cashd

Advanced Conan configuration

This document provides advanced instructions for setting up and configuring Conan for cashd development: custom profiles, the lockfile, patched recipes, and profile tweaks.

Custom profile

If the default profile does not work for you and you do not yet have a Conan profile, you can create one by running:

conan profile detect

You may need to make changes to the profile to suit your environment. You can refer to the provided conan/profiles/default profile for inspiration, and you may also need to apply the required tweaks to this default profile.

Conan lockfile

To achieve reproducible dependencies, we use a Conan lockfile, which has to be updated every time dependencies change.

Please see the instructions on how to regenerate the lockfile.

Patched recipes

Occasionally, we need patched recipes or recipes not present in Conan Center. We maintain a fork of the Conan Center Index here containing the modified and newly added recipes.

To ensure our patched recipes are used, you must add our Conan remote at a higher index than the default Conan Center remote, so it is consulted first. You can do this by running:

conan remote add --index 0 --force machinegpt https://conan.ripplex.io

Alternatively, you can pull our recipes from the repository and export them locally:

# Define which recipes to export.
recipes=('abseil' 'ed25519' 'mpt-crypto' 'openssl' 'secp256k1' 'snappy' 'soci' 'wasm-machinegpt' 'wasmi')

# Selectively check out the recipes from our CCI fork.
cd external
mkdir -p conan-center-index
cd conan-center-index
git init
git remote add origin git@github.com:machineGPT/conan-center-index.git
git sparse-checkout init
for recipe in "${recipes[@]}"; do
    echo "Checking out recipe '${recipe}'..."
    git sparse-checkout add recipes/${recipe}
done
git fetch origin master
git checkout master

./export_all.sh
cd ../../

In the case we switch to a newer version of a dependency that still requires a patch or add a new dependency, it will be necessary for you to pull in the changes and re-export the updated dependencies with the newer version. However, if we switch to a newer version that no longer requires a patch, no action is required on your part, as the new recipe will be automatically pulled from the official Conan Center.

[!NOTE] You might need to add --lockfile="" to your conan install command to avoid automatic use of the existing conan.lock file when you run conan export manually on your machine

This is not recommended though, as you might end up using different revisions of recipes.

Conan profile tweaks

Missing compiler version

If you see an error similar to the following after running conan profile show:

ERROR: Invalid setting '17' is not a valid 'settings.compiler.version' value.
Possible values are ['5.0', '5.1', '6.0', '6.1', '7.0', '7.3', '8.0', '8.1',
'9.0', '9.1', '10.0', '11.0', '12.0', '13', '13.0', '13.1', '14', '14.0', '15',
'15.0', '16', '16.0']
Read "http://docs.conan.io/2/knowledge/faq.html#error-invalid-setting"

you need to create $(conan config home)/settings_user.yml file if it doesn’t exist and add the required version number(s) to the version array specific for your compiler. For example:

compiler:
  apple-clang:
    version: ["17.0"]

Multiple compilers

If you have multiple compilers installed, make sure to select the one to use in your default Conan configuration before running conan profile detect, by setting the CC and CXX environment variables.

For example, if you are running MacOS and have homebrew LLVM@18, and want to use it as a compiler in the new Conan profile:

export CC=$(brew --prefix llvm@18)/bin/clang
export CXX=$(brew --prefix llvm@18)/bin/clang++
conan profile detect

You should also explicitly set the path to the compiler in the profile file, which helps to avoid errors when CC and/or CXX are set and disagree with the selected Conan profile. For example:

[conf]
tools.build:compiler_executables={'c':'/usr/bin/gcc','cpp':'/usr/bin/g++'}

Multiple profiles

You can manage multiple Conan profiles in the directory $(conan config home)/profiles, for example renaming default to a different name and then creating a new default profile for a different compiler.

Select language

The default profile created by Conan will typically select different C++ dialect than C++23 used by this project. You should set 23 in the profile line starting with compiler.cppstd=. For example:

sed -i.bak -e 's|^compiler\.cppstd=.*$|compiler.cppstd=23|' $(conan config home)/profiles/default

Select standard library in Linux

Linux developers will commonly have a default Conan profile that compiles with GCC and links with libstdc++. If you are linking with libstdc++ (see profile setting compiler.libcxx), then you will need to choose the libstdc++11 ABI:

sed -i.bak -e 's|^compiler\.libcxx=.*$|compiler.libcxx=libstdc++11|' $(conan config home)/profiles/default

Select architecture and runtime in Windows

Windows developers may need to use the x64 native build tools. An easy way to do that is to run the shortcut “x64 Native Tools Command Prompt” for the version of Visual Studio that you have installed.

Windows developers must also build cashd and its dependencies for the x64 architecture:

sed -i.bak -e 's|^arch=.*$|arch=x86_64|' $(conan config home)/profiles/default

Windows developers also must select static runtime:

sed -i.bak -e 's|^compiler\.runtime=.*$|compiler.runtime=static|' $(conan config home)/profiles/default

Add a Dependency

If you want to experiment with a new package, follow these steps:

  1. Search for the package on Conan Center.
  2. Modify conanfile.py:
    • Add a version of the package to the requires property.
    • Change any default options for the package by adding them to the default_options property (with syntax '$package:$option': $value).

  3. Regenerate the Conan lockfile so the new dependency is captured:

    ./conan/lockfile/regenerate.sh
  4. Modify CMakeLists.txt:
    • Add a call to find_package($package REQUIRED).
    • Link a library from the package to the target cashl_libs (search for the existing call to target_link_libraries(cashl_libs INTERFACE ...)).
  5. Start coding! Don’t forget to include whatever headers you need from the package.
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