecation ? '--trace-deprecation' : '--trace-warnings';
-    const argv0 = require('path').basename(process.argv0 || 'node');
+    const argv0 = require('path').basename(process.argv0 || 'node', '.exe');
     msg += `\n(Use \`${argv0} ${flag} ...\` to show where the warning ` +
            'was created)';
     traceWarningHelperShown = true;