Disentangle string-related headers

It's starting to hinder QStringView development
(QString::append(QStringView), e.g.).

- qbytearray.h includes qstring.h, but is included by qstring.h
  -> remove qstring.h include from qbytearray.h

- the QStringLiteral definition is used from both qstring.h and
  qstringview.h
  -> extract into its own header, move QStringViewLiteral definition
     there, too

- the qCompareStrings(), qConvertTo*() functions are used by QString
  and QStringView
  -> also extract into own header, included from qstring.h and
     qstringview.h

- QStringView::toString() depends on QString, which depends on
  QStringView
  -> move QStringView::toString() definition to qstring.h, after the
     definition of QString
  -> move qstringview.h up to all the other includes in qstring.h

This is starting to look like a DAG again, and allows to remove the
unholy

  #ifndef QSTRING_H
  #  include <qstring.h>
  #endif

hack from qstringview.h.

[ChangeLog][Potentially Source-Incompatible Changes][QByteArray]
qbytearray.h no longer includes qstring.h. In particular, this means
that in order to use QStringBuilder with QByteArray, you need to
include both qbytearray.h and qstring.h now (or <QByteArray> and
<QString>, resp.).

Change-Id: I7f8acf9c11bc1731266cd25c6eda9fb36723f364
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 12 insertions, 12 deletions

diff --git a/src/corelib/tools/qstringview.h b/src/corelib/tools/qstringview.h
index 22f20796f4..527f1d48e7 100644
--- a/src/corelib/tools/qstringview.h
+++ b/src/corelib/tools/qstringview.h
@@ -36,24 +36,24 @@
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/
+#ifndef QSTRINGVIEW_H
+#define QSTRINGVIEW_H
 
-#ifndef QSTRING_H
-# include <QtCore/qstring.h>
+#ifndef QT_STRINGVIEW_LEVEL
+#  define QT_STRINGVIEW_LEVEL 1
 #endif
 
-#ifndef QSTRINGVIEW_H
-#define QSTRINGVIEW_H
+#include <QtCore/qchar.h>
+#include <QtCore/qbytearray.h>
+#include <QtCore/qstringliteral.h>
+#include <QtCore/qstringalgorithms.h>
 
 #include <string>
 
 QT_BEGIN_NAMESPACE
 
-#ifndef QT_NO_UNICODE_LITERAL
-# ifndef QT_UNICODE_LITERAL
-#  error "If you change QStringLiteral, please change QStringViewLiteral, too"
-# endif
-# define QStringViewLiteral(str) QStringView(QT_UNICODE_LITERAL(str))
-#endif
+class QString;
+class QStringRef;
 
 namespace QtPrivate {
 template <typename Char>
@@ -205,7 +205,7 @@ public:
     QStringView(const StdBasicString &str) Q_DECL_NOTHROW
         : QStringView(str.data(), qssize_t(str.size())) {}
 
-    Q_REQUIRED_RESULT QString toString() const { return Q_ASSERT(size() == length()), QString(data(), length()); }
+    Q_REQUIRED_RESULT inline QString toString() const; // defined in qstring.h
 
     Q_REQUIRED_RESULT Q_DECL_CONSTEXPR qssize_t size() const Q_DECL_NOTHROW { return m_size; }
     Q_REQUIRED_RESULT const_pointer data() const Q_DECL_NOTHROW { return reinterpret_cast<const_pointer>(m_data); }
@@ -221,7 +221,7 @@ public:
     Q_REQUIRED_RESULT QByteArray toLatin1() const { return qConvertToLatin1(*this); }
     Q_REQUIRED_RESULT QByteArray toUtf8() const { return qConvertToUtf8(*this); }
     Q_REQUIRED_RESULT QByteArray toLocal8Bit() const { return qConvertToLocal8Bit(*this); }
-    Q_REQUIRED_RESULT inline QVector<uint> toUcs4() const;
+    Q_REQUIRED_RESULT inline QVector<uint> toUcs4() const; // defined in qvector.h
 
     Q_REQUIRED_RESULT Q_DECL_CONSTEXPR QChar at(qssize_t n) const { return (*this)[n]; }