Distinguish between compile-time and runtime classpaths

Currently, Bloop doesn’t make any distinction between compilation-time and runtime classpaths. This situation brings several problems for projects that expect to have different runtime and compile-time classpath:

• Some code may compile in Bloop, but not in the tool that generated the config (for instance, my code references a symbol that appears only on my runtime classpath)
• Some code may compile in the tool that generated the config, but not in Bloop (for instance, a name became ambiguous because of 2 wildcard imports)
• We cannot faithfully represent builds that use Gradle’s api vs implementation, sbt’s Provided or Pants’ strict_deps for instance.

The Bloop configuration file should include different fields for these different classpaths. Finally, Bloop should use the right classpath to perform the right action.

[jvican]

Even if we compress the files, the duplicate runtime/classpath fields result in higher memory usage.

Not if we intern them. In fact, we don’t need to intern them manually, Paths.get interns them right when they are created at parsing time.

Do we have an agreement to add a “runtimeClasspath” field to the JVM platform section?

Yes, but let’s call it classpath.

[jvican]

Would it make sense to move runtimeClasspath into the JVM “platform” field? It’s not possible to encode runtime classpaths for JS/Native projects. We may also want to rename the field into something like runtimeExtraClasspath to stress that these are additional classpath entries that are added on top of the classpath field.

I like the fact that you scope it to the JVM platform. It eases some of my concerns with this approach and I could make my peace with a classpath field added under runtime JVM platform. This would mean we would add a resources field there too.

But note that you cannot encode it as extraClasspath because the runtime and compile classpath can be disjoint sets of URIs. You can add new URIs to the compile classpath as well as you can remove them or even change the order of the URIs. So if you want to encode the extra classpath to avoid repeating some of the URI entries in the compile classpath and save space, we need a way for you to express that.