Optimize string building in QCommandLineParserPrivate::helpText()

- Don't detach QCoreApplication::arguments() by calling first(),
  call constFirst()
- Use
    QString foo;
    foo += initial;
  instead of
    QString foo = initial;
  where 'foo' receives more appends later (does not force an
  initial capacity that is known to be too small).
- Use QStringBuilder more
- Don't use QStringLiteral in QStringBuilder expressions
- Reserve optionNameList. Its max. size is known ahead of time.
- Don't create optionNameStrings for hidden options.
  The result was never used, they just served as placeholders
  for the lock-step iteration that followed and wrapped the text.
- Don't create a QStringList to join(), append to the result
  string directly.
- Cache the return value of option.valueName().

Not only is this faster, it also saves more than 2KiB in text
size on optimized GCC 4.9 Linux AMD64 builds.

Change-Id: Id1d88f3c36a521ac71f3a7436810ed31319077ae
Reviewed-by: David Faure <david.faure@kdab.com>

0 files changed, 0 insertions, 0 deletions