Conan Semantic Versioning Trials

It seems that there is a problem with the Semantic Versioning (https://semver.org/) concept in Conan (https://conan.io/). This repository shall be used for testing of this concept.

Setup

These files were created by running for example the following command (with Conan client v1.54.0) to create some projects for testing:

conan new semver_a/1.0.0 --template=cmake_lib

The projects were then modified to represent the following dependency tree.

Dependencies

semver_a/1.0.0 -> semver_b/1.0.0 -> semver_super/1.0.0
semver_a/1.1.0 --------------------------^

The package semver_a/1.0.0 is in subdirectory "a". The package semver_a/1.1.0 is a copy of "a" in subdirectory "a110" with the version number "1.0.0" changed to "1.1.0".

Build

Run the following commands to test if this dependency tree can be built with Conan.

Script:

./build.py

Manually:

conan create a -s:b build_type=Release
conan create b -s:b build_type=Release
conan create a110 -s:b build_type=Release
conan create super -s:b build_type=Release

Failure

With conan client v1.54.0 the build of the semver_super package fails:

WARN: semver_b/1.0.0: requirement semver_a/[~1.0.0] overridden by semver_super/1.0.0 to semver_a/1.1.0
ERROR: Version range '~1.0.0' required by 'semver_b/1.0.0' not valid for downstream requirement 'semver_a/1.1.0'

Semantic versioning with version ranges

Version ranges are documented at:

https://docs.conan.io/en/latest/versioning/version_ranges.html

We use the default versioning schema (semver_direct_mode) for these tests. Read more here:

https://docs.conan.io/en/latest/creating_packages/define_abi_compatibility.html

Problem

The problem seems to be that the version range which uses the tilde sign for semantic versioning (e.g. [~1.0.0]) is triggering additional checks of the compatibility of the dependencies.

Related issues seem to exist:

• conan-io/conan#5507
• conan-io/conan#5713
• conan-io/conan#11106

Workaround

When replacing the tilde sign with greater-equals / less-than signs, the build succeeds.

Patch 1

In "b/conanfile.py", replace:

self.requires("semver_a/[~1.0.0]")

...with:

self.requires("semver_a/[>=1.0.0 <2]")

Patch 2

In "super/conanfile.py", replace:

self.requires("semver_a/[~1.1.0]")
self.requires("semver_b/[~1.0.0]")

...with:

self.requires("semver_a/[>=1.1.0 <2]")
self.requires("semver_b/[>=1.0.0 <2]")

Branch

See branch workaround where these patches have been applied.

Conclusion

The behavior of Conan seems inconsistent in this case. The version range using tilde sign should probably behave like this workaround does.