Remove QHttpHeaders::names()

We need a way for users to consume the complete contents of
QHttpHeaders.

Until now, the only way was

    for (const auto &name : h.names())
        use(h.value/combinedValue(name));

which is quadratic.

Adding the usual iterators and operator[] would require us to
expose the underlying value_type, which we're not ready to do, yet.

So we added nameAt() and valueAt() functions in previous commits to
enable efficient indexed iteration without the need to expose a
value_type. Having added those, we can now remove names(), which had
the wrong value_type (QByteArrays are by definition UTF-8 in Qt, while
header names are L1), and is no longer needed to facilitate iteration.

In QNetworkRequestFactory, temporarily use toMultiMap() because we
need the combinedValue() of all headers here. The fix will be to make
QNetworkRequest QHttpHeaders-aware, but that's a Qt 6.8 thing, even
though we should still de-pessimize this code for Qt 6.7 with private
API.

Resulted from API-review.

Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
(cherry picked from commit fd6dc2e9e7ce12d73e095a70b3259ea649f4a62d)
Change-Id: I7b52e7df4444487f865ebfb7c9d94227f470829d
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

src/network/access/qhttpheaders.cpp

@@ -888,21 +888,6 @@ bool QHttpHeaders::contains(WellKnownHeader name) const
     return contains(headerNames[qToUnderlying(name)]);
 }
 
-/*!
-    Returns a list of unique header names.
-    Header names are case-insensitive, and the returned
-    names are lower-cased.
-*/
-QList<QByteArray> QHttpHeaders::names() const
-{
-    QList<QByteArray> names;
-    for (const Header &header: d->headers) {
-        if (!names.contains(header.name))
-            names.append(header.name);
-    }
-    return names;
-}
-
 /*!
     Removes the header \a name.
 

src/network/access/qhttpheaders.h

@@ -222,8 +222,6 @@ public:
     Q_NETWORK_EXPORT bool contains(QAnyStringView name) const;
     Q_NETWORK_EXPORT bool contains(WellKnownHeader name) const;
 
-    Q_NETWORK_EXPORT QList<QByteArray> names() const;
-
     Q_NETWORK_EXPORT void clear();
     Q_NETWORK_EXPORT void removeAll(QAnyStringView name);
     Q_NETWORK_EXPORT void removeAll(WellKnownHeader name);

src/network/access/qnetworkrequestfactory.cpp

@@ -9,6 +9,7 @@
 #endif
 
 #include <QtCore/qloggingcategory.h>
+#include <QtCore/qmap.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -497,7 +498,7 @@ QNetworkRequest QNetworkRequestFactoryPrivate::newRequest(const QUrl &url) const
     // may be multiple values per name. Note: this would not necessarily
     // produce right result for 'Set-Cookie' header if it has multiple values,
     // but since it is a purely server-side (response) header, not relevant here.
-    const auto headerNames = headers.names();
+    const auto headerNames = headers.toMultiMap().uniqueKeys(); // ### fixme: port QNR to QHH
     for (const auto &name : headerNames)
         request.setRawHeader(name, headers.combinedValue(name));
 

tests/auto/network/access/qhttpheaders/tst_qhttpheaders.cpp

@@ -166,26 +166,6 @@ void tst_QHttpHeaders::accessors()
 #undef EXISTS_N_TIMES
 #undef EXISTS_NOT
 
-    // names()
-    h1.clear();
-    QVERIFY(h1.names().isEmpty());
-    h1.append(n1, v1);
-    QCOMPARE(h1.names().size(), 1);
-    QCOMPARE(h1.size(), 1);
-    QVERIFY(h1.names().contains(n1));
-    h1.append(n2, v2);
-    QCOMPARE(h1.names().size(), 2);
-    QCOMPARE(h1.size(), 2);
-    QVERIFY(h1.names().contains(n1));
-    QVERIFY(h1.names().contains(n2));
-    h1.append(n1, v1);
-    h1.append(n1, v1);
-    QCOMPARE(h1.size(), 4);
-    QCOMPARE(h1.names().size(), 2);
-    h1.append(N1, v1); // uppercase of n1
-    QCOMPARE(h1.size(), 5);
-    QCOMPARE(h1.names().size(), 2);
-
     // valueAt()
     h1.clear();
     h1.append(n1, v1);
@@ -353,7 +333,9 @@ void tst_QHttpHeaders::headerNameField()
     h1.append(u"abcdefghijklmnopqrstuvwyxzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!#$%&'*+-.^_`|~"_s,
               v1);
     QCOMPARE(h1.size(), 4);
-    QCOMPARE(h1.names().size(), 1);
+    QCOMPARE(h1.nameAt(0), h1.nameAt(1));
+    QCOMPARE(h1.nameAt(1), h1.nameAt(2));
+    QCOMPARE(h1.nameAt(2), h1.nameAt(3));
     h1.clear();
 
     // Error cases