QLatin1String: perform the comparison to another QL1S using memcmp()

qstrncmp() would stop at the first null character, which isn't correct.
The tests that had been disabled in tst_qstring.cpp (with an inaccurate
comment) were actually passing. I've added one more to ensure that the
terminating null is compared where needed.

[ChangeLog][QtCore][QLatin1String and QUtf8StringView] Fixed a
couple of bugs where two QLatin1Strings or two QUtf8StringViews
would stop their comparisons at the first embedded null
character, instead of comparing the full string. This issue
affected both classes' relational operators (less than, greater
than, etc.) and QUtf8StringView's operator== and operator!=.

Pick-to: 5.15 6.2 6.3
Change-Id: I0e5f6bec596a4a78bd3bfffd16c90ecea71ea68e
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

1 files changed, 33 insertions, 12 deletions

diff --git a/tests/auto/corelib/text/qstring/tst_qstring.cpp b/tests/auto/corelib/text/qstring/tst_qstring.cpp
index 69166ea4f6..24aa53a024 100644
--- a/tests/auto/corelib/text/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/text/qstring/tst_qstring.cpp
@@ -6832,15 +6832,16 @@ void tst_QString::compare_data()
     QTest::newRow("data8") << upper << lower << -1 << 0;
 
     // embedded nulls
-    // These don't work as of now. It's OK that these don't work since \0 is not a valid unicode
-    /*QTest::newRow("data10") << QString(QByteArray("\0", 1)) << QString(QByteArray("\0", 1)) << 0 << 0;
-    QTest::newRow("data11") << QString(QByteArray("\0", 1)) << QString("") << 1 << 1;
-    QTest::newRow("data12") << QString("") << QString(QByteArray("\0", 1)) << -1 << -1;
-    QTest::newRow("data13") << QString("ab\0c") << QString(QByteArray("ab\0c", 4)) << 0 << 0;
+    QByteArray onenull("", 1);
+    QTest::newRow("data10") << QString(onenull) << QString(onenull) << 0 << 0;
+    QTest::newRow("data11") << QString(onenull) << QString("") << 1 << 1;
+    QTest::newRow("data12") << QString("") << QString(onenull) << -1 << -1;
+    QTest::newRow("data13") << QString::fromLatin1("ab\0c", 4) << QString(QByteArray("ab\0c", 4)) << 0 << 0;
     QTest::newRow("data14") << QString(QByteArray("ab\0c", 4)) << QString("abc") << -1 << -1;
-    QTest::newRow("data15") << QString("abc") << QString(QByteArray("ab\0c", 4)) << 1 << 1;*/
+    QTest::newRow("data15") << QString("abc") << QString(QByteArray("ab\0c", 4)) << 1 << 1;
+    QTest::newRow("data16") << QString("abc") << QString(QByteArray("abc", 4)) << -1 << -1;
 
-    // All tests below (generated by the 3 for-loops) are meant to excercise the vectorized versions
+    // All tests below (generated by the 3 for-loops) are meant to exercise the vectorized versions
     // of ucstrncmp.
 
     QString in1, in2;
@@ -6913,6 +6914,10 @@ void tst_QString::compare()
 
     QByteArray s1_8 = s1.toUtf8();
     QByteArray s2_8 = s2.toUtf8();
+    QByteArray s1_1 = s1.toLatin1();
+    QByteArray s2_1 = s2.toLatin1();
+    QLatin1String l1s1(s1_1);
+    QLatin1String l1s2(s2_1);
 
     const QStringView v1(s1);
     const QStringView v2(s2);
@@ -6933,16 +6938,24 @@ void tst_QString::compare()
     QCOMPARE(sign(QString::compare(s1, s2, Qt::CaseSensitive)), csr);
     QCOMPARE(sign(QString::compare(s1, s2, Qt::CaseInsensitive)), cir);
 
-    if (csr == 0)
+    if (csr == 0) {
         QVERIFY(qHash(s1) == qHash(s2));
+        QVERIFY(s1 == s2);
+        QVERIFY(!(s1 != s2));
+    } else {
+        QVERIFY(s1 != s2);
+        QVERIFY(!(s1 == s2));
+    }
 
     if (!cir)
         QCOMPARE(s1.toCaseFolded(), s2.toCaseFolded());
 
     if (isLatin(s2)) {
         QVERIFY(QtPrivate::isLatin1(s2));
-        QCOMPARE(sign(QString::compare(s1, QLatin1String(s2.toLatin1()))), csr);
-        QCOMPARE(sign(QString::compare(s1, QLatin1String(s2.toLatin1()), Qt::CaseInsensitive)), cir);
+        QCOMPARE(sign(QString::compare(s1, l1s2)), csr);
+        QCOMPARE(sign(QString::compare(s1, l1s2, Qt::CaseInsensitive)), cir);
+
+        // ensure it doesn't compare past the explicit size
         QByteArray l1 = s2.toLatin1();
         l1 += "x";
         QLatin1String l1str(l1.constData(), l1.size() - 1);
@@ -6952,8 +6965,16 @@ void tst_QString::compare()
 
     if (isLatin(s1)) {
         QVERIFY(QtPrivate::isLatin1(s1));
-        QCOMPARE(sign(QString::compare(QLatin1String(s1.toLatin1()), s2)), csr);
-        QCOMPARE(sign(QString::compare(QLatin1String(s1.toLatin1()), s2, Qt::CaseInsensitive)), cir);
+        QCOMPARE(sign(QString::compare(l1s1, s2)), csr);
+        QCOMPARE(sign(QString::compare(l1s1, s2, Qt::CaseInsensitive)), cir);
+    }
+
+    if (isLatin(s1) && isLatin(s2)) {
+        QCOMPARE(sign(QtPrivate::compareStrings(l1s1, l1s2)), csr);
+        QCOMPARE(sign(QtPrivate::compareStrings(l1s1, l1s2, Qt::CaseInsensitive)), cir);
+        QCOMPARE(l1s1 == l1s2, csr == 0);
+        QCOMPARE(l1s1 < l1s2, csr < 0);
+        QCOMPARE(l1s1 > l1s2, csr > 0);
     }
 }