# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
# Exceptions. See /LICENSE for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

name: test

on:
  push:
    branches: [trunk]
  pull_request:
  merge_group:

# Cancel previous workflows on the PR when there are multiple fast commits.
# https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#concurrency
concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
  cancel-in-progress: true

jobs:
  test:
    strategy:
      matrix:
        # At present, these images are newer than "latest". We use them to test
        # against more recent tooling versions.
        # https://github.com/actions/runner-images
        os: [ubuntu-22.04, macos-12]
        build_mode: [fastbuild, opt]
    runs-on: ${{ matrix.os }}

    steps:
      # Ubuntu images start with 23GB available, and this adds 14GB more. For
      # comparison, MacOS images have >100GB free.
      - name: Free up disk space (Ubuntu)
        if: matrix.os == 'ubuntu-22.04'
        uses: jlumbroso/free-disk-space@v1.2.0
        with:
          android: true
          dotnet: true
          haskell: true
          # Although we could delete more, if we run into a limit, it provides a
          # little flexibility to get space while trying to shrink the build.
          # There's also support for docker images at head (1.2.0 is still
          # the latest release).
          large-packages: false
          swap-storage: false

      # Checkout the pull request head or the branch.
      - name: Checkout pull request
        if: github.event_name == 'pull_request'
        uses: actions/checkout@v3
        with:
          ref: ${{ github.event.pull_request.head.sha }}

      - name: Checkout branch
        if: github.event_name != 'pull_request'
        uses: actions/checkout@v3

      # Tests should only run on applicable paths, but we still need to have an
      # action run for the merge queue. We filter steps based on the paths here,
      # and condition steps on the output.
      - id: filter
        uses: dorny/paths-filter@v2
        with:
          filters: |
            has_code:
              - '!{**/*.md,LICENSE,CODEOWNERS,.git*}'

      # Setup Python and related tools.
      - uses: actions/setup-python@v4
        if: steps.filter.outputs.has_code == 'true'
        with:
          # Match the min version listed in docs/project/contribution_tools.md
          python-version: '3.9'

      # Use LLVM following:
      # https://github.com/actions/runner-images/blob/main/images/macos/macos-12-Readme.md
      - name: Setup LLVM and Clang (macOS)
        if: steps.filter.outputs.has_code == 'true' && matrix.os == 'macos-12'
        run: |
          LLVM_PATH="$(brew --prefix llvm@15)"
          echo "Using ${LLVM_PATH}"
          echo "${LLVM_PATH}/bin" >> $GITHUB_PATH
          echo '*** ls "${LLVM_PATH}"'
          ls "${LLVM_PATH}"
          echo '*** ls "${LLVM_PATH}/bin"'
          ls "${LLVM_PATH}/bin"

      # Use LLVM following:
      # https://github.com/actions/runner-images/blob/main/images/linux/Ubuntu2204-Readme.md
      - name: Setup LLVM and Clang (Ubuntu)
        if:
          steps.filter.outputs.has_code == 'true' && matrix.os == 'ubuntu-22.04'
        run: |
          # TODO: Re-enable once llvm-15 is working.
          # https://github.com/actions/runner-images/issues/8253
          # LLVM_PATH="/usr/lib/llvm-15"
          # if [[ ! -e "${LLVM_PATH}" ]]; then
          LLVM_PATH="/usr/lib/llvm-14"
          # fi
          echo "Using ${LLVM_PATH}"
          echo "${LLVM_PATH}/bin" >> $GITHUB_PATH
          echo '*** ls "${LLVM_PATH}"'
          ls "${LLVM_PATH}"
          echo '*** ls "${LLVM_PATH}/bin"'
          ls "${LLVM_PATH}/bin"

      # Print the various tool paths and versions to help in debugging.
      - name: Print tool debugging info
        if: steps.filter.outputs.has_code == 'true'
        run: |
          echo '*** PATH'
          echo $PATH
          echo '*** bazelisk'
          which bazelisk
          bazelisk --version
          echo '*** python'
          which python
          python --version
          echo '*** clang'
          which clang
          clang --version
          echo '*** clang++'
          which clang++
          clang++ --version

      # Disable uploads when the remote cache is read-only.
      - name: Set up remote cache access (read-only)
        if:
          steps.filter.outputs.has_code == 'true' && github.event_name ==
          'pull_request'
        run: |
          echo "remote_cache_upload=--remote_upload_local_results=false" \
              >> $GITHUB_ENV

      # Provide a cache key when the remote cache is read-write.
      - name: Set up remote cache access (read-write)
        if:
          steps.filter.outputs.has_code == 'true' && github.event_name !=
          'pull_request'
        env:
          REMOTE_CACHE_KEY: ${{ secrets.CARBON_BUILDS_GITHUB }}
        run: |
          echo "$REMOTE_CACHE_KEY" | base64 -d > $HOME/remote_cache_key.json
          echo "remote_cache_upload=--google_credentials=$HOME/remote_cache_key.json" \
              >> $GITHUB_ENV

      # We need to replace the `.` with a `_` for the build cache.
      - name: Setup LLVM and Clang (macOS)
        if: steps.filter.outputs.has_code == 'true' && matrix.os == 'macos-12'
        run: |
          echo "os_for_cache=macos-12" >> $GITHUB_ENV
      - name: Setup LLVM and Clang (Ubuntu)
        if:
          steps.filter.outputs.has_code == 'true' && matrix.os == 'ubuntu-22.04'
        run: |
          echo "os_for_cache=ubuntu-22_04" >> $GITHUB_ENV

      # Add our bazel configuration and print basic info to ease debugging.
      - name: Configure Bazel and print info
        if: steps.filter.outputs.has_code == 'true'
        env:
          # Add a cache version for changes that bazel won't otherwise detect,
          # like llvm version changes.
          CACHE_VERSION: 1
        run: |
          cat >user.bazelrc <<EOF
          # Enable remote cache for our CI but minimize downloads.
          build --remote_cache=https://storage.googleapis.com/carbon-builds-github-v${CACHE_VERSION}-${{ env.os_for_cache }}
          build --remote_download_minimal

          build ${{ env.remote_cache_upload }}

          # Set an artificially high jobs count. This flag controls the number
          # of concurrency Bazel itself uses, which is essential for actions
          # that are internally blocked on for example downloading results form
          # the cache above. Without setting this high, Bazel will pick a small
          # number based on the available host CPUs and the reality will be a
          # long chain of largely serialized download events with little or no
          # usage of the host machine. Fortunately, local actions are
          # *separately* gated on '--local_*_resources' that will avoid a large
          # jobs value overwhelming the host. There is a bug to make downloads
          # behave completely asynchronously and remove the need for this filed
          # back in 2018 but work seemed to not finish:
          # https://github.com/bazelbuild/bazel/issues/6394
          #
          # There is a new effort (yay!) but until then it seems worth using the
          # workaround of a high jobs value. The biggest downside (increased
          # heap usage) seems like it isn't currently a big loss for our builds.
          #
          # Higher values like 50 have led to CI failures with network errors
          # and IOExceptions, see
          # https://discord.com/channels/655572317891461132/707150492370862090/1151605725576056934
          build --jobs=32

          # General build options.
          build --verbose_failures
          test --test_output=errors
          EOF
          bazelisk info

      # Just for visibility, print space before and after the build.
      - name: Disk space before build
        if: steps.filter.outputs.has_code == 'true'
        run: df -h

      # Build and run all targets on branch pushes to ensure we always have a
      # clean tree. We don't expect this to be an interactive path and so don't
      # optimize the latency of this step.
      - name: Compute impacted pull request targets (for push)
        if:
          steps.filter.outputs.has_code == 'true' && github.event_name == 'push'
        env:
          TARGETS_FILE: ${{ runner.temp }}/targets
        run: |
          echo "//..." >$TARGETS_FILE

      # Compute the set of possible rules impacted by this change using
      # Bazel-based diffing. This lets PRs and the merge queue have a much more
      # efficient test CI action by avoiding even enumerating (and downloading)
      # all of the unaffected Bazel targets.
      - name: Compute impacted pull request targets
        if:
          steps.filter.outputs.has_code == 'true' && github.event_name != 'push'
        env:
          # Compute the base SHA from the different event structures.
          GIT_BASE_SHA:
            ${{ github.event_name == 'pull_request' &&
            github.event.pull_request.base.sha ||
            github.event.merge_group.base_sha }}
          TARGETS_FILE: ${{ runner.temp }}/targets
        run: |
          # First fetch the relevant base into the git repository.
          git fetch --depth=1 origin $GIT_BASE_SHA

          # Then use `target-determinator` as wrapped by our script.
          ./scripts/target_determinator.py $GIT_BASE_SHA >$TARGETS_FILE

      # Build and run just the tests impacted by the PR or merge group.
      - name: Test (${{ matrix.build_mode }})
        if: steps.filter.outputs.has_code == 'true'
        env:
          # 'libtool_check_unique failed to generate' workaround.
          # https://github.com/bazelbuild/bazel/issues/14113#issuecomment-999794586
          BAZEL_USE_CPP_ONLY_TOOLCHAIN: 1
          TARGETS_FILE: ${{ runner.temp }}/targets
        run: |
          # Bazel requires a test target to run the test command. There may be
          # no targets or there may only be non-test targets that we want to
          # build, so simply inject an explicit no-op test target.
          echo "//scripts:no_op_test" >> $TARGETS_FILE

          for i in {1..5}; do
            if (( $i == 4 )); then
              # Decrease the jobs sharply if we see repeated failures to try to
              # work around transient network errors even if it makes things
              # slower.
              echo "build --jobs=4" >>user.bazelrc
            fi

            bazel_exit=0
            bazelisk test -c ${{ matrix.build_mode }} \
              --target_pattern_file=$TARGETS_FILE || bazel_exit=$?

            # If we succeed, we're done.
            if (( $bazel_exit == 0 )); then
              break
            fi

            # Several error codes are reliably permanent, break immediately.
            # `1`  -- The build failed.
            # `2`  -- Command line or environment problem.
            # `3`  -- Tests failed or timed out, we don't retry at this layer
            #         on execution timeout.
            # `4`  -- No tests found, which should be impossible here.
            # `8`  -- Explicitly interrupted build.
            #
            # Note that `36` is documented as "likely permanent", but we retry
            # it as most of our transient failures actually produce that error
            # code.
            if (( $bazel_exit == 1 || $bazel_exit == 2 || $bazel_exit == 3 || \
                  $bazel_exit == 4 || $bazel_exit == 8 || $bazel_exit == 8 ))
            then
              break
            fi

            echo "Retrying a failed build as it may be transient..."
            # Also sleep a bit to try to skip over transient machine load.
            sleep $i
          done

          # Propagate the Bazel exit code.
          exit $bazel_exit

      # See "Disk space before build".
      - name: Disk space after build
        if: steps.filter.outputs.has_code == 'true'
        run: df -h