Lots of fixes and minor improvements landed in the last 1.14 Conan release. Here you have an overview of them!

Chose the revision mode for your recipes

Coming in the previous 1.14 release, we introduced revisions as the way to implicitly version the changes done in a recipe without bumping the actual reference version. That is something implemented now as part of the Conan model, which means that the latest revision that exists in a remote is the one that is automatically installed (unless otherwise stated).

Take a look at the revisions section in the documentation to read more about it.

The revisions feature is one of the key steps towards reproducibility, this means that the revisions are computed as a unique ID known as the “recipe revision” and “package revision”.

The new feature coming with this release is the ability to chose the revision mode for each recipe. You either use a hash of the contents of the recipe (by default) as the recipe revision, or the commit for the SCM detected: git or SVN .

from conans import ConanFile class MyRecipe(ConanFile): name = "library" version = "1.0.3" revision_mode = "scm"

Take into account that some CVS systems, like Git, has a unique commit for all the repository. So, if you have several recipes in the same repo you probably don’t want to create a new recipe revision if you only commit changes for one of the recipes, but a new revision only for the recipe that has been modified. In that case, you should use the the default mode revision_mode = "hash" . The revision will be a hash of the recipe contents (beware of EOL between different systems).

Artifactory supports revisions now!

Released right before Conan, the new 6.9 version of Artifactory comes with full support for revisions.

All new Artifactory versions will be using revisions by default. This means that packages will be stored in the Conan repositories with a new layout: <user>/<name>/<version>/<channel>/<recipe_revision>/<package_id>/package_revision> .

Conan clients < 1.13 will still be working and a 0 recipe and package revision will be created in the repo to keep compatibility.

Bear in mind that the revision feature is opt-in in the client and you would have to activate it in your configuration with conan config set general.revisions_enabled=True or set the envrionment variable CONAN_REVISIONS_ENABLED=1 .

You can start using revisions with Artifactory Community Edition for C++.

New cmake_find_package_multi generator

Continuing with the list of new CMake generators for transparent integration, we introduce the cmake_find_package_multi generator to achieve multi-configuration of packages in Release/Debug modes.

Let’s try to make the getting started example with this new generator:

$ git clone git@github.com:conan-io/examples.git $ cd examples/libraries/poco/md5 $ ls CMakeLists.txt README.md build.bat build.sh* conanfile.txt md5.cpp

The CMakeLists.txt file will be changed to the following one:

cmake_minimum_required(VERSION 3.0) project(MD5Encrypter) set(CMAKE_PREFIX_PATH ${CMAKE_BINARY_DIR}) set(CMAKE_MODULE_PATH ${CMAKE_BINARY_DIR}) find_package(Poco) add_executable(md5 md5.cpp) target_link_libraries(md5 Poco::Poco)

And let’s use the new cmake_find_package_multi in the conanfile.txt too:

[requires] Poco/1.9.0@pocoproject/stable [generators] cmake_find_package_multi

Now we can install both Release and Debug packages and build with CMake as usual:

$ mkdir build && cd build $ conan install .. -s build_type=Debug $ conan install .. -s build_type=Release $ cmake .. -G "Visual Studio 15 2017 Win32" $ cmake --build . --config Debug .\Debug\md5.exe c3fcd3d76192e4007dfb496cca67e13b $ cmake --build . --config Release .\Release\md5.exe c3fcd3d76192e4007dfb496cca67e13b

Learn more in the cmake_find_package_multi documentation.

Install the Conan configuration to a folder

We are working towards improving the functionality of conan config install , so you can mix configuration files from different sources. Now you can select the origin folder to get the files form and the target one you want to install the files to.

$ conan config install http://url/to/some/config.zip -sf=origin -tf=target $ conan config install http://url/to/some/config.zip -sf=origin2 -tf=target2 $ conan config install http://other/url/to/other.zip -sf=hooks -tf=hooks

The actions will be cached so you can do conan config install and the previous actions will be executed in order.

This will be useful to set in place hooks from different locations, for example, to test the official hooks like this:

$ conan config install git@github.com:conan-io/hooks.git --source-folder hooks --target-folder hooks/conan-io

This can be also used to install specific profiles or remotes from a repository or zip file.

Read more in the conan config command documentation.

Install package rebuilding a reference

The command conan install . --build now accepts a full reference as argument. You can use it to rebuild specific references in the dependency graph:

$ conan install Poco/1.9.0@pocoproject/stable --build zlib/1.2.11@conan/stable

This is useful to build dependencies individually in the dependency graph, like private requirements that might be repeated in name but different in version, user or channel.

You can use wildcards with the full reference too:

$ conan install Poco/1.9.0@pocoproject/stable --build z*@conan/stable

Read more in the conan install command documentation.

Error on override of dependencies

When overriding requirements there is a possibility that instead of doing an override, you would like to explicitly depend on that dependency.

For example, when doing this in a conanfile.txt:

[requires] Poco/1.9.0@pocoproject/stable OpenSSL/1.0.2r@conan/stable

The second line will override the OpenSSL/1.0.2o@conan/stable required by Poco with OpenSSL/1.0.2r@conan/stable and add the requirement to consumer project.

$ conan install . ... WARN: Poco/1.9.0@pocoproject/stable requirement OpenSSL/1.0.2o@conan/stable overridden by your conanfile to OpenSSL/1.0.2r@conan/stable

As shown above, the output wars about this behavior by default. However, in case that you want Conan to error on that behavior, you can set the new environment variable or configuration entry in the conan.conf to avoid unnoticed overrides:

Environment variable: CONAN_ERROR_ON_OVERRIDE=1

Configuration entry: error_on_override = True

$ conan config set general.error_on_override=True $ conan install . ... ERROR: Poco/1.9.0@pocoproject/stable: requirement OpenSSL/1.0.2o@conan/stable overridden by your conanfile to OpenSSL/1.0.2r@conan/stable

Currently, it is not possible to declare a requirement and also add it with the override keyword to avoid raising errors for that specific dependency. Conan will raise an error saying it is duplicated. There is an open issue about it.

Configuration of the CA certificate

It is very common in enterprise organizations to have a custom CA certificate to be use on every HTTP request. However, if you want to install the Conan configuration via conan config install you are not able to specify the certificate to be used. You could use --verify-ssl=False to override this check but is not the most appropriate solution.

We have introduced an environment variable and configuration entry to point to the certificate file to be used:

Environment variable: CONAN_CACERT_PATH=~/cacert.pem

Configuration entry: cacert_path = ~/cacert.pem





Check the full list of features and fixes in the changelog and don’t forget to update.

Finally, if you find a bug or want to start a new discussion, please do not hesitate to open a new issue here. Many thanks!