document the fact that project/build.properties file gets created

problem

The behavior of sbtVersion is inconsistent. The help text states, “Provides the version of sbt. This setting should not be modified.” But the actual behavior is:

• In an SBT project with no project/build.properties file:
  • It creates a project/build.properties file with the version of the current SBT executable
  • It reports the SBT version it wrote in that file
• In an SBT project with an existing project/build.properties file:
  • It reports the SBT version in project/build.properties file
• In my HOME directory:
  • It creates a project directory and project/build.properties file
• In an empty directory:
  • It reports the version of the SBT executable

steps

The following examples show the issue(s).

(1) Move into an existing SBT project that has no project/build.properties file

/Users/al/Projects/Scala/CatoGui> sbt sbtVersion
[info] Updated file /Users/al/Projects/Scala/CatoGui/project/build.properties:
    set sbt.version to 1.2.6

Results:

• It creates a project/build.properties file with the version of the current SBT executable
• It reports the SBT version it wrote in that file

(2) Move into an SBT project that has an existing project/build.properties file

In this example, project/build.properties already has sbt.version=1.1.1:

> sbt sbtVersion
[info] Loading settings from idea.sbt ...
[info] Loading global plugins from /Users/al/.sbt/1.0/plugins
[info] Loading project definition from /Users/al/Projects/Scala/Tmp/project
[info] Updating ProjectRef(uri("file:/Users/al/Projects/Scala/Tmp/project/"), "tmp-build")...
[info] Done updating.
[info] Loading settings from build.sbt ...
[info] Set current project to Tmp (in build file:/Users/al/Projects/Scala/Tmp/)
[info] 1.1.1

Results:

• It reports the SBT version in project/build.properties file

(3) In my HOME directory, it creates a project directory and project/build.properties file

This is the behavior in my HOME directory:

/Users/al> sbt sbtVersion
[info] Updated file /Users/al/project/build.properties: set sbt.version to 1.2.6
[info] Loading settings for project global-plugins from idea.sbt ...
[info] Loading global plugins from /Users/al/.sbt/1.0/plugins
[info] Loading project definition from /Users/al/project
[info] Updating ProjectRef(uri("file:/Users/al/project/"), "al-build")...
[info] Done updating.
[info] Set current project to al (in build file:/Users/al/)
[info] 1.2.6

Results:

• It creates a project/build.properties file under my HOME directory with the version of the current SBT executable
• It reports the SBT version it wrote in that file

(4) In an empty directory, it reports the version of the SBT executable

This is the behavior in a non-SBT directory that is not my HOME directory:

/Users/al/tmp> sbt sbtVersion
[warn] No sbt.version set in project/build.properties, base directory: /Users/al/tmp
[info] Loading settings for project global-plugins from idea.sbt ...
[info] Loading global plugins from /Users/al/.sbt/1.0/plugins
[info] Set current project to tmp (in build file:/Users/al/tmp/)
[info] 1.2.6

Results:

• It reports the version of the sbt executable (without creating a project directory)

expectation

1. Per the help text, I expect it to report the current version of SBT, and it should not write or overwrite project/build.properties.
2. Also, it’s not clear whether the version that is reported should be the version of (a) the sbt executable installed on my system, or (b) the version of SBT that’s configured in project/build.properties of the current project, assuming I’m in an SBT project directory. It seems like these are two different requests that require different commands.

notes

sbt version: 1.2.6 (installed on MacOS with Homebrew)

[alvinj]

Thanks for your help on this!

[alvinj]

The sbt name part is also surprising. Maybe a way to describe this is that as a user I feel like I’m issuing a SQL SELECT query when I run sbtVersion or name, but under certain circumstances it also runs an INSERT as a side effect. If that’s the way it’s supposed to work, no problem, I just thought it was a bug.