Add missed defined(clang) and fix the wrong placement of #pragma push/pop for MSVC compiler (#4946)

include/flatbuffers/base.h

@@ -51,6 +51,12 @@
 
 #include "flatbuffers/stl_emulation.h"
 
+// Note the __clang__ check is needed, because clang presents itself
+// as an older GNUC compiler (4.2).
+// Clang 3.3 and later implement all of the ISO C++ 2011 standard.
+// Clang 3.4 and later implement all of the ISO C++ 2014 standard.
+// http://clang.llvm.org/cxx_status.html
+
 /// @cond FLATBUFFERS_INTERNAL
 #if __cplusplus <= 199711L && \
     (!defined(_MSC_VER) || _MSC_VER < 1600) && \
@@ -110,7 +116,8 @@
 #define FLATBUFFERS_STRING(X) FLATBUFFERS_STRING_EXPAND(X)
 
 #if (!defined(_MSC_VER) || _MSC_VER > 1600) && \
-    (!defined(__GNUC__) || (__GNUC__ * 100 + __GNUC_MINOR__ >= 407))
+    (!defined(__GNUC__) || (__GNUC__ * 100 + __GNUC_MINOR__ >= 407)) || \
+    defined(__clang__)
   #define FLATBUFFERS_FINAL_CLASS final
   #define FLATBUFFERS_OVERRIDE override
 #else
@@ -119,7 +126,8 @@
 #endif
 
 #if (!defined(_MSC_VER) || _MSC_VER >= 1900) && \
-    (!defined(__GNUC__) || (__GNUC__ * 100 + __GNUC_MINOR__ >= 406))
+    (!defined(__GNUC__) || (__GNUC__ * 100 + __GNUC_MINOR__ >= 406)) || \
+    (defined(__cpp_constexpr) && __cpp_constexpr >= 200704)
   #define FLATBUFFERS_CONSTEXPR constexpr
 #else
   #define FLATBUFFERS_CONSTEXPR
@@ -132,8 +140,9 @@
   #define FLATBUFFERS_CONSTEXPR_CPP14
 #endif
 
-#if defined(__GXX_EXPERIMENTAL_CXX0X__) && __GNUC__ * 10 + __GNUC_MINOR__ >= 46 || \
-    defined(_MSC_FULL_VER) && _MSC_FULL_VER >= 190023026
+#if (defined(__GXX_EXPERIMENTAL_CXX0X__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 406)) || \
+    (defined(_MSC_FULL_VER) && (_MSC_FULL_VER >= 190023026)) || \
+    defined(__clang__)
   #define FLATBUFFERS_NOEXCEPT noexcept
 #else
   #define FLATBUFFERS_NOEXCEPT
@@ -142,17 +151,13 @@
 // NOTE: the FLATBUFFERS_DELETE_FUNC macro may change the access mode to
 // private, so be sure to put it at the end or reset access mode explicitly.
 #if (!defined(_MSC_VER) || _MSC_FULL_VER >= 180020827) && \
-    (!defined(__GNUC__) || (__GNUC__ * 100 + __GNUC_MINOR__ >= 404))
+    (!defined(__GNUC__) || (__GNUC__ * 100 + __GNUC_MINOR__ >= 404)) || \
+    defined(__clang__)
   #define FLATBUFFERS_DELETE_FUNC(func) func = delete;
 #else
   #define FLATBUFFERS_DELETE_FUNC(func) private: func;
 #endif
 
-#if defined(_MSC_VER)
-  #pragma warning(push)
-  #pragma warning(disable: 4127) // C4127: conditional expression is constant
-#endif
-
 #ifndef FLATBUFFERS_HAS_STRING_VIEW
   // Only provide flatbuffers::string_view if __has_include can be used
   // to detect a header that provides an implementation
@@ -201,6 +206,11 @@ typedef uintmax_t largest_scalar_t;
 // We support aligning the contents of buffers up to this size.
 #define FLATBUFFERS_MAX_ALIGNMENT 16
 
+#if defined(_MSC_VER)
+  #pragma warning(push)
+  #pragma warning(disable: 4127) // C4127: conditional expression is constant
+#endif
+
 template<typename T> T EndianSwap(T t) {
   #if defined(_MSC_VER)
     #define FLATBUFFERS_BYTESWAP16 _byteswap_ushort
@@ -239,6 +249,10 @@ template<typename T> T EndianSwap(T t) {
   }
 }
 
+#if defined(_MSC_VER)
+  #pragma warning(pop)
+#endif
+
 
 template<typename T> T EndianScalar(T t) {
   #if FLATBUFFERS_LITTLEENDIAN

include/flatbuffers/flatbuffers.h

@@ -934,12 +934,12 @@ class FlatBufferBuilder {
   }
 
   /// @brief Get the released pointer to the serialized buffer.
-  /// @param The size of the memory block containing 
+  /// @param The size of the memory block containing
   /// the serialized `FlatBuffer`.
-  /// @param The offset from the released pointer where the finished 
+  /// @param The offset from the released pointer where the finished
   /// `FlatBuffer` starts.
-  /// @return A raw pointer to the start of the memory block containing 
-  /// the serialized `FlatBuffer`. 
+  /// @return A raw pointer to the start of the memory block containing
+  /// the serialized `FlatBuffer`.
   /// @remark If the allocator is owned, it gets deleted during this call.
   uint8_t *ReleaseRaw(size_t &size, size_t &offset) {
     Finished();
@@ -2482,9 +2482,6 @@ volatile __attribute__((weak)) const char *flatbuffer_version_string =
 /// @endcond
 }  // namespace flatbuffers
 
-#if defined(_MSC_VER)
-  #pragma warning(pop)
-#endif
 // clang-format on
 
 #endif  // FLATBUFFERS_H_