.github/workflows/clang_tidy.yml

# Copyright 2026 The IREE Authors
#
# Licensed under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

# This workflow uses the newest clang-tidy binary built from source after the
# latest integrate. This way we get the newest checks (incl., llvm-specific
# ones).

name: Clang Tidy

on:
  pull_request:
    paths:
      - '**.h'
      - '**.c'
      - '**.cpp'
      - '.clang-tidy'
      - '.github/workflows/clang_tidy.yml'

permissions:
  contents: write
  pull-requests: write

concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
  cancel-in-progress: true

jobs:
  clang-tidy:
    # Run expensive CI only for the lowest unmerged PR in a native stack.
    if: >-
      github.event.pull_request.stack == null ||
      github.event.pull_request.stack.base.ref == github.event.pull_request.base.ref
    runs-on: ubuntu-24.04
    container:
      image: ghcr.io/iree-org/cpubuilder_ubuntu_jammy@sha256:78a558b999b230f7e1da376639e14b44f095f30f1777d6a272ba48c0bbdd4ccb
    defaults:
      run:
        shell: bash
    env:
      BUILD_DIR: build
    steps:
      - name: Check out repository
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          submodules: false
          fetch-depth: 0

      - name: Initialize submodules
        run: |
          git config --global --add safe.directory "$GITHUB_WORKSPACE"
          git submodule update --init --depth=1

      - name: Download iree-clang-tidy artifact
        uses: dawidd6/action-download-artifact@eab87c9830c39eff17e5a6eadb20bfb4bc880477 # v27
        with:
          workflow: build_clang_tidy.yml
          name: iree-clang-tidy-linux-x86_64
          path: .iree-clang-tidy

      - name: Setup iree-clang-tidy
        run: |
          # Make executable (artifact download doesn't preserve permissions).
          chmod +x .iree-clang-tidy/clang-tidy
          echo "Using clang-tidy from llvm-project revision:"
          cat .iree-clang-tidy/llvm-project-revision.txt
          .iree-clang-tidy/clang-tidy --version

      - name: Install Python requirements
        run: |
          # Use uv instead of plain pip since cpp-linter uses it anyway.
          curl -LsSf https://astral.sh/uv/install.sh | sh
          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
          export PATH="$HOME/.local/bin:$PATH"
          uv pip install --system -r ./runtime/bindings/python/iree/runtime/build_requirements.txt
          uv pip install --system -r ./build_tools/github_actions/ci_requirements.txt

      - name: Generate compilation database (compile_commands.json)
        run: |
          IREE_CONFIGURE_ONLY=1 ./build_tools/cmake/build_all.sh "${BUILD_DIR}"

      - name: Select clang-tidy diff mode
        id: tidy-diff-mode
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
        run: |
          status_code=$(curl -sS -o /tmp/pr.diff -w "%{http_code}" \
            -H "Authorization: Bearer ${GITHUB_TOKEN}" \
            -H "Accept: application/vnd.github.v3.diff" \
            "${GITHUB_API_URL}/repos/${GITHUB_REPOSITORY}/pulls/${PR_NUMBER}")
          if [[ "${status_code}" == "200" ]]; then
            echo "use_cpp_linter=true" >> "${GITHUB_OUTPUT}"
          else
            echo "GitHub PR diff request returned ${status_code}; running clang-tidy locally on changed files."
            echo "use_cpp_linter=false" >> "${GITHUB_OUTPUT}"
          fi

      - name: Run clang-tidy
        if: steps.tidy-diff-mode.outputs.use_cpp_linter == 'true'
        uses: cpp-linter/cpp-linter-action@8120e05c7fbd25fa09fa93424ec49f55f7b304ab # v1.11.4
        id: linter
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          version: .iree-clang-tidy
          style: ''  # Disable clang-format (already handled by pre-commit).
          tidy-checks: ''  # Use .clang-tidy config files.
          database: ${{ env.BUILD_DIR }}
          files-changed-only: true
          lines-changed-only: diff
          ignore: 'third_party'
          thread-comments: false
          step-summary: true

      - name: Skip clang-tidy on large diff
        if: steps.tidy-diff-mode.outputs.use_cpp_linter == 'false'
        env:
          BASE_SHA: ${{ github.event.pull_request.base.sha }}
          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
        run: |
          changed_files="${RUNNER_TEMP}/clang-tidy-changed-files.txt"

          git diff --name-only --diff-filter=ACMRT "${BASE_SHA}" "${HEAD_SHA}" \
            | grep -E '\.(c|h|C|H|cpp|hpp|cc|hh|c\+\+|h\+\+|cxx|hxx)$' \
            | grep -Ev '(^|/)third_party/' \
            | sort -u > "${changed_files}" || true

          if [[ ! -s "${changed_files}" ]]; then
            echo "No changed C/C++ files found."
            exit 0
          fi

          echo "::warning title=clang-tidy skipped::GitHub refused the PR diff because it exceeds the 20,000-line API limit, so cpp-linter cannot compute changed-line diagnostics for $(wc -l < "${changed_files}") changed C/C++ files."