Fix cross-Scala suffix conflict warning

Fixes sbt/sbt#6578

Problem
-------
The regex currently expects two segments like2.x or 3.x,
but Scala 3 uses _3 as the cross suffix, and it's not caught.

Solution
--------
Change the regex.

core/src/main/scala/sbt/librarymanagement/ConflictWarning.scala

@@ -59,7 +59,7 @@ object ConflictWarning {
  private[this] def groupByRawName(ms: Seq[ModuleID]): Map[(String, String), Seq[ModuleID]] =
  ms.groupBy(m => (m.organization, dropCrossSuffix(m.name)))
 
- private[this] val CrossSuffixPattern = """(.+)_(\d+\.\d+(?:\.\d+)?(?:-.+)?)""".r
+ private[this] val CrossSuffixPattern = """(.+)_(\d+(?:\.\d+)?(?:\.\d+)?(?:-.+)?)""".r
  private[this] def dropCrossSuffix(s: String): String = s match {
  case CrossSuffixPattern(raw, _) => raw
  case _ => s

ivy/src/test/scala/sbt/internal/librarymanagement/ConflictWarningSpec.scala

@@ -0,0 +1,40 @@
+package sbt.internal.librarymanagement
+
+import sbt.librarymanagement._
+import sbt.librarymanagement.syntax._
+
+object ConflictWarningSpec extends BaseIvySpecification {
+
+ test("it should print out message about the cross-Scala conflict") {
+ var found = false
+ val deps = Vector(
+ `scala2.13.6`,
+ `cats-effect3.1.1`,
+ `cats-core2.6.1`.cross(CrossVersion.for3Use2_13),
+ )
+ val m = module(defaultModuleId, deps, Some("3.0.1-RC2"))
+ val report = ivyUpdate(m)
+ val w = ConflictWarning.default("foo")
+
+ try {
+ ConflictWarning(w, report, log)
+ } catch {
+ case e: Throwable =>
+ found = true
+ assert(
+ e.getMessage.linesIterator.toList.head
+ .startsWith("Conflicting cross-version suffixes in")
+ )
+ }
+ if (!found) {
+ sys.error("conflict warning was expected, but didn't happen sbt/sbt#6578")
+ }
+ }
+
+ lazy val `scala2.13.6` =
+ ModuleID("org.scala-lang", "scala-library", "2.13.6").withConfigurations(Some("compile"))
+ lazy val `cats-effect3.1.1` =
+ ("org.typelevel" %% "cats-effect" % "3.1.1").withConfigurations(Some("compile"))
+ lazy val `cats-core2.6.1` =
+ ("org.typelevel" %% "cats-core" % "2.6.1").withConfigurations(Some("compile"))
+}