sil hidden @$s4main1a1bQrxyXE_tAA1PRzlF : $@convention(thin) <τ_0_0 where τ_0_0 : P> (@guaranteed @noescape @callee_guaranteed @substituted <τ_0_0> () -> @out τ_0_0 for <τ_0_0>) -> @out @_opaqueReturnTypeOf("$s4main1a1bQrxyXE_tAA1PRzlF", 0) __<τ_0_0> {

これ型変数1個なんですね