From 4d4e88beb5f08bc2d5c694dcf943dbd661296eb5 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Fri, 7 Jul 2023 13:10:43 +0200
Subject: [PATCH] QDebug: rewrite timeUnit() into putTimeUnit()

This avoids us committing to the QByteArray return value, which is
overkill for short strings. Instead, pull the streaming of the unit
behind the ABI boundary, so we're free to change the implementation to
either stream directly or use SSO'ed std::string.

Change-Id: I10927acb9d64077d9018b667958ca16be218012a
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 568ab62185bfa7876db4d8804101a8f946b04898)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/io/qdebug.cpp | 17 +++++++++++------
 src/corelib/io/qdebug.h   |  5 +++--
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/corelib/io/qdebug.cpp b/src/corelib/io/qdebug.cpp
index 56deeb7cf75..240cc2ea959 100644
--- a/src/corelib/io/qdebug.cpp
+++ b/src/corelib/io/qdebug.cpp
@@ -347,12 +347,7 @@ void QDebug::putByteArray(const char *begin, size_t length, Latin1Content conten
     }
 }
 
-/*!
-    \since 6.6
-    \internal
-    Helper to the std::chrono::duration debug streaming output.
- */
-QByteArray QDebug::timeUnit(qint64 num, qint64 den)
+static QByteArray timeUnit(qint64 num, qint64 den)
 {
     using namespace std::chrono;
     using namespace q20::chrono;
@@ -431,6 +426,16 @@ QByteArray QDebug::timeUnit(qint64 num, qint64 den)
     return QByteArray(buf, len + strlen(unit));
 }
 
+/*!
+    \since 6.6
+    \internal
+    Helper to the std::chrono::duration debug streaming output.
+ */
+void QDebug::putTimeUnit(qint64 num, qint64 den)
+{
+    stream->ts << timeUnit(num, den); // ### optimize
+}
+
 /*!
     \fn QDebug::swap(QDebug &other)
     \since 5.0
diff --git a/src/corelib/io/qdebug.h b/src/corelib/io/qdebug.h
index 7390a9c8bce..8469a4a8206 100644
--- a/src/corelib/io/qdebug.h
+++ b/src/corelib/io/qdebug.h
@@ -68,7 +68,7 @@ class QT6_ONLY(Q_CORE_EXPORT) QDebug : public QIODeviceBase
     QT7_ONLY(Q_CORE_EXPORT) void putUcs4(uint ucs4);
     QT7_ONLY(Q_CORE_EXPORT) void putString(const QChar *begin, size_t length);
     QT7_ONLY(Q_CORE_EXPORT) void putByteArray(const char *begin, size_t length, Latin1Content content);
-    QT7_ONLY(Q_CORE_EXPORT) static QByteArray timeUnit(qint64 num, qint64 den);
+    QT7_ONLY(Q_CORE_EXPORT) void putTimeUnit(qint64 num, qint64 den);
 public:
     explicit QDebug(QIODevice *device) : stream(new Stream(device)) {}
     explicit QDebug(QString *string) : stream(new Stream(string)) {}
@@ -194,7 +194,8 @@ public:
     template <typename Rep, typename Period>
     QDebug &operator<<(std::chrono::duration<Rep, Period> duration)
     {
-        stream->ts << duration.count() << timeUnit(Period::num, Period::den);
+        stream->ts << duration.count();
+        putTimeUnit(Period::num, Period::den);
         return maybeSpace();
     }