qoperatingsystemversion_win: cache the retrieved version

Make it a static variable to avoid acquiring
the system version multiple times. The system
version won't change at runtime after all.

Pick-to: 6.2
Change-Id: Ic381e5dd7b482fedc9c01242482559ffca9d3f2b
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

1 files changed, 8 insertions, 6 deletions

diff --git a/src/corelib/global/qoperatingsystemversion_win.cpp b/src/corelib/global/qoperatingsystemversion_win.cpp
index 37f2362d0c..e8c32be56b 100644
--- a/src/corelib/global/qoperatingsystemversion_win.cpp
+++ b/src/corelib/global/qoperatingsystemversion_win.cpp
@@ -110,12 +110,14 @@ OSVERSIONINFOEX qWindowsVersionInfo()
 
 QOperatingSystemVersion QOperatingSystemVersion::current()
 {
-    QOperatingSystemVersion v;
-    v.m_os = currentType();
-    const OSVERSIONINFOEX osv = qWindowsVersionInfo();
-    v.m_major = osv.dwMajorVersion;
-    v.m_minor = osv.dwMinorVersion;
-    v.m_micro = osv.dwBuildNumber;
+    static QOperatingSystemVersion v;
+    if (v.m_os == Unknown) {
+        v.m_os = currentType();
+        const OSVERSIONINFOEX osv = qWindowsVersionInfo();
+        v.m_major = osv.dwMajorVersion;
+        v.m_minor = osv.dwMinorVersion;
+        v.m_micro = osv.dwBuildNumber;
+    }
     return v;
 }