<li><a href="../userguide/feature_variants.html">Modeling Feature Variants and Optional Dependencies</a></li>
                        <li><a href="../userguide/variant_model.html">Understanding Variant Selection</a></li>
                        <li><a href="../userguide/variant_attributes.html">Declaring Variant Attributes</a></li>

[[sec:implementation-conflict]]
== Implementation conflict resolution

Gradle uses variants and capabilities to identify what a module _provides_.

This is a unique feature that deserves its <<variant_model.adoc#understanding-variant-selection,own chapter>> to understand what it means and enables.

A conflict occurs the moment two modules either:

* Attempt to select incompatible variants,
* Declare the same capability

If your build consumes modules with Ivy metadata, you might be able to activate api and implementation separation as described <<variant_model.adoc#sub:ivy-mapping-to-variants,here>> if all modules follow a certain structure.

NOTE: Separating compile and runtime scope of modules is active by default in Gradle 5.0+.

2. as a _consumer_, to resolve a set of dependencies to files
3. as a _producer_, to expose artifacts and their dependencies for consumption by other projects
   (such _consumable_ configurations usually represent the <<variant_model.adoc#understanding-variant-selection,variants>> the producer offers to its consumers)

For example, to express that an application `app` _depends on_ library `lib`, _at least_ one configuration is required:

include::sample[dir="snippets/java/apt/groovy", files="build.gradle[tags=annotation-processing]"]
====

== Variant aware selection

The whole set of JVM plugins leverage <<variant_model.adoc#understanding-variant-selection,variant aware resolution>> for the dependencies used.

Almost every Gradle project has the _default_ and _archives_ configurations which are added by the _base_ plugin.
These configurations are no longer used in modern Gradle builds that use <<variant_model.adoc#understanding-variant-selection,variant aware dependency management>> and the <<publishing_setup.adoc#publishing_components,new publishing plugins>>.

* Variant names must be unique,
* Each variant must have at least <<variant_attributes.adoc#variant_attributes,one attribute>>,
* Two variants cannot have the <<variant_model.adoc#understanding-variant-selection,exact same attributes and capabilities>>,
* If there are dependencies, at least one, across all variants, must carry <<rich_versions.adoc#rich-version-constraints,version information>>.