Guardrails / scala

Scala version is declared

scala/version-declared@v1

The build declares the Scala version it compiles against, and that version is no older than the configured floor.

Id	scala/version-declared
Version	v1
Category	scala
Default severity	warning
Interpreter	python3
Timeout	30 seconds
Violations tolerated	0
Collects	scala

Collectors

This guardrail gathers nothing itself. It depends on the collectors below, which the CLI runs once per build before any check, and reads what they found out of GUARDRAIL_FACTS. A collector that collects nothing skips this guardrail rather than failing it.

Collector	Gathers	Inputs it is given
scala	The sbt build in the project directory: the Scala and sbt versions it pins, every subproject the reader saw, the library dependencies each build file names with their configurations, and the plugins the build itself runs. build.sbt is Scala rather than a declaration, so what it declares indirectly is not seen and scanned says so.	projectDir

The inputs above are this guardrail's own, passed straight through. Configuring one in buildnote.json changes what is collected, and two guardrails configured the same way share the one collection.

Configuration

{
  "guardrails": {
      "failOn": "error",
      "comment": true,
      "checks": [
          {
              "use": "scala/version-declared@v1",
              "severity": "warning",
              "with": {
                  "projectDir": ".",
                  "minVersion": "2.13"
              },
              "exemptions": []
          }
      ]
  }
}

Inputs

Input	Description	Default	Environment variable
projectDir	Directory holding the project, relative to the directory the CLI runs in.	.	GUARDRAIL_INPUT_PROJECTDIR
minVersion	Oldest Scala version accepted. A declared version below this is a violation.	2.13	GUARDRAIL_INPUT_MINVERSION

How to fix

Declare the compiler once in build.sbt, so every subproject inherits it:

ThisBuild / scalaVersion := "3.4.1"

Without it sbt compiles against the Scala version its own launcher was built with, so the compiler that produced the artifact is a property of the machine that ran the build rather than of the checkout, and it changes under you the day the launcher does.

More in scala

• scala/dependencies-pinned. Every library dependency read out of the build names a literal revision. build.sbt is Scala read by pattern, so a dependency built by a function, added inside a condition or held in a variable is not seen and the list is a floor rather than the whole of it.
• scala/no-snapshot-dependencies. No library dependency read out of the build is a -SNAPSHOT. build.sbt is Scala read by pattern, so the dependencies it declares indirectly are not seen and the list is a floor rather than the whole of it.
• scala/sbt-version-pinned. project/build.properties pins the sbt version the build runs under, rather than leaving it to the launcher the machine happens to carry.

All 4 scala guardrails