It is a queryable database of semantic information about the program which is generated by the compiler (compiler plugin, to be precise). Once generated, other tools which need semantic information, like linters or language servers, can consume it without having to worry about how to actually generate it.
You might enjoy a talk about it: How We Built Tools That Scale to Millions of Lines of Code by Eugene Burmako
https://scalameta.org/docs/semanticdb/guide.html
It is a queryable database of semantic information about the program which is generated by the compiler (compiler plugin, to be precise). Once generated, other tools which need semantic information, like linters or language servers, can consume it without having to worry about how to actually generate it.
You might enjoy a talk about it: How We Built Tools That Scale to Millions of Lines of Code by Eugene Burmako
https://www.youtube.com/watch?v=C770WpI_odM
Kythe by Google is also a similar thing: https://kythe.io/