Assume we're always on Rust 1.30+

build.rs

@@ -1,14 +1,10 @@
 extern crate rustc_version;
-use rustc_version::{version, version_meta, Version, Channel};
+use rustc_version::{version, version_meta, Channel};
 
 fn main() {
     let mut current = version().unwrap();
     current.pre = Vec::new();
 
-    if current >= Version::parse( "1.30.0" ).unwrap() {
-        println!( "cargo:rustc-cfg=rust_1_30_or_newer" );
-    }
-
     if version_meta().unwrap().channel == Channel::Nightly {
         println!( "cargo:rustc-cfg=rust_nightly" );
     }

src/lib.rs

@@ -111,7 +111,7 @@
     unused_qualifications
 )]
 #![cfg_attr(
-    all(test, rust_1_30_or_newer, rust_nightly),
+    all(test, rust_nightly),
     feature(linkage) // Needed for async tests.
 )]
 #![cfg_attr(rust_nightly, feature(core_intrinsics))]
@@ -130,17 +130,14 @@ extern crate serde_json;
 #[macro_use]
 extern crate serde_derive;
 
-#[cfg(rust_1_30_or_newer)]
 extern crate stdweb_internal_macros;
 
 #[cfg(all(
-    rust_1_30_or_newer,
     target_arch = "wasm32",
     target_os = "unknown"
 ))]
 pub use stdweb_internal_macros::js_export;
 
-#[cfg(rust_1_30_or_newer)]
 pub use stdweb_internal_macros::async_test;
 
 #[cfg(feature = "futures-support")]

stdweb-internal-macros/Cargo.toml

@@ -11,8 +11,6 @@ keywords = ["web", "asmjs", "webasm", "javascript"]
 categories = ["api-bindings", "gui", "web-programming"]
 description = "Internal procedural macros for the `stdweb` crate"
 
-build = "build.rs"
-
 [lib]
 proc-macro = true
 
@@ -29,5 +27,3 @@ version = "0.15"
 default-features = false
 features = ["full", "parsing", "printing", "clone-impls"]
 
-[build-dependencies]
-rustc_version = "0.2"

stdweb-internal-macros/src/lib.rs

@@ -11,18 +11,14 @@ extern crate serde;
 extern crate serde_derive;
 extern crate serde_json;
 
-#[cfg(rust_1_30_or_newer)]
 mod macro_js_export;
-#[cfg(rust_1_30_or_newer)]
 mod macro_async_test;
 
-#[cfg(rust_1_30_or_newer)]
 #[proc_macro_attribute]
 pub fn js_export( attrs: proc_macro::TokenStream, input: proc_macro::TokenStream ) -> proc_macro::TokenStream {
     macro_js_export::js_export( attrs, input )
 }
 
-#[cfg(rust_1_30_or_newer)]
 #[proc_macro_attribute]
 pub fn async_test( attrs: proc_macro::TokenStream, input: proc_macro::TokenStream ) -> proc_macro::TokenStream {
     macro_async_test::async_test( attrs, input )