Hi,
Resharper uses a separate IntelliSense engine, so unless JetBrains explicitly adds support for parsing VisualGDB projects, it may not work properly.
We do recommend using our Clang IntelliSense engine for VisualGDB projects as it is especially optimized for GCC-specific code and provides many improvements compared to the regular Visual C++ IntelliSense.
If you miss some of the features with it, please let us know and we will consider adding them.