QRegularExpression: introduce (global)matchView

QRegularExpression::match (and globalMatch) is currently overloaded
for QString and QStringView. This creates a subtle API asymmetry:

  QRegularExpression re;

  auto m1 = re.match(getQString());       // OK
  auto m2 = re.match(getStdU16String());  // Dangling

This goes against our decision that every time that there's a possible
lifetime issue at play, it should be "evident". Solving the lifetime
issue here is possible, but tricky -- since QRegularExpression
is out-of-line, one needs a type-erased container for the input
string (basically, std::any) to keep it alive and so on.

Instead I went for the simpler solution: deprecate match(QStringView)
and introduce matchView(QStringView) (same for globalMatch). This
makes it clear that the call is matching over a view and therefore
users are supposed to keep the source object alive.

Drive-by, remove the documentation that says that the QString
overloads might not keep the string alive: they do and forever will.

[ChangeLog][QtCore][QRegularExpression] Added the matchView()
and globalMatchView() functions that operate on string views.
The match(QStringView) and globalMatch(QStringView) overloads
have been deprecated.

Change-Id: I054b8605c2fdea59b556dcfea8920ef4eee78ee9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/corelib/text/qregularexpression.h b/src/corelib/text/qregularexpression.h
index 9b7de26d07..fc0f1302e3 100644
--- a/src/corelib/text/qregularexpression.h
+++ b/src/corelib/text/qregularexpression.h
@@ -91,11 +91,20 @@ public:
                                   MatchType matchType       = NormalMatch,
                                   MatchOptions matchOptions = NoMatchOption) const;
 
+#if QT_DEPRECATED_SINCE(6, 8)
     [[nodiscard]]
+    QT_DEPRECATED_VERSION_X_6_8("Use matchView instead.")
     QRegularExpressionMatch match(QStringView subjectView,
                                   qsizetype offset          = 0,
                                   MatchType matchType       = NormalMatch,
                                   MatchOptions matchOptions = NoMatchOption) const;
+#endif
+
+    [[nodiscard]]
+    QRegularExpressionMatch matchView(QStringView subjectView,
+                                      qsizetype offset          = 0,
+                                      MatchType matchType       = NormalMatch,
+                                      MatchOptions matchOptions = NoMatchOption) const;
 
     [[nodiscard]]
     QRegularExpressionMatchIterator globalMatch(const QString &subject,
@@ -103,11 +112,20 @@ public:
                                                 MatchType matchType       = NormalMatch,
                                                 MatchOptions matchOptions = NoMatchOption) const;
 
+#if QT_DEPRECATED_SINCE(6, 8)
     [[nodiscard]]
+    QT_DEPRECATED_VERSION_X_6_8("Use globalMatchView instead.")
     QRegularExpressionMatchIterator globalMatch(QStringView subjectView,
                                                 qsizetype offset          = 0,
                                                 MatchType matchType       = NormalMatch,
                                                 MatchOptions matchOptions = NoMatchOption) const;
+#endif
+
+    [[nodiscard]]
+    QRegularExpressionMatchIterator globalMatchView(QStringView subjectView,
+                                                    qsizetype offset          = 0,
+                                                    MatchType matchType       = NormalMatch,
+                                                    MatchOptions matchOptions = NoMatchOption) const;
 
     void optimize() const;