Merge remote-tracking branch 'origin/tqtc/lts-5.15.11' into tqtc/lts-5.15-opensourcev5.15.11-lts-lgpl

Change-Id: Iac056a5e9f59fc8d1929171c18039aeb45be22b8

1 files changed, 10 insertions, 7 deletions

diff --git a/src/corelib/doc/snippets/qloggingcategory/main.cpp b/src/corelib/doc/snippets/qloggingcategory/main.cpp
index f5c47b2ae8..237ba5437e 100644
--- a/src/corelib/doc/snippets/qloggingcategory/main.cpp
+++ b/src/corelib/doc/snippets/qloggingcategory/main.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2022 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the documentation of the Qt Toolkit.
@@ -86,15 +86,20 @@ void myCategoryFilter(QLoggingCategory *);
 //![20]
 
 //![21]
-QLoggingCategory::CategoryFilter oldCategoryFilter;
+static QLoggingCategory::CategoryFilter oldCategoryFilter = nullptr;
 
 void myCategoryFilter(QLoggingCategory *category)
 {
-    // configure driver.usb category here, otherwise forward to to default filter.
+    // For a category set up after this filter is installed, we first set it up
+    // with the old filter. This ensures that any driver.usb logging configured
+    // by the user is kept, aside from the one level we override; and any new
+    // categories we're not interested in get configured by the old filter.
+    if (oldCategoryFilter)
+        oldCategoryFilter(category);
+
+    // Tweak driver.usb's logging, over-riding the default filter:
     if (qstrcmp(category->categoryName(), "driver.usb") == 0)
         category->setEnabled(QtDebugMsg, true);
-    else
-        oldCategoryFilter(category);
 }
 //![21]
 
@@ -107,8 +112,6 @@ int main(int argc, char *argv[])
 //![2]
 
 //![22]
-
-// ...
 oldCategoryFilter = QLoggingCategory::installFilter(myCategoryFilter);
 //![22]