commit a76004f16fdc43e1b7af83bfdf3f1a613491b234
Author: Paul Wicking <paul.wicking@qt.io>
Date:   Thu Mar 26 07:09:43 2026 +0100

    qyieldcpu: Fix compilation with macOS 26.4 SDK
    
    After updating to the macOS 26.4 SDK, qtbase fails to compile on
    Apple Silicon with an implicit function declaration error for
    __yield() in qyieldcpu.h. It appears that the SDK's Clang now
    reports __has_builtin(__yield) as true, but __yield() requires
    <arm_acle.h> for its declaration.
    
    The compiler's own __builtin_arm_yield intrinsic was already checked
    further down in the cascade. Moving it above the __yield check resolves
    the build failure, without unnecessarily pulling in the header.
    
    Fixes: QTBUG-145239
    Change-Id: I94b4d8f72385a4944c272ed7a66d249537a82e7d
    Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
    Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

--- a/qtbase/src/corelib/thread/qyieldcpu.h
+++ b/qtbase/src/corelib/thread/qyieldcpu.h
@@ -31,7 +31,9 @@ void qYieldCpu(void)
     noexcept
 #endif
 {
-#if __has_builtin(__yield)
+#if __has_builtin(__builtin_arm_yield)
+    __builtin_arm_yield();
+#elif __has_builtin(__yield)
     __yield();              // Generic
 #elif defined(_YIELD_PROCESSOR) && defined(Q_CC_MSVC)
     _YIELD_PROCESSOR();     // Generic; MSVC's <atomic>
@@ -45,9 +47,6 @@ void qYieldCpu(void)
     _mm_pause();
 #elif defined(Q_PROCESSOR_X86)
     __asm__("pause");           // hopefully asm() works in this compiler
-
-#elif __has_builtin(__builtin_arm_yield)
-    __builtin_arm_yield();
 #elif defined(Q_PROCESSOR_ARM) && Q_PROCESSOR_ARM >= 7 && defined(Q_CC_GNU)
     __asm__("yield");           // this works everywhere
 
