How to have a shader with multi_compile_local supporting older version of Unity?

Hi guys,
I wanted to take advantage of the "new" shader local keywords introduced in Unity 2019.1.0 by using multi_compile_local instead of multi_compile.
However I need my shader to be compatible with older versions of Unity which don't support this feature. So I told myself that's easy, I just have to do that:

Code (CSharp):

1. CGPROGRAM
2. #pragma vertex vert
3. #pragma fragment frag
4. #pragma multi_compile_fog
5.  
6. #if UNITY_VERSION >= 201910
7.     #pragma multi_compile_local __ FOO_ON
8. #else
9.     #pragma multi_compile __ FOO_ON
10. #endif
11.  
12. #include "UnityCG.cginc"
13.  
14. struct appdata
15. {
16.     float4 vertex : POSITION;
17.     float2 uv : TEXCOORD0;
18. };

While this works, it generates this very annoying warning message (tried in Unity 2019.3.14)

So why Unity tries to evaluate code which is supposed to be disabled by the preprocessor, and how can I support that without any warning?

Thanks

 

Thanks for the answer.
Indeed, it looks like the #pragma multi_compile_local are ignored in Unity 2018.4.21 without generating an error, but I can't do that since I would just looe my shader variants then...
I think the only option is to stick with multi_compile for now...
Thanks