CXX Modules Builder

Compiles projects using C++20 modules and header units.

Only supports master branches of clang and ninja, with patches

This is still very much a POC. It may eat your homework.

Examples

You can find an example configuration for cxx-modules-sandbox in examples/cxx-modules-sandbox.build.yaml. To try it:

# Apply patches and compile clang and ninja
export PATH="path/to/patched/clang/bin:path/to/patched/ninja/bin:$PATH"
git clone https://github.com/RedBeard0531/cxx_modules_builder
git clone https://github.com/mathstuf/cxx-modules-sandbox

pip3 install --user -r cxx_modules_builder/requirements.txt # or install pyyaml some other way
cd cxx-modules-sandbox
cp ../cxx_modules_builder/examples/cxx-modules-sandbox.build.yml ./build.yml
../cxx_modules_builder/modules_builder.py
ninja

Configuration

modules_builder.py currently takes no arguments and is completely configured by a build.yml file in the working directory, which should generally be the root of your project. A basic build.yaml contains the following:

# Where to store build output.
build_root: build

# List header units.
header_units:
  - path/to/header.h
  # As an optional convenience, you can use nesting to avoid duplicating
  # directories in all file lists.
  - src:
    - include:
      - header1.h
      - header2.h
      - details:
        - secrets.h
  # Absolute paths are also accepted.
  - /usr/include/c++/v1:
    - algorithm
    - string
    - vector

# Libraries (currently just treated as a named collection of files,
# so no .a or .so will be built)
- libs:
  reader: # Name of lib
    libdeps: [] # Other libs this depends on 
    sources: # List of source files
      - src/reader.cpp
  worker:
    libdeps:
      - reader
    syslibdeps: # Optional. Passed with -lNAME when linking
      - m
      - rt
    sources:
      - src/worker:
        - worker.cpp
        - utils.cpp

# Binaries
- bins:
  frobnicator:
    libdeps:
      # transitive libdeps and syslibdeps are pulled in automatically
      - worker
    syslibdeps:
      - z
    sources:
      - src/frobnicator.cpp

TODOs

• Features
  • Support basic settings on command line (compiler, build_root, etc)
  • Support configuring the compiler flags without editing header.ninja
  • Support choosing names other than build.ninja to keep multiple configs around
  • Allow including build.yml files in subdirectories
  • Globs in file lists
• Implementation
  • Use separate rules for compiling from .cpp -> .o vs .pcm -> .o
  • Use a better scanner
  • Look into gcc support
• Documentation
  • More examples
• External
  • File issue with ninja so we won't need patch anymore (need minimal repro first)
  • ninja can't handle multiple outputs and deps = gcc
  • Keep an eye on clang bugs to remove patches and workarounds
    • deduction guides + header units = 😢
    • import + clang -E = 💀