feat: Add deprecation warning for `Deno.customInspect` (#22027)

This change sets the removal version of `Deno.customInspect` for Deno
v2.

Towards #22021

---------

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

3 files changed, 42 insertions, 17 deletions

diff --git a/cli/tsc/dts/lib.deno.ns.d.ts b/cli/tsc/dts/lib.deno.ns.d.ts
index f695a68c2..8d1e28d4b 100644
--- a/cli/tsc/dts/lib.deno.ns.d.ts
+++ b/cli/tsc/dts/lib.deno.ns.d.ts
@@ -5034,8 +5034,8 @@ declare namespace Deno {
    * called when `Deno.inspect()` is called, or when the object is logged to
    * the console.
    *
-   * @deprecated This symbol is deprecated since 1.9. Use
-   * `Symbol.for("Deno.customInspect")` instead.
+   * @deprecated Use `Symbol.for("Deno.customInspect")` instead. This symbol
+   * will be removed in Deno 2.0.
    *
    * @category Console and Debugging
    */
diff --git a/runtime/js/90_deno_ns.js b/runtime/js/90_deno_ns.js
index e404d34d7..25ba2ef26 100644
--- a/runtime/js/90_deno_ns.js
+++ b/runtime/js/90_deno_ns.js
@@ -83,9 +83,6 @@ const denoNs = {
   futime: fs.futime,
   futimeSync: fs.futimeSync,
   errors: errors.errors,
-  // TODO(kt3k): Remove this export at v2
-  // See https://github.com/denoland/deno/issues/9294
-  customInspect: console.customInspect,
   inspect: console.inspect,
   env: os.env,
   exit: os.exit,
diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js
index 54a4406b2..a038de518 100644
--- a/runtime/js/99_main.js
+++ b/runtime/js/99_main.js
@@ -43,6 +43,7 @@ import * as version from "ext:runtime/01_version.ts";
 import * as os from "ext:runtime/30_os.js";
 import * as timers from "ext:deno_web/02_timers.js";
 import {
+  customInspect,
   getDefaultInspectOptions,
   getNoColor,
   inspectArgs,
@@ -111,12 +112,13 @@ function warnOnDeprecatedApi(apiName, stack, suggestion) {
   // to make it more useful.
   const stackLines = StringPrototypeSplit(stack, "\n");
   ArrayPrototypeShift(stackLines);
-  while (true) {
+  while (stackLines.length > 0) {
     // Filter out internal frames at the top of the stack - they are not useful
     // to the user.
     if (
       StringPrototypeIncludes(stackLines[0], "(ext:") ||
-      StringPrototypeIncludes(stackLines[0], "(node:")
+      StringPrototypeIncludes(stackLines[0], "(node:") ||
+      StringPrototypeIncludes(stackLines[0], "<anonymous>")
     ) {
       ArrayPrototypeShift(stackLines);
     } else {
@@ -127,6 +129,7 @@ function warnOnDeprecatedApi(apiName, stack, suggestion) {
   // event loop tick or promise handler calling a user function - again not
   // useful to the user.
   if (
+    stackLines.length > 0 &&
     StringPrototypeIncludes(stackLines[stackLines.length - 1], "(ext:core/")
   ) {
     ArrayPrototypePop(stackLines);
@@ -168,16 +171,17 @@ function warnOnDeprecatedApi(apiName, stack, suggestion) {
       "color: yellow;",
     );
   }
-
-  console.error("%c\u2502", "color: yellow;");
-  console.error("%c\u2514 Stack trace:", "color: yellow;");
-  for (let i = 0; i < stackLines.length; i++) {
-    console.error(
-      `%c  ${i == stackLines.length - 1 ? "\u2514" : "\u251c"}\u2500 ${
-        StringPrototypeTrim(stackLines[i])
-      }`,
-      "color: yellow;",
-    );
+  if (stackLines.length > 0) {
+    console.error("%c\u2502", "color: yellow;");
+    console.error("%c\u2514 Stack trace:", "color: yellow;");
+    for (let i = 0; i < stackLines.length; i++) {
+      console.error(
+        `%c  ${i == stackLines.length - 1 ? "\u2514" : "\u251c"}\u2500 ${
+          StringPrototypeTrim(stackLines[i])
+        }`,
+        "color: yellow;",
+      );
+    }
   }
   console.error();
 }
@@ -626,6 +630,18 @@ function bootstrapMainRuntime(runtimeOptions) {
     noColor: util.getterOnly(() => ops.op_bootstrap_no_color()),
     args: util.getterOnly(opArgs),
     mainModule: util.getterOnly(opMainModule),
+    // TODO(kt3k): Remove this export at v2
+    // See https://github.com/denoland/deno/issues/9294
+    customInspect: {
+      get() {
+        warnOnDeprecatedApi(
+          "Deno.customInspect",
+          new Error().stack,
+          'Use `Symbol.for("Deno.customInspect")` instead.',
+        );
+        return customInspect;
+      },
+    },
   });
 
   // TODO(bartlomieju): deprecate --unstable
@@ -769,6 +785,18 @@ function bootstrapWorkerRuntime(
     pid: util.getterOnly(opPid),
     noColor: util.getterOnly(() => ops.op_bootstrap_no_color()),
     args: util.getterOnly(opArgs),
+    // TODO(kt3k): Remove this export at v2
+    // See https://github.com/denoland/deno/issues/9294
+    customInspect: {
+      get() {
+        warnOnDeprecatedApi(
+          "Deno.customInspect",
+          new Error().stack,
+          'Use `Symbol.for("Deno.customInspect")` instead.',
+        );
+        return customInspect;
+      },
+    },
   });
   // Setup `Deno` global - we're actually overriding already
   // existing global `Deno` with `Deno` namespace from "./deno.ts".