Limits of Ceylon 1.3.3 Module System for Transitive Dependency Version Conflicts

Direct answer

Ceylon 1.3.3 does not perform automatic mediation for transitive dependency version conflicts. The module system permits only one version of a given module to be loaded into the runtime at a time. When two transitive dependencies require incompatible versions of the same module, the compiler or module loader raises a ModuleResolutionException instead of selecting a “nearest” or “highest” version.

Established behavior versus items needing verification

Well-established design characteristics of Ceylon 1.3.3 include:

• Single-version-per-module semantics in the Ceylon module system.
• No built-in “nearest-wins” or version-range resolution for transitive conflicts.
• module-info.ceylon declares dependencies and exports; it does not provide an <exclusion> element analogous to Maven.

Uncertain for this specific version: the exact wording and diagnostic detail of the ModuleResolutionException message, and whether command-line and embedded resolution paths are byte-for-byte identical. Ceylon 1.3.3 predates widespread Java 9+ JPMS adoption, so interaction between Ceylon modules and JPMS modules is not covered by the core Ceylon specification and should be tested locally.

Descriptor syntax for exclusion or alignment

There is no documented exclusion syntax in module-info.ceylon. The supported alignment strategy is to declare the desired version explicitly as a direct dependency in the top-level descriptor. This overrides transitive requests by making the selected version part of the root module’s constraint set.

module my.app "1.0.0" {
    shared dependency ceylon.math "1.3.3";
}

Be aware that forcing a version can introduce binary incompatibility. If the chosen version lacks classes or methods expected by a transitive dependency, the failure may shift from resolution time to a runtime NoClassDefFoundError or LinkageError.

Exception guidance

The ModuleResolutionException indicates that the dependency graph cannot be satisfied by a single version. Any specific message text, error codes, or diagnostic detail should be treated as unverified until reproduced in your Ceylon 1.3.3 environment.

Verification steps for this case

1. Create a minimal project with two dependencies that pull incompatible versions of a shared module.
2. Run ceylon compile and capture the full stack trace.
3. Add a direct dependency on the intended version in module-info.ceylon and recompile.
4. Run the application to ensure no linkage errors appear.

If the conflicting artifact is a Java 9+ JPMS module rather than a Ceylon module, the resolution path may differ. Is your conflict between two Ceylon modules, or does it involve a JPMS module on the module path?