Function string_injections 

fn string_injections(
    hl: &mut Highlights,
    sema: &Semantics<'_, RootDatabase>,
    config: &HighlightConfig<'_>,
    file_id: EditionedFileId,
    krate: Option<Crate>,
    token: SyntaxToken,
    descended_token: &SyntaxToken,
) -> ControlFlow<()>