patches/version.diff

diff --git a/src/lib.rs b/src/lib.rs
index 2e8f1b9..e826b25 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -182,7 +182,16 @@ use crate::error::Error;
 use crate::version::Version;
 use proc_macro::TokenStream;
 
-const RUSTVERSION: Version = include!(concat!(env!("OUT_DIR"), "/version.expr"));
+// ANDROID: Soong is providing the version of rustc via an env variable.
+const ANDROID_RUSTVERSION: Option<&str> = option_env!("ANDROID_RUST_VERSION");
+fn rust_version() -> Version {
+    let v: Vec<&str> = ANDROID_RUSTVERSION.unwrap().split('.').collect();
+    Version {
+        minor: v[1].parse().unwrap(),
+        patch: v[2].parse().unwrap(),
+        channel: version::Channel::Stable,
+    }
+}
 
 #[proc_macro_attribute]
 pub fn stable(args: TokenStream, input: TokenStream) -> TokenStream {
@@ -239,7 +248,7 @@ pub fn cfg(input: TokenStream) -> TokenStream {
         let ref mut args = iter::new(input);
         let expr = expr::parse(args)?;
         token::parse_end(args)?;
-        let boolean = expr.eval(RUSTVERSION);
+        let boolean = expr.eval(rust_version());
         let ident = Ident::new(&boolean.to_string(), Span::call_site());
         Ok(TokenStream::from(TokenTree::Ident(ident)))
     })()
diff --git a/src/expand.rs b/src/expand.rs
index 813ba85..3d4e314 100644
--- a/src/expand.rs
+++ b/src/expand.rs
@@ -23,7 +23,7 @@ fn try_cfg(introducer: &str, args: TokenStream, input: TokenStream) -> Result<To
     let expr = expr::parse(full_args)?;
     token::parse_end(full_args)?;
 
-    if expr.eval(crate::RUSTVERSION) {
+    if expr.eval(crate::rust_version()) {
         Ok(input)
     } else {
         Ok(TokenStream::new())
@@ -31,7 +31,7 @@ fn try_cfg(introducer: &str, args: TokenStream, input: TokenStream) -> Result<To
 }
 
 pub fn try_attr(args: attr::Args, input: TokenStream) -> Result<TokenStream> {
-    if !args.condition.eval(crate::RUSTVERSION) {
+    if !args.condition.eval(crate::rust_version()) {
         return Ok(input);
     }