QtCore: Use Q_REQUIRED_RESULT in many more places

gcc doesn't yet warn when a non-POD return datatype is unused,
but clang does, at least.

This detected two bugs in qtbase due to the bad QDate method naming,
and will help application developers to avoid this trap too.

Change-Id: I106c1a32d2c6fc8d02f57beb7b61940605c80d76
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

4 files changed, 55 insertions, 55 deletions

diff --git a/src/corelib/tools/qbytearray.h b/src/corelib/tools/qbytearray.h
index 0a2f7a9e53..9155ddc977 100644
--- a/src/corelib/tools/qbytearray.h
+++ b/src/corelib/tools/qbytearray.h
@@ -247,9 +247,9 @@ public:
     int count(const char *a) const;
     int count(const QByteArray &a) const;
 
-    QByteArray left(int len) const;
-    QByteArray right(int len) const;
-    QByteArray mid(int index, int len = -1) const;
+    QByteArray left(int len) const Q_REQUIRED_RESULT;
+    QByteArray right(int len) const Q_REQUIRED_RESULT;
+    QByteArray mid(int index, int len = -1) const Q_REQUIRED_RESULT;
 
     bool startsWith(const QByteArray &a) const;
     bool startsWith(char c) const;
@@ -262,13 +262,13 @@ public:
     void truncate(int pos);
     void chop(int n);
 
-    QByteArray toLower() const;
-    QByteArray toUpper() const;
+    QByteArray toLower() const Q_REQUIRED_RESULT;
+    QByteArray toUpper() const Q_REQUIRED_RESULT;
 
-    QByteArray trimmed() const;
-    QByteArray simplified() const;
-    QByteArray leftJustified(int width, char fill = ' ', bool truncate = false) const;
-    QByteArray rightJustified(int width, char fill = ' ', bool truncate = false) const;
+    QByteArray trimmed() const Q_REQUIRED_RESULT;
+    QByteArray simplified() const Q_REQUIRED_RESULT;
+    QByteArray leftJustified(int width, char fill = ' ', bool truncate = false) const Q_REQUIRED_RESULT;
+    QByteArray rightJustified(int width, char fill = ' ', bool truncate = false) const Q_REQUIRED_RESULT;
 
     QByteArray &prepend(char c);
     QByteArray &prepend(const char *s);
@@ -300,7 +300,7 @@ public:
 
     QList<QByteArray> split(char sep) const;
 
-    QByteArray repeated(int times) const;
+    QByteArray repeated(int times) const Q_REQUIRED_RESULT;
 
 #ifndef QT_NO_CAST_TO_ASCII
     QT_ASCII_CAST_WARN QByteArray &append(const QString &s);
@@ -349,16 +349,16 @@ public:
     QByteArray &setNum(double, char f = 'g', int prec = 6);
     QByteArray &setRawData(const char *a, uint n); // ### Qt 6: use an int
 
-    static QByteArray number(int, int base = 10);
-    static QByteArray number(uint, int base = 10);
-    static QByteArray number(qlonglong, int base = 10);
-    static QByteArray number(qulonglong, int base = 10);
-    static QByteArray number(double, char f = 'g', int prec = 6);
-    static QByteArray fromRawData(const char *, int size);
-    static QByteArray fromBase64(const QByteArray &base64, Base64Options options);
-    static QByteArray fromBase64(const QByteArray &base64); // ### Qt6 merge with previous
-    static QByteArray fromHex(const QByteArray &hexEncoded);
-    static QByteArray fromPercentEncoding(const QByteArray &pctEncoded, char percent = '%');
+    static QByteArray number(int, int base = 10) Q_REQUIRED_RESULT;
+    static QByteArray number(uint, int base = 10) Q_REQUIRED_RESULT;
+    static QByteArray number(qlonglong, int base = 10) Q_REQUIRED_RESULT;
+    static QByteArray number(qulonglong, int base = 10) Q_REQUIRED_RESULT;
+    static QByteArray number(double, char f = 'g', int prec = 6) Q_REQUIRED_RESULT;
+    static QByteArray fromRawData(const char *, int size) Q_REQUIRED_RESULT;
+    static QByteArray fromBase64(const QByteArray &base64, Base64Options options) Q_REQUIRED_RESULT;
+    static QByteArray fromBase64(const QByteArray &base64) Q_REQUIRED_RESULT; // ### Qt6 merge with previous
+    static QByteArray fromHex(const QByteArray &hexEncoded) Q_REQUIRED_RESULT;
+    static QByteArray fromPercentEncoding(const QByteArray &pctEncoded, char percent = '%') Q_REQUIRED_RESULT;
 
 #if defined(Q_OS_MAC) || defined(Q_QDOC)
     static QByteArray fromCFData(CFDataRef data);
diff --git a/src/corelib/tools/qdatetime.h b/src/corelib/tools/qdatetime.h
index b9f6995155..ac7296f742 100644
--- a/src/corelib/tools/qdatetime.h
+++ b/src/corelib/tools/qdatetime.h
@@ -94,9 +94,9 @@ QT_DEPRECATED inline bool setYMD(int y, int m, int d)
 
     void getDate(int *year, int *month, int *day);
 
-    QDate addDays(qint64 days) const;
-    QDate addMonths(int months) const;
-    QDate addYears(int years) const;
+    QDate addDays(qint64 days) const Q_REQUIRED_RESULT;
+    QDate addMonths(int months) const Q_REQUIRED_RESULT;
+    QDate addYears(int years) const Q_REQUIRED_RESULT;
     qint64 daysTo(const QDate &) const;
 
     bool operator==(const QDate &other) const { return jd == other.jd; }
@@ -157,9 +157,9 @@ public:
 #endif
     bool setHMS(int h, int m, int s, int ms = 0);
 
-    QTime addSecs(int secs) const;
+    QTime addSecs(int secs) const Q_REQUIRED_RESULT;
     int secsTo(const QTime &) const;
-    QTime addMSecs(int ms) const;
+    QTime addMSecs(int ms) const Q_REQUIRED_RESULT;
     int msecsTo(const QTime &) const;
 
     bool operator==(const QTime &other) const { return mds == other.mds; }
@@ -251,11 +251,11 @@ public:
     QString toString(Qt::DateFormat f = Qt::TextDate) const;
     QString toString(const QString &format) const;
 #endif
-    QDateTime addDays(qint64 days) const;
-    QDateTime addMonths(int months) const;
-    QDateTime addYears(int years) const;
-    QDateTime addSecs(qint64 secs) const;
-    QDateTime addMSecs(qint64 msecs) const;
+    QDateTime addDays(qint64 days) const Q_REQUIRED_RESULT;
+    QDateTime addMonths(int months) const Q_REQUIRED_RESULT;
+    QDateTime addYears(int years) const Q_REQUIRED_RESULT;
+    QDateTime addSecs(qint64 secs) const Q_REQUIRED_RESULT;
+    QDateTime addMSecs(qint64 msecs) const Q_REQUIRED_RESULT;
 
     QDateTime toTimeSpec(Qt::TimeSpec spec) const;
     inline QDateTime toLocalTime() const { return toTimeSpec(Qt::LocalTime); }
diff --git a/src/corelib/tools/qline.h b/src/corelib/tools/qline.h
index 69e8a8245a..9b41d7b83e 100644
--- a/src/corelib/tools/qline.h
+++ b/src/corelib/tools/qline.h
@@ -75,8 +75,8 @@ public:
     inline void translate(const QPoint &p);
     inline void translate(int dx, int dy);
 
-    Q_DECL_CONSTEXPR inline QLine translated(const QPoint &p) const;
-    Q_DECL_CONSTEXPR inline QLine translated(int dx, int dy) const;
+    Q_DECL_CONSTEXPR inline QLine translated(const QPoint &p) const Q_REQUIRED_RESULT;
+    Q_DECL_CONSTEXPR inline QLine translated(int dx, int dy) const Q_REQUIRED_RESULT;
 
     inline void setP1(const QPoint &p1);
     inline void setP2(const QPoint &p2);
@@ -216,7 +216,7 @@ public:
     Q_DECL_CONSTEXPR inline QLineF(qreal x1, qreal y1, qreal x2, qreal y2);
     Q_DECL_CONSTEXPR inline QLineF(const QLine &line) : pt1(line.p1()), pt2(line.p2()) { }
 
-    static QLineF fromPolar(qreal length, qreal angle);
+    static QLineF fromPolar(qreal length, qreal angle) Q_REQUIRED_RESULT;
 
     Q_DECL_CONSTEXPR bool isNull() const;
 
@@ -240,8 +240,8 @@ public:
 
     qreal angleTo(const QLineF &l) const;
 
-    QLineF unitVector() const;
-    Q_DECL_CONSTEXPR inline QLineF normalVector() const;
+    QLineF unitVector() const Q_REQUIRED_RESULT;
+    Q_DECL_CONSTEXPR inline QLineF normalVector() const Q_REQUIRED_RESULT;
 
     // ### Qt 6: rename intersects() or intersection() and rename IntersectType IntersectionType
     IntersectType intersect(const QLineF &l, QPointF *intersectionPoint) const;
@@ -252,8 +252,8 @@ public:
     inline void translate(const QPointF &p);
     inline void translate(qreal dx, qreal dy);
 
-    Q_DECL_CONSTEXPR inline QLineF translated(const QPointF &p) const;
-    Q_DECL_CONSTEXPR inline QLineF translated(qreal dx, qreal dy) const;
+    Q_DECL_CONSTEXPR inline QLineF translated(const QPointF &p) const Q_REQUIRED_RESULT;
+    Q_DECL_CONSTEXPR inline QLineF translated(qreal dx, qreal dy) const Q_REQUIRED_RESULT;
 
     inline void setP1(const QPointF &p1);
     inline void setP2(const QPointF &p2);
diff --git a/src/corelib/tools/qrect.h b/src/corelib/tools/qrect.h
index 2bb74e8221..8ee08877e8 100644
--- a/src/corelib/tools/qrect.h
+++ b/src/corelib/tools/qrect.h
@@ -68,7 +68,7 @@ public:
     Q_DECL_CONSTEXPR inline int top() const;
     Q_DECL_CONSTEXPR inline int right() const;
     Q_DECL_CONSTEXPR inline int bottom() const;
-    QRect normalized() const;
+    QRect normalized() const Q_REQUIRED_RESULT;
 
     Q_DECL_CONSTEXPR inline int x() const;
     Q_DECL_CONSTEXPR inline int y() const;
@@ -102,8 +102,8 @@ public:
 
     inline void translate(int dx, int dy);
     inline void translate(const QPoint &p);
-    Q_DECL_CONSTEXPR inline QRect translated(int dx, int dy) const;
-    Q_DECL_CONSTEXPR inline QRect translated(const QPoint &p) const;
+    Q_DECL_CONSTEXPR inline QRect translated(int dx, int dy) const Q_REQUIRED_RESULT;
+    Q_DECL_CONSTEXPR inline QRect translated(const QPoint &p) const Q_REQUIRED_RESULT;
 
     inline void moveTo(int x, int t);
     inline void moveTo(const QPoint &p);
@@ -115,7 +115,7 @@ public:
     inline void getCoords(int *x1, int *y1, int *x2, int *y2) const;
 
     inline void adjust(int x1, int y1, int x2, int y2);
-    Q_DECL_CONSTEXPR inline QRect adjusted(int x1, int y1, int x2, int y2) const;
+    Q_DECL_CONSTEXPR inline QRect adjusted(int x1, int y1, int x2, int y2) const Q_REQUIRED_RESULT;
 
     Q_DECL_CONSTEXPR inline QSize size() const;
     Q_DECL_CONSTEXPR inline int width() const;
@@ -133,8 +133,8 @@ public:
     bool contains(const QPoint &p, bool proper=false) const;
     inline bool contains(int x, int y) const;
     inline bool contains(int x, int y, bool proper) const;
-    inline QRect united(const QRect &other) const;
-    inline QRect intersected(const QRect &other) const;
+    inline QRect united(const QRect &other) const Q_REQUIRED_RESULT;
+    inline QRect intersected(const QRect &other) const Q_REQUIRED_RESULT;
     bool intersects(const QRect &r) const;
 
     Q_DECL_CONSTEXPR inline QRect marginsAdded(const QMargins &margins) const;
@@ -143,8 +143,8 @@ public:
     inline QRect &operator-=(const QMargins &margins);
 
 #if QT_DEPRECATED_SINCE(5, 0)
-    QT_DEPRECATED QRect unite(const QRect &r) const { return united(r); }
-    QT_DEPRECATED QRect intersect(const QRect &r) const { return intersected(r); }
+    QT_DEPRECATED QRect unite(const QRect &r) const Q_REQUIRED_RESULT { return united(r); }
+    QT_DEPRECATED QRect intersect(const QRect &r) const Q_REQUIRED_RESULT { return intersected(r); }
 #endif
 
     friend Q_DECL_CONSTEXPR inline bool operator==(const QRect &, const QRect &);
@@ -510,7 +510,7 @@ public:
     Q_DECL_CONSTEXPR inline bool isNull() const;
     Q_DECL_CONSTEXPR inline bool isEmpty() const;
     Q_DECL_CONSTEXPR inline bool isValid() const;
-    QRectF normalized() const;
+    QRectF normalized() const Q_REQUIRED_RESULT;
 
     Q_DECL_CONSTEXPR inline qreal left() const { return xp; }
     Q_DECL_CONSTEXPR inline qreal top() const { return yp; }
@@ -550,8 +550,8 @@ public:
     inline void translate(qreal dx, qreal dy);
     inline void translate(const QPointF &p);
 
-    Q_DECL_CONSTEXPR inline QRectF translated(qreal dx, qreal dy) const;
-    Q_DECL_CONSTEXPR inline QRectF translated(const QPointF &p) const;
+    Q_DECL_CONSTEXPR inline QRectF translated(qreal dx, qreal dy) const Q_REQUIRED_RESULT;
+    Q_DECL_CONSTEXPR inline QRectF translated(const QPointF &p) const Q_REQUIRED_RESULT;
 
     inline void moveTo(qreal x, qreal y);
     inline void moveTo(const QPointF &p);
@@ -563,7 +563,7 @@ public:
     inline void getCoords(qreal *x1, qreal *y1, qreal *x2, qreal *y2) const;
 
     inline void adjust(qreal x1, qreal y1, qreal x2, qreal y2);
-    Q_DECL_CONSTEXPR inline QRectF adjusted(qreal x1, qreal y1, qreal x2, qreal y2) const;
+    Q_DECL_CONSTEXPR inline QRectF adjusted(qreal x1, qreal y1, qreal x2, qreal y2) const Q_REQUIRED_RESULT;
 
     Q_DECL_CONSTEXPR inline QSizeF size() const;
     Q_DECL_CONSTEXPR inline qreal width() const;
@@ -580,8 +580,8 @@ public:
     bool contains(const QRectF &r) const;
     bool contains(const QPointF &p) const;
     inline bool contains(qreal x, qreal y) const;
-    inline QRectF united(const QRectF &other) const;
-    inline QRectF intersected(const QRectF &other) const;
+    inline QRectF united(const QRectF &other) const Q_REQUIRED_RESULT;
+    inline QRectF intersected(const QRectF &other) const Q_REQUIRED_RESULT;
     bool intersects(const QRectF &r) const;
 
     Q_DECL_CONSTEXPR inline QRectF marginsAdded(const QMarginsF &margins) const;
@@ -590,15 +590,15 @@ public:
     inline QRectF &operator-=(const QMarginsF &margins);
 
 #if QT_DEPRECATED_SINCE(5, 0)
-    QT_DEPRECATED QRectF unite(const QRectF &r) const { return united(r); }
-    QT_DEPRECATED QRectF intersect(const QRectF &r) const { return intersected(r); }
+    QT_DEPRECATED QRectF unite(const QRectF &r) const Q_REQUIRED_RESULT { return united(r); }
+    QT_DEPRECATED QRectF intersect(const QRectF &r) const Q_REQUIRED_RESULT { return intersected(r); }
 #endif
 
     friend Q_DECL_CONSTEXPR inline bool operator==(const QRectF &, const QRectF &);
     friend Q_DECL_CONSTEXPR inline bool operator!=(const QRectF &, const QRectF &);
 
-    Q_DECL_CONSTEXPR inline QRect toRect() const;
-    QRect toAlignedRect() const;
+    Q_DECL_CONSTEXPR inline QRect toRect() const Q_REQUIRED_RESULT;
+    QRect toAlignedRect() const Q_REQUIRED_RESULT;
 
 private:
     qreal xp;