[question] Do versioning conflicts between dependencies cause missing packages?

Hi, I’m having some issues with dependencies’ versions mismatch between a consumer project and its dependencies. It forced conan to report that the dependencies were missing and requiring building missing packages from source.

Let say I have:

• a project A depending on project B.
• Both of the projects depend on C.
• However, A requires C version 1.
• B requires C version 2.
• B’s package was already built with C version 2.

In this case, when building A’s package, conan reported that the prebuilt package of B is missing.

Is there a way to mix and match common dependencies between projects like that. It’s inconvenient that all projects have to require the same dependencies’ versions considering the projects are controlled by different teams.

[memsharded]

Btw, can I have one more question? Some dependencies’ versioning conflicts didn’t force source rebuild at all. May I know what is the default binary compatible mode?

Sure, the current default mode is semver_direct_mode. Which means, a new binary will be required if the direct declared dependencies (not the transitive ones) bumps their major version, or if its major version is zero 0.X.Y and minor or patch changes. It can also fire for dependencies not following semver specification (using letters, or any other non conformant version). It is not a very good default but it was there since very early in the beginning, and it couldn’t be changed without breaking. Most likely Conan 2.0 will use another default. The other modes that can be selected, like minor_mode, recipe_revision_mode, etc., are all transitive, they will include both the direct dependencies and the transitive dependencies.

[kakashidinho]

I’m just thinking if the 2 projects are shared library and they are statically linked against the same lib but different versions, it shouldn’t be an issue.

Yes, that can be problematic as well. Even for shared libraries, depending on the encapsulation and isolation and what is passed in the API, could break things at runtime in ugly ways. As a general rule, the same library, with the same version and configuration must be used to avoid problems.

I know this. Anw, this enforcement basically causes the same Microsoft VC++ library’s compatible hell which requires us to build multiple versions of a static lib, one for each version of Visual studio.

Btw, can I have one more question? Some dependencies’ versioning conflicts didn’t force source rebuild at all. May I know what is the default binary compatible mode?