My IDE inspects my CSS files, and complains if I put a font-family rule which does not have a generic fallback. In general, I have to agree with my IDE, and I will happily add the font callback.
Example:
.selector {
font-family: Arial; /* IDE complains. */
font-family: Arial, sans-serif; /* IDE is happy. */
}
However, sometime the font-family is an icon font (I think fontawesome is one of those), and a fallback does not really make sense. Or does it?
.my-icon {
font-family: 'my-icon-font'; /* IDE complains. */
font-family: 'my-icon-font', serif; /* IDE is happy, but it does not make sense. */
}
Could there be any sensible fallback that would make sense to append to a font-family rule with an icon font?
In my case, it is mainly my IDE that is nudging me to add a generic font callback. As a last resort I could disable, suppress or ignore this inspection.
However, in other teams there might be strict rules about code conventions, perhaps even a mechanism that blocks commits if they do not comply.
Or what if I am the author of a code inspection tool, or in the process of defining the coding conventions to be used in a project? Then I definitely want to know what would be the "correct" or smartest way to do this :)
As discussed in the comments, this is a bogus warning.
As you point out yourself, there is no generic font family that is suitable as a fallback for an icon font - nor can there be, as icon fonts are not standardized.
The relevant spec (CSS Fonts Module Level 3) only lists the following generic families:
None of these is suitable - as they are all explicitly not intended for icon/picture fonts.
So you should probably find a way to suppress the warning. Ideally, the system would allow you to add a list of fonts that the warning should be suppressed for (such as icon fonts). Otherwise, you'll just have to suppress the warning entirely.
Side note: Fallback fonts are only really necessary if you want to use a font that is installed on the user's computer - such as standard Windows fonts like Arial. In that case you need a fallback, because you cannot be sure what the user has installed.
If you use a web font that the browser can download, there should never be a need for a fallback font. It is still nice to include in case the font download fails, but IMHO not as important.