TypeLoc buildTypeLoc(ASTContext *const c, const QualType qt)
{
       TypeLocBuilder tlb;
       return tlb.getTypeLocInContext(*c, qt);
}

SourceRange getQualTypeSourceRange(ASTContext *const c, const QualType qt)
{
      return buildTypeLoc(c, qt).getSourceRange();
}

for(clang::ASTUnit::top_level_iterator dit = au -> top_level_begin(); dit != au -> top_level_end(); dit++) {
        if (isa<VarDecl>(*dit)) {
                const VarDecl *vd = static_cast<const VarDecl *>(*dit);

                SourceRange sr = getQualTypeSourceRange(&au -> getASTContext(), vd -> getType());
        }
}