CMake VS conan

I thought I would share my custom installer script for the latest GitHub versions of CMake, Ninja, and Meson.

The same thing probably applies if you use the FindGlut.cmake module which is documented here: https://cmake.org/cmake/help/latest/module/FindGLUT.html

building cmake - version 3.26.3 ==================================== Downloading https://github.com/kitware/cmake/archive/refs/tags/v3.26.3.tar.gz as cmake-3.26.3.tar.gz Download Completed File extracted: cmake-3.26.3.tar.gz $ ./configure --prefix=/root/ffmpeg-build-script/workspace --parallel=40 --enable-ccache -- -DCMAKE_USE_OPENSSL=OFF $ make -j 40

find_package(Python3 ...) will look for a file FindPython3.cmake shipped with CMake. I urge you to try to go over its contents to get an idea of what it does underneath.

The file FindSomePKG.cmake (module approach) is supposed to be written either by you (you write it manually and put in a cmake subdirectory in your git repo) or it's an official package file shipped along with CMake, e.g FindOpenSSL.cmake with documentation here.

sudo apt-get install build-essential libncurses5-dev gnutls-dev bison zlib1g-dev ccache libssl-dev # Get cmake # Downloaded under ~/ wget https://github.com/Kitware/CMake/releases/download/v3.25.2/cmake-3.25.2.tar.gz cd cmake-3.25.2 ~/cmake-3.25.2 $ ./bootstrap ~/cmake-3.25.2 $ make ~/cmake-3.25.2 $ sudo make install

Note that `assert`s are disabled if you define the macro `NDEBUG`, e.g. https://godbolt.org/z/hMWo8KM7q

CMake adds these flags to release builds: https://github.com/Kitware/CMake/blob/e1eacbe2c522a8bf9a82af...

Would be nice to have a non-macro solution for controlling behavior at configure time, but the `NDEBUG` macro is basically already your `DEBUG` constexpr.

It's open-source. It might get merged in!

FROM node:16 WORKDIR /cmake COPY cmake-3.25.0-rc4-linux-x86_64.sh ./ # OR # RUN apt update && apt install -y g++ wget bash # RUN wget https://github.com/Kitware/CMake/releases/download/v3.25.0-rc4/cmake-3.25.0-rc4-linux-x86_64.sh RUN ./cmake-3.25.0-rc4-linux-x86_64.sh --skip-license && rm cmake-3.25.0-rc4-linux-x86_64.sh ENV PATH="$PATH:/cmake/bin" WORKDIR /app RUN npm i [email protected] COPY package.json . COPY package-lock.json . RUN npm --verbose i COPY . . RUN npm --verbose run build

Silly question: What's the difference between C++20 modules and https://conan.io? (Google was vague, and ChatGPT, you know, sometimes makes things up so I rather ask fellow humans...)

Conan is a package manager for C/C++. See: https://conan.io/.

The way it works is that you can provide "recipes", which are Python scripts, that automate the process of collecting source code (usually from a remote Git repository, or a remote source tarball), patching it, making its dependencies and transitive dependencies available, building for specific platform and architecture (via any number of build systems), then packaging up and serving binaries. There's a lot of complexity involved.

Here are the two recipes I mentioned:

libcurl: https://github.com/conan-io/conan-center-index/blob/master/r...

OpenSSL v3: https://github.com/conan-io/conan-center-index/blob/master/r...

Now, for the sake of this thread I want to highlight three things here:

- Conan recipes are usually made by people unaffiliated with the libraries they're packaging;

- The recipes are fully Turing-complete, do a lot of work, have their own bugs - therefore they should really be treated as software comonents themselves, for the purpose of OSS clearing/supply chain verification, except as far as I know, nobody does it;

- The recipes can, and do, patch source code and build scripts. There's supporting infrastruture for this built into Conan, and of course one can also do it by brute-force search and replace. See e.g. ZLib recipe that does it both at the same time:

https://github.com/conan-io/conan-center-index/blob/7b0ac710... -- `_patch_sources` does both direct search-and-replace in source files, and applies the patches from https://github.com/conan-io/conan-center-index/tree/master/r....

Now, good luck keeping track of what's going on there.

There were various approaches recommended depending on our language and ecosystem. My classmates who developed using Node.js were recommended npm, and PyPI or poetry for Python. Since my program is written in C++, I was recommended to look into one of vcpkg or conan, but I ultimately did not use either package manager.

Hi u/instinkt900, Conan maintainer here. Thanks for your feedback! Please remember that we actively monitor and respond to our issue tracker on GitHub (https://github.com/conan-io/conan/issues/new/choose), we’d love to hear about your specific use cases or pain points, so that we can improve your experience and that of other users. The motivation behind most of the updates in Conan 2.0 was precisely feedback from the community, and to improve our ability to continue delivering features in the constantly changing C++ ecosystem. We can certainly do this at a quicker pace, with some exciting new features recently released and in the pipeline: package metadata, transparent backup of downloaded package sources, cache least-recently-used cleanup, etc. A lot of the big decisions that we took for Conan 2.0 were taken with consensus from expert users and contributors (https://conan.io/tribe) and https://github.com/conan-io/tribe. Some specific workflows may not have 1:1 replacements in Conan 2.0, and are likely to affect some of the “less travelled roads” of Conan 1.x, including some features that were always marked as experimental. We are happy to hear feedback so that we can best satisfy these use cases. Conan 2.0 also includes a more sophisticated API to cover cases where the built-in integrations may not satisfy users needs. For what it’s worth - we have also heard very positive feedback from users about how Conan 2.0 simplifies their workflows when compared to Conan 1.x. The C++ tooling ecosystem is fragmented and moves at different speeds, including our users. So it’s always a fine balancing act, but we don’t want to leave anyone behind! An example is Conan Center - over 90% (~1200) of all recipes have been migrated to support Conan 2.0, while still maintaining compatibility with Conan 1.x, precisely to avoid breaking users that are still on Conan 1.x.

Solution: don't use git submodules - use a package manager like Conan or vcpkg.

The closest thing we have at the moment is conan[1]. It’s a cross platform package manager that attempts to implement “toolchains”, whereby different build systems can be integrated[2]. This is a big problem with package management in C/C++, there’s no single, standardised build system that most projects use. There isn’t even a standardised compiler! So when hosting your own packages using Conan, often you need to make sure you build your application for three different compilers, for three different platforms. Sometimes (for modern MacOS) also for two different architectures each.

If you control the compiler AND build system you can get away with just one package for most cases. This true for Microsoft’s C/C++ package manager, NuGet[3]

Historically, the convention has been to use the package manager of the underlying system to install packages, as there are so many different build configurations to worry about when packaging the libraries. The other advantage of using the system package manager is that dependencies (shared libraries) that are common can be shared between many applications, saving space.

[1] https://conan.io/

Anyway, the problems are today starting to get fewer, as more an more adopt standard cross-platform portable build systems, a.k.a. CMake and package managers such as vcpkg or Conan. Together this will take care of building, installing, linking and using the entire dependency tree.

Simply use a package manager: Crypto++ is available on both vcpkg and Conan.

If you want a specific version or provide a more integrated workflow that is easier to use across platforms and among many developers, use a package manager like vcpkg or Conan.

I do however always recommend using a package manager: vcpkg or Conan to install and integrate third party libraries (together with CMake). This normally solves all the typical problems with dependencies.