Run Miri on CI

The pin guarantees are guarantees of a library, so Miri does not detect
violations of the pin API. However, if the generated unsafe code causes
UB, Miri may be possible to detect it.

.github/workflows/ci.yml

@@ -75,7 +75,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install Rust and rustfmt
+      - name: Install Rust and Rustfmt
         run: ci/install-component.sh rustfmt
       - name: Install cargo-expand
         run: |
@@ -84,6 +84,18 @@ jobs:
         run: |
           bash scripts/expandtest.sh
 
+  miri:
+    name: miri
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Rust and Miri
+        run: ci/install-component.sh miri
+      - name: cargo miri test
+        run: |
+          cargo miri setup
+          cargo miri test
+
   clippy:
     name: clippy
     runs-on: ubuntu-latest
@@ -100,7 +112,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install Rust and rustfmt
+      - name: Install Rust and Rustfmt
         run: ci/install-component.sh rustfmt
       - name: cargo fmt --check
         run: |

tests/compiletest.rs

@@ -1,3 +1,4 @@
+#![cfg(not(miri))]
 #![warn(rust_2018_idioms, single_use_lifetimes)]
 
 #[rustversion::attr(not(nightly), ignore)]

tests/lint.rs

@@ -310,6 +310,7 @@ pub mod clippy_used_underscore_binding {
     }
 }
 
+#[cfg(not(miri))]
 #[allow(box_pointers)]
 #[allow(clippy::restriction)]
 #[rustversion::attr(not(nightly), ignore)]