Whitelist some hardcoded targets, which allow run Mill without a buil…

…d.sc
com-lihaoyi · Jul 26, 2023 · 2b82b8e · 2b82b8e
1 parent 718c614
commit 2b82b8e
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Showing 3 changed files with 31 additions and 10 deletions.
diff --git a/bsp/worker/src/mill/bsp/worker/State.scala b/bsp/worker/src/mill/bsp/worker/State.scala
@@ -39,7 +39,8 @@ private class State(projectRoot: os.Path, baseLogger: ColorLogger, debug: String
       threadCount = None,
       targetsAndParams = Seq("resolve", "_"),
       prevRunnerState = mill.runner.RunnerState.empty,
-      logger = baseLogger
+      logger = baseLogger,
+      needBuildSc = true
     ).evaluate()
 
     val rootModules0 = evaluated.result.frames

diff --git a/runner/src/mill/runner/MillBuildBootstrap.scala b/runner/src/mill/runner/MillBuildBootstrap.scala
@@ -35,7 +35,8 @@ class MillBuildBootstrap(
     threadCount: Option[Int],
     targetsAndParams: Seq[String],
     prevRunnerState: RunnerState,
-    logger: ColorLogger
+    logger: ColorLogger,
+    needBuildSc: Boolean
 ) {
   import MillBuildBootstrap._
 
@@ -60,7 +61,7 @@ class MillBuildBootstrap(
   }
 
   def evaluateRec(depth: Int): RunnerState = {
-    println(s"+evaluateRec($depth) " + recRoot(projectRoot, depth))
+//    println(s"+evaluateRec($depth) " + recRoot(projectRoot, depth))
     val prevFrameOpt = prevRunnerState.frames.lift(depth)
     val prevOuterFrameOpt = prevRunnerState.frames.lift(depth - 1)
 
@@ -69,14 +70,19 @@ class MillBuildBootstrap(
         // On this level we typically want assume a Mill project, which means we want to require an existing `build.sc`.
         // Unfortunately, some targets also make sense without a `build.sc`, e.g. the `init` command.
         // Hence we only report a missing `build.sc` as an problem if the command itself does not succeed.
-        val state = evaluateRec(depth + 1)
+        lazy val state = evaluateRec(depth + 1)
         if (os.exists(recRoot(projectRoot, depth) / "build.sc")) state
         else {
-          state match {
-            case RunnerState(bootstrapModuleOpt, frames, Some(error)) =>
-              val msg = "build.sc file not found. Are you in a Mill project folder?\n"
-              RunnerState(bootstrapModuleOpt, frames, Some(msg + error))
-            case state => state
+          val msg = "build.sc file not found. Are you in a Mill project folder?"
+          if (needBuildSc) {
+            RunnerState(None, Nil, Some(msg))
+          } else {
+            state match {
+              case RunnerState(bootstrapModuleOpt, frames, Some(error)) =>
+                // Add a potential clue (missing build.sc) to the underlying error message
+                RunnerState(bootstrapModuleOpt, frames, Some(msg + "\n" + error))
+              case state => state
+            }
           }
         }
       } else {

diff --git a/runner/src/mill/runner/MillMain.scala b/runner/src/mill/runner/MillMain.scala
@@ -202,7 +202,8 @@ object MillMain {
                       threadCount = threadCount,
                       targetsAndParams = targetsAndParams,
                       prevRunnerState = prevState.getOrElse(stateCache),
-                      logger = logger
+                      logger = logger,
+                      needBuildSc = needBuildSc(targetsAndParams)
                     ).evaluate()
                   }
                 )
@@ -262,6 +263,19 @@ object MillMain {
     logger
   }
 
+  private def needBuildSc(targetsAndParams: Seq[String]): Boolean = {
+    // Tasks, for which running Mill without an existing buildfile is allowed.
+    val noBuildFileTaskWhitelist = Seq(
+      "init",
+      "version",
+      "mill.scalalib.giter8.Giter8Module/init"
+    )
+    val whitelistMatch =
+      targetsAndParams.nonEmpty && noBuildFileTaskWhitelist.exists(targetsAndParams.head == _)
+
+    !whitelistMatch
+  }
+
   def checkMillVersionFromFile(projectDir: os.Path, stderr: PrintStream) = {
     Seq(
       projectDir / ".config" / "mill-version",