tidy-llvm

[CSears]

Summary

Using clang-tidy on LLVM itself (the proverbial eating your own dogfood) is a little different from using a clang-tidy installation on another source tree. clang-tidy needs to know where to find include files within the LLVM source tree itself.

This is a Python script, tidy-llvm, which finds the root of the llvm tree, verifies LLVM build requirements (LLVM_ENABLE_PROJECTS:STRING=clang;clang-tools-extra and CMAKE_EXPORT_COMPILE_COMMANDS:UNINITIALIZED=On), constructs llvm and current directory include paths, concatenates up an argument list and then runs clang-tidy on the .h and .cpp files on the command line.

tidy-llvm XXAsmPrinter.cpp generates a clang-tidy command line that looks like:

clang-tidy -checks="llvm-*" -p .../build XXAsmPrinter.cpp -- -I.
  -IAsmParser -IGISel -IDisassembler -ITargetInfo -IXX -IMCTargetDesc
  -I.../libcxx/include -I.../build/include -I.../llvm/include

I'm pretty sure that the llvm include directories (-I.../libcxx/include -I.../build/include -I.../llvm/include others?) have to be enumerated rather than simply inheriting where clang-tidy thinks they are in the installation. Unless I manually specified them, clang-tidy wasn't finding them.

I think someone more expert in the build machinery could improve it greatly. For example, it currently gets a strange error about __config_site (which doesn't prevent the rest of the clang-tidy checking):

Error while processing path to XXAsmPrinter.cpp.
path/libcxx/include/__config:13:10: error: '__config_site' file not found [clang-diagnostic-error]
#include <__config_site>

config_site is indeed not in my build tree. There is a file libcxx/include/config_site.in but that's it. Again, someone more knowledgable in the build machinery might understand why this is the case.

clang-tidy still interprets its .clang_tidy file wherever it finds it. It's better to leave most of the -checks there. The tidy-llvm Python script itself is currently set to -checks=\"llvm-*\". I set modernize in the .clang_tidy file for my backend. I can imagine having a .clang-tidy file at the root of the llvm tree.

Adding support for run-clang-tidy would be nice but for tidying individual files it really won't matter.

[lebedev.ri]

Just use compilation database?
https://github.com/llvm-mirror/clang-tools-extra/blob/1c8cadde7ea4ca20a449edcffe10d23b612fe5d6/clang-tidy/tool/run-clang-tidy.py#L100

[beanz]

Sorry I’m a bit late here. If you want to use clang-tidy on a CMake built project (like LLVM) you can use CMake’s built-in support for clang-tidy:

https://cmake.org/cmake/help/latest/variable/CMAKE_LANG_CLANG_TIDY.html

This will run clang-tidy during the project build with each compile invocation.

[lebedev.ri]

This review may be stuck/dead, consider abandoning if no longer relevant.
Removing myself as reviewer in attempt to clean dashboard.

clang-tools-extra/clang-tidy/tool/tidy-llvm.py

+#!/usr/bin/env python
+#
+#===- tidy-llvm  --------------------------------------------*- python -*--===#
+#
+# Part of the LLVM Project, 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
+#
+#===-----------------------------------------------------------------------===#
+
+
+"""
+tidy-llvm
+==========================
+
+Runs clang-tidy over named .cpp and .h files.
+tidy-llvm must be run from inside an LLVM source tree.
+But otherwise, it finds the root of the llvm tree, verifies build requirements,
+constructs include paths, concatenates an argument list and then runs clang-tidy.
+clang-tidy will in turn examine any .clang-tidy in the path
+"""
+
+import os
+import sys
+
+def fail(s):
+  print(s)
+  sys.exit(1)
+
+def file_exists(name):
+  if not os.path.isfile(name):
+    fail('Cannot find ' + name)
+  return name
+
+def dir_exists(name):
+  if not os.path.isdir(name):
+    fail('Cannot find ' + name)
+  return name
+
+def find_llvm_root():
+  result = './'
+  while not os.path.isdir(os.path.join(result, "build")):
+    if os.path.realpath(result) == '/':
+      fail('Error: could not find llvm root.')
+    result += '../'
+  return os.path.realpath(result)
+
+# LLVM_ENABLE_PROJECTS:STRING=clang;clang-tools-extra
+# CMAKE_EXPORT_COMPILE_COMMANDS:UNINITIALIZED=On
+
+def verify_config(root):
+  found = 0
+  for line in open(file_exists(os.path.join(root, "build/CMakeCache.txt")), 'r'):
+    if "LLVM_ENABLE_PROJECTS:STRING=" in line:
+      if "clang;clang-tools-extra" not in line:
+        fail('Build needs clang;clang-tools-extra')
+      found = 1
+      break
+  if not found:
+    fail('Build needs clang;clang-tools-extra')
+  for line in open(file_exists(os.path.join(root, "build/CMakeCache.txt")), 'r'):
+    if "CMAKE_EXPORT_COMPILE_COMMANDS:UNINITIALIZED=On" in line:
+      return
+  fail('Build needs CMAKE_EXPORT_COMPILE_COMMANDS:UNINITIALIZED=On')
+
+def construct_llvm_include_paths(root):
+  libcxx = dir_exists(os.path.join(root, "libcxx/include"))
+  build_include = dir_exists(os.path.join(root, "build/include"))
+  llvm_include = dir_exists(os.path.join(root, "llvm/include"))
+  return "-I" + libcxx + " -I" + build_include + " -I" + llvm_include
+
+def construct_current_include_paths():
+  paths = ""
+  for e in os.listdir():
+    if os.path.isdir(e):
+      paths += " -I" + e
+  return paths
+
+def process_args(root, cmd_args):
+  for name in cmd_args:
+    if not name.endswith(".h") and not name.endswith(".cpp"):
+      fail(name + " does not end with .h or .cpp")
+    file_exists(name)
+  return " ".join(str(f) for f in cmd_args)
+
+def main():
+  root = find_llvm_root()
+  verify_config(root)
+  llvm_include_paths = construct_llvm_include_paths(root)
+  current_include_paths = construct_current_include_paths()
+  if len(sys.argv) == 1:
+    fail("tidy-llvm: [.cpp and .h files]")
+  args = process_args(root, sys.argv[1:])
+  cmd = ("clang-tidy -checks=\"llvm-*\" -p "
+  + os.path.join(root, "build") + " " + args + " -- -I."
+  + current_include_paths + " " + llvm_include_paths)
+  os.system(cmd)
+
+if __name__ == '__main__':
+  main()