revert to building qmake with qconfig.cpp

turns out that just appending builtin-qt.conf isn't a good idea:
executable-editing tools (objcopy, prelink, etc.) will happily drop the
"attachment".

a safe method would be adding a proper section to the executable, but
there doesn't appear to be an objcopy equivalent in msvc, and using
entirely different methods of embedding the file with different
toolchains seems like a rather bad idea.

so instead go back to the old method of building qmake with a generated
qconfig.cpp. of course, as said file is now created by qmake itself, we
have to compile qlibraryinfo.cpp a second time, and link a second qmake
executable.

Task-number: QTBUG-57803
Change-Id: I9e232693550aa870cec154e49cc06add13017cc2
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

2 files changed, 16 insertions, 85 deletions

diff --git a/src/corelib/global/qlibraryinfo.cpp b/src/corelib/global/qlibraryinfo.cpp
index 3ff37a5818..0de8b50900 100644
--- a/src/corelib/global/qlibraryinfo.cpp
+++ b/src/corelib/global/qlibraryinfo.cpp
@@ -41,18 +41,15 @@
 #include "qdir.h"
 #include "qstringlist.h"
 #include "qfile.h"
-#include "qtemporaryfile.h"
 #include "qsettings.h"
 #include "qlibraryinfo.h"
 #include "qscopedpointer.h"
 
 #ifdef QT_BUILD_QMAKE
 QT_BEGIN_NAMESPACE
-extern QString qmake_absoluteLocation();
 extern QString qmake_libraryInfoFile();
 QT_END_NAMESPACE
 #else
-# include "qconfig.cpp"
 # include "qcoreapplication.h"
 #endif
 
@@ -60,6 +57,10 @@ QT_END_NAMESPACE
 #  include "private/qcore_mac_p.h"
 #endif
 
+#ifndef QT_BUILD_QMAKE_BOOTSTRAP
+# include "qconfig.cpp"
+#endif
+
 #include "archdetect.cpp"
 
 QT_BEGIN_NAMESPACE
@@ -72,16 +73,9 @@ struct QLibrarySettings
 {
     QLibrarySettings();
     void load();
-#ifdef QT_BUILD_QMAKE
-    void loadBuiltinValues(QSettings *config);
-#endif
 
     QScopedPointer<QSettings> settings;
 #ifdef QT_BUILD_QMAKE
-    QString builtinValues[QLibraryInfo::LastHostPath + 1];
-# ifndef Q_OS_WIN
-    QString builtinSettingsPath;
-# endif
     bool haveDevicePaths;
     bool haveEffectiveSourcePaths;
     bool haveEffectivePaths;
@@ -113,18 +107,6 @@ public:
                          ? ls->haveDevicePaths
                          : ls->havePaths) : false;
     }
-    static QString builtinValue(int loc)
-    {
-        QLibrarySettings *ls = qt_library_settings();
-        return ls ? ls->builtinValues[loc] : QString();
-    }
-# ifndef Q_OS_WIN
-    static QString builtinSettingsPath()
-    {
-        QLibrarySettings *ls = qt_library_settings();
-        return ls ? ls->builtinSettingsPath : QString();
-    }
-# endif
 #endif
     static QSettings *configuration()
     {
@@ -148,20 +130,6 @@ QLibrarySettings::QLibrarySettings()
     load();
 }
 
-#ifdef QT_BUILD_QMAKE
-static QByteArray qtconfSeparator()
-{
-# ifdef Q_OS_WIN
-    QByteArray header = QByteArrayLiteral("\r\n===========================================================\r\n");
-# else
-    QByteArray header = QByteArrayLiteral("\n===========================================================\n");
-# endif
-    QByteArray content = QByteArrayLiteral("==================== qt.conf beginning ====================");
-    // Assemble from pieces to avoid that the string appears in a raw executable
-    return header + content + header;
-}
-#endif
-
 void QLibrarySettings::load()
 {
     // If we get any settings here, those won't change when the application shows up.
@@ -199,27 +167,6 @@ void QLibrarySettings::load()
         havePaths = false;
 #endif
     }
-
-#ifdef QT_BUILD_QMAKE
-    // Try to use an embedded qt.conf appended to the QMake executable.
-    QFile qmakeFile(qmake_absoluteLocation());
-    if (!qmakeFile.open(QIODevice::ReadOnly))
-        return;
-    qmakeFile.seek(qmakeFile.size() - 10000);
-    QByteArray tail = qmakeFile.read(10000);
-    QByteArray separator = qtconfSeparator();
-    int qtconfOffset = tail.lastIndexOf(separator);
-    if (qtconfOffset < 0)
-        return;
-    tail.remove(0, qtconfOffset + separator.size());
-    // If QSettings had a c'tor taking a QIODevice, we'd pass a QBuffer ...
-    QTemporaryFile tmpFile;
-    tmpFile.open();
-    tmpFile.write(tail);
-    tmpFile.close();
-    QSettings builtinSettings(tmpFile.fileName(), QSettings::IniFormat);
-    loadBuiltinValues(&builtinSettings);
-#endif
 }
 
 QSettings *QLibraryInfoPrivate::findConfiguration()
@@ -482,24 +429,11 @@ static const struct {
     { "HostData", "." },
     { "TargetSpec", "" },
     { "HostSpec", "" },
-    { "ExtPrefix", "" },
     { "HostPrefix", "" },
 #endif
 };
 
 #ifdef QT_BUILD_QMAKE
-void QLibrarySettings::loadBuiltinValues(QSettings *config)
-{
-    config->beginGroup(QLatin1String("Paths"));
-    for (int i = 0; i <= QLibraryInfo::LastHostPath; i++)
-        builtinValues[i] = config->value(QLatin1String(qtConfEntries[i].key),
-                                         QLatin1String(qtConfEntries[i].value)).toString();
-# ifndef Q_OS_WIN
-    builtinSettingsPath = config->value(QLatin1String("Settings")).toString();
-# endif
-    config->endGroup();
-}
-
 void QLibraryInfo::reload()
 {
     QLibraryInfoPrivate::reload();
@@ -613,34 +547,32 @@ QLibraryInfo::rawLocation(LibraryLocation loc, PathGroup group)
     }
 #endif // QT_NO_SETTINGS
 
+#ifndef QT_BUILD_QMAKE_BOOTSTRAP
     if (!fromConf) {
-#ifdef QT_BUILD_QMAKE
-        if ((unsigned)loc <= (unsigned)LastHostPath) {
-            if (loc == PrefixPath && group != DevicePaths)
-                ret = QLibraryInfoPrivate::builtinValue(ExtPrefixPath);
-            else
-                ret = QLibraryInfoPrivate::builtinValue(loc);
-# ifndef Q_OS_WIN // On Windows we use the registry
-        } else if (loc == SettingsPath) {
-            ret = QLibraryInfoPrivate::builtinSettingsPath();
-# endif
-        }
-#else // QT_BUILD_QMAKE
         const char * volatile path = 0;
         if (loc == PrefixPath) {
-            path = QT_CONFIGURE_PREFIX_PATH;
+            path =
+# ifdef QT_BUILD_QMAKE
+                (group != DevicePaths) ?
+                    QT_CONFIGURE_EXT_PREFIX_PATH :
+# endif
+                    QT_CONFIGURE_PREFIX_PATH;
         } else if (unsigned(loc) <= sizeof(qt_configure_str_offsets)/sizeof(qt_configure_str_offsets[0])) {
             path = qt_configure_strs + qt_configure_str_offsets[loc - 1];
 #ifndef Q_OS_WIN // On Windows we use the registry
         } else if (loc == SettingsPath) {
             path = QT_CONFIGURE_SETTINGS_PATH;
 #endif
+# ifdef QT_BUILD_QMAKE
+        } else if (loc == HostPrefixPath) {
+            path = QT_CONFIGURE_HOST_PREFIX_PATH;
+# endif
         }
 
         if (path)
             ret = QString::fromLocal8Bit(path);
-#endif
     }
+#endif
 
 #ifdef QT_BUILD_QMAKE
     // These values aren't actually paths and thus need to be returned verbatim.
diff --git a/src/corelib/global/qlibraryinfo.h b/src/corelib/global/qlibraryinfo.h
index 812ab9a263..809813d99d 100644
--- a/src/corelib/global/qlibraryinfo.h
+++ b/src/corelib/global/qlibraryinfo.h
@@ -97,7 +97,6 @@ public:
         HostDataPath,
         TargetSpecPath,
         HostSpecPath,
-        ExtPrefixPath,
         HostPrefixPath,
         LastHostPath = HostPrefixPath,
 #endif