std_call_scan

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A tiny Clang LibTooling utility that parses C++ source files into an AST, finds every function/method/constructor call, and reports whether the callee is noexcept.
The tool prints a CSV to stdout, which you can redirect to a file.

Columns: file,line,col,kind,qualified-name,noexcept,signature,callee-source

Features

• Walks calls to free functions, member methods, constructors, and overloaded operators
• Evaluates noexcept via FunctionProtoType::isNothrow()
• Optional filters:
  • --only-std — keep only calls whose qualified name starts with std::
  • --name-prefix <prefix> — keep only calls with a given qualified-name prefix (e.g., std::filesystem::)
  • --csv-header — print a header row
• (By default) system headers are excluded; you can tweak the matcher in the source if you need them

Requirements

• CMake ≥ 3.20
• A working LLVM/Clang development environment (headers + libs)
  • Rocky/Red Hat example:

    sudo dnf install clang clang-devel llvm llvm-devel libedit-devel libffi-devel libxml2-devel zlib-devel libzstd-devel

  • Ubuntu example:

    sudo apt install clang libclang-dev llvm-dev libedit-dev libffi-dev libxml2-dev zlib1g-dev libzstd-dev

Build

Linux

# from the project root
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j

This will produce an executable (e.g., build/std_call_scan).

Windows

• (1) Download LLVM and Clang from the following site:

  • https://github.com/vovkos/llvm-package-windows

  • Files (install the latest version. amd64: 64-bit, msvc17: VS2022)

    • llvm-x.x.x-windows-amd64-msvc17-XXX.7z
    • clang-x.x.x-windows-amd64-msvc17-XXX.7z

• (2) Extract them to the same path.

  • Assume extraction to C:\llvm-package.

• (3) Set environment variables as follows:

  • PATH : C:\llvm-package\bin
  • LLVM_DIR : C:\llvm-package\lib\cmake\llvm
  • Clang_DIR : C:\llvm-package\lib\cmake\clang

• (4) Run cmake in the Visual Studio command prompt (make sure ninja is pre-installed):

    mkdir build && cd build
  
    cmake -G Ninja ^
      -DCMAKE_BUILD_TYPE=Release ^
      -DCMAKE_C_COMPILER=clang-cl ^
      -DCMAKE_CXX_COMPILER=clang-cl ^
      -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreadedDLL ^
      -DLLVM_DIR="C:/llvm-package/lib/cmake/llvm" ^
      -DClang_DIR="C:/llvm-package/lib/cmake/clang" ^
      ..

  • One-line command:

    cmake -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=clang-cl -DCMAKE_CXX_COMPILER=clang-cl -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreadedDLL -DLLVM_DIR="C:/llvm-package/lib/cmake/llvm" -DClang_DIR="C:/llvm-package/lib/cmake/clang" ..

• (5) Execute build:

  ninja -v

Usage

Linux

# Edit variable in build_scan_env.sh, before execute script
./sh/build_scan_env.sh

CSV Schema

• file: source file path containing the call site
• line, col: 1‑based position of the call site
• kind: call (free function), method (member), construct (constructor), opcall (operator call), etc.
• qualified-name: fully qualified callee name (e.g., std::filesystem::create_directory)
• noexcept: 1 if the callee is nothrow (per Clang's type system), 0 otherwise
• signature: a pretty function signature
• callee-source: a short source snippet of the call expression

⚠️ Notes & Limitations

• Results can vary by standard library implementation (libstdc++/libc++/MSVC STL) and template instantiation.
• System headers are excluded by default; edit the matcher in scanner.cpp if you want to include them.
• The noexcept result reflects the callee type as seen by Clang; it does not run your code.

Examples

# Current project file as a smoke test
./build/std_call_scan --csv-header scanner.cpp

License

See LICENSE.

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