Fix QFontDatabase::hasFamily() for ambiguous families

If a font family has several instances from different foundries,
we disambiguate this by adding the foundry name in brackets behind
the family. But QFontDatabase::hasFamily() would only check for
families().contains(familyName). So if the database contains e.g.
Foo [Bar] and Foo [Baz] then a check for hasFamily("Foo") would
fail.

So we need to actually check for the family name instead. In
doing this, we also skip the extra step of building the list
and then searching it, but just go directly to the source.

This removes the BLACKLISTing of Ubuntu and also introduces a
QSKIP on Unix-based platforms without fontconfig, since there
is no way to know which default fonts are acceptable on those
platforms.

Fixes: QTBUG-86967
Change-Id: Id8ad80a1671daf1c14fbad8bb8f4c51ee1c59709
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
(cherry picked from commit 360f1547f70fd5752a3a44892bfe5009a4357f3c)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/gui/text/qfontdatabase.cpp

@@ -1892,7 +1892,19 @@ bool QFontDatabase::hasFamily(const QString &family)
     QString parsedFamily, foundry;
     parseFontName(family, foundry, parsedFamily);
     const QString familyAlias = QFontDatabasePrivate::resolveFontFamilyAlias(parsedFamily);
-    return families().contains(familyAlias, Qt::CaseInsensitive);
+
+    QMutexLocker locker(fontDatabaseMutex());
+    QFontDatabasePrivate *d = QFontDatabasePrivate::ensureFontDatabase();
+
+    for (int i = 0; i < d->count; i++) {
+        QtFontFamily *f = d->families[i];
+        if (f->populated && f->count == 0)
+            continue;
+        if (familyAlias.compare(f->name, Qt::CaseInsensitive) == 0)
+            return true;
+    }
+
+    return false;
 }
 
 

tests/auto/gui/text/qfont/BLACKLIST

@@ -1,12 +1,8 @@
 [defaultFamily:cursive]
-ubuntu-20.04
-ubuntu-22.04
 centos
 b2qt
 rhel
 [defaultFamily:fantasy]
-ubuntu-20.04
-ubuntu-22.04
 centos
 b2qt
 rhel

tests/auto/gui/text/qfont/tst_qfont.cpp

@@ -589,6 +589,11 @@ void tst_QFont::defaultFamily()
             break;
         }
     }
+
+#if defined(Q_OS_UNIX) && defined(QT_NO_FONTCONFIG)
+    QSKIP("This platform does not support checking for default font acceptability");
+#endif
+
 #ifdef Q_PROCESSOR_ARM_32
     if (QTestPrivate::isRunningArmOnX86())
         QEXPECT_FAIL("", "Fails on ARMv7 QEMU (QTQAINFRA-4127)", Continue);