glib-macros: add clone_block attribute

Author: jf2048

glib-macros/Cargo.toml

@@ -17,14 +17,17 @@ heck = "0.4"
 proc-macro-error = "1.0"
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "1.0", features = ["full"], default-features = false }
+syn = { version = "1.0", features = ["full", "visit-mut"], default-features = false }
 proc-macro-crate = "1.0"
 deluxe = "0.4.1"
 
 [lib]
 proc-macro = true
 
 [dev-dependencies]
+futures-channel = "0.3"
+futures-executor = "0.3"
+futures-util = "0.3"
 glib = { path = "../glib" }
 trybuild2 = "1.0"
 once_cell = "1.9.0"