Require proc-macro2 ^0.4.2
`proc-macro` 0.4.1 no longer works after
@@ -29,7 +29,7 @@ extra-traits = []
proc-macro = ["proc-macro2/proc-macro", "quote/proc-macro"]
[dependencies]
-proc-macro2 = { version = "0.4.1", default-features = false }
+proc-macro2 = { version = "0.4.2", default-features = false }
quote = { version = "0.6", optional = true, default-features = false }
unicode-xid = "0.1"
