CI: add fmt and clippy check

cargo fmt is enforced, but clippy failures are allowed for now.

Author: Mingshen Sun

.travis.yml

@@ -5,8 +5,8 @@ rust:
   - stable
   - nightly
 env:
-  - TARGET=x86_64-unknown-linux-gnu RUN_TEST=1
-  - TARGET=x86_64-unknown-linux-musl RUN_TEST=1
+  - TARGET=x86_64-unknown-linux-gnu TEST=1
+  - TARGET=x86_64-unknown-linux-musl TEST=1
   - TARGET=aarch64-unknown-linux-gnu RUSTFLAGS="-C linker=aarch64-linux-gnu-gcc"
   - TARGET=arm-unknown-linux-gnueabi RUSTFLAGS="-C linker=arm-linux-gnueabi-gcc"
 matrix:
@@ -25,6 +25,22 @@ matrix:
       script:
         - ./ci/run-cov
         - bash <(curl -s https://codecov.io/bash) -f final.info
+    - rust: stable
+      env: TARGET=x86_64-unknown-linux-gnu FMT=1
+      before_install:
+      install:
+      before_script:
+        - rustup component add rustfmt-preview
+      script:
+        - cargo fmt -- --write-mode check
+    - rust: nightly
+      env: TARGET=x86_64-unknown-linux-gnu CLIPPY=1
+      before_install:
+      install:
+      before_script:
+        - cargo +nightly install clippy
+      script:
+        - cargo clippy
   allow_failures:
     - rust: nightly
   fast_finish: true
@@ -39,7 +55,7 @@ before_script:
 script:
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then cargo build --verbose --no-default-features --features gnu,lsb,networking,posix --target $TARGET; fi
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then cargo build --verbose --all --target $TARGET; fi
-  - if [[ "$RUN_TEST" == "1" ]]; then cargo test --verbose --all --target $TARGET; fi
+  - if [[ "$TEST" == "1" ]]; then cargo test --verbose --all --target $TARGET; fi
 notifications:
   email:
     on_success: never