clang-build 0.0.1.dev89

Easy build tool for C++ projects focussing on simplicity

Clang-build
===========

Linux and OSX test: |Test status| Windows test: |Test status| Code quality: |codacy|

**Motivation:**

- Meta build systems are inherently the wrong way to go, either the build system or the compiler should be platform-agnostic (ideally both).
- Trying to cover all use-cases is the wrong way to go - there is no need to let people do it the wrong way
- CMake is cumbersome, unnecessarily generic and verbose and people should not need a programming/scripting language whose only purpose is to build C++
- With Clang, finally a properly cross-platform compiler exists

**Goals:**

- One compiler (Clang), one build system (written in Python)
- Simple projects should be simple to build
- Build process for reasonable project structures should still be easy
- Adding third-party dependencies should be manageable

**Related resources:**

- `CppCon 2017: Isabella Muerte "There Will Be Build Systems: I
Configure Your
Milkshake" <https://www.youtube.com/watch?v=7THzO-D0ta4>`__
- https://medium.com/@corentin.jabot/accio-dependency-manager-b1846e1caf76


Usage
=====

In order to run ``clang-build``, you only need Clang and Python3.
Install via ``pip install clang-build`` (add the ``--user`` flag if you don't have admin rights).

Running ``clang-build`` will try to build the current directory.
The command-line options include

- ``-d path/to/dir`` to build a different directory
- ``-p`` to show a progress bar
- ``-V`` to print some additional info
- ``--debug`` to print the called clang commands

The given directory will be searched for a ``clang-build.toml`` file, which you can use to configure
your build targets, if necessary. However, if you only want to build an executable, you will
likely not even need a build file.

clang-build tries to use sane defaults, designed to make most projects very easy to configure
and even complex projects far easier than with common build or meta-build systems.


General Ideas
=============
*Note: not all of these are implemented, yet.*

What should be trivial
----------------------

This would be things that require only the invocation of ``clang-build``
and no build file.

- build a hello world program (i.e anything with single main and
without non-std dependencies)
- build a reasonable MWE with local dependencies (potentially folder
structure with e.g. ``src``, ``include/MWE`` and
``include/thirdparty``)
- include stdlib
- include anything that can be found by sane default search
- using command line arguments:
- specify root/source folder
- set build type from (last used should be cached/remembered)
- set build verbosity

Sane defaults and default behaviour:

- platform-independence
- build into a "build/" directory, not into toplevel
- for multiple targets build into "build/target"
- default search paths for different platforms, including also e.g.
"./include", "./lib", "./build/lib", "/usr/local/...", ...

What should be easy
-------------------

This would be things that only require a minimal TOML project file

- add dependency / external project from source folder or remote (e.g.
github)
- header-only should be trivial
- for a regular (not too complicated) library it should be easy to
write a build config
- create a library from one subfolder, an executable from another and
link them
- setting target-specific (note: defaults should be sane!)
- source file extensions
- source directories
- compile and link flags
- optional version
- dependencies (which may include non-targets, e.g. configuration
steps)
- properties (required c++ version, definitions/\ ``#define``\ s, ...)
- access to flag "lists" such as flags for
- coverage
- cuda
- openmp
- set target-specific flags, include folders, etc. which should not be
propagated to dependency parents as "private"

What should be possible
-----------------------

Steps that would involve more effort from the user, including possibly
some python code

- a Target configuration step before building (e.g. for more involved
version numbering)
- through the configuration step, inclusion of e.g. CMake-project
should be possible
- packaging: any target may be packaged, meaning it's dependencies are
handled and if built, binaries may be bundled
- external package dependencies
- binaries on a server
- source on a server (fallback from binaries)
- binaries on disk, try to determine version from path and file names
- source on disk, try to determine version from path and file names


Project File By Example
=======================

A single target
---------------

Note:

- by default, the root and <targetname> folders, as well as "include" and "src" subdirectories will be searched for ".hpp", ".hxx", ".h" and ".cpp", ".cxx" and ".c" files
- a target without ``target_type``, but with source files will be an executable
- ``output_name`` should not contain pre- or suffixes such as lib, .exe, .so, as they are added automatically
- if we don't care about the output name, in this case we could skip the project file entirely

.. code:: toml

# Top-level brackets indicate a target
[hello]
output_name = "runHello"

Two targets with linking
------------------------

.. code:: toml

# Build a library
[mylib]
target_type = "shared library"

# Build an executable and link the library
[myexe]
output_name = "runExe"
target_type = "executable"
dependencies = ["mylib"]
[myexe.flags]
link = ["-DMYEXE_SOME_DEFINE"]

Adding external dependencies
----------------------------

Note:

- external projects will be copied/downloaded into "build/targetname/external_sources"
- you can specify a subdirectory, if the thirdparty code has an unusual structure
- further granularity is given by ``include_directories`` and ``source_directories``

.. code:: toml

[mylib]
external = true
url = "https://github.com/trick-17/mylib"
version = 1.1 # will try to git checkout [v]1.1[.*]
directory = "sources" # will point to "build/mylib/external_sources/sources"
include_directories = ["mylib/include"] # will point to "build/mylib/external_sources/sources/mylib"
source_directories = ["mylib/src"] # will point to "build/mylib/external_sources/sources/mylib"
# Maybe we need to deactivate annoying warnings coming from the library
[mylib.flags]
compile = ["-Wno-deprecated-declarations", "-Wno-self-assign"]

# Build an executable and link the library
[myexe]
dependencies = ["mylib"]


.. |Test status| image:: https://travis-ci.org/Trick-17/clang-build.svg?branch=master
:target: https://travis-ci.org/Trick-17/clang-build
.. |Test status| image:: https://ci.appveyor.com/api/projects/status/57qv53r4totihxrj/branch/master?svg=true
:target: https://ci.appveyor.com/project/GPMueller/clang-build
.. |codacy| image:: https://api.codacy.com/project/badge/Grade/2bcc761ed19844c48f92f7779e2cf67f
:target: https://www.codacy.com/app/Trick-17/clang-build?utm_source=github.com&amp;utm_medium=referral&amp;utm_content=Trick-17/clang-build&amp;utm_campaign=Badge_Grade