cpplint

Warnings

• breaking Python 2 and Python 3.7 are no longer supported. Users must upgrade to Python 3.8 or newer.
  Fix: Upgrade your Python environment to 3.8 or later. The current minimum requirement is Python 3.9.
• breaking The `setup.py lint` subcommand was removed. Direct invocation of `cpplint` commands is now required.
  Fix: Remove any reliance on `python setup.py lint`. Instead, run `cpplint` directly from the command line with appropriate arguments.
• gotcha As of version 2.0.2, non-const references are no longer erred on by default. This changes previous behavior where they might have been flagged as style violations.
  Fix: If your project requires strict checking for non-const references, you may need to explicitly enable a corresponding filter if one becomes available, or consider this change in your style enforcement.
• gotcha cpplint strictly enforces Google's C++ Style Guide, which may not align with all project or team-specific style preferences.
  Fix: Customize linting rules using the `--filter` command-line option (e.g., `cpplint --filter=-whitespace/line_length`) or by creating a `CPPLINT.cfg` file in your project directory.
• gotcha cpplint is rules-based and uses heuristics, which can lead to occasional false positives or negatives. It is not a substitute for a comprehensive code review.
  Fix: Use `// NOLINT(category)` comments on specific lines to suppress known false positives for particular categories. For blocks of code, use `// NOLINTBEGIN(category)` and `// NOLINTEND`.

Install

• pip install cpplint Install cpplint

Quickstart

The primary way to use cpplint is as a command-line tool. This example creates a C++ file, runs `cpplint` on it with a common filter to ignore line length, and prints the output. Note that `cpplint` writes its findings to stderr. Configuration can also be managed via a `CPPLINT.cfg` file in the project directory.

# Create a dummy C++ file for linting
with open("main.cpp", "w") as f:
    f.write("""#include <iostream>\n\nint main() {\n  std::cout << "Hello, World!" << std::endl;  // Missing space before '!'\n  return 0;\n}\n""")

# Run cpplint on the file
# This is primarily a command-line tool, so we use subprocess
import subprocess
import os

try:
    # cpplint usually exits with non-zero on errors, so capture output
    # Using --filter to ignore common line_length warnings for this example
    result = subprocess.run(
        ["cpplint", "--filter=-whitespace/line_length", "main.cpp"],
        capture_output=True,
        text=True,
        check=False  # Don't raise CalledProcessError for non-zero exit codes
    )
    print("cpplint output (stdout):")
    print(result.stdout)
    print("\ncpplint output (stderr):")
    print(result.stderr)
    if result.returncode != 0:
        print("\nLinting found issues. Return code:", result.returncode)
    else:
        print("\nNo linting issues found (or filtered out).")
except FileNotFoundError:
    print("Error: cpplint command not found. Ensure it's installed and in your PATH.")
finally:
    # Clean up the dummy file
    if os.path.exists("main.cpp"):
        os.remove("main.cpp")