Support exclude attribute in Dep parser

docs/modules/ROOT/pages/Library_Dependencies.adoc

@@ -10,12 +10,18 @@ For more details about coursier, refer to the {link-coursier-doc}[coursier docum
 
 == Dependencies in General
 
-Mill dependencies have the form:
+Mill dependencies have the simple form:
 
 ----
 ivy"{organization}:{name}:{version}"
 ----
 
+Additional attributes are also supported:
+
+----
+ivy"{organization}:{name}:{version}[;{attribute}={value}]*"
+----
+
 When working in other Java and Scala projects, you will find some synonyms, which typically all mean the same.
 
 For example in the Maven ecosystem, the `organization` is called the `group` and the `name` is called the `artifact`.
@@ -225,6 +231,15 @@ def deps = Agg(
 
 You can also use `.excludeOrg` or `excludeName`:
 
+There is also a short notation available:
+
+.Example: Shot notation to exclude `fansi_2.12` library from transitive dependency set of `pprint`.
+[source,scala]
+----
+def deps = Agg(
+  ivy"com.lihaoyi::pprint:0.5.3;exclude=com.lihaoyi:fansi_2.12"
+)
+----
 
 .Example: Exclude all `com.lihaoyi` libraries from transitive dependency set of `pprint`.
 [source,scala]

scalalib/src/mill/scalalib/Dep.scala

@@ -106,14 +106,17 @@ object Dep {
   implicit def parse(signature: String): Dep = {
     val parts = signature.split(';')
     val module = parts.head
+    var exclusions = Seq.empty[(String, String)]
     val attributes = parts.tail.foldLeft(coursier.Attributes()) { (as, s) =>
       s.split('=') match {
         case Array("classifier", v) => as.withClassifier(coursier.Classifier(v))
         case Array("type", v) => as.withType(coursier.Type(v))
+        case Array("exclude", s"${org}:${name}") => exclusions ++= Seq((org, name)); as
         case Array(k, v) => throw new Exception(s"Unrecognized attribute: [$s]")
         case _ => throw new Exception(s"Unable to parse attribute specifier: [$s]")
       }
     }
+
     (module.split(':') match {
       case Array(a, b, c) => Dep(a, b, c, cross = empty(platformed = false))
       case Array(a, b, "", c) => Dep(a, b, c, cross = empty(platformed = true))
@@ -122,7 +125,9 @@ object Dep {
       case Array(a, "", "", b, c) => Dep(a, b, c, cross = Full(platformed = false))
       case Array(a, "", "", b, "", c) => Dep(a, b, c, cross = Full(platformed = true))
       case _ => throw new Exception(s"Unable to parse signature: [$signature]")
-    }).configure(attributes = attributes)
+    })
+      .exclude(exclusions.sorted: _*)
+      .configure(attributes = attributes)
   }
 
   @unused private implicit val depFormat: RW[Dependency] = mill.scalalib.JsonFormatters.depFormat
@@ -141,7 +146,11 @@ object Dep {
       case "" => ""
       case s => s";type=$s"
     }
-    val attrs = classifierAttr + typeAttr
+
+    val excludeAttr =
+      dep.dep.exclusions().toSeq.sorted.map(e => s";exclude=${e._1.value}:${e._2.value}").mkString
+
+    val attrs = classifierAttr + typeAttr + excludeAttr
 
     val prospective = dep.cross match {
       case CrossVersion.Constant("", false) => Some(s"$org:$mod:$ver$attrs")

scalalib/test/src/mill/scalalib/ResolveDepsTests.scala

@@ -54,14 +54,14 @@ object ResolveDepsTests extends TestSuite {
 
     test("excludeTransitiveDeps") {
       val deps = Agg(ivy"com.lihaoyi::pprint:0.5.3".exclude("com.lihaoyi" -> "fansi_2.12"))
-      assertRoundTrip(deps, simplified = false)
+      assertRoundTrip(deps, simplified = true)
       val Success(paths) = evalDeps(deps)
       assert(!paths.exists(_.path.toString.contains("fansi_2.12")))
     }
 
     test("excludeTransitiveDepsByOrg") {
       val deps = Agg(ivy"com.lihaoyi::pprint:0.5.3".excludeOrg("com.lihaoyi"))
-      assertRoundTrip(deps, simplified = false)
+      assertRoundTrip(deps, simplified = true)
       val Success(paths) = evalDeps(deps)
       assert(!paths.exists(path =>
         path.path.toString.contains("com/lihaoyi") && !path.path.toString.contains("pprint_2.12")
@@ -70,7 +70,7 @@ object ResolveDepsTests extends TestSuite {
 
     test("excludeTransitiveDepsByName") {
       val deps = Agg(ivy"com.lihaoyi::pprint:0.5.3".excludeName("fansi_2.12"))
-      assertRoundTrip(deps, simplified = false)
+      assertRoundTrip(deps, simplified = true)
       val Success(paths) = evalDeps(deps)
       assert(!paths.exists(_.path.toString.contains("fansi_2.12")))
     }