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Fix mill visualize with no arguments failing with MatchError #6973

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Fix mill visualize with no arguments failing with MatchError #6973

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bae49df
Initial plan
Copilot Mar 30, 2026
5d13d20
Add helpful error message when visualize is called with no arguments
Copilot Mar 30, 2026
7b36cb7
Replace return statements with if/else expressions in visualize0
Copilot Apr 3, 2026
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120 changes: 66 additions & 54 deletions libs/util/src/mill/util/VisualizeModule.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -74,42 +74,48 @@ object VisualizeModule extends ExternalModule {
toolsClasspath: Seq[PathRef],
planTasks: Option[List[Task.Named[?]]]
): Result[Seq[PathRef]] = {
def callVisualizeModule(
tasks: List[Task.Named[?]],
transitiveTasks: List[Task.Named[?]]
): Result[Seq[PathRef]] = {
val transitive = evaluator.transitiveTasks(tasks)
val topoSorted = evaluator.topoSorted(transitive)
val sortedGroups = evaluator.groupAroundImportantTasks(topoSorted) {
case x: Task.Named[?] if transitiveTasks.contains(x) => x
}
val plan = evaluator.plan(transitiveTasks)
val payloadPath = writePayload(tasks, transitiveTasks, sortedGroups, plan)
try {
mill.util.Jvm.callProcess(
mainClass = "mill.graphviz.VisualizeWorkerMain",
classPath = toolsClasspath.map(_.path).toVector,
mainArgs = Seq(payloadPath.toString, ctx.dest.toString),
stdin = os.Inherit,
stdout = os.Inherit
)(using ctx)

BuildCtx.withFilesystemCheckerDisabled {
os.list(ctx.dest).sorted.map(PathRef(_))
if (tasks.isEmpty)
Result.Failure(
"visualize requires at least one task to visualize, e.g. `mill visualize __.compile`"
)
else {
def callVisualizeModule(
tasks: List[Task.Named[?]],
transitiveTasks: List[Task.Named[?]]
): Result[Seq[PathRef]] = {
val transitive = evaluator.transitiveTasks(tasks)
val topoSorted = evaluator.topoSorted(transitive)
val sortedGroups = evaluator.groupAroundImportantTasks(topoSorted) {
case x: Task.Named[?] if transitiveTasks.contains(x) => x
}
val plan = evaluator.plan(transitiveTasks)
val payloadPath = writePayload(tasks, transitiveTasks, sortedGroups, plan)
try {
mill.util.Jvm.callProcess(
mainClass = "mill.graphviz.VisualizeWorkerMain",
classPath = toolsClasspath.map(_.path).toVector,
mainArgs = Seq(payloadPath.toString, ctx.dest.toString),
stdin = os.Inherit,
stdout = os.Inherit
)(using ctx)

BuildCtx.withFilesystemCheckerDisabled {
os.list(ctx.dest).sorted.map(PathRef(_))
}
} finally {
os.remove(payloadPath, checkExists = false)
}
} finally {
os.remove(payloadPath, checkExists = false)
}
}

evaluator.resolveTasks(tasks, SelectMode.Multi).flatMap { rs =>
val rendered = planTasks match {
case Some(allRs) => callVisualizeModule(rs, allRs)
case None => callVisualizeModule(rs, rs)
}
rendered.map { v =>
println(upickle.write(v.map(_.path.toString()), indent = 2))
v
evaluator.resolveTasks(tasks, SelectMode.Multi).flatMap { rs =>
val rendered = planTasks match {
case Some(allRs) => callVisualizeModule(rs, allRs)
case None => callVisualizeModule(rs, rs)
}
rendered.map { v =>
println(upickle.write(v.map(_.path.toString()), indent = 2))
v
}
}
}
}
Expand All @@ -123,29 +129,35 @@ object VisualizeModule extends ExternalModule {
vizWorker: VizWorker,
planTasks: Option[List[Task.Named[?]]] = None
): Result[Seq[PathRef]] = {
def callVisualizeModule(
tasks: List[Task.Named[?]],
transitiveTasks: List[Task.Named[?]]
): Result[Seq[PathRef]] = {
val (in, out) = vizWorker
val transitive = evaluator.transitiveTasks(tasks)
val topoSorted = evaluator.topoSorted(transitive)
val sortedGroups = evaluator.groupAroundImportantTasks(topoSorted) {
case x: Task.Named[?] if transitiveTasks.contains(x) => x
}
val plan = evaluator.plan(transitiveTasks)
in.put((tasks, transitiveTasks, sortedGroups, plan, ctx.dest))
val res = out.take()
res.map { v =>
println(upickle.write(v.map(_.path.toString()), indent = 2))
v
if (tasks.isEmpty)
Result.Failure(
"visualize requires at least one task to visualize, e.g. `mill visualize __.compile`"
)
else {
def callVisualizeModule(
tasks: List[Task.Named[?]],
transitiveTasks: List[Task.Named[?]]
): Result[Seq[PathRef]] = {
val (in, out) = vizWorker
val transitive = evaluator.transitiveTasks(tasks)
val topoSorted = evaluator.topoSorted(transitive)
val sortedGroups = evaluator.groupAroundImportantTasks(topoSorted) {
case x: Task.Named[?] if transitiveTasks.contains(x) => x
}
val plan = evaluator.plan(transitiveTasks)
in.put((tasks, transitiveTasks, sortedGroups, plan, ctx.dest))
val res = out.take()
res.map { v =>
println(upickle.write(v.map(_.path.toString()), indent = 2))
v
}
}
}

evaluator.resolveTasks(tasks, SelectMode.Multi).flatMap { rs =>
planTasks match {
case Some(allRs) => callVisualizeModule(rs, allRs)
case None => callVisualizeModule(rs, rs)
evaluator.resolveTasks(tasks, SelectMode.Multi).flatMap { rs =>
planTasks match {
case Some(allRs) => callVisualizeModule(rs, allRs)
case None => callVisualizeModule(rs, rs)
}
}
}
}
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