Remove the build-key from the plugin verification data

The build-key is an old mechanism to work around binary
incompatibilities in GCC 3.x versions. Modern GCC has not broken binary
compatibility since 3.4, making this mechanism obsolete.

The cache value stored now only includes Qt version, the debug/release
boolean, and the last modified time for the plugin. Old 4-value keys
will be replaced with new keys as the plugins are reloaded the first
time.

This also removes QLibraryInfo::buildKey(), which is a source-incompatible
change.

The UNIX and Windows configure tools have been updated to stop
outputting the QT_BUILD_KEY preprocessor directive.

See also:
http://lists.qt.nokia.com/pipermail/qt5-feedback/2011-August/000892.html

Change-Id: I7d06969a370d3d2c6de413c1230d9d6789cbf195
Reviewed-on: http://codereview.qt.nokia.com/3977
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>

10 files changed, 19 insertions, 401 deletions

diff --git a/configure b/configure
index 83d5662912..0344057730 100755
--- a/configure
+++ b/configure
@@ -781,7 +781,6 @@ CFG_AVX=auto
 CFG_REDUCE_RELOCATIONS=no
 CFG_NAS=no
 CFG_QWS_DEPTHS=all
-CFG_USER_BUILD_KEY=
 CFG_ACCESSIBILITY=auto
 CFG_QT3SUPPORT=no
 CFG_ENDIAN=auto
@@ -1059,7 +1058,7 @@ while [ "$#" -gt 0 ]; do
         shift
         VAL=$1
         ;;
-    -prefix|-docdir|-headerdir|-plugindir|-importdir|-datadir|-libdir|-bindir|-translationdir|-sysconfdir|-examplesdir|-depths|-make|-nomake|-platform|-xplatform|-buildkey|-sdk|-arch|-host-arch|-mysql_config)
+    -prefix|-docdir|-headerdir|-plugindir|-importdir|-datadir|-libdir|-bindir|-translationdir|-sysconfdir|-examplesdir|-depths|-make|-nomake|-platform|-xplatform|-sdk|-arch|-host-arch|-mysql_config)
         VAR=`echo $1 | sed "s,^-\(.*\),\1,"`
         shift
         VAL="$1"
@@ -1322,9 +1321,6 @@ while [ "$#" -gt 0 ]; do
     bindir)
         QT_INSTALL_BINS="$VAL"
         ;;
-    buildkey)
-        CFG_USER_BUILD_KEY="$VAL"
-        ;;
     sxe)
 	CFG_SXE="$VAL"
         ;;
@@ -3722,7 +3718,7 @@ if [ "$OPT_HELP" = "yes" ]; then
 Usage:  $relconf [-h] [-prefix <dir>] [-prefix-install] [-bindir <dir>] [-libdir <dir>]
         [-docdir <dir>] [-headerdir <dir>] [-plugindir <dir> ] [-importdir <dir>] [-datadir <dir>]
         [-translationdir <dir>] [-sysconfdir <dir>] [-examplesdir <dir>]
-        [-buildkey <key>] [-release] [-debug] [-debug-and-release]
+        [-release] [-debug] [-debug-and-release]
         [-developer-build] [-shared] [-static] [-no-fast] [-fast] [-no-largefile]
         [-largefile] [-no-exceptions] [-exceptions] [-no-accessibility]
         [-accessibility] [-no-stl] [-stl] [-no-sql-<driver>] [-sql-<driver>]
@@ -3800,12 +3796,6 @@ cat <<EOF
     -examplesdir <dir> .... Examples will be installed to <dir>
                             (default PREFIX/examples)
 
- You may use these options to turn on strict plugin loading.
-
-    -buildkey <key> .... Build the Qt library and plugins using the specified
-                         <key>.  When the library loads plugins, it will only
-                         load those that have a matching key.
-
 Configure options:
 
  The defaults (*) are usually acceptable. A plus (+) denotes a default value
@@ -7737,226 +7727,6 @@ if [ "$PLATFORM_MAC" = "yes" ] && [ "$CFG_MAC_XARCH" != "no" ] ; then
 fi
 
 #-------------------------------------------------------------------------------
-# generate QT_BUILD_KEY
-#-------------------------------------------------------------------------------
-
-# some compilers generate binary incompatible code between different versions,
-# so we need to generate a build key that is different between these compilers
-COMPAT_COMPILER=
-case "$COMPILER" in
-g++*)
-    # GNU C++
-    COMPILER_VERSION=`${QMAKE_CONF_COMPILER} -dumpversion 2>/dev/null`
-
-    case "$COMPILER_VERSION" in
-    *.*.*)
-        QT_GCC_MAJOR_VERSION=`echo $COMPILER_VERSION | sed 's,^\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*,\1,'`
-        QT_GCC_MINOR_VERSION=`echo $COMPILER_VERSION | sed 's,^\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*,\2,'`
-        QT_GCC_PATCH_VERSION=`echo $COMPILER_VERSION | sed 's,^\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*,\3,'`
-        ;;
-    *.*)
-        QT_GCC_MAJOR_VERSION=`echo $COMPILER_VERSION | sed 's,^\([0-9]*\)\.\([0-9]*\).*,\1,'`
-        QT_GCC_MINOR_VERSION=`echo $COMPILER_VERSION | sed 's,^\([0-9]*\)\.\([0-9]*\).*,\2,'`
-        QT_GCC_PATCH_VERSION=0
-        ;;
-    esac
-
-    case "$COMPILER_VERSION" in
-    2.95.*)
-        COMPILER_VERSION="2.95.*"
-        ;;
-    3.*)
-        COMPILER_VERSION="3.*"
-        ;;
-    4.*)
-        COMPILER_VERSION="4"
-        ;;
-    *)
-        ;;
-    esac
-    [ '!' -z "$COMPILER_VERSION" ] && COMPILER="g++-${COMPILER_VERSION}"
-    ;;
-icc*)
-    # The Intel CC compiler on Unix systems matches the ABI of the g++
-    # that is found on PATH
-    COMPAT_COMPILER="icc"
-    COMPILER="g++-4"
-    case "`g++ -dumpversion` 2>/dev/null" in
-    2.95.*)
-        COMPILER="g++-2.95.*"
-        ;;
-    3.*)
-a        COMPILER="g++-3.*"
-        ;;
-    *)
-        ;;
-    esac
-    ;;
-*)
-    #
-    ;;
-esac
-
-# QT_CONFIG can contain the following:
-#
-# Things that affect the Qt API/ABI:
-#
-#   Options:
-#     minimal-config small-config medium-config large-config full-config
-#
-#   Different edition modules:
-#     gui network canvas table xml opengl sql
-#
-# Things that do not affect the Qt API/ABI:
-#     stl
-#     system-jpeg no-jpeg jpeg
-#     system-mng no-mng mng
-#     system-png no-png png
-#     system-zlib no-zlib zlib
-#     system-libtiff no-libtiff
-#     no-gif gif
-#     debug release
-#     dll staticlib
-#
-#     nocrosscompiler
-#     GNUmake
-#     largefile
-#     nis
-#     nas
-#     tablet
-#     ipv6
-#
-#     X11     : x11sm xinerama xcursor xfixes xrandr xrender mitshm fontconfig xkb
-#     Embedded: embedded qpa freetype
-#
-ALL_OPTIONS=
-BUILD_CONFIG=
-BUILD_OPTIONS=
-
-# determine the build options
-for config_option in $QMAKE_CONFIG $QT_CONFIG; do
-    SKIP="yes"
-    case "$config_option" in
-    *-config)
-        # take the last *-config setting.  this is the highest config being used,
-        # and is the one that we will use for tagging plugins
-        BUILD_CONFIG="$config_option"
-        ;;
-
-    *) # skip all other options since they don't affect the Qt API/ABI.
-        ;;
-    esac
-
-    if [ "$SKIP" = "no" ]; then
-        BUILD_OPTIONS="$BUILD_OPTIONS $config_option"
-    fi
-done
-
-# put the options that we are missing into .options
-rm -f .options
-for opt in `echo $ALL_OPTIONS`; do
-    SKIP="no"
-    if echo $BUILD_OPTIONS | grep $opt >/dev/null 2>&1; then
-        SKIP="yes"
-    fi
-    if [ "$SKIP" = "no" ]; then
-        echo "$opt" >> .options
-    fi
-done
-
-# reconstruct BUILD_OPTIONS with a sorted negative feature list
-# (ie. only things that are missing are will be put into the build key)
-BUILD_OPTIONS=
-if [ -f .options ]; then
-    for opt in `sort -f .options | uniq`; do
-        BUILD_OPTIONS="$BUILD_OPTIONS no-$opt"
-    done
-fi
-rm -f .options
-
-# QT_NO* defines affect the Qt API (and binary compatibility).  they need
-# to be included in the build key
-for build_option in $D_FLAGS; do
-    build_option=`echo $build_option | cut -d \" -f 2 -`
-    case "$build_option" in
-    QT_NO*)
-        echo "$build_option" >> .options
-        ;;
-    *)
-        # skip all other compiler defines
-        ;;
-    esac
-done
-
-# sort the compile time defines (helps ensure that changes in this configure
-# script don't affect the QT_BUILD_KEY generation)
-if [ -f .options ]; then
-    for opt in `sort -f .options | uniq`; do
-        BUILD_OPTIONS="$BUILD_OPTIONS $opt"
-    done
-fi
-rm -f .options
-
-BUILD_OPTIONS="$BUILD_CONFIG $BUILD_OPTIONS"
-# extract the operating system from the XPLATFORM
-TARGET_OPERATING_SYSTEM=`echo $XPLATFORM | cut -f 2- -d/ | cut -f -1 -d-`
-if [ "$XPLATFORM_SYMBIAN" = "yes" ]; then
-    QT_BUILD_KEY_SYSTEM_PART="Symbian"
-else
-    QT_BUILD_KEY_SYSTEM_PART="$CFG_ARCH $TARGET_OPERATING_SYSTEM $COMPILER"
-fi
-
-# when cross-compiling, don't include build-host information (build key is target specific)
-QT_BUILD_KEY="$CFG_USER_BUILD_KEY $QT_BUILD_KEY_SYSTEM_PART $BUILD_OPTIONS"
-if [ -n "$QT_NAMESPACE" ]; then
-    QT_BUILD_KEY="$QT_BUILD_KEY $QT_NAMESPACE"
-fi
-MAC_NEED_TWO_BUILD_KEYS="no"
-if [ "$PLATFORM_MAC" = "yes" -a "$CFG_MAC_COCOA" = "yes" ]; then
-    QT_BUILD_KEY_CARBON=$QT_BUILD_KEY
-    TARGET_OPERATING_SYSTEM="$TARGET_OPERATING_SYSTEM-cocoa"
-    QT_BUILD_KEY_COCOA="$CFG_USER_BUILD_KEY $CFG_ARCH $TARGET_OPERATING_SYSTEM $COMPILER $BUILD_OPTIONS"
-    if [ "$CFG_MAC_CARBON" = "no" ]; then
-        QT_BUILD_KEY=$QT_BUILD_KEY_COCOA
-    else
-        MAC_NEED_TWO_BUILD_KEYS="yes"
-    fi
-fi
-# don't break loading plugins build with an older version of Qt
-QT_BUILD_KEY_COMPAT=
-if [ "$QT_CROSS_COMPILE" = "no" ]; then
-    # previous versions of Qt used a build key built from the uname
-    QT_BUILD_KEY_COMPAT="$CFG_USER_BUILD_KEY $UNAME_MACHINE $UNAME_SYSTEM $COMPILER $BUILD_OPTIONS"
-    if [ -n "$QT_NAMESPACE" ]; then
-        QT_BUILD_KEY_COMPAT="$QT_BUILD_KEY_COMPAT $QT_NAMESPACE"
-    fi
-fi
-
-# is this compiler compatible with some other "standard" build key
-QT_BUILD_KEY_COMPAT_COMPILER=
-if [ ! -z "$COMPAT_COMPILER" ]; then
-    QT_BUILD_KEY_COMPAT_COMPILER="$CFG_USER_BUILD_KEY $CFG_ARCH $TARGET_OPERATING_SYSTEM $COMPAT_COMPILER $BUILD_OPTIONS"
-    if [ -n "$QT_NAMESPACE" ]; then
-        QT_BUILD_KEY_COMPAT_COMPILER="$QT_BUILD_KEY_COMPAT_COMPILER $QT_NAMESPACE"
-    fi
-fi
-
-# is this arch compatible with some other "standard" build key
-QT_BUILD_KEY_COMPAT_ARCH=
-if [ ! -z "$COMPAT_ARCH" ]; then
-    QT_BUILD_KEY_COMPAT_ARCH="$CFG_USER_BUILD_KEY $COMPAT_ARCH $TARGET_OPERATING_SYSTEM $COMPILER $BUILD_OPTIONS"
-    if [ -n "$QT_NAMESPACE" ]; then
-        QT_BUILD_KEY_COMPAT_COMPILER="$QT_BUILD_KEY_COMPAT_ARCH $QT_NAMESPACE"
-    fi
-fi
-
-# strip out leading/trailing/extra whitespace
-QT_BUILD_KEY=`echo $QT_BUILD_KEY | sed -e "s,  *, ,g" -e "s,^  *,," -e "s,  *$,,"`
-QT_BUILD_KEY_COMPAT=`echo $QT_BUILD_KEY_COMPAT | sed -e "s,  *, ,g" -e "s,^  *,," -e "s,  *$,,"`
-QT_BUILD_KEY_COMPAT_COMPILER=`echo $QT_BUILD_KEY_COMPAT_COMPILER | sed -e "s,  *, ,g" -e "s,^  *,," -e "s,  *$,,"`
-QT_BUILD_KEY_COMPAT_ARCH=`echo $QT_BUILD_KEY_COMPAT_ARCH | sed -e "s,  *, ,g" -e "s,^  *,," -e "s,  *$,,"`
-
-#-------------------------------------------------------------------------------
 # part of configuration information goes into qconfig.h
 #-------------------------------------------------------------------------------
 
@@ -7988,32 +7758,6 @@ cat >>"$outpath/src/corelib/global/qconfig.h.new" <<EOF
 #define Q_LITTLE_ENDIAN 1234
 EOF
 
-if [ "$MAC_NEED_TWO_BUILD_KEYS" = "no" ]; then
-    echo "#define QT_BUILD_KEY \"$QT_BUILD_KEY\"" \
-        >> "$outpath/src/corelib/global/qconfig.h.new"
-else
-    cat >>"$outpath/src/corelib/global/qconfig.h.new" <<EOF
-
-#define QT_BUILD_KEY_CARBON "$QT_BUILD_KEY_CARBON"
-#define QT_BUILD_KEY_COCOA "$QT_BUILD_KEY_COCOA"
-EOF
-fi
-
-if [ -n "$QT_BUILD_KEY_COMPAT" ]; then
-    echo "#define QT_BUILD_KEY_COMPAT \"$QT_BUILD_KEY_COMPAT\"" \
-        >> "$outpath/src/corelib/global/qconfig.h.new"
-fi
-if [ -n "$QT_BUILD_KEY_COMPAT_COMPILER" ]; then
-    echo "#define QT_BUILD_KEY_COMPAT2 \"$QT_BUILD_KEY_COMPAT_COMPILER\"" \
-        >> "$outpath/src/corelib/global/qconfig.h.new"
-fi
-if [ -n "$QT_BUILD_KEY_COMPAT_ARCH" ]; then
-    echo "#define QT_BUILD_KEY_COMPAT3 \"$QT_BUILD_KEY_COMPAT_ARCH\"" \
-        >> "$outpath/src/corelib/global/qconfig.h.new"
-fi
-
-echo "" >>"$outpath/src/corelib/global/qconfig.h.new"
-
 echo "#ifdef QT_BOOTSTRAPPED" >>"$outpath/src/corelib/global/qconfig.h.new"
 if [ "$CFG_HOST_ENDIAN" = "auto" ]; then
     cat >>"$outpath/src/corelib/global/qconfig.h.new" <<EOF
diff --git a/dist/changes-5.0.0 b/dist/changes-5.0.0
index 32ca8dbd66..abe5a825d1 100644
--- a/dist/changes-5.0.0
+++ b/dist/changes-5.0.0
@@ -24,6 +24,10 @@ information about a particular change.
   via QT_DISABLE_DEPRECATED_BEFORE), use
   QSslCertificate::subjectAlternativeNames() instead.
 
+- QLibraryInfo::buildKey() has been removed. Likewise, the QT_BUILD_KEY
+  preprocessor #define has also been removed. The build-key is obsolete
+  and is no longer necessary.
+
 ****************************************************************************
 *                           General                                        *
 ****************************************************************************
diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 56022a7e6e..901f4e50ee 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -301,9 +301,6 @@ namespace QT_NAMESPACE {}
 #ifdef QT_AUTODETECT_COCOA
 #  ifdef Q_OS_MAC64
 #    define QT_MAC_USE_COCOA 1
-#    define QT_BUILD_KEY QT_BUILD_KEY_COCOA
-#  else
-#    define QT_BUILD_KEY QT_BUILD_KEY_CARBON
 #  endif
 #endif
 
@@ -1197,10 +1194,6 @@ Q_DECL_CONSTEXPR inline const T &qBound(const T &min, const T &val, const T &max
 
 class QDataStream;
 
-#ifndef QT_BUILD_KEY
-#define QT_BUILD_KEY "unspecified"
-#endif
-
 #if defined(Q_WS_MAC)
 #  ifndef QMAC_QMENUBAR_NO_EVENT
 #    define QMAC_QMENUBAR_NO_EVENT
diff --git a/src/corelib/global/qlibraryinfo.cpp b/src/corelib/global/qlibraryinfo.cpp
index 88f12ab1f7..d70c77afae 100644
--- a/src/corelib/global/qlibraryinfo.cpp
+++ b/src/corelib/global/qlibraryinfo.cpp
@@ -203,21 +203,6 @@ QLibraryInfo::licensedProducts()
 }
 
 /*!
-    Returns a unique key identifying this build of Qt and its
-    configurations. This key is not globally unique, rather only useful
-    for establishing of two configurations are compatible. This can be
-    used to compare with the \c QT_BUILD_KEY preprocessor symbol.
-
-    \sa location()
-*/
-
-QString
-QLibraryInfo::buildKey()
-{
-    return QString::fromLatin1(QT_BUILD_KEY);
-}
-
-/*!
     \since 4.6
     Returns the installation date for this build of Qt. The install date will
     usually be the last time that Qt sources were configured.
@@ -514,18 +499,6 @@ void qt_core_boilerplate()
            "Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).\n"
            "Contact: Nokia Corporation (qt-info@nokia.com)\n"
            "\n"
-           "Build key:           " QT_BUILD_KEY "\n"
-           "Compat build key:    "
-#ifdef QT_BUILD_KEY_COMPAT
-           "| " QT_BUILD_KEY_COMPAT " "
-#endif
-#ifdef QT_BUILD_KEY_COMPAT2
-           "| " QT_BUILD_KEY_COMPAT2 " "
-#endif
-#ifdef QT_BUILD_KEY_COMPAT3
-           "| " QT_BUILD_KEY_COMPAT3 " "
-#endif
-           "|\n"
            "Build date:          %s\n"
            "Installation prefix: %s\n"
            "Library path:        %s\n"
diff --git a/src/corelib/global/qlibraryinfo.h b/src/corelib/global/qlibraryinfo.h
index a8fb90968c..4dcd8e1e5e 100644
--- a/src/corelib/global/qlibraryinfo.h
+++ b/src/corelib/global/qlibraryinfo.h
@@ -59,7 +59,6 @@ public:
     static QString licensee();
     static QString licensedProducts();
 
-    static QString buildKey();
 #ifndef QT_NO_DATESTRING
     static QDate buildDate();
 #endif //QT_NO_DATESTRING
diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
index 45515f32e1..0a4ab77189 100644
--- a/src/corelib/plugin/qlibrary.cpp
+++ b/src/corelib/plugin/qlibrary.cpp
@@ -250,7 +250,7 @@ static int qt_tokenize(const char *s, ulong s_len, ulong *advance,
 /*
   returns true if the string s was correctly parsed, false otherwise.
 */
-static bool qt_parse_pattern(const char *s, uint *version, bool *debug, QByteArray *key)
+static bool qt_parse_pattern(const char *s, uint *version, bool *debug)
 {
     bool ret = true;
 
@@ -282,10 +282,6 @@ static bool qt_parse_pattern(const char *s, uint *version, bool *debug, QByteArr
             }
         } else if (qstrncmp("debug", pinfo.results[0], pinfo.lengths[0]) == 0) {
             *debug = qstrncmp("true", pinfo.results[1], pinfo.lengths[1]) == 0;
-        } else if (qstrncmp("buildkey", pinfo.results[0],
-                              pinfo.lengths[0]) == 0){
-            // save buildkey
-            *key = QByteArray(pinfo.results[1], pinfo.lengths[1]);
         }
     } while (parse == 1 && parselen > 0);
 
@@ -337,11 +333,11 @@ static long qt_find_pattern(const char *s, ulong s_len,
   we can get the verification data without have to actually load the library.
   This lets us detect mismatches more safely.
 
-  Returns false if version/key information is not present, or if the
+  Returns false if version information is not present, or if the
                 information could not be read.
-  Returns  true if version/key information is present and successfully read.
+  Returns  true if version information is present and successfully read.
 */
-static bool qt_unix_query(const QString &library, uint *version, bool *debug, QByteArray *key, QLibraryPrivate *lib = 0)
+static bool qt_unix_query(const QString &library, uint *version, bool *debug, QLibraryPrivate *lib = 0)
 {
     QFile file(library);
     if (!file.open(QIODevice::ReadOnly)) {
@@ -396,7 +392,7 @@ static bool qt_unix_query(const QString &library, uint *version, bool *debug, QB
 #endif // defined(Q_OF_ELF) && defined(Q_CC_GNU)
     bool ret = false;
     if (pos >= 0)
-        ret = qt_parse_pattern(filedata + pos, version, debug, key);
+        ret = qt_parse_pattern(filedata + pos, version, debug);
 
     if (!ret && lib)
         lib->errorString = QLibrary::tr("Plugin verification data mismatch in '%1'").arg(library);
@@ -636,7 +632,7 @@ typedef const char * __stdcall (*QtPluginQueryVerificationDataFunction)();
 typedef const char * (*QtPluginQueryVerificationDataFunction)();
 #endif
 
-bool qt_get_verificationdata(QtPluginQueryVerificationDataFunction pfn, uint *qt_version, bool *debug, QByteArray *key, bool *exceptionThrown)
+bool qt_get_verificationdata(QtPluginQueryVerificationDataFunction pfn, uint *qt_version, bool *debug, bool *exceptionThrown)
 {
     *exceptionThrown = false;
     const char *szData = 0;
@@ -649,7 +645,7 @@ bool qt_get_verificationdata(QtPluginQueryVerificationDataFunction pfn, uint *qt
 #else
     szData = pfn();
 #endif
-    return qt_parse_pattern(szData, qt_version, debug, key);
+    return qt_parse_pattern(szData, qt_version, debug);
 }
 
 bool QLibraryPrivate::isPlugin(QSettings *settings)
@@ -660,7 +656,6 @@ bool QLibraryPrivate::isPlugin(QSettings *settings)
 
 #ifndef QT_NO_PLUGIN_CHECK
     bool debug = !QLIBRARY_AS_DEBUG;
-    QByteArray key;
     bool success = false;
 
 #if defined(Q_OS_UNIX) && !defined(Q_OS_MAC)
@@ -710,16 +705,15 @@ bool QLibraryPrivate::isPlugin(QSettings *settings)
     }
     reg = settings->value(regkey).toStringList();
 #endif
-    if (reg.count() == 4 && lastModified == reg.at(3)) {
+    if (reg.count() == 3 && lastModified == reg.at(2)) {
         qt_version = reg.at(0).toUInt(0, 16);
         debug = bool(reg.at(1).toInt());
-        key = reg.at(2).toLatin1();
         success = qt_version != 0;
     } else {
 #if defined(Q_OS_UNIX) && !defined(Q_OS_MAC) && !defined(Q_OS_SYMBIAN)
         if (!pHnd) {
             // use unix shortcut to avoid loading the library
-            success = qt_unix_query(fileName, &qt_version, &debug, &key, this);
+            success = qt_unix_query(fileName, &qt_version, &debug, this);
         } else
 #endif
         {
@@ -767,11 +761,10 @@ bool QLibraryPrivate::isPlugin(QSettings *settings)
 #endif
                 bool exceptionThrown = false;
                 bool ret = qt_get_verificationdata(qtPluginQueryVerificationDataFunction,
-                                                   &qt_version, &debug, &key, &exceptionThrown);
+                                                   &qt_version, &debug, &exceptionThrown);
                 if (!exceptionThrown) {
                     if (!ret) {
                         qt_version = 0;
-                        key = "unknown";
                         if (temporary_load)
                             unload_sys();
                     } else {
@@ -801,14 +794,10 @@ bool QLibraryPrivate::isPlugin(QSettings *settings)
                                         // exception is thrown(will happen only when using a MS compiler)
         }
 
-        // Qt 4.5 compatibility: stl doesn't affect binary compatibility
-        key.replace(" no-stl", "");
-
 #ifndef QT_NO_SETTINGS
         QStringList queried;
         queried << QString::number(qt_version,16)
                 << QString::number((int)debug)
-                << QLatin1String(key)
                 << lastModified;
         settings->setValue(regkey, queried);
 #endif
@@ -840,31 +829,6 @@ bool QLibraryPrivate::isPlugin(QSettings *settings)
             .arg((qt_version&0xff00) >> 8)
             .arg(qt_version&0xff)
             .arg(debug ? QLatin1String("debug") : QLatin1String("release"));
-    } else if (key != QT_BUILD_KEY
-               // we may have some compatibility keys, try them too:
-#ifdef QT_BUILD_KEY_COMPAT
-               && key != QT_BUILD_KEY_COMPAT
-#endif
-#ifdef QT_BUILD_KEY_COMPAT2
-               && key != QT_BUILD_KEY_COMPAT2
-#endif
-#ifdef QT_BUILD_KEY_COMPAT3
-               && key != QT_BUILD_KEY_COMPAT3
-#endif
-               ) {
-        if (qt_debug_component()) {
-            qWarning("In %s:\n"
-                 "  Plugin uses incompatible Qt library\n"
-                 "  expected build key \"%s\", got \"%s\"",
-                 (const char*) QFile::encodeName(fileName),
-                 QT_BUILD_KEY,
-                 key.isEmpty() ? "<null>" : (const char *) key);
-        }
-        errorString = QLibrary::tr("The plugin '%1' uses incompatible Qt library."
-                 " Expected build key \"%2\", got \"%3\"")
-                 .arg(fileName)
-                 .arg(QLatin1String(QT_BUILD_KEY))
-                 .arg(key.isEmpty() ? QLatin1String("<null>") : QLatin1String((const char *) key));
 #ifndef QT_NO_DEBUG_PLUGIN_CHECK
     } else if(debug != QLIBRARY_AS_DEBUG) {
         //don't issue a qWarning since we will hopefully find a non-debug? --Sam
diff --git a/src/corelib/plugin/qplugin.h b/src/corelib/plugin/qplugin.h
index 40e6e66de3..52661671b5 100644
--- a/src/corelib/plugin/qplugin.h
+++ b/src/corelib/plugin/qplugin.h
@@ -117,8 +117,7 @@ void Q_CORE_EXPORT qRegisterStaticPluginInstanceFunction(QtPluginInstanceFunctio
     static const char qt_plugin_verification_data[] = \
       "pattern=""QT_PLUGIN_VERIFICATION_DATA""\n" \
       "version="QT_VERSION_STR"\n" \
-      "debug="QPLUGIN_DEBUG_STR"\n" \
-      "buildkey="QT_BUILD_KEY;
+      "debug="QPLUGIN_DEBUG_STR;
 
 #  if defined (Q_OF_ELF) && defined (Q_CC_GNU)
 #  define Q_PLUGIN_VERIFICATION_SECTION \
diff --git a/tests/baselineserver/shared/baselineprotocol.cpp b/tests/baselineserver/shared/baselineprotocol.cpp
index 630ca88e5b..9cbf67856d 100644
--- a/tests/baselineserver/shared/baselineprotocol.cpp
+++ b/tests/baselineserver/shared/baselineprotocol.cpp
@@ -56,7 +56,6 @@ const QString PI_HostAddress(QLS("HostAddress"));
 const QString PI_OSName(QLS("OSName"));
 const QString PI_OSVersion(QLS("OSVersion"));
 const QString PI_QtVersion(QLS("QtVersion"));
-const QString PI_BuildKey(QLS("BuildKey"));
 const QString PI_GitCommit(QLS("GitCommit"));
 const QString PI_QMakeSpec(QLS("QMakeSpec"));
 const QString PI_PulseGitBranch(QLS("PulseGitBranch"));
@@ -93,7 +92,6 @@ PlatformInfo PlatformInfo::localHostInfo()
     pi.insert(PI_HostName, QHostInfo::localHostName());
     pi.insert(PI_QtVersion, QLS(qVersion()));
     pi.insert(PI_QMakeSpec, QString(QLS(QMAKESPEC)).remove(QRegExp(QLS("^.*mkspecs/"))));
-    pi.insert(PI_BuildKey, QLibraryInfo::buildKey());
 #if defined(Q_OS_LINUX)
     pi.insert(PI_OSName, QLS("Linux"));
     QProcess uname;
diff --git a/tests/baselineserver/shared/baselineprotocol.h b/tests/baselineserver/shared/baselineprotocol.h
index 0b08e444fd..cc501e1d53 100644
--- a/tests/baselineserver/shared/baselineprotocol.h
+++ b/tests/baselineserver/shared/baselineprotocol.h
@@ -61,7 +61,6 @@ extern const QString PI_HostAddress;
 extern const QString PI_OSName;
 extern const QString PI_OSVersion;
 extern const QString PI_QtVersion;
-extern const QString PI_BuildKey;
 extern const QString PI_GitCommit;
 extern const QString PI_QMakeSpec;
 extern const QString PI_PulseGitBranch;
diff --git a/tools/configure/configureapp.cpp b/tools/configure/configureapp.cpp
index 3b7f190736..afaab16f93 100644
--- a/tools/configure/configureapp.cpp
+++ b/tools/configure/configureapp.cpp
@@ -495,13 +495,6 @@ void Configure::parseCmdLine()
             dictionary[ "QCONFIG" ] = configCmdLine.at(i);
         }
 
-        else if (configCmdLine.at(i) == "-buildkey") {
-            ++i;
-            if (i == argCount)
-                break;
-            dictionary[ "USER_BUILD_KEY" ] = configCmdLine.at(i);
-        }
-
         else if (configCmdLine.at(i) == "-release") {
             dictionary[ "BUILD" ] = "release";
             if (dictionary[ "BUILDALL" ] == "auto")
@@ -1661,11 +1654,11 @@ QString Configure::locateFile(const QString &fileName)
 bool Configure::displayHelp()
 {
     if (dictionary[ "HELP" ] == "yes") {
-        desc("Usage: configure [-buildkey <key>]\n"
+        desc("Usage: configure\n"
 //      desc("Usage: configure [-prefix dir] [-bindir <dir>] [-libdir <dir>]\n"
 //                  "[-docdir <dir>] [-headerdir <dir>] [-plugindir <dir>]\n"
 //                  "[-importdir <dir>] [-datadir <dir>] [-translationdir <dir>]\n"
-//                  "[-examplesdir <dir>] [-buildkey <key>]\n"
+//                  "[-examplesdir <dir>]\n"
                     "[-release] [-debug] [-debug-and-release] [-shared] [-static]\n"
                     "[-no-fast] [-fast] [-no-exceptions] [-exceptions]\n"
                     "[-no-accessibility] [-accessibility] [-no-rtti] [-rtti]\n"
@@ -1711,10 +1704,6 @@ bool Configure::displayHelp()
         desc(                   "-translationdir <dir>","Translations of Qt programs will be installed to dir\n(default PREFIX/translations)\n");
         desc(                   "-examplesdir <dir>",   "Examples will be installed to dir\n(default PREFIX/examples)");
 */
-        desc(" You may use these options to turn on strict plugin loading:\n\n", 0, 1);
-
-        desc(                   "-buildkey <key>",      "Build the Qt library and plugins using the specified <key>.  "
-                                                        "When the library loads plugins, it will only load those that have a matching <key>.\n");
 
         desc("Configure options:\n\n");
 
@@ -2470,53 +2459,11 @@ void Configure::generateBuildKey()
     // Sorted defines that start with QT_NO_
     QStringList build_defines = qmakeDefines.filter(QRegExp("^QT_NO_"));
     build_defines.sort();
-
-    // Build up the QT_BUILD_KEY ifdef
-    QString buildKey = "QT_BUILD_KEY \"";
-    if (!dictionary["USER_BUILD_KEY"].isEmpty())
-        buildKey += dictionary["USER_BUILD_KEY"] + " ";
-
-    QString build32Key = buildKey + "Windows " + compiler + " %1 " + build_options.join(" ") + " " + build_defines.join(" ");
-    QString build64Key = buildKey + "Windows x64 " + compiler + " %1 " + build_options.join(" ") + " " + build_defines.join(" ");
-    QString buildSymbianKey = buildKey + "Symbian " + build_options.join(" ") + " " + build_defines.join(" ");
-    build32Key = build32Key.simplified();
-    build64Key = build64Key.simplified();
-    buildSymbianKey = buildSymbianKey.simplified();
-    build32Key.prepend("#   define ");
-    build64Key.prepend("#   define ");
-    buildSymbianKey.prepend("# define ");
-
-    QString buildkey = "#if defined(__SYMBIAN32__)\n"
-                       + buildSymbianKey + "\"\n"
-                       "#else\n"
-                       // Debug builds
-                       "# if !defined(QT_NO_DEBUG)\n"
-                       "#  if (defined(WIN64) || defined(_WIN64) || defined(__WIN64__))\n"
-                       + build64Key.arg("debug") + "\"\n"
-                       "#  else\n"
-                       + build32Key.arg("debug") + "\"\n"
-                       "#  endif\n"
-                       "# else\n"
-                       // Release builds
-                       "#  if (defined(WIN64) || defined(_WIN64) || defined(__WIN64__))\n"
-                       + build64Key.arg("release") + "\"\n"
-                       "#  else\n"
-                       + build32Key.arg("release") + "\"\n"
-                       "#  endif\n"
-                       "# endif\n"
-                       "#endif\n";
-
-    dictionary["BUILD_KEY"] = buildkey;
 }
 
 void Configure::generateOutputVars()
 {
     // Generate variables for output
-    // Build key ----------------------------------------------------
-    if (dictionary.contains("BUILD_KEY")) {
-        qmakeVars += dictionary.value("BUILD_KEY");
-    }
-
     QString build = dictionary[ "BUILD" ];
     bool buildAll = (dictionary[ "BUILDALL" ] == "yes");
     if (build == "debug") {
@@ -3141,8 +3088,6 @@ void Configure::generateConfigfiles()
         tmpStream << "#  define QT_EDITION " << dictionary["QT_EDITION"] << endl;
         tmpStream << "#endif" << endl;
         tmpStream << endl;
-        tmpStream << dictionary["BUILD_KEY"];
-        tmpStream << endl;
         if (dictionary["BUILDDEV"] == "yes") {
             dictionary["QMAKE_INTERNAL"] = "yes";
             tmpStream << "/* Used for example to export symbols for the certain autotests*/" << endl;