Add origin filter to WConf, DeprecationWarning (#21404)

The `origin` parameter to `deprecationWarning` is optional; the
parameter to `DeprecationWarning` is not.

The `origin` of a deprecation is simply the deprecated symbol. The full
name is matched by the regex specified by `-Wconf`.

The other important use case is the `origin` of an unused element, in
particular, the selector which causes an "unused import" warning. That
use case will be supported in a follow-up PR, and should work as in
Scala 2.

Fixes #17538

Author: lrytz

Diff for: compiler/src/dotty/tools/dotc/config/CompilerCommand.scala

@@ -9,7 +9,8 @@ abstract class CompilerCommand extends CliCommand:
 
   final def helpMsg(using settings: ConcreteSettings)(using SettingsState, Context): String =
     settings.allSettings.find(isHelping) match
-      case Some(s) => availableOptionsMsg(_ == s, showArgFileMsg = false)
+      case Some(s @ settings.language) => availableOptionsMsg(_ == s, showArgFileMsg = false)
+      case Some(s) => s.description
       case _ =>
         if (settings.help.value) usageMessage
         else if (settings.Vhelp.value) vusageMessage

Diff for: compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -233,7 +233,7 @@ private sealed trait WarningSettings:
     "patterns",
     default = List(),
     descr =
-      s"""Configure compiler warnings.
+    raw"""Configure compiler warnings.
          |Syntax: -Wconf:<filters>:<action>,<filters>:<action>,...
          |multiple <filters> are combined with &, i.e., <filter>&...&<filter>
          |
@@ -254,6 +254,9 @@ private sealed trait WarningSettings:
          |  - Source location: src=regex
          |    The regex is evaluated against the full source path.
          |
+         |  - Origin of warning: origin=regex
+         |    The regex must match the full name (`package.Class.method`) of the deprecated entity.
+         |
          |In verbose warning mode the compiler prints matching filters for warnings.
          |Verbose mode can be enabled globally using `-Wconf:any:verbose`, or locally
          |using the @nowarn annotation (example: `@nowarn("v") def test = try 1`).
@@ -273,6 +276,7 @@ private sealed trait WarningSettings:
          |Examples:
          |  - change every warning into an error: -Wconf:any:error
          |  - silence deprecations: -Wconf:cat=deprecation:s
+         |  - silence a deprecation: -Wconf:origin=java\.lang\.Thread\.getId:s
          |  - silence warnings in src_managed directory: -Wconf:src=src_managed/.*:s
          |
          |Note: on the command-line you might need to quote configurations containing `*` or `&`

Diff for: compiler/src/dotty/tools/dotc/report.scala

@@ -23,8 +23,8 @@ object report:
   private def issueWarning(warning: Warning)(using Context): Unit =
     ctx.reporter.report(warning)
 
-  def deprecationWarning(msg: Message, pos: SrcPos)(using Context): Unit =
-    issueWarning(new DeprecationWarning(msg, pos.sourcePos))
+  def deprecationWarning(msg: Message, pos: SrcPos, origin: String = "")(using Context): Unit =
+    issueWarning(new DeprecationWarning(msg, pos.sourcePos, origin))
 
   def migrationWarning(msg: Message, pos: SrcPos)(using Context): Unit =
     issueWarning(new MigrationWarning(msg, pos.sourcePos))

Diff for: compiler/src/dotty/tools/dotc/reporting/Diagnostic.scala

@@ -75,7 +75,8 @@ object Diagnostic:
 
   class DeprecationWarning(
     msg: Message,
-    pos: SourcePosition
+    pos: SourcePosition,
+    val origin: String
   ) extends ConditionalWarning(msg, pos) {
     def enablingOption(using Context): Setting[Boolean] = ctx.settings.deprecation
   }

Diff for: compiler/src/dotty/tools/dotc/reporting/MessageRendering.scala

@@ -15,7 +15,7 @@ import util.{ SourcePosition, NoSourcePosition }
 import util.Chars.{ LF, CR, FF, SU }
 import scala.annotation.switch
 
-import scala.collection.mutable
+import scala.collection.mutable.StringBuilder
 
 trait MessageRendering {
   import Highlight.*
@@ -209,22 +209,27 @@ trait MessageRendering {
     sb.toString
   }
 
-  private def appendFilterHelp(dia: Diagnostic, sb: mutable.StringBuilder): Unit =
-    import dia.*
+  private def appendFilterHelp(dia: Diagnostic, sb: StringBuilder): Unit =
+    import dia.msg
     val hasId = msg.errorId.errorNumber >= 0
-    val category = dia match {
-      case _: UncheckedWarning => "unchecked"
-      case _: DeprecationWarning => "deprecation"
-      case _: FeatureWarning => "feature"
-      case _ => ""
-    }
-    if (hasId || category.nonEmpty)
-      sb.append(EOL).append("Matching filters for @nowarn or -Wconf:")
-      if (hasId)
-        sb.append(EOL).append("  - id=E").append(msg.errorId.errorNumber)
-        sb.append(EOL).append("  - name=").append(msg.errorId.productPrefix.stripSuffix("ID"))
-      if (category.nonEmpty)
-        sb.append(EOL).append("  - cat=").append(category)
+    val (category, origin) = dia match
+      case _: UncheckedWarning => ("unchecked", "")
+      case w: DeprecationWarning => ("deprecation", w.origin)
+      case _: FeatureWarning => ("feature", "")
+      case _ => ("", "")
+    var entitled = false
+    def addHelp(what: String)(value: String): Unit =
+      if !entitled then
+        sb.append(EOL).append("Matching filters for @nowarn or -Wconf:")
+        entitled = true
+      sb.append(EOL).append("  - ").append(what).append(value)
+    if hasId then
+      addHelp("id=E")(msg.errorId.errorNumber.toString)
+      addHelp("name=")(msg.errorId.productPrefix.stripSuffix("ID"))
+    if category.nonEmpty then
+      addHelp("cat=")(category)
+    if origin.nonEmpty then
+      addHelp("origin=")(origin)
 
   /** The whole message rendered from `msg` */
   def messageAndPos(dia: Diagnostic)(using Context): String = {
@@ -236,7 +241,7 @@ trait MessageRendering {
       else 0
     given Level = Level(level)
     given Offset = Offset(maxLineNumber.toString.length + 2)
-    val sb = mutable.StringBuilder()
+    val sb = StringBuilder()
     val posString = posStr(pos, msg, diagnosticLevel(dia))
     if (posString.nonEmpty) sb.append(posString).append(EOL)
     if (pos.exists) {

Diff for: compiler/src/dotty/tools/dotc/reporting/WConf.scala

@@ -19,23 +19,27 @@ enum MessageFilter:
     case Deprecated => message.isInstanceOf[Diagnostic.DeprecationWarning]
     case Feature => message.isInstanceOf[Diagnostic.FeatureWarning]
     case Unchecked => message.isInstanceOf[Diagnostic.UncheckedWarning]
+    case MessageID(errorId) => message.msg.errorId == errorId
     case MessagePattern(pattern) =>
       val noHighlight = message.msg.message.replaceAll("\\e\\[[\\d;]*[^\\d;]","")
       pattern.findFirstIn(noHighlight).nonEmpty
-    case MessageID(errorId) => message.msg.errorId == errorId
     case SourcePattern(pattern) =>
       val source = message.position.orElse(NoSourcePosition).source()
       val path = source.jfile()
         .map(_.toPath.toAbsolutePath.toUri.normalize().getRawPath)
         .orElse(source.path())
       pattern.findFirstIn(path).nonEmpty
-
+    case Origin(pattern) =>
+      message match
+      case message: Diagnostic.DeprecationWarning => pattern.findFirstIn(message.origin).nonEmpty
+      case _ => false
     case None => false
 
   case Any, Deprecated, Feature, Unchecked, None
   case MessagePattern(pattern: Regex)
   case MessageID(errorId: ErrorMessageID)
   case SourcePattern(pattern: Regex)
+  case Origin(pattern: Regex)
 
 enum Action:
   case Error, Warning, Verbose, Info, Silent
@@ -96,6 +100,7 @@ object WConf:
         case _             => Left(s"unknown category: $conf")
 
       case "src" => regex(conf).map(SourcePattern.apply)
+      case "origin" => regex(conf).map(Origin.apply)
 
       case _ => Left(s"unknown filter: $filter")
     case _ => Left(s"unknown filter: $s")

Diff for: compiler/src/dotty/tools/dotc/typer/CrossVersionChecks.scala

@@ -78,7 +78,7 @@ class CrossVersionChecks extends MiniPhase:
     do
       val msg = annot.argumentConstantString(0).map(msg => s": $msg").getOrElse("")
       val since = annot.argumentConstantString(1).map(version => s" (since: $version)").getOrElse("")
-      report.deprecationWarning(em"inheritance from $psym is deprecated$since$msg", parent.srcPos)
+      report.deprecationWarning(em"inheritance from $psym is deprecated$since$msg", parent.srcPos, origin=psym.showFullName)
   }
 
   override def transformValDef(tree: ValDef)(using Context): ValDef =
@@ -171,7 +171,7 @@ object CrossVersionChecks:
     def maybeWarn(annotee: Symbol, annot: Annotation) = if !skipWarning(sym) then
       val message = annot.argumentConstantString(0).filter(!_.isEmpty).map(": " + _).getOrElse("")
       val since = annot.argumentConstantString(1).filter(!_.isEmpty).map(" since " + _).getOrElse("")
-      report.deprecationWarning(em"${annotee.showLocated} is deprecated${since}${message}", pos)
+      report.deprecationWarning(em"${annotee.showLocated} is deprecated${since}${message}", pos, origin=annotee.showFullName)
     sym.getAnnotation(defn.DeprecatedAnnot) match
       case Some(annot) => maybeWarn(sym, annot)
       case _ =>

Diff for: compiler/src/dotty/tools/dotc/typer/RefChecks.scala

@@ -484,7 +484,9 @@ object RefChecks {
       def overrideDeprecation(what: String, member: Symbol, other: Symbol, fix: String): Unit =
         report.deprecationWarning(
           em"overriding $what${infoStringWithLocation(other)} is deprecated;\n  ${infoString(member)} should be $fix.",
-          if member.owner == clazz then member.srcPos else clazz.srcPos)
+          if member.owner == clazz then member.srcPos else clazz.srcPos,
+          origin = other.showFullName
+        )
 
       def autoOverride(sym: Symbol) =
         sym.is(Synthetic) && (

Diff for: compiler/test/dotty/tools/dotc/config/ScalaSettingsTests.scala

@@ -81,7 +81,7 @@ class ScalaSettingsTests:
     val conf = sets.Wconf.valueIn(proc.sstate)
     val sut  = reporting.WConf.fromSettings(conf).getOrElse(???)
     val msg  = "There was a problem!".toMessage
-    val depr = new Diagnostic.DeprecationWarning(msg, util.NoSourcePosition)
+    val depr = new Diagnostic.DeprecationWarning(msg, util.NoSourcePosition, origin="")
     assertEquals(Action.Silent, sut.action(depr))
     val feat = new Diagnostic.FeatureWarning(msg, util.NoSourcePosition)
     assertEquals(Action.Error, sut.action(feat))
@@ -197,7 +197,7 @@ class ScalaSettingsTests:
     val proc = sets.processArguments(sumy, processAll = true, skipped = Nil)
     val conf = sets.Wconf.valueIn(proc.sstate)
     val msg  = "Don't use that!".toMessage
-    val depr = new Diagnostic.DeprecationWarning(msg, util.NoSourcePosition)
+    val depr = new Diagnostic.DeprecationWarning(msg, util.NoSourcePosition, origin="")
     val sut  = reporting.WConf.fromSettings(conf).getOrElse(???)
     assertEquals(Action.Silent, sut.action(depr))
 
@@ -293,7 +293,8 @@ class ScalaSettingsTests:
         util.SourcePosition(
           source = util.SourceFile.virtual(new URI("file:///some/path/file.scala"), ""),
           span = util.Spans.Span(1L)
-        )
+        ),
+        origin="",
       )
     )
     assertEquals(result, Right(reporting.Action.Error))

Diff for: tests/warn/deprecated-origin-verbose.check

@@ -0,0 +1,14 @@
+-- Deprecation Warning: tests/warn/deprecated-origin-verbose.scala:12:18 -----------------------------------------------
+12 |  class D extends C // warn
+   |                  ^
+   |                  class C in package p is deprecated since 1.0: Old style
+Matching filters for @nowarn or -Wconf:
+  - cat=deprecation
+  - origin=p.C
+-- Deprecation Warning: tests/warn/deprecated-origin-verbose.scala:13:20 -----------------------------------------------
+13 |  class Oil extends Crude // warn
+   |                    ^^^^^
+   |                    class Crude in package p is deprecated since 1.0: Bad style
+Matching filters for @nowarn or -Wconf:
+  - cat=deprecation
+  - origin=p.Crude

Diff for: tests/warn/deprecated-origin-verbose.scala

@@ -0,0 +1,15 @@
+//> using options -deprecation -Wconf:any:verbose
+
+package p:
+  @deprecated("Old style", since="1.0")
+  class C
+  @deprecated("Bad style", since="1.0")
+  class Crude
+
+package q:
+  import annotation.*
+  import p.*
+  class D extends C // warn
+  class Oil extends Crude // warn
+  @nowarn("""origin=p\.Crude""")
+  class Language extends Crude // nowarn obvs

Diff for: tests/warn/deprecated-origin.scala

@@ -0,0 +1,15 @@
+//> using options -deprecation -Wconf:origin=p\.C$:s
+
+package p:
+  @deprecated("Old style", since="1.0")
+  class C
+  @deprecated("Bad style", since="1.0")
+  class Crude
+
+package q:
+  import annotation.*
+  import p.*
+  class D extends C // nowarn - C$ pattern avoids matching Crude
+  class Oil extends Crude // warn
+  @nowarn("""origin=p\.Crude""")
+  class Language extends Crude // nowarn obvs