From 568ab62185bfa7876db4d8804101a8f946b04898 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.

Pick-to: 6.6
Change-Id: I10927acb9d64077d9018b667958ca16be218012a
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
---
 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 f8402dfedae..1671914f5e7 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 39f706b0648..f5a35236e1a 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)) {}
@@ -197,7 +197,8 @@ 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();
     }