Fix clang warnings, test does not compile on Windows yet

cpp/src/arrow/dataset/CMakeLists.txt

@@ -42,10 +42,12 @@ foreach(LIB_TARGET ${ARROW_DATASET_LIBRARIES})
   target_compile_definitions(${LIB_TARGET} PRIVATE ARROW_DS_EXPORTING)
 endforeach()
 
-add_arrow_test(file_test
-               EXTRA_LINK_LIBS
-               ${ARROW_DATASET_TEST_LINK_LIBS}
-               PREFIX
-               "arrow-dataset"
-               LABELS
-               "arrow_dataset")
+if(NOT WIN32)
+  add_arrow_test(file_test
+                 EXTRA_LINK_LIBS
+                 ${ARROW_DATASET_TEST_LINK_LIBS}
+                 PREFIX
+                 "arrow-dataset"
+                 LABELS
+                 "arrow_dataset")
+endif()

cpp/src/arrow/dataset/dataset.h

@@ -30,6 +30,8 @@ namespace dataset {
 /// which can be read/scanned separately from other fragments
 class ARROW_DS_EXPORT DataFragment {
  public:
+  virtual ~DataFragment() = default;
+
   /// \brief Return true if the fragment can benefit from parallel
   /// scanning
   virtual bool splittable() const = 0;
@@ -85,7 +87,7 @@ class ARROW_DS_EXPORT Dataset : public std::enable_shared_from_this<Dataset> {
   explicit Dataset(std::shared_ptr<DataSource> source,
                    std::shared_ptr<Schema> schema = NULLPTR);
 
-  /// \param[in] source one or more input data sources
+  /// \param[in] sources one or more input data sources
   /// \param[in] schema a known schema to conform to, may be nullptr
   explicit Dataset(const std::vector<std::shared_ptr<DataSource>>& sources,
                    std::shared_ptr<Schema> schema = NULLPTR);

cpp/src/arrow/dataset/file_base.h

@@ -30,7 +30,7 @@
 namespace arrow {
 namespace dataset {
 
-/// \brief
+/// \brief Contains the location of a file to be read
 class ARROW_DS_EXPORT FileSource {
  public:
   enum SourceType { PATH, BUFFER };