Mojo: First stab at making MessagePipes work across OS pipes.

base/compiler_specific.h

Index: base/compiler_specific.h
diff --git a/base/compiler_specific.h b/base/compiler_specific.h
index 07b680b78441e1196b5bf7148b5a2ba164bfe7bf..409a613964cef2cf74c36ade8b040e5e63656757 100644
--- a/base/compiler_specific.h
+++ b/base/compiler_specific.h
@@ -68,6 +68,28 @@
 #endif  // COMPILER_MSVC
 
 
+// The C++ standard requires that static const members have an out-of-class
+// definition (in a single compilation unit), but MSVC chokes on this (when
+// language extensions, which are required, are enabled). (You're only likely to
+// notice the need for a definition if you take the address of the member or,
+// more commonly, pass it to a function that takes it as a reference argument --
+// probably an STL function.) This macro makes MSVC do the right thing. See
+// http://msdn.microsoft.com/en-us/library/34h23df8(v=vs.100).aspx for more
+// information. Use like:
+//
+// In .h file:
+//   struct Foo {
+//     static const int kBar = 5;
+//   };
+//
+// In .cc file:
+//   STATIC_CONST_MEMBER_DEFINITION const int Foo::kBar;
+#if defined(COMPILER_MSVC)
+#define STATIC_CONST_MEMBER_DEFINITION __declspec(selectany)
+#else
+#define STATIC_CONST_MEMBER_DEFINITION
+#endif

[Nico, 2013/11/07 19:50:35]

Ugh, can we just use an enum? That's what we've done so far and it works well
enough. Do you really need this?

[viettrungluu, 2013/11/08 19:05:41]

a) enums aren't typed, which is unfortunate.
b) It isn't what we've done so far. So far, people mostly don't encounter the
problem (if they don't pass their static const members as arguments to things
taking reference arguments) or manually ifdef out based on COMPILER_MSVC if they
do encounter the problem. (Or, maybe sometimes people don't declare the values
of their static const members in the header when they should.)

+
 // Annotate a variable indicating it's ok if the variable is not used.
 // (Typically used to silence a compiler warning when the assignment
 // is important for some other reason.)