Backport "Force conditional warnings when configured" to 3.3 LTS

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

@@ -159,10 +159,14 @@ abstract class Reporter extends interfaces.ReporterResult {
     unreportedWarnings = unreportedWarnings.updated(key, count + n)
 
   /** Issue the diagnostic, ignoring `-Wconf` and `@nowarn` configurations,
-   *  but still honouring `-nowarn`, `-Werror`, and conditional warnings. */
-  def issueUnconfigured(dia: Diagnostic)(using Context): Unit = dia match
+   *  but still honouring `-nowarn`, `-Werror`, and conditional warnings.
+   *
+   *  Avoid forcing elaboration of the message, but if already `forced`,
+   *  then do issue the diagnostic with usual `isHidden` check.
+   */
+  def issueUnconfigured(dia: Diagnostic, forced: Boolean = false)(using Context): Unit = dia match
     case w: Warning if ctx.settings.silentWarnings.value    =>
-    case w: ConditionalWarning if w.isSummarizedConditional =>
+    case w: ConditionalWarning if !forced && w.isSummarizedConditional =>
       val key = w.enablingOption.name
       addUnreported(key, 1)
     case _                                                  =>
@@ -204,10 +208,11 @@ abstract class Reporter extends interfaces.ReporterResult {
       dia match
         case w: Warning => WConf.parsed.action(dia) match
           case Error   => issueUnconfigured(w.toError)
-          case Warning => issueUnconfigured(toErrorIfFatal(w))
+          case Warning => issueUnconfigured(toErrorIfFatal(w), forced = true) 
           case Verbose => issueUnconfigured(toErrorIfFatal(w.setVerbose()))
           case Info    => issueUnconfigured(w.toInfo)
           case Silent  =>
+          case Default => issueUnconfigured(w)
         case _ => issueUnconfigured(dia)
 
     // `ctx.run` can be null in test, also in the repl when parsing the first line. The parser runs early, the Run is

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

@@ -49,6 +49,6 @@ class StoreReporter(outer: Reporter | Null = Reporter.NoReporter, fromTyperState
   // so that then only when the messages are unbuffered (when the reporter if flushed)
   // do they go through -Wconf, and possibly then buffered on the Run as a suspended message
   override def report(dia: Diagnostic)(using Context): Unit =
-    if fromTyperState then issueUnconfigured(dia)
+    if fromTyperState then issueUnconfigured(dia, forced = false)
     else super.report(dia)
 }

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

@@ -46,12 +46,13 @@ enum MessageFilter:
   case Origin(pattern: Regex)
 
 enum Action:
-  case Error, Warning, Verbose, Info, Silent
+  case Error, Warning, Verbose, Info, Silent, Default
 
 final case class WConf(confs: List[(List[MessageFilter], Action)]):
-  def action(message: Diagnostic): Action = confs.collectFirst {
-    case (filters, action) if filters.forall(_.matches(message)) => action
-  }.getOrElse(Action.Warning)
+  def action(message: Diagnostic): Action =
+    confs.collectFirst:
+      case (filters, action) if filters.forall(_.matches(message)) => action
+    .getOrElse(Action.Default)
 
 object WConf:
   import Action.*

compiler/src/dotty/tools/dotc/transform/Recheck.scala

@@ -351,9 +351,6 @@ abstract class Recheck extends Phase, SymTransformer:
         def toAvoid(tp: NamedType) =
            tp.symbol.is(Case) && tp.symbol.owner.isContainedIn(ctx.owner)
 
-      val rawType = recheck(tree.expr)
-      val ownType = avoidMap(rawType)
-
       // The pattern matching translation, which runs before this phase
       // sometimes instantiates return types with singleton type alternatives
       // but the returned expression is widened. We compensate by widening the expected
@@ -366,7 +363,10 @@ abstract class Recheck extends Phase, SymTransformer:
         case tp: AndOrType => tp.derivedAndOrType(widened(tp.tp1), widened(tp.tp2))
         case tp @ AnnotatedType(tp1, ann) => tp.derivedAnnotatedType(widened(tp1), ann)
         case _ => tp
-      checkConforms(ownType, widened(tree.from.symbol.returnProto), tree)
+      val expected = widened(tree.from.symbol.returnProto)
+      val rawType = recheck(tree.expr, expected)
+      val ownType = avoidMap(rawType)
+      checkConforms(ownType, expected, tree)
       defn.NothingType
     end recheckReturn
 
@@ -575,5 +575,3 @@ class TestRecheck extends Recheck:
   def phaseName: String = "recheck"
   override def isEnabled(using Context) = ctx.settings.YrecheckTest.value
   def newRechecker()(using Context): Rechecker = Rechecker(ctx)
-
-

compiler/test/dotty/tools/dotc/config/ScalaSettingsTests.scala

@@ -85,7 +85,7 @@ class ScalaSettingsTests:
     val feat = new Diagnostic.FeatureWarning(msg, util.NoSourcePosition)
     assertEquals(Action.Error, sut.action(feat))
     val warn = new Diagnostic.Warning(msg, util.NoSourcePosition)
-    assertEquals(Action.Warning, sut.action(warn))
+    assertEquals(Action.Default, sut.action(warn))
     val nowr = new Diagnostic.Warning("This is a problem.".toMessage, util.NoSourcePosition)
     assertEquals(Action.Silent, sut.action(nowr))
 
@@ -136,7 +136,7 @@ class ScalaSettingsTests:
         )
       )
     )
-    assertEquals(result, Right(reporting.Action.Warning))
+    assertEquals(Right(reporting.Action.Default), result)
 
   @Test def `WConf src filter silences warnings from a matching path for real file`: Unit =
     val result = Using.resource(Files.createTempFile("myfile", ".scala").nn) { file =>
@@ -165,8 +165,8 @@ class ScalaSettingsTests:
           )
         )
       )
-    }(Files.deleteIfExists(_))
-    assertEquals(result, Right(reporting.Action.Warning))
+    }(using Files.deleteIfExists(_))
+    assertEquals(Right(reporting.Action.Default), result)
 
   @Test def `WConf src filter reports an error on an invalid regex`: Unit =
     val result = wconfSrcFilterTest(

tests/neg-custom-args/captures/i25320a.check

@@ -0,0 +1,11 @@
+-- [E007] Type Mismatch Error: tests/neg-custom-args/captures/i25320a.scala:6:9 ----------------------------------------
+6 |    case Box(y) => y  // error
+  |         ^^^^^^^^^^^
+  |         Found:    A^{y, any}
+  |         Required: A
+  |
+  |         Note that capability `y` cannot flow into capture set {}.
+  |
+  |         where:    any is a root capability in the type of value x7
+  |
+  | longer explanation available when compiling with `-explain`

tests/neg-custom-args/captures/i25320a.scala

@@ -0,0 +1,6 @@
+import language.experimental.captureChecking
+sealed trait AbstractBox[A]
+case class Box[A](x: A) extends AbstractBox[A]
+def leak[A](x: Box[A^]): A =
+  x match
+    case Box(y) => y  // error

tests/neg-custom-args/captures/i25320b.check

@@ -0,0 +1,9 @@
+-- [E007] Type Mismatch Error: tests/neg-custom-args/captures/i25320b.scala:6:16 ---------------------------------------
+6 |    case Box(y) => Box(y)  // error
+  |                ^^^^^^^^^
+  |                Found:    Box[Foo]^'s1
+  |                Required: Box[Foo^{y}]^'s2
+  |
+  |                Note that capability `y` cannot flow into capture set {}.
+  |
+  | longer explanation available when compiling with `-explain`

tests/neg-custom-args/captures/i25320b.scala

@@ -0,0 +1,8 @@
+import language.experimental.captureChecking
+case class Foo()
+case class Box[A](x: A)
+def fooLeak(x: Box[Foo^]): Box[Foo] = {
+  x match {
+    case Box(y) => Box(y)  // error
+  }
+}

tests/neg-custom-args/captures/match-return-avoid.check

@@ -0,0 +1,9 @@
+-- [E007] Type Mismatch Error: tests/neg-custom-args/captures/match-return-avoid.scala:8:11 ----------------------------
+8 |    case y => Box(y) // error
+  |           ^^^^^^^^^
+  |           Found:    Box[Foo]^'s1
+  |           Required: Box[Foo^{y}]^'s2
+  |
+  |           Note that capability `y` cannot flow into capture set {}.
+  |
+  | longer explanation available when compiling with `-explain`

tests/neg-custom-args/captures/match-return-avoid.scala

@@ -0,0 +1,8 @@
+import language.experimental.captureChecking
+
+case class Foo()
+case class Box[A](x: A)
+
+def f(x: Foo^): Box[Foo^{}] =
+  x match
+    case y => Box(y) // error

tests/neg/i25548.scala

@@ -0,0 +1,6 @@
+//> using options -Wconf:any:error,cat=deprecation:warning -Werror
+
+class Location @deprecated("", "") (value: String)
+object Location {
+  def apply(value: String): Location = new Location(value) // nopos-error
+}

tests/warn/i25548.check

@@ -0,0 +1,4 @@
+-- Deprecation Warning: tests/warn/i25548.scala:5:43 -------------------------------------------------------------------
+5 |  def apply(value: String): Location = new Location(value) // warn
+  |                                           ^^^^^^^^
+  |                                           constructor Location in class Location is deprecated

tests/warn/i25548.scala

@@ -0,0 +1,6 @@
+//> using options -Wconf:cat=deprecation:warning
+
+class Location @deprecated("", "") (value: String)
+object Location {
+  def apply(value: String): Location = new Location(value) // warn
+}

tests/warn/i25548b.scala

@@ -0,0 +1,11 @@
+//> using options -Wconf:cat=deprecation&msg=bruh:warning
+
+class Location @deprecated("No loke", since="1.0") (value: String)
+object Location {
+  def apply(value: String): Location = new Location(value) // nopos-warn summarized 1 deprecation warning
+}
+
+class Brocation @deprecated("bruh!", since="1.0") (value: String)
+object Brocation {
+  def apply(value: String): Brocation = new Brocation(value) // warn reported deprecated since 1.0: bruh!
+}