From c78a716b723812e14563b2e1c96c050703dbc9c7 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Thu, 29 Aug 2019 21:58:32 +0200
Subject: [PATCH] QDateTimeParser: replace QVector with QVarLengthArray<12>

The lists of month and day-of-week names usually currently do not
exceed 13 elements (incl. possible leap months), so don't use
QVector, use QVarLengthArray with Prealloc = 13.

This value may be increased when ISO week-as-month is merged, but
the container remains valid even with 52 "months" (though the code
that calculates its runtime size will naturally need to be adjusted).

Change-Id: I4ead897d933f89fc092850fcc22ca41da0a6ddc6
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
---
 src/corelib/time/qdatetimeparser.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/corelib/time/qdatetimeparser.cpp b/src/corelib/time/qdatetimeparser.cpp
index 3c54a259a41..d0f34358b98 100644
--- a/src/corelib/time/qdatetimeparser.cpp
+++ b/src/corelib/time/qdatetimeparser.cpp
@@ -60,6 +60,9 @@
 
 QT_BEGIN_NAMESPACE
 
+template <typename T>
+using ShortVector = QVarLengthArray<T, 13>; // enough for month (incl. leap) and day-of-week names
+
 QDateTimeParser::~QDateTimeParser()
 {
 }
@@ -1538,7 +1541,7 @@ QDateTimeParser::parse(QString input, int position, const QDateTime &defaultValu
   length of overlap in *used (if \a used is non-NULL) and the first entry that
   overlapped this much in *usedText (if \a usedText is non-NULL).
  */
-static int findTextEntry(const QString &text, const QVector<QString> &entries, QString *usedText, int *used)
+static int findTextEntry(const QString &text, const ShortVector<QString> &entries, QString *usedText, int *used)
 {
     if (text.isEmpty())
         return -1;
@@ -1586,7 +1589,7 @@ int QDateTimeParser::findMonth(const QString &str1, int startMonth, int sectionI
 
     QLocale::FormatType type = sn.count == 3 ? QLocale::ShortFormat : QLocale::LongFormat;
     QLocale l = locale();
-    QVector<QString> monthNames;
+    ShortVector<QString> monthNames;
     monthNames.reserve(13 - startMonth);
     for (int month = startMonth; month <= 12; ++month)
         monthNames.append(calendar.monthName(l, month, year, type));
@@ -1605,7 +1608,7 @@ int QDateTimeParser::findDay(const QString &str1, int startDay, int sectionIndex
 
     QLocale::FormatType type = sn.count == 4 ? QLocale::LongFormat : QLocale::ShortFormat;
     QLocale l = locale();
-    QVector<QString> daysOfWeek;
+    ShortVector<QString> daysOfWeek;
     daysOfWeek.reserve(8 - startDay);
     for (int day = startDay; day <= 7; ++day)
         daysOfWeek.append(l.dayName(day, type));