--warn:0 still shows warnings

[T-Gro]

The --warn:n is a fsc.exe CLI flag to tune the number of warnings.
C# compiler has the same switch - https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/compiler-options/errors-warnings .

In C# docs, the value 0 is defined as Turns off emission of all warning messages..

Since F# docs refers to C# docs, the value of 0 should be implemented to hide all warnings and infos as well:
F# docs for the --warn flag:

Sets a warning level (0 to 5). 
The default level is 3. 
Each warning is given a level based on its severity. 
Level 5 gives more, but less severe, warnings than level 1.

This compiler option is equivalent to the C# compiler option of the same name. 
For more information, see 

/warn (C# Compiler Options).