Stop defining setImmediate and clearImmediate from TimerManager when using microtasks (facebook#45090)

Summary:
Pull Request resolved: facebook#45090

Changelog: [internal]

The definition of these methods is redundant when using microtasks, so it's better to avoid defining them in the first place (to also detect issues if the setup is not what we expect).

Reviewed By: sammy-SC

Differential Revision: D58816582

fbshipit-source-id: dd1b07f8b11069605e3184b1272a9bbc3b44ca75

Author: rubennorte

packages/react-native/ReactCommon/react/runtime/TimerManager.cpp

@@ -8,6 +8,7 @@
 #include "TimerManager.h"
 
 #include <cxxreact/SystraceSection.h>
+#include <react/featureflags/ReactNativeFeatureFlags.h>
 #include <utility>
 
 namespace facebook::react {
@@ -148,60 +149,64 @@ void TimerManager::callTimer(TimerHandle timerHandle) {
 void TimerManager::attachGlobals(jsi::Runtime& runtime) {
   // Install host functions for timers.
   // TODO (T45786383): Add missing timer functions from JSTimers
-  // TODO (T96212789): Remove when JSVM microtask queue is used everywhere in
-  // bridgeless mode. This is being overwritten in JS in that case.
-  runtime.global().setProperty(
-      runtime,
-      "setImmediate",
-      jsi::Function::createFromHostFunction(
-          runtime,
-          jsi::PropNameID::forAscii(runtime, "setImmediate"),
-          2, // Function, ...args
-          [this](
-              jsi::Runtime& rt,
-              const jsi::Value& thisVal,
-              const jsi::Value* args,
-              size_t count) {
-            if (count == 0) {
-              throw jsi::JSError(
-                  rt,
-                  "setImmediate must be called with at least one argument (a function to call)");
-            }
-
-            if (!args[0].isObject() || !args[0].asObject(rt).isFunction(rt)) {
-              throw jsi::JSError(
-                  rt, "The first argument to setImmediate must be a function.");
-            }
-            auto callback = args[0].getObject(rt).getFunction(rt);
-
-            // Package up the remaining argument values into one place.
-            std::vector<jsi::Value> moreArgs;
-            for (size_t extraArgNum = 1; extraArgNum < count; extraArgNum++) {
-              moreArgs.emplace_back(rt, args[extraArgNum]);
-            }
-
-            return createReactNativeMicrotask(
-                std::move(callback), std::move(moreArgs));
-          }));
 
-  runtime.global().setProperty(
-      runtime,
-      "clearImmediate",
-      jsi::Function::createFromHostFunction(
-          runtime,
-          jsi::PropNameID::forAscii(runtime, "clearImmediate"),
-          1, // handle
-          [this](
-              jsi::Runtime& rt,
-              const jsi::Value& thisVal,
-              const jsi::Value* args,
-              size_t count) {
-            if (count > 0 && args[0].isNumber()) {
-              auto handle = (TimerHandle)args[0].asNumber();
-              deleteReactNativeMicrotask(rt, handle);
-            }
-            return jsi::Value::undefined();
-          }));
+  // Ensure that we don't define `setImmediate` and `clearImmediate` if
+  // microtasks are enabled (as we polyfill them using `queueMicrotask` then).
+  if (!ReactNativeFeatureFlags::enableMicrotasks()) {
+    runtime.global().setProperty(
+        runtime,
+        "setImmediate",
+        jsi::Function::createFromHostFunction(
+            runtime,
+            jsi::PropNameID::forAscii(runtime, "setImmediate"),
+            2, // Function, ...args
+            [this](
+                jsi::Runtime& rt,
+                const jsi::Value& thisVal,
+                const jsi::Value* args,
+                size_t count) {
+              if (count == 0) {
+                throw jsi::JSError(
+                    rt,
+                    "setImmediate must be called with at least one argument (a function to call)");
+              }
+
+              if (!args[0].isObject() || !args[0].asObject(rt).isFunction(rt)) {
+                throw jsi::JSError(
+                    rt,
+                    "The first argument to setImmediate must be a function.");
+              }
+              auto callback = args[0].getObject(rt).getFunction(rt);
+
+              // Package up the remaining argument values into one place.
+              std::vector<jsi::Value> moreArgs;
+              for (size_t extraArgNum = 1; extraArgNum < count; extraArgNum++) {
+                moreArgs.emplace_back(rt, args[extraArgNum]);
+              }
+
+              return createReactNativeMicrotask(
+                  std::move(callback), std::move(moreArgs));
+            }));
+
+    runtime.global().setProperty(
+        runtime,
+        "clearImmediate",
+        jsi::Function::createFromHostFunction(
+            runtime,
+            jsi::PropNameID::forAscii(runtime, "clearImmediate"),
+            1, // handle
+            [this](
+                jsi::Runtime& rt,
+                const jsi::Value& thisVal,
+                const jsi::Value* args,
+                size_t count) {
+              if (count > 0 && args[0].isNumber()) {
+                auto handle = (TimerHandle)args[0].asNumber();
+                deleteReactNativeMicrotask(rt, handle);
+              }
+              return jsi::Value::undefined();
+            }));
+  }
 
   runtime.global().setProperty(
       runtime,