@eed3si9n eed3si9n released this Jul 17, 2017 · 968 commits to 1.x since this release

Assets 8

See sbt 1.0 roadmap and beta-1 for scheduled timeline.

sbt 1.0.0-RC2

This is the RC-2 release of sbt 1.0.

Features, fixes, changes with compatibility implications

  • Many of the case classes are replaced with pseudo case classes generated using Contraband. Migrate .copy(foo = xxx) to withFoo(xxx).
  • sbt 1.0 uses Scala 2.12 for build definitions and plugins. This also requires JDK 8.
  • Non-auto sbt.Plugin trait is dropped. Please migrate to AutoPlugin. Auto plugins are easier to configure, and work better with each other.
  • sbt 0.12 style Build trait that was deprecated in sbt 0.13.12, is removed. Please migrate to build.sbt. Auto plugins and Build trait do not work well together, and its feature is now largely subsumed by multi-project build.sbt.
  • sbt 0.12 style Project(...) constructor is restricted down to two parameters. This is because settings parameter does not work well with Auto Plugins. Use project instead.
  • sbt 0.12 style key dependency operators <<=, <+=, <++= are removed. Please migrate to :=, +=, and ++=. These operators have been sources of confusion for many users, and have long been removed from 0.13 docs, and have been formally deprecated since sbt 0.13.13.
  • Zinc 1 drops support for Scala 2.9 and earlier. Scala 2.10 must use 2.10.2 and above. Scala 2.11 must use 2.11.2 and above. (latest patch releases are recommended)
  • config("tooling") must be directly assigned to a capitalized val, like val Tooling = config("tooling"). This captures the lhs identifier into the configuration so we can use it from the shell later.
  • Changes publishTo and otherResolvers from SettingKeys to TaskKeys. #2059/#2662 by @dwijnand
  • Path.relativizeFile(baseFile, file) is renamed to IO.relativizeFile(baseFile, file).
  • PathFinder's .*** method is renamed to .allPaths method.
  • PathFinder.x_!(mapper) is moved to def pair on PathFinder.
  • Drops sbt 0.12 style hyphen-separated key names (use publishLocal instead of publish-local).
  • Renames early command feature from --<command> to early(<command>).
  • Log options -error, -warn, -info, -debug are added as shorthand for "early(error)" etc.
  • sbt.Process and sbt.ProcessExtra are dropped. Use scala.sys.process instead.
  • incOptions.value.withNameHashing(...) option is removed because name hashing is always on.
  • TestResult.Value is now called TestResult.
  • The scripted plugin is cross-versioned now, so you must use %% when depending on it
  • Removes the settingsSets method from Project (along with add/setSbtFiles).
  • Drops deprecated InputTask apply method and inputTask DSL method. Use Def.inputTask and Def.spaceDelimited().parsed.
  • Drops deprecated ProjectReference implicit lifts. Use RootProject(<uri>), RootProject(<file>) or LocalProject(<string>).
  • Drops deprecated seq(..) DSL method. Use Seq or pass in the settings without wrapping.
  • Drops deprecated File/Seq[File] setting enrichments. Use .value and Def.setting.
  • Drops deprecated SubProcess apply overload. Use SubProcess(ForkOptions(runJVMOptions = ..)).
  • Drops toError(opt: Option[String]): Unit (equivalent to opt foreach sys.error); if used to wrap
    ScalaRun#run then the replacement is foreach (sys error _.getMessage)
  • A number of the methods on sbt.Path (such as relativeTo and rebase and flat) are now no longer in the
    default namespace by virtue of being mixed into the sbt package object. Use to access them
  • sbt 1.0 renames Global as scope component to Zero to disambiguate from GlobalScope. @eed3si9n
  • sbt 1.0 uses ConfigRef in places where String was used to reference configuration, such as update.value.configuration(...). Pass in Configuration, which implicitly converts to ConfigRef.
  • Changes sourceArtifactTypes and docArtifactTypes from Set[String] to Seq[String] settings.

The Scala Center is working with Lightbend to provide [an automatic migration tool][sbt-migration-rewrites].


  • New incremental compiler called Zinc 1. Details below.
  • The interactive shell is adds network API. Details below.



  • Scala Center contributed a Java-friendly Zinc API. This was a overhaul of the Zinc internal API for a good Scala integration with other build tools. zinc#304 by @jvican
  • Scala Center contributed a binary format for Zinc's internal storage. See below
  • Scala Center contributed static validation of build.sbt. See below
  • Library management API and parallel artifact download. See below.
  • The startup log level is dropped to -error in script mode using scalas. #840 by @eed3si9n
  • Replace cross building support with sbt-doge. This allows builds with projects that have multiple different combinations of cross scala versions to be cross built correctly. The behaviour of ++ is changed so that it only updates the Scala version of projects that support that Scala version, but the Scala version can be post fixed with ! to force it to change for all projects. A -v argument has been added that prints verbose information about which projects are having their settings changed along with their cross scala versions. #2613 by @jroper
  • ivyLoggingLevel is dropped to UpdateLogging.Quiet when CI environment is detected. @eed3si9n
  • Add logging of the name of the different build.sbt (matching *.sbt) files used. #1911 by @valydia
  • Add the ability to call aggregate for the current project inside a build sbt file. By [@xuwei-k][@xuwei-k]
  • Add new global setting asciiGraphWidth that controls the maximum width of the ASCII graphs printed by commands like inspect tree. Default value corresponds to the previously hardcoded value of 40 characters. By @RomanIakovlev.
  • Revamped documentation for Scopes, and added Scope Delegation. @eed3si9n
  • Ports sbt-cross-building's ^ and ^^ commands for plugin cross building. See below.
  • Adds support for cross-versioned exclusions. #1518/lm#88 by @jvican
  • Adds new offline mode to the Ivy-based library management. lm#92 by @jvican
  • A number of features related to dependency locking. See below.
  • Improved eviction warning presentation. See below.
  • A better main class detection. zinc#287 by @smarter
  • For faster startup, sbt will use Java refection to discover autoImport . #3115 by @jvican
  • For faster startup, reuse the same global instance for parsing. #3115 by @jvican
  • Adds InteractionService from sbt-core-next to keep compatibility with sbt 0.13. #3182 by @eed3si9n
  • Adds new WatchService that abstracts PollingWatchService and Java NIO. io#47 by @Duhemm on behalf of The Scala Center.
  • Adds variants of IO.copyFile and IO.copyDirectory that accept See below for details.
  • and Path.contentOf are donated from sbt-native-packager io#38 by @muuki88
  • ApiDiff feature used to debug Zinc uses Scala implementation borrowed from Dotty. zinc#346 by @Krever
  • In Zinc internal, make ExtractAPI use perRunCaches. zinc#347 by @gheine


  • Adopted Scalafmt for formatting the source code using neo-scalafmt.
  • Scala Center contributed a redesign of the scripted test framework that has batch mode execution. Scripted now reuses the same sbt instance to run sbt tests, which reduces the CI build times by 50% #3151 by @jvican
  • sbt 1.0.0-M6 is built using sbt 1.0.0-M5. #3184 by @dwijnand

Details of major changes

Zinc 1: Class-based name hashing

A major improvement brought into Zinc 1.0 by Grzegorz Kossakowski (commissioned by Lightbend) is class-based name hashing, which will speed up the incremental compilation of Scala in large projects.

Zinc 1.0's name hashing tracks your code dependendencies at the class level, instead of at the source file level. The GitHub issue sbt/sbt#1104 lists some comparisons of adding a method to an existing class in some projects:

ScalaTest   AndHaveWord class:          Before 49s, After 4s (12x)
Specs2      OptionResultMatcher class:  Before 48s, After 1s (48x)
scala/scala Platform class:             Before 59s, After 15s (3.9x)
scala/scala MatchCodeGen class:         Before 48s, After 17s (2.8x)

This depends on some factors such as how your classes are organized, but you can see 3x ~ 40x improvements. The reason for the speedup is because it compiles fewer source files than before by untangling the classes from source files. In the example adding a method to scala/scala's Platform class, sbt 0.13's name hashing used to compile 72 sources, but the new Zinc compiles 6 sources.

Zinc API changes

  • Java classes under the xsbti.compile package such as IncOptions hides the constructor. Use the factory method xsbti.compile.Foo.of(...).
  • Renames ivyScala: IvyScala key to scalaModuleInfo: ScalaModuleInfo.
  • xsbti.Reporter#log(...) takes xsbti.Problem as the parameter. Call log(problem.position, problem.message, problem.severity) to delegate to the older log(...).
  • xsbi.Maybe, xsbti.F0, and sxbti.F1 are changed to corresponding Java 8 classes java.util.Optional, java.util.Supplier and java.util.Function.
  • Removes unused "resident" option. zinc#345 by @lukeindykiewicz

sbt server: JSON API for tooling integration

sbt 1.0 includes server feature, which allows IDEs and other tools to query the build for settings, and invoke commands via a JSON API. Similar to the way that the interactive shell in sbt 0.13 is implemented with shell command, "server" is also just shell command that listens to both human input and network input. As a user, there should be minimal impact because of the server.

In March 2016, we rebooted the "server" feature to make it as small as possible. We worked in collaboration with JetBrains' @jastice who works on IntelliJ's sbt interface to narrow down the feature list. sbt 1.0 will not have all the things we originally wanted, but in the long term, we hope to see better integration between IDE and sbt ecosystem using this system. For example, IDEs will be able to issue the compile task and retrieve compiler warning as JSON events:

{"type":"xsbti.Problem","message":{"category":"","severity":"Warn","message":"a pure expression does nothing in statement position; you may be omitting necessary parentheses","position":{"line":2,"lineContent":"  1","offset":29,"pointer":2,"pointerSpace":"  ","sourcePath":"/tmp/hello/Hello.scala","sourceFile":"file:/tmp/hello/Hello.scala"}},"level":"warn"}

Another related feature that was added is the bgRun task which, for example, enables a server process to be run in the background while you run tests against it.

Static validation of build.sbt

sbt 1.0 prohibits .value calls inside the bodies of if expressions and anonymous functions in a task, @sbtUnchecked annotation can be used to override the check.

The static validation also catches if you forget to call .value in a body of a task.

#3216 and #3225 by @jvican

Eviction warning presentation

sbt 1.0 improves the eviction warning presetation.


[warn] There may be incompatibilities among your library dependencies.
[warn] Here are some of the libraries that were evicted:
[warn]  * -> 3.0.0
[warn] Run 'evicted' to see detailed eviction warnings


[warn] Found version conflict(s) in library dependencies; some are suspected to be binary incompatible:
[warn]      * com.typesafe.akka:akka-actor_2.12:2.5.0 is selected over 2.4.17
[warn]          +- de.heikoseeberger:akka-log4j_2.12:1.4.0            (depends on 2.5.0)
[warn]          +- com.typesafe.akka:akka-parsing_2.12:10.0.6         (depends on 2.4.17)
[warn]          +- com.typesafe.akka:akka-stream_2.12:2.4.17 ()       (depends on 2.4.17)
[warn] Run 'evicted' to see detailed eviction warnings

#3202 by @eed3si9n


@jrudolph's sbt-cross-building is a plugin author's plugin.
It adds cross command ^ and sbtVersion switch command ^^, similar to + and ++,
but for switching between multiple sbt versions across major versions.
sbt 0.13.16 merges these commands into sbt because the feature it provides is useful as we migrate plugins to sbt 1.0.

To switch the sbtVersion in pluginCrossBuild from the shell use:

^^ 1.0.0-M5

Your plugin will now build with sbt 1.0.0-M5 (and its Scala version 2.12.2).

If you need to make changes specific to a sbt version, you can now include them into src/main/scala-sbt-0.13,
and src/main/scala-sbt-1.0.0-M5, where the binary sbt version number is used as postfix.

To run a command across multiple sbt versions, set:

crossSbtVersions := Vector("0.13.15", "1.0.0-M5")

Then, run:

^ compile

[#3133][3133] by @eed3si9n (forward ported from 0.13.16-M1)


sbt IO 1.0 add variant of IO.copyFile and IO.copyDirectory that accept
CopyOptions() is an example of pseudo case class similar to the builder pattern.

import{ IO, CopyOptions }

IO.copyDirectory(source, target)

// The above is same as the following
IO.copyDirectory(source, target, CopyOptions()

io#53 by @dwijnand

Library management API and parallel artifact download

sbt 1.0 adds Library management API co-authored by Eugene Yokota (@eed3si9n) from Lightbend and Martin Duhem (@Duhemm) from Scala Center.
This API aims to abstract Apache Ivy as well as alternative dependency resolution engines Ivy, cached resolution, and Coursier.

Parallel artifact download for Ivy engine was contributed by Jorge (@jvican) from Scala Center.
It also introduces Gigahorse OkHttp as the Network API, and it uses Square OkHttp for artifact download as well.

lm#124 by @eed3si9n/@Duhemm,
lm#90 by @jvican/@jsuereth
and lm#104 by @eed3si9n.

Binary format for Zinc's internal storage

Jorge (@jvican) from Scala Center contributed a binary format for Zinc's internal storage using Google Procol Buffer.
The new format provides us with three main advantages:

  1. Backwards and forwards binary compatibility at the analysis format level.
  2. Faster (1.5 ~ 2x) serialization/deserialization of the analysis file.
  3. Provides a better way to make the analysis file machine-independent.

zinc#351 by @jvican

Dependency locking

Dependency locking feature is still in progress, but Jorge (@jvican) from Scala Center has added a number of related features
that would should work together to allow dependency locking.

  • Frozen mode to the Ivy-based library management, which makes sure that the resolution is always intransitive. lm#100
  • Adds support to specify a resolver for dependencies. lm#97
  • Adds "managed checksums", which tells Ivy to skip the checksum process. lm#111