message: greatly simplify logic -- thanks Lachlan!
diff: @@ -105,22 +105,13 @@ enum Backend {
  impl Backend {
  pub fn variants() -> &'static [&'static str] {
  - #[cfg(all(feature = "backend:singlepass", feature = "backend:llvm"))]
  - {
  - &["cranelift", "singlepass", "llvm"]
  - }
  - #[cfg(all(not(feature = "backend:singlepass"), feature = "backend:llvm"))]
  - {
  - &["cranelift", "llvm"]
  - }
  - #[cfg(all(feature = "backend:singlepass", not(feature = "backend:llvm")))]
  - {
  - &["cranelift", "singlepass"]
  - }
  - #[cfg(all(not(feature = "backend:singlepass"), not(feature = "backend:llvm")))]
  - {
  - &["cranelift"]
  - }
  + &[
  + "cranelift",
  + #[cfg(feature = "backend:singlepass")]
  + "singlepass",
  + #[cfg(feature = "backend:llvm")]
  + "llvm",
  + ]
  }
  }
  