Get VS 2015 to use const int definitions

VC++ up to VS 2015 RTM does not require explicit storage allocation for
static const integers declared in classes. VS 2015 Update 1 requires
these storage definitions in some cases. It's unclear exactly what
cases - simple tests work with and without the explicit storage
allocation.

Many previous versions of VC++ have theoretically *allowed* a
definition to supply storage, but tests on VC++ 2013 show that this
doesn't actually work correctly - it leads to duplicate definition
errors in Chromium. So, the change is scoped to VS 2015 only.

This change also updates the generated files to match the new generator.

TL;DR - this change is necessary in order for Chromium to build with
VS 2015 Update 1.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/google/protobuf/compiler/cpp/cpp_enum.cc b/src/google/protobuf/compiler/cpp/cpp_enum.cc
index de4d7cc7..1a11bce8 100644
--- a/src/google/protobuf/compiler/cpp/cpp_enum.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_enum.cc
@@ -278,9 +278,9 @@ void EnumGenerator::GenerateMethods(io::Printer* printer) {
   if (descriptor_->containing_type() != NULL) {
     // We need to "define" the static constants which were declared in the
     // header, to give the linker a place to put them.  Or at least the C++
-    // standard says we have to.  MSVC actually insists tha we do _not_ define
-    // them again in the .cc file.
-    printer->Print("#ifndef _MSC_VER\n");
+    // standard says we have to.  MSVC actually insists that we do _not_ define
+    // them again in the .cc file, prior to VC++ 2015.
+    printer->Print("#if !defined(_MSC_VER) || _MSC_VER >= 1900\n");
 
     vars["parent"] = ClassName(descriptor_->containing_type(), false);
     vars["nested_name"] = descriptor_->name();
@@ -297,7 +297,7 @@ void EnumGenerator::GenerateMethods(io::Printer* printer) {
         "const int $parent$::$nested_name$_ARRAYSIZE;\n");
     }
 
-    printer->Print("#endif  // _MSC_VER\n");
+    printer->Print("#endif  // !defined(_MSC_VER) || _MSC_VER >= 1900\n");
   }
 }