Pedantic Visual Studio build (/W4 /WX) (#4214)

* Pedantic Visual Studio build (/W4 /WX)

* Pedantic Visual Studio build (/W4 /WX)

* Pedantic Visual Studio build (/W4 /WX)

* Remove /wd4512 from CMakeLists.txt

* Suppress Visual Studio 4512 warning ('class' : assignment operator could not be generated)

CMakeLists.txt

@@ -144,8 +144,8 @@ elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
     "${CMAKE_CXX_FLAGS} -fsigned-char")
 
 elseif(MSVC)
-  # warning C4512: assignment operator could not be generated
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /wd4512")
+  # Visual Studio pedantic build settings
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4 /WX")
 endif()
 
 if(FLATBUFFERS_CODE_COVERAGE)

include/flatbuffers/flexbuffers.h

@@ -26,6 +26,11 @@
 #include <intrin.h>
 #endif
 
+#if defined(_MSC_VER)
+#pragma warning(push)
+#pragma warning(disable: 4127) // C4127: conditional expression is constant
+#endif
+
 namespace flexbuffers {
 
 class Reference;
@@ -105,7 +110,7 @@ inline Type ToTypedVectorElementType(Type t) {
 inline Type ToFixedTypedVectorElementType(Type t, uint8_t *len) {
   assert(IsFixedTypedVector(t));
   auto fixed_type = t - TYPE_VECTOR_INT2;
-  *len = fixed_type / 3 + 2;  // 3 types each, starting from length 2.
+  *len = static_cast<uint8_t>(fixed_type / 3 + 2);  // 3 types each, starting from length 2.
   return static_cast<Type>(fixed_type % 3 + TYPE_INT);
 }
 
@@ -602,7 +607,7 @@ class Reference {
 
   template<typename T> bool Mutate(const uint8_t *dest, T t, size_t byte_width,
                                    BitWidth value_width) {
-    auto fits = static_cast<size_t>(1U << value_width) <= byte_width;
+    auto fits = static_cast<size_t>(static_cast<size_t>(1U) << value_width) <= byte_width;
     if (fits) {
       t = flatbuffers::EndianScalar(t);
       memcpy(const_cast<uint8_t *>(dest), &t, byte_width);
@@ -1073,7 +1078,7 @@ class Builder FLATBUFFERS_FINAL_CLASS {
     auto byte_width = 1U << alignment;
     buf_.insert(buf_.end(), flatbuffers::PaddingBytes(buf_.size(), byte_width),
                 0);
-    return byte_width;
+    return static_cast<uint8_t>(byte_width);
   }
 
   void WriteBytes(const void *val, size_t size) {
@@ -1177,7 +1182,7 @@ class Builder FLATBUFFERS_FINAL_CLASS {
           auto offset = offset_loc - u_;
           // Does it fit?
           auto bit_width = WidthU(offset);
-          if (static_cast<size_t>(1U << bit_width) == byte_width)
+          if (static_cast<size_t>(static_cast<size_t>(1U) << bit_width) == byte_width)
             return bit_width;
         }
         assert(false);  // Must match one of the sizes above.
@@ -1340,4 +1345,8 @@ class Builder FLATBUFFERS_FINAL_CLASS {
 
 }  // namespace flexbuffers
 
+#if defined(_MSC_VER)
+#pragma warning(pop)
+#endif
+
 #endif  // FLATBUFFERS_FLEXBUFFERS_H_

src/code_generators.cpp

@@ -18,6 +18,11 @@
 #include <assert.h>
 #include "flatbuffers/util.h"
 
+#if defined(_MSC_VER)
+#pragma warning(push)
+#pragma warning(disable: 4127) // C4127: conditional expression is constant
+#endif
+
 namespace flatbuffers {
 
 void CodeWriter::operator+=(std::string text) {
@@ -156,3 +161,8 @@ void GenComment(const std::vector<std::string> &dc, std::string *code_ptr,
 }
 
 }  // namespace flatbuffers
+
+#if defined(_MSC_VER)
+#pragma warning(pop)
+#endif
+

src/idl_gen_grpc.cpp

@@ -24,6 +24,11 @@
 #include "src/compiler/cpp_generator.h"
 #include "src/compiler/go_generator.h"
 
+#if defined(_MSC_VER)
+#pragma warning(push)
+#pragma warning(disable: 4512) // C4512: 'class' : assignment operator could not be generated
+#endif
+
 namespace flatbuffers {
 
 class FlatBufMethod : public grpc_generator::Method {
@@ -269,3 +274,7 @@ bool GenerateCppGRPC(const Parser &parser,
 
 }  // namespace flatbuffers
 
+#if defined(_MSC_VER)
+#pragma warning(pop)
+#endif
+