Suppress warnings in Function.cpp

[jslee02]

For backward compatibility, we have to call deprecated functions in Function.cpp, but the compilers complain for these calls. This pull request suppresses the warnings only for those calls. See also #544.

Note that the suppression code couldn't be made as macros. It needs to use compiler dependent #pragma directives but directives is not allowed to be declared in macros.

[mxgrey]

I wonder if we could make this more reusable, for example maybe we could have

#define DART_SUPPRESS_DEPRECATED_START // begin suppressing deprecated warnings, based on the compiler
#define DART_SUPPRESS_DEPRECATED_END // stop suppressing deprecated warnings, based on the compiler

And then we could wrap those around any function calls that we don't want to see deprecation warnings for.

[mkoval]

@mxgrey I don't think this is possible because of what @jslee02 said in his original post:

It needs to use compiler dependent #pragma directives but directives is not allowed to be declared in macros.

[mxgrey]

Right, I see. I guess the only way to overcome it would be to do some pre-preprocessing, but it's probably not worth it to take that route for this.

[mkoval]

Actually, that isn't quite true. According to StackOverflow you can use _Pragma("foo") as an equivalent to #pragma foo that can be used in macros.

[Edit] This appears to be an addition in C++11.

[jslee02]

@mxgrey Yes, I started with similar approach you suggested, but couldn't find a way to contain #pragma in macro. However, _Pragma(string) seems to be able to do it, and clang, gcc, and MSVC all support this operator. I will try with it now. Thanks @mkoval !

[jslee02]

Updated the warning suppression with macros using _Pragma operator.

[Edit] This appears to be an addition in C++11.

Hm, I need to check if MSVC supports this.

[mkoval]

As usual, MSVC is a pain in the ass. It uses __pragma(foo) instead of _Pragma("foo"): note the two underscores, case, and lack of quotes. I think you can wrap this in a macro like this:

#ifdef _MSC_VER
#define PRAGMA(x) __pragma(x)
#else
#define PRAGMA(x) _Pragma(#x)
#endif

[jslee02]

Right, I had to use __pragma for MSVC. Many times MSVC requires special treatment.

The wrapper looks good but I would prefer to use it when we found more use cases.

[mxgrey]

This looks really good now 👍

[jslee02]

Thanks! Merging now.