1 files changed, 83 insertions, 0 deletions
diff --git a/backend/cmake/modules/RCCBackendClangTidy.cmake b/backend/cmake/modules/RCCBackendClangTidy.cmake
new file mode 100644
index 0000000..16afeb4
--- /dev/null
+++ b/backend/cmake/modules/RCCBackendClangTidy.cmake
@@ -0,0 +1,83 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+foreach(Variable IN ITEMS RCC_TIDY_GIT RCC_TIDY_SOURCE_DIR RCC_TIDY_BINARY_DIR RCC_TIDY_BASE
+                          RCC_TIDY_JOBS RCC_TIDY_DIFF)
+  if(NOT DEFINED ${Variable} OR "${${Variable}}" STREQUAL "")
+    message(FATAL_ERROR "${Variable} is required for incremental clang-tidy")
+  endif()
+endforeach()
+
+execute_process(
+  COMMAND "${RCC_TIDY_GIT}" -C "${RCC_TIDY_SOURCE_DIR}" rev-parse --show-toplevel
+  RESULT_VARIABLE GitRootResult
+  OUTPUT_VARIABLE GitRoot
+  ERROR_VARIABLE GitRootError
+  OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+if(NOT GitRootResult EQUAL 0)
+  message(FATAL_ERROR "cannot locate the Git worktree: ${GitRootError}")
+endif()
+
+file(RELATIVE_PATH TidyPath "${GitRoot}" "${RCC_TIDY_SOURCE_DIR}")
+if(TidyPath MATCHES "^\\.\\.")
+  message(FATAL_ERROR "backend source directory is outside its Git worktree")
+endif()
+
+set(DiffFile "${RCC_TIDY_BINARY_DIR}/CMakeFiles/rcc-backend-clang-tidy.diff")
+execute_process(
+  COMMAND "${RCC_TIDY_GIT}" -C "${GitRoot}" diff --no-ext-diff --unified=0 --merge-base
+          "${RCC_TIDY_BASE}" -- "${TidyPath}"
+  RESULT_VARIABLE DiffResult
+  OUTPUT_FILE "${DiffFile}"
+  ERROR_VARIABLE DiffError
+)
+if(NOT DiffResult EQUAL 0)
+  message(FATAL_ERROR "cannot produce incremental clang-tidy diff: ${DiffError}")
+endif()
+
+# git diff does not include untracked source files. Add their ordinary Git diff form so
+# LLVM's unchanged clang-tidy-diff.py driver checks new translation units before staging.
+execute_process(
+  COMMAND "${RCC_TIDY_GIT}" -C "${GitRoot}" ls-files --others --exclude-standard -- "${TidyPath}"
+  RESULT_VARIABLE UntrackedResult
+  OUTPUT_VARIABLE UntrackedFiles
+  ERROR_VARIABLE UntrackedError
+  OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+if(NOT UntrackedResult EQUAL 0)
+  message(FATAL_ERROR "cannot list untracked clang-tidy files: ${UntrackedError}")
+endif()
+if(NOT UntrackedFiles STREQUAL "")
+  string(REPLACE "\n" ";" UntrackedFiles "${UntrackedFiles}")
+  foreach(UntrackedFile IN LISTS UntrackedFiles)
+    execute_process(
+      COMMAND "${RCC_TIDY_GIT}" -C "${GitRoot}" diff --no-index --no-ext-diff --unified=0 --
+              /dev/null "${UntrackedFile}"
+      RESULT_VARIABLE UntrackedDiffResult
+      OUTPUT_VARIABLE UntrackedDiff
+      ERROR_VARIABLE UntrackedDiffError
+    )
+    if(NOT UntrackedDiffResult EQUAL 0 AND NOT UntrackedDiffResult EQUAL 1)
+      message(FATAL_ERROR "cannot diff untracked file '${UntrackedFile}': ${UntrackedDiffError}")
+    endif()
+    file(APPEND "${DiffFile}" "${UntrackedDiff}")
+  endforeach()
+endif()
+
+execute_process(
+  COMMAND "${RCC_TIDY_DIFF}" -path "${RCC_TIDY_BINARY_DIR}" -p1 -quiet -j "${RCC_TIDY_JOBS}"
+  INPUT_FILE "${DiffFile}"
+  WORKING_DIRECTORY "${GitRoot}"
+  RESULT_VARIABLE TidyResult
+  OUTPUT_VARIABLE TidyOutput
+  ERROR_VARIABLE TidyError
+)
+set(TidyDiagnostics "${TidyOutput}\n${TidyError}")
+string(REGEX REPLACE "[0-9]+ warnings generated\\." "" TidyDiagnostics "${TidyDiagnostics}")
+string(STRIP "${TidyDiagnostics}" TidyDiagnostics)
+if(NOT TidyDiagnostics STREQUAL "")
+  message("${TidyDiagnostics}")
+endif()
+if(NOT TidyResult EQUAL 0 OR NOT TidyDiagnostics STREQUAL "")
+  message(FATAL_ERROR "incremental clang-tidy failed")
+endif()