Fix [[nodiscard]] compile errors in QLocale benchmark

QString::toUpper() now insists we use its return, so the benchmark
won't compile unless we do so. Also document the helper macro used by
the tests, to explain why it's even there at all.

Change-Id: I830f121d92867bcd09277ecdeb1c764413b34fa6
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>

1 files changed, 5 insertions, 4 deletions

diff --git a/tests/benchmarks/corelib/text/qlocale/main.cpp b/tests/benchmarks/corelib/text/qlocale/main.cpp
index 38d94af143..7047338800 100644
--- a/tests/benchmarks/corelib/text/qlocale/main.cpp
+++ b/tests/benchmarks/corelib/text/qlocale/main.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2020 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -44,25 +44,26 @@ static QString data()
     return QStringLiteral("/qt-5/qtbase/tests/benchmarks/corelib/tools/qlocale");
 }
 
+// Make individual cycles O(a few) msecs, rather than tiny fractions thereof:
 #define LOOP(s) for (int i = 0; i < 5000; ++i) { s; }
 
 void tst_QLocale::toUpper_QLocale_1()
 {
     QString s = data();
-    QBENCHMARK { LOOP(QLocale().toUpper(s)) }
+    QBENCHMARK { LOOP(QString t(QLocale().toUpper(s))) }
 }
 
 void tst_QLocale::toUpper_QLocale_2()
 {
     QString s = data();
     QLocale l;
-    QBENCHMARK { LOOP(l.toUpper(s)) }
+    QBENCHMARK { LOOP(QString t(l.toUpper(s))) }
 }
 
 void tst_QLocale::toUpper_QString()
 {
     QString s = data();
-    QBENCHMARK { LOOP(s.toUpper()) }
+    QBENCHMARK { LOOP(QString t(s.toUpper())) }
 }
 
 QTEST_MAIN(tst_QLocale)