Add % syntax for configuration scoping

src/main/scala/sbt/internal/ProjectMatrix.scala

@@ -160,6 +160,14 @@ object ProjectMatrix {
     override def toString: String = s"ProjectRow($autoScalaLibrary, $axisValues)"
   }
 
+  final class ProjectMatrixReferenceSyntax(m: ProjectMatrixReference) {
+    def %(conf: String): ProjectMatrix.MatrixClasspathDependency =
+      ProjectMatrix.MatrixClasspathDependency(m, Some(conf))
+
+    def %(conf: Configuration): ProjectMatrix.MatrixClasspathDependency =
+      ProjectMatrix.MatrixClasspathDependency(m, Some(conf.name))
+  }
+
   final case class MatrixClasspathDependency(
       matrix: ProjectMatrixReference,
       configuration: Option[String]

src/main/scala/sbtprojectmatrix/ProjectMatrixPlugin.scala

@@ -11,9 +11,14 @@ object ProjectMatrixPlugin extends AutoPlugin {
   object autoImport {
     def projectMatrix: ProjectMatrix = macro ProjectMatrix.projectMatrixMacroImpl
 
-   implicit def matrixClasspathDependency[T](
+    implicit def matrixClasspathDependency[T](
       m: T
-   )(implicit ev: T => ProjectMatrixReference): ProjectMatrix.MatrixClasspathDependency =
-     ProjectMatrix.MatrixClasspathDependency(m, None)
+    )(implicit ev: T => ProjectMatrixReference): ProjectMatrix.MatrixClasspathDependency =
+      ProjectMatrix.MatrixClasspathDependency(m, None)
+
+    implicit def matrixReferenceSyntax[T](
+      m: T
+    )(implicit ev: T => ProjectMatrixReference): ProjectMatrix.ProjectMatrixReferenceSyntax =
+      new ProjectMatrix.ProjectMatrixReferenceSyntax(m)
   }
 }

src/sbt-test/projectMatrix/jvm-with-scoping/app/src/main/scala/Main.scala

@@ -0,0 +1,5 @@
+package a
+
+object Main extends App {
+  val core = Core
+}

src/sbt-test/projectMatrix/jvm-with-scoping/build.sbt

@@ -0,0 +1,32 @@
+lazy val check = taskKey[Unit]("")
+
+lazy val root = (project in file("."))
+  .aggregate(core.projectRefs ++ app.projectRefs: _*)
+  .settings(
+  )
+
+lazy val app = (projectMatrix in file("app"))
+  .aggregate(core, intf)
+  .dependsOn(core % Compile, intf % "compile->compile;test->test")
+  .settings(
+    name := "app"
+  )
+  .jvmPlatform(scalaVersions = Seq("2.12.8"))
+
+lazy val core = (projectMatrix in file("core"))
+  .settings(
+    check := {
+      assert(moduleName.value == "core", s"moduleName is ${moduleName.value}")
+    },
+  )
+  .jvmPlatform(scalaVersions = Seq("2.12.8", "2.11.12"))
+
+lazy val intf = (projectMatrix in file("intf"))
+  .settings(
+    check := {
+      assert(moduleName.value == "intf", s"moduleName is ${moduleName.value}")
+    },
+  )
+  .jvmPlatform(autoScalaLibrary = false)
+
+lazy val core212 = core.jvm("2.12.8")

src/sbt-test/projectMatrix/jvm-with-scoping/core/src/main/scala/Core.scala

@@ -0,0 +1,6 @@
+package a
+
+class Core {
+}
+
+object Core extends Core

src/sbt-test/projectMatrix/jvm-with-scoping/project/plugins.sbt

@@ -0,0 +1,5 @@
+sys.props.get("plugin.version") match {
+  case Some(x) => addSbtPlugin("com.eed3si9n" % "sbt-projectmatrix" % x)
+  case _ => sys.error("""|The system property 'plugin.version' is not defined.
+                         |Specify this property using the scriptedLaunchOpts -D.""".stripMargin)
+}

src/sbt-test/projectMatrix/jvm-with-scoping/test

@@ -0,0 +1,6 @@
+> compile
+
+$ exists core/target/jvm-2.12/classes/a/Core.class
+$ exists core/target/jvm-2.11/classes/a/Core.class
+
+> coreJVM2_12/check