Function clippy_lints::utils::is_direct_expn_of

pub fn is_direct_expn_of(cx: &LateContext,
                         span: Span,
                         name: &str)
                         -> Option<Span>

Return the pre-expansion span if is this directly comes from an expansion of the macro name. The difference with is_expn_of is that in rust,ignore foo!(bar!(42)); 42 is considered expanded from foo! and bar! by is_expn_of but only bar! by is_direct_expn_of.