Ensure unreported warning summaries are also emitted via sbt-bridge

The sbt-bridge uses a delegating reporter that overrides the base
implementation of `printSummary` and delegates to the sbt implementation.

However that implementation only provides summary reporting of warning
and error counts, and the _compiler_ is responsible for emitting any
summary diagnostics regarding unreported warnings.

This commit separates emitting those unreported warning summaries from
the base implementation of Reporter#printSummary so as not to be
overriden by the DelegatingReporter in sbt-bridge.

Author: griggt

compiler/src/dotty/tools/dotc/Run.scala

@@ -321,11 +321,12 @@ class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with Constraint
     compileSources(sources)
   }
 
-  /** Print summary; return # of errors encountered */
+  /** Print summary of warnings and errors encountered */
   def printSummary(): Unit = {
     printMaxConstraint()
     val r = runContext.reporter
     r.printSummary
+    r.summarizeUnreportedWarnings
   }
 
   override def reset(): Unit = {

compiler/src/dotty/tools/dotc/reporting/Reporter.scala

@@ -207,11 +207,16 @@ abstract class Reporter extends interfaces.ReporterResult {
       b += countString(warningCount, "warning") + " found"
     if (errorCount > 0)
       b += countString(errorCount, "error") + " found"
-    for ((settingName, count) <- unreportedWarnings)
-      b += s"there were $count ${settingName.tail} warning(s); re-run with $settingName for details"
     b.mkString("\n")
   }
 
+  def summarizeUnreportedWarnings(using Context): Unit =
+    val b = mutable.ListBuffer[String]()
+    for (settingName, count) <- unreportedWarnings do
+      b += s"there were $count ${settingName.tail} warning(s); re-run with $settingName for details"
+    val s = b.mkString("\n")
+    if s.nonEmpty then report(Info(s, NoSourcePosition))
+
   /** Print the summary of warnings and errors */
   def printSummary(using Context): Unit = {
     val s = summary

sbt-test/compilerReporter/i14576/Test.scala

@@ -0,0 +1,17 @@
+// lampepfl/dotty#14576, Writer is in a separate file and not declared `open`
+//   under -source:future this requires -language:adhocExtensions
+class ExtWriter extends Writer
+
+class Text(val str: String)
+
+object Test:
+  // lampepfl/dotty#14500, requires implicitConversions feature
+  given Conversion[String, Text] = Text(_)
+  def f(x: Text) = println(x.str)
+  f("abc")
+
+  // private[this] and = _ are deprecated under -source:future
+  private[this] var x: AnyRef = _
+
+  // under -source:future, `_` is deprecated for wildcard arguments of types: use `?` instead
+  val xs: List[_] = Nil

sbt-test/compilerReporter/i14576/Writer.scala

@@ -0,0 +1 @@
+class Writer

sbt-test/compilerReporter/i14576/build.sbt

@@ -0,0 +1,38 @@
+import sbt.internal.util.ConsoleAppender
+
+scalaVersion := sys.props("plugin.scalaVersion")
+
+lazy val assertFeatureSummary = taskKey[Unit]("checks that feature warning summary is emitted")
+lazy val assertNoFeatureSummary = taskKey[Unit]("checks that no feature warning summary is emitted")
+lazy val assertDeprecationSummary = taskKey[Unit]("checks that deprecation warning summary is emitted")
+lazy val assertNoDeprecationSummary = taskKey[Unit]("checks that no deprecation warning summary is emitted")
+lazy val resetMessages = taskKey[Unit]("empties the messages list")
+
+lazy val root = (project in file("."))
+  .settings(
+    scalacOptions += "-source:future",
+    extraAppenders := { s => Seq(ConsoleAppender(FakePrintWriter)) },
+    assertFeatureSummary := {
+      assert {
+        FakePrintWriter.messages.exists(_.contains("there were 2 feature warning(s); re-run with -feature for details"))
+      }
+    },
+    assertNoFeatureSummary := {
+      assert {
+        FakePrintWriter.messages.forall(!_.contains("feature warning(s); re-run with -feature for details"))
+      }
+    },
+    assertDeprecationSummary := {
+      assert {
+        FakePrintWriter.messages.exists(_.contains("there were 3 deprecation warning(s); re-run with -deprecation for details"))
+      }
+    },
+    assertNoDeprecationSummary := {
+      assert {
+        FakePrintWriter.messages.forall(!_.contains("deprecation warning(s); re-run with -deprecation for details"))
+      }
+    },
+    resetMessages := {
+      FakePrintWriter.resetMessages
+    },
+  )

sbt-test/compilerReporter/i14576/project/FakePrintWriter.scala

@@ -0,0 +1,6 @@
+object FakePrintWriter extends java.io.PrintWriter("fake-print-writer") {
+  @volatile var messages = List.empty[String]
+  def resetMessages = messages = List.empty[String]
+  override def println(x: String): Unit = messages = x :: messages
+  override def print(x: String): Unit = messages = x :: messages
+}

sbt-test/compilerReporter/i14576/test

@@ -0,0 +1,18 @@
+> compile
+> assertFeatureSummary
+> assertDeprecationSummary
+
+> resetMessages
+
+> set scalacOptions += "-feature"
+> compile
+> assertNoFeatureSummary
+
+> resetMessages
+
+> set scalacOptions += "-deprecation"
+> compile
+> assertNoFeatureSummary
+> assertNoDeprecationSummary
+
+> resetMessages