Lift -Ysafe-init to -Wsafe-init

Author: rochala

Test.scala

@@ -149,7 +149,7 @@ final case class SbtCommunityProject(
 object SbtCommunityProject:
   def scalacOptions = List(
     "-Xcheck-macros",
-    "-Ysafe-init",
+    "-Wsafe-init",
   )
 
 object projects:
@@ -362,7 +362,7 @@ object projects:
     project = "shapeless-3",
     sbtTestCommand = "testJVM; testJS",
     sbtDocCommand = forceDoc("typeable", "deriving"),
-    scalacOptions = "-source" :: "3.3" :: SbtCommunityProject.scalacOptions.filter(_ != "-Ysafe-init"), // due to -Xfatal-warnings
+    scalacOptions = "-source" :: "3.3" :: SbtCommunityProject.scalacOptions.filter(!List("-Ysafe-init", "-Wsafe-init").contains), // due to -Xfatal-warnings
   )
 
   lazy val xmlInterpolator = SbtCommunityProject(
@@ -429,7 +429,7 @@ object projects:
     sbtTestCommand   = "unitTests/test",
     // Adds <empty> package
     sbtDocCommand   = "coreJVM/doc",
-    scalacOptions = SbtCommunityProject.scalacOptions.filter(_ != "-Ysafe-init"),
+    scalacOptions = SbtCommunityProject.scalacOptions.filter(!List("-Ysafe-init", "-Wsafe-init").contains),
     dependencies = List(munit, scodecBits),
   )
 
@@ -510,7 +510,7 @@ object projects:
     project = "discipline",
     sbtTestCommand = "coreJVM/test;coreJS/test",
     sbtPublishCommand = "set every credentials := Nil;coreJVM/publishLocal;coreJS/publishLocal",
-    scalacOptions = SbtCommunityProject.scalacOptions.filter(_ != "-Ysafe-init"),
+    scalacOptions = SbtCommunityProject.scalacOptions.filter(!List("-Ysafe-init", "-Wsafe-init").contains),
     dependencies = List(scalacheck)
   )
 
@@ -526,7 +526,7 @@ object projects:
     sbtTestCommand = "test",
     sbtPublishCommand = "coreJVM/publishLocal;coreJS/publishLocal",
     dependencies = List(discipline),
-    scalacOptions = SbtCommunityProject.scalacOptions.filter(_ != "-Ysafe-init")
+    scalacOptions = SbtCommunityProject.scalacOptions.filter(!List("-Ysafe-init", "-Wsafe-init").contains)
   )
 
   lazy val simulacrumScalafixAnnotations = SbtCommunityProject(
@@ -540,7 +540,7 @@ object projects:
     sbtTestCommand = "set Global/scalaJSStage := FastOptStage;rootJVM/test;rootJS/test",
     sbtPublishCommand = "rootJVM/publishLocal;rootJS/publishLocal",
     dependencies = List(discipline, disciplineMunit, scalacheck, simulacrumScalafixAnnotations),
-    scalacOptions = SbtCommunityProject.scalacOptions.filter(_ != "-Ysafe-init") // disable -Ysafe-init, due to -Xfatal-warning
+    scalacOptions = SbtCommunityProject.scalacOptions.filter(!List("-Ysafe-init", "-Wsafe-init").contains) // disable -Ysafe-init or -Wsafe-init, due to -Xfatal-warning
 
   )
 
@@ -656,7 +656,7 @@ object projects:
       """set actorTests/Compile/scalacOptions -= "-Xfatal-warnings"""",
       "akka-actor-tests/Test/compile",
     ).mkString("; "),
-    scalacOptions = SbtCommunityProject.scalacOptions.filter(_ != "-Ysafe-init"),
+    scalacOptions = SbtCommunityProject.scalacOptions.filter(!List("-Ysafe-init", "-Wsafe-init").contains),
     dependencies = List(scalatest, scalatestplusJunit, scalatestplusScalacheck)
   )
 
@@ -707,7 +707,7 @@ object projects:
     project = "fs2",
     sbtTestCommand = "coreJVM/test; coreJS/test",  // io/test requires JDK9+
     sbtPublishCommand = "coreJVM/publishLocal; coreJS/publishLocal",
-    scalacOptions = SbtCommunityProject.scalacOptions.filter(_ != "-Ysafe-init"),
+    scalacOptions = SbtCommunityProject.scalacOptions.filter(!List("-Ysafe-init", "-Wsafe-init").contains),
     dependencies = List(cats, catsEffect3, munitCatsEffect, scalacheckEffect, scodecBits)
   )
 
@@ -744,7 +744,7 @@ object projects:
     project = "http4s",
     sbtTestCommand = """set ThisBuild / tlFatalWarnings := false; rootJVM/test""",
     sbtPublishCommand = "publishLocal",
-    scalacOptions = SbtCommunityProject.scalacOptions.filter(_ != "-Ysafe-init"),
+    scalacOptions = SbtCommunityProject.scalacOptions.filter(!List("-Ysafe-init", "-Wsafe-init").contains),
     dependencies = List(cats, catsEffect3, fs2, disciplineMunit, scalacheckEffect)
   )
 

community-build/src/scala/dotty/communitybuild/projects.scala

@@ -292,6 +292,7 @@ private sealed trait WarningSettings:
     def typeParameterShadow(using Context) =
       allOr("type-parameter-shadow")
 
+  val WcheckInit: Setting[Boolean] = BooleanSetting(WarningSetting, "Wsafe-init", "Ensure safe initialization of objects.")
 
 /** -X "Extended" or "Advanced" settings */
 private sealed trait XSettings:
@@ -323,12 +324,18 @@ private sealed trait XSettings:
   val Xdumpclasses: Setting[String] = StringSetting(AdvancedSetting, "Xdump-classes", "dir", "Dump the generated bytecode to .class files (useful for reflective compilation that utilizes in-memory classloaders).", "")
   val XjarCompressionLevel: Setting[Int] = IntChoiceSetting(AdvancedSetting, "Xjar-compression-level", "compression level to use when writing jar files", Deflater.DEFAULT_COMPRESSION to Deflater.BEST_COMPRESSION, Deflater.DEFAULT_COMPRESSION)
   val XkindProjector: Setting[String] = ChoiceSetting(AdvancedSetting, "Xkind-projector", "[underscores, enable, disable]", "Allow `*` as type lambda placeholder to be compatible with kind projector. When invoked as -Xkind-projector:underscores will repurpose `_` to be a type parameter placeholder, this will disable usage of underscore as a wildcard.", List("disable", "", "underscores"), "disable", legacyArgs = true)
+
+  /** Documentation related settings */
   val XdropComments: Setting[Boolean] = BooleanSetting(AdvancedSetting, "Xdrop-docs", "Drop documentation when scanning source files.", aliases = List("-Xdrop-comments"))
   val XcookComments: Setting[Boolean] = BooleanSetting(AdvancedSetting, "Xcook-docs", "Cook the documentation (type check `@usecase`, etc.)", aliases = List("-Xcook-comments"))
   val XreadComments: Setting[Boolean] = BooleanSetting(AdvancedSetting, "Xread-docs", "Read documentation from tasty.")
+
+  /** Area-specific debug output */
   val XnoDecodeStacktraces: Setting[Boolean] = BooleanSetting(AdvancedSetting, "Xno-decode-stacktraces", "Show raw StackOverflow stacktraces, instead of decoding them into triggering operations.")
   val XnoEnrichErrorMessages: Setting[Boolean] = BooleanSetting(AdvancedSetting, "Xno-enrich-error-messages", "Show raw error messages, instead of enriching them with contextual information.")
   val XdebugMacros: Setting[Boolean] = BooleanSetting(AdvancedSetting, "Xdebug-macros", "Show debug info when quote pattern match fails")
+
+  /** Pipeline compilation options */
   val XjavaTasty: Setting[Boolean] = BooleanSetting(AdvancedSetting, "Xjava-tasty", "Pickler phase should compute TASTy for .java defined symbols for use by build tools", aliases = List("-Xpickle-java"), preferPrevious = true)
   val XearlyTastyOutput: Setting[AbstractFile] = OutputSetting(AdvancedSetting, "Xearly-tasty-output", "directory|jar", "Destination to write generated .tasty files to for use in pipelined compilation.", NoAbstractFile, aliases = List("-Xpickle-write"), preferPrevious = true)
   val XallowOutlineFromTasty: Setting[Boolean] = BooleanSetting(AdvancedSetting, "Xallow-outline-from-tasty", "Allow outline TASTy to be loaded with the -from-tasty option.")
@@ -440,7 +447,6 @@ private sealed trait YSettings:
   val YnoKindPolymorphism: Setting[Boolean] = BooleanSetting(ForkSetting, "Yno-kind-polymorphism", "Disable kind polymorphism.")
   val YexplicitNulls: Setting[Boolean] = BooleanSetting(ForkSetting, "Yexplicit-nulls", "Make reference types non-nullable. Nullable types can be expressed with unions: e.g. String|Null.")
   val YnoFlexibleTypes: Setting[Boolean] = BooleanSetting(ForkSetting, "Yno-flexible-types", "Disable turning nullable Java return types and parameter types into flexible types, which behave like abstract types with a nullable lower bound and non-nullable upper bound.")
-  val YcheckInit: Setting[Boolean] = BooleanSetting(ForkSetting, "Ysafe-init", "Ensure safe initialization of objects.")
   val YcheckInitGlobal: Setting[Boolean] = BooleanSetting(ForkSetting, "Ysafe-init-global", "Check safe initialization of global objects.")
   val YrequireTargetName: Setting[Boolean] = BooleanSetting(ForkSetting, "Yrequire-targetName", "Warn if an operator is defined without a @targetName annotation.")
   val YrecheckTest: Setting[Boolean] = BooleanSetting(ForkSetting, "Yrecheck-test", "Run basic rechecking (internal test only).")
@@ -472,4 +478,7 @@ private sealed trait YSettings:
   val YjavaTasty: Setting[Boolean] = BooleanSetting(ForkSetting, "Yjava-tasty", "Pickler phase should compute TASTy for .java defined symbols for use by build tools", aliases = List("-Ypickle-java"), preferPrevious = true, deprecation = Some(Deprecation("Use -Xjava-tasty instead.", "-Xjava-tasty")))
   val YearlyTastyOutput: Setting[AbstractFile] = OutputSetting(ForkSetting, "Yearly-tasty-output", "directory|jar", "Destination to write generated .tasty files to for use in pipelined compilation.", NoAbstractFile, aliases = List("-Ypickle-write"), preferPrevious = true, deprecation = Some(Deprecation("Use -Xearly-tasty-output instead.", "-Xearly-tasty-output")))
   val YallowOutlineFromTasty: Setting[Boolean] = BooleanSetting(ForkSetting, "Yallow-outline-from-tasty", "Allow outline TASTy to be loaded with the -from-tasty option.", deprecation = Some(Deprecation("Use -Xallow-outline-from-tasty instead.", "-Xallow-outline-from-tasty")))
+
+  // Deprecated: lifted from -Y to -W
+  val YcheckInit: Setting[Boolean] = BooleanSetting(ForkSetting, "Ysafe-init", "Ensure safe initialization of objects.", deprecation = Some(Deprecation("Use -Wsafe-init instead.", "-Wsafe-init")))
 end YSettings

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -84,7 +84,7 @@ object Symbols extends SymUtils {
       ctx.settings.YretainTrees.value ||
       denot.owner.isTerm ||                // no risk of leaking memory after a run for these
       denot.isOneOf(InlineOrProxy) ||      // need to keep inline info
-      ctx.settings.YcheckInit.value ||     // initialization check
+      ctx.settings.WcheckInit.value ||     // initialization check
       ctx.settings.YcheckInitGlobal.value
 
     /** The last denotation of this symbol */

compiler/src/dotty/tools/dotc/core/Symbols.scala

@@ -29,7 +29,7 @@ class Checker extends Phase:
   override val runsAfter = Set(Pickler.name)
 
   override def isEnabled(using Context): Boolean =
-    super.isEnabled && (ctx.settings.YcheckInit.value || ctx.settings.YcheckInitGlobal.value)
+    super.isEnabled && (ctx.settings.WcheckInit.value || ctx.settings.YcheckInitGlobal.value)
 
   def traverse(traverser: InitTreeTraverser)(using Context): Boolean = monitor(phaseName):
     val unit = ctx.compilationUnit
@@ -50,7 +50,7 @@ class Checker extends Phase:
     cancellable {
       val classes = traverser.getClasses()
 
-      if ctx.settings.YcheckInit.value then
+      if ctx.settings.WcheckInit.value then
         Semantic.checkClasses(classes)(using checkCtx)
 
       if ctx.settings.YcheckInitGlobal.value then

compiler/src/dotty/tools/dotc/transform/init/Checker.scala

@@ -31,18 +31,18 @@ class CompilationTests {
   @Test def pos: Unit = {
     implicit val testGroup: TestGroup = TestGroup("compilePos")
     var tests = List(
-      compileFilesInDir("tests/pos", defaultOptions.and("-Ysafe-init", "-Wunused:all", "-Wshadow:private-shadow", "-Wshadow:type-parameter-shadow"), FileFilter.include(TestSources.posLintingAllowlist)),
-      compileFilesInDir("tests/pos", defaultOptions.and("-Ysafe-init"), FileFilter.exclude(TestSources.posLintingAllowlist)),
+      compileFilesInDir("tests/pos", defaultOptions.and("-Wsafe-init", "-Wunused:all", "-Wshadow:private-shadow", "-Wshadow:type-parameter-shadow"), FileFilter.include(TestSources.posLintingAllowlist)),
+      compileFilesInDir("tests/pos", defaultOptions.and("-Wsafe-init"), FileFilter.exclude(TestSources.posLintingAllowlist)),
       compileFilesInDir("tests/pos-deep-subtype", allowDeepSubtypes),
       compileFilesInDir("tests/pos-special/sourcepath/outer", defaultOptions.and("-sourcepath", "tests/pos-special/sourcepath")),
       compileFile("tests/pos-special/sourcepath/outer/nested/Test4.scala", defaultOptions.and("-sourcepath", "tests/pos-special/sourcepath")),
       compileFilesInDir("tests/pos-scala2", defaultOptions.and("-source", "3.0-migration")),
       compileFilesInDir("tests/pos-custom-args/captures", defaultOptions.and("-language:experimental.captureChecking")),
       compileFile("tests/pos-special/utf8encoded.scala", defaultOptions.and("-encoding", "UTF8")),
       compileFile("tests/pos-special/utf16encoded.scala", defaultOptions.and("-encoding", "UTF16")),
-      compileDir("tests/pos-special/i18589", defaultOptions.and("-Ysafe-init").without("-Ycheck:all")),
+      compileDir("tests/pos-special/i18589", defaultOptions.and("-Wsafe-init").without("-Ycheck:all")),
       // Run tests for legacy lazy vals
-      compileFilesInDir("tests/pos", defaultOptions.and("-Ysafe-init", "-Ylegacy-lazy-vals", "-Ycheck-constraint-deps"), FileFilter.include(TestSources.posLazyValsAllowlist)),
+      compileFilesInDir("tests/pos", defaultOptions.and("-Wsafe-init", "-Ylegacy-lazy-vals", "-Ycheck-constraint-deps"), FileFilter.include(TestSources.posLazyValsAllowlist)),
       compileDir("tests/pos-special/java-param-names", defaultOptions.withJavacOnlyOptions("-parameters")),
     ) ::: (
       // TODO create a folder for capture checking tests with the stdlib, or use tests/pos-custom-args/captures under this mode?
@@ -51,7 +51,7 @@ class CompilationTests {
     )
 
     if scala.util.Properties.isJavaAtLeast("16") then
-      tests ::= compileFilesInDir("tests/pos-java16+", defaultOptions.and("-Ysafe-init"))
+      tests ::= compileFilesInDir("tests/pos-java16+", defaultOptions.and("-Wsafe-init"))
 
     aggregateTests(tests*).checkCompile()
   }
@@ -157,11 +157,11 @@ class CompilationTests {
   @Test def runAll: Unit = {
     implicit val testGroup: TestGroup = TestGroup("runAll")
     aggregateTests(
-      compileFilesInDir("tests/run", defaultOptions.and("-Ysafe-init")),
+      compileFilesInDir("tests/run", defaultOptions.and("-Wsafe-init")),
       compileFilesInDir("tests/run-deep-subtype", allowDeepSubtypes),
       compileFilesInDir("tests/run-custom-args/captures", allowDeepSubtypes.and("-language:experimental.captureChecking")),
       // Run tests for legacy lazy vals.
-      compileFilesInDir("tests/run", defaultOptions.and("-Ysafe-init", "-Ylegacy-lazy-vals", "-Ycheck-constraint-deps"), FileFilter.include(TestSources.runLazyValsAllowlist)),
+      compileFilesInDir("tests/run", defaultOptions.and("-Wsafe-init", "-Ylegacy-lazy-vals", "-Ycheck-constraint-deps"), FileFilter.include(TestSources.runLazyValsAllowlist)),
     ).checkRuns()
   }
 
@@ -225,9 +225,9 @@ class CompilationTests {
   // initialization tests
   @Test def checkInit: Unit = {
     implicit val testGroup: TestGroup = TestGroup("checkInit")
-    val options = defaultOptions.and("-Ysafe-init", "-Xfatal-warnings")
+    val options = defaultOptions.and("-Wsafe-init", "-Xfatal-warnings")
     compileFilesInDir("tests/init/neg", options).checkExpectedErrors()
-    compileFilesInDir("tests/init/warn", defaultOptions.and("-Ysafe-init")).checkWarnings()
+    compileFilesInDir("tests/init/warn", defaultOptions.and("-Wsafe-init")).checkWarnings()
     compileFilesInDir("tests/init/pos", options).checkCompile()
     compileFilesInDir("tests/init/crash", options.without("-Xfatal-warnings")).checkCompile()
     // The regression test for i12128 has some atypical classpath requirements.

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -103,6 +103,7 @@ class ScalaSettingsTests:
       createTestCase(settings.YjavaTasty            , settings.XjavaTasty),
       createTestCase(settings.YearlyTastyOutput     , settings.XearlyTastyOutput, ":./"),
       createTestCase(settings.YallowOutlineFromTasty, settings.XallowOutlineFromTasty),
+      createTestCase(settings.YcheckInit            , settings.WcheckInit),
     ).map: (deprecatedArgument, newSetting) =>
       val args = List(deprecatedArgument)
       val argSummary = ArgsSummary(settings.defaultState, args, errors = Nil, warnings = Nil)
@@ -130,6 +131,7 @@ class ScalaSettingsTests:
       createTestCase(settings.YjavaTasty            , settings.XjavaTasty),
       createTestCase(settings.YearlyTastyOutput     , settings.XearlyTastyOutput, ":./"),
       createTestCase(settings.YallowOutlineFromTasty, settings.XallowOutlineFromTasty),
+      createTestCase(settings.YcheckInit            , settings.WcheckInit),
     ).flatten.map: (deprecatedArgument, newSetting) =>
       val args = List(deprecatedArgument)
       val argSummary = ArgsSummary(settings.defaultState, args, errors = Nil, warnings = Nil)

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

@@ -85,7 +85,7 @@ val c = new C()
 // c.f == "field is null"
 ```
 
-The unsoundness above can be caught by the compiler with the option `-Ysafe-init`.
+The unsoundness above can be caught by the compiler with the option `-Wsafe-init`.
 More details can be found in [safe initialization](../other-new-features/safe-initialization.md).
 
 ## Equality

docs/_docs/reference/experimental/explicit-nulls.md

@@ -4,7 +4,7 @@ title: "Safe Initialization"
 nightlyOf: https://docs.scala-lang.org/scala3/reference/other-new-features/safe-initialization.html
 ---
 
-Scala 3 implements experimental safe initialization check, which can be enabled by the compiler option `-Ysafe-init`.
+Scala 3 implements experimental safe initialization check, which can be enabled by the compiler option `-Wsafe-init`.
 
 The design and implementation of the initialization checker is described in the
 paper _Safe object initialization, abstractly_ [3].

docs/_docs/reference/other-new-features/safe-initialization.md

@@ -4,7 +4,7 @@ title: "Safe Initialization"
 nightlyOf: https://docs.scala-lang.org/scala3/reference/other-new-features/safe-initialization.html
 ---
 
-Scala 3 implements experimental safe initialization check, which can be enabled by the compiler option `-Ysafe-init`.
+Scala 3 implements experimental safe initialization check, which can be enabled by the compiler option `-Wsafe-init`.
 
 The design and implementation of the initialization checker is described in the
 paper _Safe object initialization, abstractly_ [3].

docs/_spec/TODOreference/other-new-features/safe-initialization.md

@@ -602,8 +602,8 @@ object Build {
 
   // Settings shared between scala3-compiler and scala3-compiler-bootstrapped
   lazy val commonDottyCompilerSettings = Seq(
-       // Note: bench/profiles/projects.yml should be updated accordingly.
-       Compile / scalacOptions ++= Seq("-Yexplicit-nulls", "-Ysafe-init"),
+      // Note: bench/profiles/projects.yml should be updated accordingly.
+      Compile / scalacOptions ++= Seq("-Yexplicit-nulls"),
 
       // Use source 3.3 to avoid fatal migration warnings on scalajs-ir
       scalacOptions ++= Seq("-source", "3.3"),
@@ -880,6 +880,8 @@ object Build {
   }
 
   lazy val nonBootstrappedDottyCompilerSettings = commonDottyCompilerSettings ++ Seq(
+    // FIXME revert this to commonDottyCompilerSettings, when we bump reference version to 3.5.0
+    scalacOptions += "-Ysafe-init",
     // packageAll packages all and then returns a map with the abs location
     packageAll := Def.taskDyn { // Use a dynamic task to avoid loops when loading the settings
       Def.task {
@@ -907,6 +909,8 @@ object Build {
   )
 
   lazy val bootstrappedDottyCompilerSettings = commonDottyCompilerSettings ++ Seq(
+    // FIXME revert this to commonDottyCompilerSettings, when we bump reference version to 3.5.0
+    scalacOptions += "-Wsafe-init",
     javaOptions ++= {
       val jars = packageAll.value
       Seq(
@@ -1335,7 +1339,7 @@ object Build {
       BuildInfoPlugin.buildInfoScopedSettings(Test) ++
       BuildInfoPlugin.buildInfoDefaultSettings
 
-  lazy val presentationCompilerSettings = {
+  def presentationCompilerSettings(implicit mode: Mode) = {
     val mtagsVersion = "1.2.2+44-42e0515a-SNAPSHOT"
 
     Seq(
@@ -1349,7 +1353,11 @@ object Build {
       ivyConfigurations += SourceDeps.hide,
       transitiveClassifiers := Seq("sources"),
       scalacOptions ++= Seq("-source", "3.3"), // To avoid fatal migration warnings
-      Compile / scalacOptions ++= Seq("-Yexplicit-nulls", "-Ysafe-init"),
+      // FIXME change this to just Seq("-Yexplicit-nulls, "-Wsafe-init") when reference is set to 3.5.0
+      Compile / scalacOptions ++= (mode match {
+        case Bootstrapped => Seq("-Yexplicit-nulls", "-Wsafe-init")
+        case NonBootstrapped => Seq("-Yexplicit-nulls", "-Ysafe-init")
+      }),
       Compile / sourceGenerators += Def.task {
         val s = streams.value
         val cacheDir = s.cacheDirectory