Gate benchmarks behind feature flag

This way everything should build on stable, and you can enable the
nighly-only benchmarks explicitly if you want to.

It would be nice if there were a way to just detect if we're on nightly,
but if there is I can't find it!

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: nightly
+          toolchain: stable
           override: true
       - uses: actions-rs/cargo@v1
         with:
@@ -25,12 +25,28 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: nightly
+          toolchain: stable
           override: true
       - uses: actions-rs/cargo@v1
         with:
           command: test
 
+  fmt:
+    name: Rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - run: rustup component add rustfmt
+      - uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
   clippy:
     name: Clippy
     runs-on: ubuntu-latest
@@ -39,10 +55,25 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: nightly
+          toolchain: stable
           override: true
       - run: rustup component add clippy
       - uses: actions-rs/cargo@v1
         with:
           command: clippy
           args: -- -D warnings
+
+  benchmark:
+    name: Benchmark
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: nightly
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          command: bench
+          args: --features benchmarks

Cargo.toml

@@ -8,6 +8,9 @@ edition = "2018"
 getopts = "0.2"
 rand = "0.7.3"
 
+[features]
+benchmarks = []
+
 [[bin]]
 path = "src/main.rs"
 name = "markovpass"

src/lib/mod.rs

@@ -1,3 +1,4 @@
+#[cfg(feature = "benchmarks")]
 extern crate test;
 
 mod corpus;
@@ -44,6 +45,7 @@ mod tests {
         assert_eq!(passphrases.len(), 5);
     }
 
+    #[cfg(feature = "benchmarks")]
     #[bench]
     fn bench_gen_passphrases(b: &mut test::Bencher) {
         let options = get_test_options();
@@ -67,3 +69,5 @@ mod tests {
         }
     }
 }
+
+mod bench {}

src/main.rs

@@ -1,4 +1,4 @@
-#![feature(test)]
+#![cfg_attr(feature = "benchmarks", feature(test))]
 
 mod args;
 mod lib;