[clangd] Hover: Only drop UsingDecl instead of BaseUsingDecl

[tom-anders]

Summary

Since https://reviews.llvm.org/D135506 it's sufficient to only drop UsingDecl here

clang-tools-extra/clangd/Hover.cpp

const NamedDecl *pickDeclToUse(llvm::ArrayRef<const NamedDecl *> Candidates) {
 
   // This is e.g the case for
   //     namespace ns { void foo(); }
   //     void bar() { using ns::foo; f^oo(); }
   // One declaration in Candidates will refer to the using declaration,
   // which isn't really useful for Hover. So use the other one,
   // which in this example would be the actual declaration of foo.
   if (Candidates.size() <= 2) {
-    if (llvm::isa<BaseUsingDecl>(Candidates.front()))
+    if (llvm::isa<UsingDecl>(Candidates.front()))
       return Candidates.back();
     return Candidates.front();
   }
 
   // For something like
   //     namespace ns { void foo(int); void foo(char); }
   //     using ns::foo;
   //     template <typename T> void bar() { fo^o(T{}); }
   // we actually want to show the using declaration,
   // it's not clear which declaration to pick otherwise.
   auto BaseDecls = llvm::make_filter_range(Candidates, [](const NamedDecl *D) {
-    return llvm::isa<BaseUsingDecl>(D);
+    return llvm::isa<UsingDecl>(D);
   });
   if (std::distance(BaseDecls.begin(), BaseDecls.end()) == 1)
     return *BaseDecls.begin();
 
   return Candidates.front();
 }
 
 } // namespace