Remove dependency on scan-build wrapper script for Clang analysis builds.

build/toolchain/clang_static_analyzer_wrapper.py

Index: build/toolchain/clang_static_analyzer_wrapper.py
diff --git a/build/toolchain/clang_static_analyzer_wrapper.py b/build/toolchain/clang_static_analyzer_wrapper.py
index cc13888f3c28ccda32266a3f7ca9e5996602cd5e..b3b9ce7475046d4c65ed9877ceead0edc34b8811 100755
--- a/build/toolchain/clang_static_analyzer_wrapper.py
+++ b/build/toolchain/clang_static_analyzer_wrapper.py
@@ -1,61 +1,72 @@
 #!/usr/bin/env python
-# Copyright 2016 The Chromium Authors. All rights reserved.
+# Copyright 2017 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""Invokes the Clang static analysis command using arguments provided on the
-command line.
+"""Adds an analysis build step to invocations of the Clang C/C++ compiler.
+
+Usage: clang_static_analyzer_wrapper.py <compiler> [args...]
 """
 
 import argparse
 import fnmatch
+import itertools
 import os
-import shutil
 import sys
-import tempfile
-
 import wrapper_utils
 
+# Flags used to enable analysis for Clang invocations.
+analyzer_enable_flags = [
+    '--analyze',
+    '-fdiagnostics-show-option'
+]
+
+# Clang flags specifying which checkers should be run.
+# The full list of checkers can be found at
+# https://clang-analyzer.llvm.org/available_checks.html.
+analyzer_option_flags = [
+      '-analyzer-output=text',
+      '-analyzer-opt-analyze-nested-blocks',
+      '-analyzer-eagerly-assume',
+      '-analyzer-checker=core',
+      '-analyzer-checker=unix',
+      '-analyzer-checker=deadcode',
+      '-analyzer-checker=cplusplus',

[Nico, 2017/02/06 22:19:12]

Why this list and not a different one?


Before, upstream got to pick what they thought was a good default set.

[Kevin M, 2017/02/08 19:41:33]

This is the default list that's set by scan-build and scan-build-py, minus a few
security checks for certain unsafe low level functions that aren't applicable to
Chromium's codebase.

Maintaining our own list makes sense if we want to add support for new checker
plugins in the future.

+]
+
 
 def main():
-  parser = argparse.ArgumentParser(description=__doc__)
-  parser.add_argument('--clang-cc-path',
-                      help='Path to the clang compiler.',
-                      metavar='PATH')
-  parser.add_argument('--clang-cxx-path',
-                      help='Path to the clang++ compiler',
-                      metavar='PATH')
-  parser.add_argument('--analyzer',
-                      help='Path to the language-specific Clang analysis tool.',
-                      required=True,
-                      metavar='PATH')
-  args, compile_args = parser.parse_known_args()
-
-  # Check that only one of --clang-cc-path or --clang-cxx-path are set.
-  assert ((args.clang_cc_path != None) != (args.clang_cxx_path != None))
-
-  is_cxx = args.clang_cxx_path != None
-  env = os.environ
-  env['CCC_ANALYZER_FORCE_ANALYZE_DEBUG_CODE'] = '0'
-  env['CCC_ANALYZER_OUTPUT_FORMAT'] = 'text'
-  clang_path = args.clang_cxx_path or args.clang_cc_path
-  if is_cxx:
-    env['CCC_CXX'] = clang_path
-    env['CLANG_CXX'] = clang_path
-  else:
-    env['CCC_CC'] = clang_path
-    env['CLANG'] = clang_path
-
-  # TODO(kmarshall): Place the summarized output in a useful directory.
-  temp_dir = tempfile.mkdtemp()
-  try:
-    env['CCC_ANALYZER_HTML'] = temp_dir
-    returncode, stderr = wrapper_utils.CaptureCommandStderr(
-        wrapper_utils.CommandToRun([args.analyzer] + compile_args), env)
-    sys.stderr.write(stderr)
-    return returncode
-  finally:
-    shutil.rmtree(temp_dir)
-
-if __name__ == "__main__":
+  args = sys.argv[1:]
+  assert(args)
+
+  # Interleave 'analyzer_option_flags' flags w/'-Xanalyzer' so that Clang
+  # passes them to the analysis tool.
+  # e.g. ['-analyzer-foo', '-analyzer-bar'] => ['-Xanalyzer', '-analyzer-foo',
+  #                                             '-Xanalyzer', '-analyzer-bar']
+  interleaved_analyzer_flags = reduce(
+      lambda x, y: x + ['-Xanalyzer', y], analyzer_option_flags, [])
+
+  returncode, stderr = wrapper_utils.CaptureCommandStderr(
+      wrapper_utils.CommandToRun(args + analyzer_enable_flags +
+                                 interleaved_analyzer_flags))
+
+  # TODO(kmarshall): Post-process the analysis output and remove any eror text
+  # originating from excluded files. (crbug.com/688616)
+  sys.stderr.write(stderr)
+
+  if returncode != 0:
+    # The analyzer is a little buggy and can crash midway through an AST parse
+    # on otherwise buildable code.
+    # If it fails, we should recover gracefully and continue with the build.

[Nico, 2017/02/06 22:19:12]

Huh? Shouldn't we report the crash upstream instead?

[Kevin M, 2017/02/08 19:41:33]

Upstream yes, but as the crashes aren't actionable for users - they originate
from the same Clang AST traversal crash - it would be better to track this as an
LLVM bug and hide the noise from Chromium devs.

+    sys.stderr.write(
+        'WARNING: Clang analyzer exited with return code %d.\n' % (returncode))
+
+  # Build the object file.
+  returncode, stderr = wrapper_utils.CaptureCommandStderr(
+    wrapper_utils.CommandToRun(args))
+
+  sys.stderr.write(stderr)
+  return returncode
+
+if __name__ == '__main__':
   sys.exit(main())