[clangd] Hide position line and column fields.

clangd/index/Index.h

struct Position {
 
     bool hasOverflow() const {
       return Line >= MaxLine || Column >= MaxColumn;
     }
 
     static constexpr uint32_t MaxLine = (1 << 20) - 1;
     static constexpr uint32_t MaxColumn = (1 << 12) - 1;
 
-    // Clients should use getters and setters to access these members.
-    // FIXME: hide these members.
+  private:
     uint32_t Line : 20; // 0-based
     // Using UTF-16 code units.
     uint32_t Column : 12; // 0-based
   };
 
   // The URI of the source file where a symbol occurs.
   llvm::StringRef FileURI;