I was wandering if $L = \{\langle G \rangle \mid \ G \text{ is a context free grammar and } \mathcal L(G) = A \}$ is decidable where A is a some regular language. Is $L' = \{ \langle G \rangle \mid \ G \text{ is a context free grammar and } \mathcal L(G) = \overline A \}$ decidable ?  I feel like $L'$ should be decidable, but can't see how. Or does it depends on $A$?
Deciding whether the language of a CFG equals some specific regular language
undecidability