Auto merge of #5071 - flip1995:gha, r=<try>

[WIP][DNM] Switch to GitHub Actions

cc #4577

This is just an experiment. I don't think we have a consensus _if_ we should move away from travis/appveyor.

GHA would let us run up to 20 concurrent jobs. Since we have 15 integration tests and 4 (linux, linux 32-bit, macos, windows) basic tests, we would be able to run everything concurrently. ~~Also IIUC we only have to build Clippy once for every initegration test and then only check the repos.~~ Nope, dependent jobs exist, but they won't keep the artifacts (not even the checkout).

TODO before merge:

- [ ] Add `DEPLOY_KEY` secret to github repo
- [ ] test deployment on test branch `gh-test`
- [ ] talk with `@rust-lang/infra` for bors
- [ ] Add GHA badge to Cargo.toml (blocked on rust-lang/crates.io#1838)
- [ ] Add back travis + appveyor files for transition period (?)

changelog: none

.github/workflows/clippy.yml

@@ -0,0 +1,98 @@
+name: Clippy Test
+
+on:
+  push:
+    # Ignore bors branches, since they are covered by `clippy_bors.yml`
+    branches-ignore: [auto, try]
+    # Don't run Clippy tests, when only textfiles were modified
+    paths-ignore:
+    - 'COPYRIGHT'
+    - 'LICENSE-*'
+    - '**.md'
+    - '**.txt'
+  pull_request:
+    # Don't run Clippy tests, when only textfiles were modified
+    paths-ignore:
+    - 'COPYRIGHT'
+    - 'LICENSE-*'
+    - '**.md'
+    - '**.txt'
+
+env:
+  RUST_BACKTRACE: 1
+  CARGO_TARGET_DIR: '${{ github.workspace }}/target'
+  GHA_CI: 1
+
+jobs:
+  base:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: rust-toolchain
+      uses: actions-rs/toolchain@v1.0.3
+      with:
+        toolchain: nightly
+        target: x86_64-unknown-linux-gnu
+        profile: minimal
+    - name: Cache cargo dir
+      uses: actions/cache@v1
+      with:
+        path: ~/.cargo
+        key: ${{ runner.os }}-x86_64-unknown-linux-gnu
+    - name: Checkout
+      uses: actions/checkout@v2.0.0
+    - name: Master Toolchain Setup
+      run: bash setup-toolchain.sh
+
+    - name: Set LD_LIBRARY_PATH (Linux)
+      run: |
+        SYSROOT=$(rustc --print sysroot)
+        echo "::set-env name=LD_LIBRARY_PATH::${SYSROOT}/lib${LD_LIBRARY_PATH+:${LD_LIBRARY_PATH}}"
+    - name: Build
+      run: cargo build --features deny-warnings
+    - name: Test
+      run: cargo test --features deny-warnings
+    - name: Test clippy_lints
+      run: cargo test --features deny-warnings
+      working-directory: clippy_lints
+    - name: Test rustc_tools_util
+      run: cargo test --features deny-warnings
+      working-directory: rustc_tools_util
+    - name: Test clippy_dev
+      run: cargo test --features deny-warnings
+      working-directory: clippy_dev
+    - name: Test cargo-clippy
+      run: ../target/debug/cargo-clippy
+      working-directory: clippy_workspace_tests
+    - name: Test clippy-driver
+      run: |
+        (
+          set -ex
+          # Check sysroot handling
+          sysroot=$(./target/debug/clippy-driver --print sysroot)
+          test "$sysroot" = "$(rustc --print sysroot)"
+
+          desired_sysroot=/tmp
+          sysroot=$(./target/debug/clippy-driver --sysroot $desired_sysroot --print sysroot)
+          test "$sysroot" = $desired_sysroot
+
+          sysroot=$(SYSROOT=$desired_sysroot ./target/debug/clippy-driver --print sysroot)
+          test "$sysroot" = $desired_sysroot
+
+          # Make sure this isn't set - clippy-driver should cope without it
+          unset CARGO_MANIFEST_DIR
+
+          # Run a lint and make sure it produces the expected output. It's also expected to exit with code 1
+          # FIXME: How to match the clippy invocation in compile-test.rs?
+          ./target/debug/clippy-driver -Dwarnings -Aunused -Zui-testing --emit metadata --crate-type bin tests/ui/cstring.rs 2> cstring.stderr && exit 1
+          sed -e 's,tests/ui,$DIR,' -e '/= help/d' cstring.stderr > normalized.stderr
+          diff normalized.stderr tests/ui/cstring.stderr
+
+          # TODO: CLIPPY_CONF_DIR / CARGO_MANIFEST_DIR
+        )
+
+    - name: Run cargo-cache --autoclean
+      run: |
+        cargo install cargo-cache --debug
+        find ~/.cargo/bin ! -type d -exec strip {} \;
+        cargo cache --autoclean