From 3fda04644a4d036f4227fe97cb58ababdafcc9f9 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Thu, 4 May 2023 11:17:22 +0200
Subject: [PATCH] QRunnable: Extract Method warnNullCallable()

The warning doesn't depend on the template argument, so factor it into
an out-of-line Q_DECL_COLD_FUNCTION. This will automatically mark the
is_null check as [[unlikely]], too.

As a drive-by, use printf-style qWarning() (expands to less code and
doesn't require #include <qdebug.h>).

Change-Id: I9ac2d912eb1d4f3d1d9b41d77700bed6d6850b0a
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
---
 src/corelib/thread/qrunnable.cpp | 10 ++++++++++
 src/corelib/thread/qrunnable.h   | 10 +++++-----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/corelib/thread/qrunnable.cpp b/src/corelib/thread/qrunnable.cpp
index 068dc1af2a1..684593e16b8 100644
--- a/src/corelib/thread/qrunnable.cpp
+++ b/src/corelib/thread/qrunnable.cpp
@@ -9,6 +9,16 @@ QRunnable::~QRunnable()
 {
 }
 
+/*!
+    \internal
+    Prints a warning and returns nullptr.
+*/
+QRunnable *QRunnable::warnNullCallable()
+{
+    qWarning("Trying to create null QRunnable. This may stop working.");
+    return nullptr;
+}
+
 /*!
     \class QRunnable
     \inmodule QtCore
diff --git a/src/corelib/thread/qrunnable.h b/src/corelib/thread/qrunnable.h
index 3b25b678363..37a99ea8413 100644
--- a/src/corelib/thread/qrunnable.h
+++ b/src/corelib/thread/qrunnable.h
@@ -5,7 +5,6 @@
 #define QRUNNABLE_H
 
 #include <QtCore/qcompilerdetection.h>
-#include <QtCore/qdebug.h>
 
 #include <functional>
 #include <type_traits>
@@ -64,6 +63,9 @@ protected:
         {
         }
     };
+
+private:
+    static Q_DECL_COLD_FUNCTION QRunnable *warnNullCallable();
 };
 
 class QGenericRunnable : public QRunnable
@@ -105,10 +107,8 @@ QRunnable *QRunnable::create(Callable &&functionToRun)
         const void *functionPtr = reinterpret_cast<void *>(functionToRun);
         is_null = !functionPtr;
     }
-    if (is_null) {
-        qWarning() << "Trying to create null QRunnable. This may stop working.";
-        return nullptr;
-    }
+    if (is_null)
+        return warnNullCallable();
 
     return new QGenericRunnable(
             new QGenericRunnableHelper<std::decay_t<Callable>>(