Use 3.0.0-M1 nightly as a reference compiler

compiler/src/dotty/tools/backend/jvm/BCodeAsmCommon.scala

@@ -11,7 +11,7 @@ import dotty.tools.dotc.report
  * the compiler cake (Global).
  */
 final class BCodeAsmCommon[I <: DottyBackendInterface](val interface: I) {
-  import interface.{_, given _}
+  import interface.{_, given}
   import DottyBackendInterface.symExtensions
 
   /**

compiler/src/dotty/tools/backend/jvm/BCodeBodyBuilder.scala

@@ -33,7 +33,7 @@ trait BCodeBodyBuilder extends BCodeSkelBuilder {
   // import global._
   // import definitions._
   import tpd._
-  import int.{_, given _}
+  import int.{_, given}
   import DottyBackendInterface.symExtensions
   import bTypes._
   import coreBTypes._

compiler/src/dotty/tools/backend/jvm/BCodeHelpers.scala

@@ -47,7 +47,7 @@ trait BCodeHelpers extends BCodeIdiomatic with BytecodeWriters {
   import bTypes._
   import tpd._
   import coreBTypes._
-  import int.{_, given _}
+  import int.{_, given}
   import DottyBackendInterface._
 
   def ScalaATTRName: String = "Scala"
@@ -468,7 +468,7 @@ trait BCodeHelpers extends BCodeIdiomatic with BytecodeWriters {
   } // end of trait BCAnnotGen
 
   trait BCJGenSigGen {
-    import int.{_, given _}
+    import int.{_, given}
 
     def getCurrentCUnit(): CompilationUnit
 

compiler/src/dotty/tools/backend/jvm/BCodeIdiomatic.scala

@@ -20,7 +20,7 @@ trait BCodeIdiomatic {
   val int: DottyBackendInterface
   final lazy val bTypes = new BTypesFromSymbols[int.type](int)
 
-  import int.{_, given _}
+  import int.{_, given}
   import bTypes._
   import coreBTypes._
 

compiler/src/dotty/tools/backend/jvm/BCodeSkelBuilder.scala

@@ -31,7 +31,7 @@ import dotty.tools.dotc.transform.SymUtils._
  *
  */
 trait BCodeSkelBuilder extends BCodeHelpers {
-  import int.{_, given _}
+  import int.{_, given}
   import DottyBackendInterface.{symExtensions, _}
   import tpd._
   import bTypes._

compiler/src/dotty/tools/backend/jvm/BCodeSyncAndTry.scala

@@ -18,7 +18,7 @@ import dotty.tools.dotc.ast.tpd.TreeOps
  *
  */
 trait BCodeSyncAndTry extends BCodeBodyBuilder {
-  import int.{_, given _}
+  import int.{_, given}
   import tpd._
   import bTypes._
   import coreBTypes._

compiler/src/dotty/tools/backend/jvm/BTypes.scala

@@ -15,7 +15,7 @@ import scala.tools.asm
 abstract class BTypes {
 
   val int: DottyBackendInterface
-  import int.{_, given _}
+  import int.{_, given}
   /**
    * A map from internal names to ClassBTypes. Every ClassBType is added to this map on its
    * construction.

compiler/src/dotty/tools/backend/jvm/BTypesFromSymbols.scala

@@ -28,7 +28,7 @@ import dotty.tools.dotc.util.WeakHashSet
  * not have access to the compiler instance.
  */
 class BTypesFromSymbols[I <: DottyBackendInterface](val int: I) extends BTypes {
-  import int.{_, given _}
+  import int.{_, given}
   import DottyBackendInterface.{symExtensions, _}
 
   lazy val TransientAttr = requiredClass[scala.transient]

compiler/src/dotty/tools/backend/jvm/BytecodeWriters.scala

@@ -20,7 +20,7 @@ class FileConflictException(msg: String, val file: AbstractFile) extends IOExcep
  */
 trait BytecodeWriters {
   val int: DottyBackendInterface
-  import int.{_, given _}
+  import int.{_, given}
 
   /**
    * @param clsName cls.getName

compiler/src/dotty/tools/backend/jvm/CoreBTypes.scala

@@ -33,7 +33,7 @@ import dotty.tools.dotc.transform.Erasure
  */
 class CoreBTypes[BTFS <: BTypesFromSymbols[_ <: DottyBackendInterface]](val bTypes: BTFS) {
   import bTypes._
-  import int.{_, given _}
+  import int.{_, given}
   import DottyBackendInterface._
 
   //import global._

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

@@ -5,7 +5,7 @@ package config
 import core._
 import Contexts._, Symbols._, Names._, NameOps._, Phases._
 import StdNames.nme
-import Decorators.{_, given _}
+import Decorators.{_, given}
 import util.SrcPos
 import SourceVersion._
 import reporting.Message

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

@@ -5,7 +5,7 @@ package config
 import core.Contexts._
 import core.Names.TermName
 import core.StdNames.nme
-import core.Decorators.{_, given _}
+import core.Decorators.{_, given}
 import util.Property
 
 enum SourceVersion:

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

@@ -16,7 +16,7 @@ import ast.untpd
 import Flags.GivenOrImplicit
 import util.{NoSource, SimpleIdentityMap, SourceFile, HashSet}
 import typer.{Implicits, ImportInfo, Inliner, SearchHistory, SearchRoot, TypeAssigner, Typer, Nullables}
-import Nullables.{NotNullInfo, given _}
+import Nullables.{NotNullInfo, given}
 import Implicits.ContextualImplicits
 import config.Settings._
 import config.Config

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -3117,8 +3117,9 @@ object Parsers {
             case GIVEN =>
               val start = in.skipToken()
               if in.token == USCORE then
+                deprecationWarning(em"`given _` is deprecated in imports; replace with just `given`", start)
                 in.nextToken()
-                ImportSelector(givenSelectorId(start)) // Let the selector span all of `given _`; needed for -Ytest-pickler
+                ImportSelector(givenSelectorId(start)) // Let the selector span all of `given`; needed for -Ytest-pickler
               else if canStartTypeTokens.contains(in.token) then
                 ImportSelector(givenSelectorId(start), bound = rejectWildcardType(infixType()))
               else

compiler/src/dotty/tools/dotc/semanticdb/ExtractSemanticDB.scala

@@ -21,7 +21,7 @@ import dotty.tools.dotc.transform.SymUtils._
 
 import PartialFunction.condOpt
 
-import ast.untpd.{given _}
+import ast.untpd.given
 import NameOps._
 
 import scala.annotation.{ threadUnsafe => tu, tailrec }
@@ -32,8 +32,8 @@ import scala.annotation.{ threadUnsafe => tu, tailrec }
  *  TODO: Also extract type information
  */
 class ExtractSemanticDB extends Phase:
-  import Scala3.{_, given _}
-  import Symbols.{given _}
+  import Scala3.{_, given}
+  import Symbols.given
 
   override val phaseName: String = ExtractSemanticDB.name
 

compiler/src/dotty/tools/dotc/semanticdb/Tools.scala

@@ -4,7 +4,7 @@ import java.nio.file._
 import java.nio.charset.StandardCharsets
 import scala.collection.JavaConverters._
 import dotty.tools.dotc.util.SourceFile
-import dotty.tools.dotc.semanticdb.Scala3.{_, given _}
+import dotty.tools.dotc.semanticdb.Scala3.{_, given}
 
 object Tools:
 

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -27,7 +27,7 @@ import Inferencing._
 import reporting._
 import transform.TypeUtils._
 import transform.SymUtils._
-import Nullables.{postProcessByNameArgs, given _}
+import Nullables.{postProcessByNameArgs, given}
 import config.Feature
 
 import collection.mutable

compiler/src/dotty/tools/dotc/typer/Docstrings.scala

@@ -3,7 +3,7 @@ package dotc
 package typer
 
 import core._
-import Contexts._, Symbols._, Decorators._, Comments.{_, given _}
+import Contexts._, Symbols._, Decorators._, Comments.{_, given}
 import ast.tpd
 
 object Docstrings {

compiler/src/dotty/tools/dotc/typer/Inliner.scala

@@ -23,7 +23,7 @@ import config.Printers.inlining
 import ErrorReporting.errorTree
 import dotty.tools.dotc.util.{SimpleIdentityMap, SimpleIdentitySet, EqHashMap, SourceFile, SourcePosition, SrcPos}
 import dotty.tools.dotc.parsing.Parsers.Parser
-import Nullables.{given _}
+import Nullables.given
 
 import collection.mutable
 import reporting.trace

compiler/src/dotty/tools/dotc/typer/Namer.scala

@@ -6,7 +6,7 @@ import core._
 import ast._
 import Trees._, StdNames._, Scopes._, Denotations._, NamerOps._, ContextOps._
 import Contexts._, Symbols._, Types._, SymDenotations._, Names._, NameOps._, Flags._
-import Decorators._, Comments.{_, given _}
+import Decorators._, Comments.{_, given}
 import NameKinds.DefaultGetterName
 import TypeApplications.TypeParamInfo
 import ast.desugar, ast.desugar._

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -44,7 +44,7 @@ import NavigateAST._
 import transform.SymUtils._
 import transform.TypeUtils._
 import reporting._
-import Nullables.{NotNullInfo, given _}
+import Nullables.{NotNullInfo, given}
 import NullOpsDecorator._
 
 object Typer {

compiler/test/dotty/tools/dotc/parsing/ModifiersParsingTest.scala

@@ -74,7 +74,7 @@ object ModifiersParsingTest {
 
 
 class ModifiersParsingTest {
-  import ModifiersParsingTest.{_, given _}
+  import ModifiersParsingTest.{_, given}
 
 
   @Test def valDef = {

compiler/test/dotty/tools/dotc/semanticdb/SemanticdbTests.scala

@@ -19,7 +19,7 @@ import org.junit.experimental.categories.Category
 
 import dotty.BootstrappedOnlyTests
 import dotty.tools.dotc.Main
-import dotty.tools.dotc.semanticdb.Scala3.{given _}
+import dotty.tools.dotc.semanticdb.Scala3.given
 import dotty.tools.dotc.util.SourceFile
 
 @main def updateExpect =

doc-tool/src/dotty/tools/dottydoc/util/syntax.scala

@@ -3,7 +3,7 @@ package dottydoc
 package util
 
 import dotc.core.Contexts.{Context, ctx}
-import dotc.core.Comments.{_, given _}
+import dotc.core.Comments.{_, given}
 import model.Package
 import core.ContextDottydoc
 import dotc.core.Symbols._

project/Build.scala

@@ -53,7 +53,7 @@ object MyScalaJSPlugin extends AutoPlugin {
 }
 
 object Build {
-  val referenceVersion = "0.27.0-RC1"
+  val referenceVersion = "3.0.0-M1-bin-20201021-97da3cb-NIGHTLY"
 
   val baseVersion = "3.0.0-M1"
   val baseSbtDottyVersion = "0.4.5"

tests/neg/i9928.scala

@@ -9,7 +9,7 @@ object Magic:
 
 opaque type Foo = String
 object Foo:
-  import Magic.{given _}
+  import Magic.given
   def apply(s: String): Foo = s
 
   given Magic[Foo]:

tests/run/i9928.scala

@@ -12,7 +12,7 @@ object test1:
 
   opaque type Foo = String
   object Foo extends LowPrio:
-    import Magic.{given _}
+    import Magic.given
     def apply(s: String): Foo = s
 
     given Magic[Foo]:
@@ -32,7 +32,7 @@ object test2:
 
   opaque type Foo = String
   object Foo extends LowPrio:
-    import Magic.{given _}
+    import Magic.given
     def apply(s: String): Foo = s
 
     def test: Unit =