Merge pull request #13729 from dotty-staging/wip-expnull-library

enable -Yexplicit-nulls for scala3-library

Author: olhotak

library/src/scala/IArray.scala

@@ -328,54 +328,59 @@ object IArray:
   extension [T, U >: T: ClassTag](x: T)
     def +:(arr: IArray[U]): IArray[U] = genericArrayOps(arr).prepended(x)
 
+  // For backwards compatibility with code compiled without -Yexplicit-nulls
+  private inline def mapNull[A, B](a: A, inline f: B): B =
+    if((a: A|Null) == null) null.asInstanceOf[B] else f
+
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def genericWrapArray[T](arr: IArray[T]): ArraySeq[T] =
-    if arr eq null then null else ArraySeq.unsafeWrapArray(arr)
+    mapNull(arr, ArraySeq.unsafeWrapArray(arr))
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapRefArray[T <: AnyRef](arr: IArray[T]): ArraySeq.ofRef[T] =
     // Since the JVM thinks arrays are covariant, one 0-length Array[AnyRef]
     // is as good as another for all T <: AnyRef.  Instead of creating 100,000,000
     // unique ones by way of this implicit, let's share one.
-    if (arr eq null) null
-    else if (arr.length == 0) ArraySeq.empty[AnyRef].asInstanceOf[ArraySeq.ofRef[T]]
-    else ArraySeq.ofRef(arr.asInstanceOf[Array[T]])
+    mapNull(arr,
+      if (arr.length == 0) ArraySeq.empty[AnyRef].asInstanceOf[ArraySeq.ofRef[T]]
+      else ArraySeq.ofRef(arr.asInstanceOf[Array[T]])
+    )
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapIntArray(arr: IArray[Int]): ArraySeq.ofInt =
-    if (arr ne null) new ArraySeq.ofInt(arr.asInstanceOf[Array[Int]]) else null
+    mapNull(arr, new ArraySeq.ofInt(arr.asInstanceOf[Array[Int]]))
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapDoubleIArray(arr: IArray[Double]): ArraySeq.ofDouble =
-    if (arr ne null) new ArraySeq.ofDouble(arr.asInstanceOf[Array[Double]]) else null
+    mapNull(arr, new ArraySeq.ofDouble(arr.asInstanceOf[Array[Double]]))
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapLongIArray(arr: IArray[Long]): ArraySeq.ofLong =
-    if (arr ne null) new ArraySeq.ofLong(arr.asInstanceOf[Array[Long]]) else null
+    mapNull(arr, new ArraySeq.ofLong(arr.asInstanceOf[Array[Long]]))
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapFloatIArray(arr: IArray[Float]): ArraySeq.ofFloat =
-    if (arr ne null) new ArraySeq.ofFloat(arr.asInstanceOf[Array[Float]]) else null
+    mapNull(arr, new ArraySeq.ofFloat(arr.asInstanceOf[Array[Float]]))
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapCharIArray(arr: IArray[Char]): ArraySeq.ofChar =
-    if (arr ne null) new ArraySeq.ofChar(arr.asInstanceOf[Array[Char]]) else null
+    mapNull(arr, new ArraySeq.ofChar(arr.asInstanceOf[Array[Char]]))
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapByteIArray(arr: IArray[Byte]): ArraySeq.ofByte =
-    if (arr ne null) new ArraySeq.ofByte(arr.asInstanceOf[Array[Byte]]) else null
+    mapNull(arr, new ArraySeq.ofByte(arr.asInstanceOf[Array[Byte]]))
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapShortIArray(arr: IArray[Short]): ArraySeq.ofShort =
-    if (arr ne null) new ArraySeq.ofShort(arr.asInstanceOf[Array[Short]]) else null
+    mapNull(arr, new ArraySeq.ofShort(arr.asInstanceOf[Array[Short]]))
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapBooleanIArray(arr: IArray[Boolean]): ArraySeq.ofBoolean =
-    if (arr ne null) new ArraySeq.ofBoolean(arr.asInstanceOf[Array[Boolean]]) else null
+    mapNull(arr, new ArraySeq.ofBoolean(arr.asInstanceOf[Array[Boolean]]))
 
   /** Conversion from IArray to immutable.ArraySeq */
   implicit def wrapUnitIArray(arr: IArray[Unit]): ArraySeq.ofUnit =
-    if (arr ne null) new ArraySeq.ofUnit(arr.asInstanceOf[Array[Unit]]) else null
+    mapNull(arr, new ArraySeq.ofUnit(arr.asInstanceOf[Array[Unit]]))
 
   /** Convert an array into an immutable array without copying, the original array
    *   must _not_ be mutated after this or the guaranteed immutablity of IArray will

library/src/scala/reflect/Selectable.scala

@@ -21,7 +21,7 @@ trait Selectable extends scala.Selectable:
   final def selectDynamic(name: String): Any =
     val rcls = selectedValue.getClass
     try
-      val fld = rcls.getField(name)
+      val fld = rcls.getField(name).nn
       ensureAccessible(fld)
       fld.get(selectedValue)
     catch case ex: NoSuchFieldException =>
@@ -35,7 +35,7 @@ trait Selectable extends scala.Selectable:
    */
   final def applyDynamic(name: String, paramTypes: Class[_]*)(args: Any*): Any =
     val rcls = selectedValue.getClass
-    val mth = rcls.getMethod(name, paramTypes: _*)
+    val mth = rcls.getMethod(name, paramTypes: _*).nn
     ensureAccessible(mth)
     mth.invoke(selectedValue, args.asInstanceOf[Seq[AnyRef]]: _*)
 

library/src/scala/runtime/LazyVals.scala

@@ -5,21 +5,21 @@ package scala.runtime
  */
 object LazyVals {
   private[this] val unsafe: sun.misc.Unsafe =
-      classOf[sun.misc.Unsafe].getDeclaredFields.find { field =>
-        field.getType == classOf[sun.misc.Unsafe] && {
-          field.setAccessible(true)
+      classOf[sun.misc.Unsafe].getDeclaredFields.nn.find { field =>
+        field.nn.getType == classOf[sun.misc.Unsafe] && {
+          field.nn.setAccessible(true)
           true
         }
       }
-      .map(_.get(null).asInstanceOf[sun.misc.Unsafe])
+      .map(_.nn.get(null).asInstanceOf[sun.misc.Unsafe])
       .getOrElse {
         throw new ExceptionInInitializerError {
           new IllegalStateException("Can't find instance of sun.misc.Unsafe")
         }
       }
 
   private[this] val base: Int = {
-    val processors = java.lang.Runtime.getRuntime.availableProcessors()
+    val processors = java.lang.Runtime.getRuntime.nn.availableProcessors()
     8 * processors * processors
   }
   private[this] val monitors: Array[Object] =

library/src/scala/runtime/Scala3RunTime.scala

@@ -15,7 +15,8 @@ object Scala3RunTime:
    *  Extracted to minimize the bytecode size at call site.
    */
   def nn[T](x: T | Null): x.type & T =
-    if (x == null) throw new NullPointerException("tried to cast away nullability, but value is null")
+    val isNull = x == null
+    if (isNull) throw new NullPointerException("tried to cast away nullability, but value is null")
     else x.asInstanceOf[x.type & T]
 
 end Scala3RunTime

library/src/scala/util/FromDigits.scala

@@ -135,7 +135,7 @@ object FromDigits {
         case ex: NumberFormatException => throw MalformedNumber()
       }
     if (x.isInfinite) throw NumberTooLarge()
-    if (x == 0.0f && !zeroFloat.pattern.matcher(digits).matches) throw NumberTooSmall()
+    if (x == 0.0f && !zeroFloat.pattern.matcher(digits).nn.matches) throw NumberTooSmall()
     x
   }
 
@@ -153,7 +153,7 @@ object FromDigits {
         case ex: NumberFormatException => throw MalformedNumber()
       }
     if (x.isInfinite) throw NumberTooLarge()
-    if (x == 0.0d && !zeroFloat.pattern.matcher(digits).matches) throw NumberTooSmall()
+    if (x == 0.0d && !zeroFloat.pattern.matcher(digits).nn.matches) throw NumberTooSmall()
     x
   }
 

project/Build.scala

@@ -790,6 +790,7 @@ object Build {
     (Compile / scalacOptions) ++= Seq(
       // Needed so that the library sources are visible when `dotty.tools.dotc.core.Definitions#init` is called
       "-sourcepath", (Compile / sourceDirectories).value.map(_.getAbsolutePath).distinct.mkString(File.pathSeparator),
+      "-Yexplicit-nulls",
     ),
   )