Fix #5110: allow semanticdbVersion override

main/src/main/scala/sbt/plugins/SemanticdbPlugin.scala

@@ -21,14 +21,14 @@ object SemanticdbPlugin extends AutoPlugin {
     semanticdbEnabled := false,
     semanticdbIncludeInJar := false,
     semanticdbOptions := List("-Yrangepos"),
-    semanticdbVersion := "4.1.0",
-    semanticdbCompilerPlugin := {
-      val v = semanticdbVersion.value
-      ("org.scalameta" % "semanticdb-scalac" % v).cross(CrossVersion.full)
-    }
+    semanticdbVersion := "4.1.0"
   )
 
   override lazy val projectSettings = Seq(
+    semanticdbCompilerPlugin := {
+      val v = semanticdbVersion.value
+      ("org.scalameta" % "semanticdb-scalac" % v).cross(CrossVersion.full)
+    },
     allDependencies ++= {
       val sdb = semanticdbEnabled.value
       val m = semanticdbCompilerPlugin.value

sbt/src/sbt-test/project/semanticdb-version/build.sbt

@@ -0,0 +1,18 @@
+ThisBuild / scalaVersion := "2.12.8"
+ThisBuild / semanticdbEnabled := true
+ThisBuild / semanticdbVersion := "4.2.3"
+ThisBuild / semanticdbIncludeInJar := false
+
+lazy val root = (project in file("."))
+
+lazy val check = taskKey[Unit]("Checks the configured semanticdbVersion")
+
+check := {
+	val expected = Some("4.2.3")
+	val actual = allDependencies
+	  .value
+	  .find(_.name == "semanticdb-scalac")
+	  .map(_.revision)
+		
+	assert(actual == expected, s"Expected version to be $expected, was $actual")
+}

sbt/src/sbt-test/project/semanticdb-version/src/main/scala/foo/Test.scala

@@ -0,0 +1,7 @@
+package foo
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    println("hello world")
+  }
+}

sbt/src/sbt-test/project/semanticdb-version/test

@@ -0,0 +1 @@
+> check