qtModule: say the magic words

pkgs/development/libraries/qt-5/qtModule.nix

@@ -31,6 +31,23 @@ mkDerivation (args // {
     ${args.preConfigure or ""}
 
     fixQtBuiltinPaths . '*.pr?'
+  '' + lib.optionalString (builtins.compareVersions "5.15.0" version <= 0)
+  # Note: We use ${version%%-*} to remove any tag from the end of the version
+  # string. Version tags are added by Nixpkgs maintainers and not reflected in
+  # the source version.
+  ''
+    if [[ -z "$dontCheckQtModuleVersion" ]] \
+        && grep -q '^MODULE_VERSION' .qmake.conf 2>/dev/null \
+        && ! grep -q -F "''${version%%-*}" .qmake.conf 2>/dev/null
+    then
+      echo >&2 "error: could not find version ''${version%%-*} in .qmake.conf"
+      echo >&2 "hint: check .qmake.conf and update the package version in Nixpkgs"
+      exit 1
+    fi
+
+    if [[ -z "$dontSyncQt" ]] && [[ -f sync.profile ]]; then
+      syncqt.pl -version "''${version%%-*}"
+    fi
   '';
 
   dontWrapQtApps = args.dontWrapQtApps or true;