[llvm-cov] Document a few private fields of CodeCoverageTool (NFC)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275639 91177308-0d34-0410-b5e6-96231b3b80d8

tools/llvm-cov/CodeCoverage.cpp

@@ -101,11 +101,14 @@ public:
   std::string CoverageArch;
 
 private:
+  /// File paths (absolute, or otherwise) to input source files.
   std::vector<std::string> CollectedPaths;
 
+  /// Errors and warnings which have not been printed.
   std::mutex DeferredMessagesLock;
   std::vector<std::string> DeferredMessages;
 
+  /// A container for input source file buffers.
   std::mutex LoadedSourceFilesLock;
   std::vector<std::pair<std::string, std::unique_ptr<MemoryBuffer>>>
       LoadedSourceFiles;

tools/llvm-cov/CoverageViewOptions.h

@@ -40,7 +40,7 @@ struct CoverageViewOptions {
   }
 
   /// \brief Check if an output directory has been specified.
-  bool hasOutputDirectory() const { return ShowOutputDirectory != ""; }
+  bool hasOutputDirectory() const { return !ShowOutputDirectory.empty(); }
 };
 }