Description

This project is meant to showcase a discrepancy between how sbt and coursier resolve dependencies.

If you try to compile the project, you'll see the below error reported:

[info] Compiling 1 Scala source to /Users/mirco/tmp/coursier-test/target/scala-2.10/classes...
[error] /Users/mirco/tmp/coursier-test/src/main/scala/App.scala:5: value configure is not a member of object ch.qos.logback.classic.BasicConfigurator
[error]   BasicConfigurator.configure(new LoggerContext())
[error]                     ^
[error] one error found
[error] (compile:compileIncremental) Compilation failed
[error] Total time: 2 s, completed Jun 7, 2017 3:12:29 PM

The problem has to do with the logback-classic JAR version that is in the classpath. The project's build specifies logback-classic version 1.1.1, which does contain the static method configure in the class BasicConfigurator. Surprisingly, it's not version 1.1.1 that is going to be in the compile classpath. The logback-classic version used is actually 1.1.7, and compilation fails because there is no static method named configure in the BasicConfigurator class.

Why is that happening? If you look here, you'll see there is a sbt plugin that is scoping the logback dependency version 1.1.7 to a custom configuration Foo. The configuration Foo doesn't extend any other configuration, so there should be no interaction between the dependency scoped to Foo and the project ones that are scoped to Compile. Unfortunately, that doesn't seem to be true when using coursier, as this project demonstrates. However, if the coursier plugin is removed, then the project will compile just fine.

An additional discrepancy I noticed between the stock sbt behavior and coursier is that if this line is removed, resolution will fail with the stock sbt, while it will work just fine with coursier. The error reported by sbt after removing the mentioned line is:

> compile
[info] Updating {file:/Users/mirco/tmp/coursier-test/}coursier-test...
[trace] Stack trace suppressed: run last *:update for the full output.
[error] (*:update) java.lang.IllegalArgumentException: Cannot add dependency 'org.slf4j#slf4j-api;1.7.0' to configuration 'foo' of module default#coursier-test_2.10;0.1-SNAPSHOT because this configuration doesn't exist!

Not sure if the two issues are connected.