Intercepted methods transformer

    Replace member references for:
    methods inside Any( == and !=)
    ## on primitives
    .getClass on primitives

5 files changed, 163 insertions, 7 deletions

diff --git a/src/dotty/tools/dotc/Compiler.scala b/src/dotty/tools/dotc/Compiler.scala
index 1e8f13578..8bcd919c2 100644
--- a/src/dotty/tools/dotc/Compiler.scala
+++ b/src/dotty/tools/dotc/Compiler.scala
@@ -21,7 +21,7 @@ class Compiler {
     List(
       List(new FrontEnd),
       List(new LazyValsCreateCompanionObjects, new PatternMatcher),    //force separataion between lazyVals and LVCreateCO
-      List(new LazyValTranformContext().transformer, new Splitter, new TypeTestsCasts),
+      List(new LazyValTranformContext().transformer, new Splitter, new TypeTestsCasts, new InterceptedMethods),
       List(new Erasure),
       List(new UncurryTreeTransform)
     )
diff --git a/src/dotty/tools/dotc/core/Contexts.scala b/src/dotty/tools/dotc/core/Contexts.scala
index b0214a631..d6852fe13 100644
--- a/src/dotty/tools/dotc/core/Contexts.scala
+++ b/src/dotty/tools/dotc/core/Contexts.scala
@@ -205,7 +205,8 @@ object Contexts {
 
     final def withPhase(phase: Phase): Context =
       withPhase(phase.id)
-  /** If -Ydebug is on, the top of the stack trace where this context
+
+   /** If -Ydebug is on, the top of the stack trace where this context
      *  was created, otherwise `null`.
      */
     private var creationTrace: Array[StackTraceElement] = _
@@ -298,6 +299,7 @@ object Contexts {
       setCreationTrace()
       this
     }
+
     /** A fresh clone of this context. */
     def fresh: FreshContext = clone.asInstanceOf[FreshContext].init(this)
 
diff --git a/src/dotty/tools/dotc/core/Definitions.scala b/src/dotty/tools/dotc/core/Definitions.scala
index 46878d3ca..40fd33671 100644
--- a/src/dotty/tools/dotc/core/Definitions.scala
+++ b/src/dotty/tools/dotc/core/Definitions.scala
@@ -126,6 +126,7 @@ class Definitions {
 
   lazy val AnyValClass: ClassSymbol = ctx.requiredClass("scala.AnyVal")
 
+    lazy val AnyVal_getClass     = AnyValClass.requiredMethod(nme.getClass_)
     lazy val Any_==       = newMethod(AnyClass, nme.EQ, methOfAny(BooleanType), Final)
     lazy val Any_!=       = newMethod(AnyClass, nme.NE, methOfAny(BooleanType), Final)
     lazy val Any_equals   = newMethod(AnyClass, nme.equals_, methOfAny(BooleanType))
@@ -154,6 +155,7 @@ class Definitions {
     ScalaPackageClass, tpnme.Null, AbstractFinal, List(ObjectClass.typeRef))
 
   lazy val ScalaPredefModule = ctx.requiredModule("scala.Predef")
+  lazy val ScalaRuntimeModule = ctx.requiredModule("scala.runtime.ScalaRunTime")
   lazy val DottyPredefModule = ctx.requiredModule("dotty.DottyPredef")
   lazy val NilModule = ctx.requiredModule("scala.collection.immutable.Nil")
 
@@ -170,7 +172,7 @@ class Definitions {
 
   lazy val UnitClass = valueClassSymbol("scala.Unit", BoxedUnitClass, java.lang.Void.TYPE, UnitEnc)
   lazy val BooleanClass = valueClassSymbol("scala.Boolean", BoxedBooleanClass, java.lang.Boolean.TYPE, BooleanEnc)
-
+    lazy val Boolean_! = BooleanClass.requiredMethod(nme.UNARY_!)
     lazy val Boolean_and = BooleanClass.requiredMethod(nme.ZAND)
 
   lazy val ByteClass = valueClassSymbol("scala.Byte", BoxedByteClass, java.lang.Byte.TYPE, ByteEnc)
@@ -178,6 +180,12 @@ class Definitions {
   lazy val CharClass = valueClassSymbol("scala.Char", BoxedCharClass, java.lang.Character.TYPE, CharEnc)
   lazy val IntClass = valueClassSymbol("scala.Int", BoxedIntClass, java.lang.Integer.TYPE, IntEnc)
   lazy val LongClass = valueClassSymbol("scala.Long", BoxedLongClass, java.lang.Long.TYPE, LongEnc)
+    lazy val Long_XOR_Long = LongClass.info.member(nme.XOR).requiredSymbol(
+      x => (x is Method) && (x.info.firstParamTypes.head isRef defn.LongClass)
+    )
+    lazy val Long_LSR_Int = LongClass.info.member(nme.LSR).requiredSymbol(
+      x => (x is Method) && (x.info.firstParamTypes.head isRef defn.IntClass)
+    )
   lazy val FloatClass = valueClassSymbol("scala.Float", BoxedFloatClass, java.lang.Float.TYPE, FloatEnc)
   lazy val DoubleClass = valueClassSymbol("scala.Double", BoxedDoubleClass, java.lang.Double.TYPE, DoubleEnc)
 
@@ -421,9 +429,7 @@ class Definitions {
 
   // ----- primitive value class machinery ------------------------------------------
 
-  lazy val ScalaValueClasses: collection.Set[Symbol] = Set(
-    UnitClass,
-    BooleanClass,
+  lazy val ScalaNumericValueClasses: collection.Set[Symbol] =  Set(
     ByteClass,
     ShortClass,
     CharClass,
@@ -431,6 +437,8 @@ class Definitions {
     LongClass,
     FloatClass,
     DoubleClass)
+  
+  lazy val ScalaValueClasses: collection.Set[Symbol] = ScalaNumericValueClasses + UnitClass + BooleanClass
 
   lazy val ScalaBoxedClasses = ScalaValueClasses map boxedClass
 
diff --git a/src/dotty/tools/dotc/transform/InterceptedMethods.scala b/src/dotty/tools/dotc/transform/InterceptedMethods.scala
new file mode 100644
index 000000000..b56985ffe
--- /dev/null
+++ b/src/dotty/tools/dotc/transform/InterceptedMethods.scala
@@ -0,0 +1,145 @@
+package dotty.tools.dotc
+package transform
+
+import TreeTransforms._
+import core.DenotTransformers._
+import core.Denotations._
+import core.SymDenotations._
+import core.Contexts._
+import core.Types._
+import ast.Trees._
+import ast.tpd.{Apply, Tree, cpy}
+import dotty.tools.dotc.ast.tpd
+import scala.collection.mutable
+import dotty.tools.dotc._
+import core._
+import Contexts._
+import Symbols._
+import Decorators._
+import NameOps._
+import dotty.tools.dotc.transform.TreeTransforms.{TransformerInfo, TreeTransformer, TreeTransform}
+import dotty.tools.dotc.ast.Trees._
+import dotty.tools.dotc.ast.{untpd, tpd}
+import dotty.tools.dotc.core.Constants.Constant
+import dotty.tools.dotc.core.Types.MethodType
+import dotty.tools.dotc.core.Names.Name
+import dotty.runtime.LazyVals
+import scala.collection.mutable.ListBuffer
+import dotty.tools.dotc.core.Denotations.SingleDenotation
+import dotty.tools.dotc.core.SymDenotations.SymDenotation
+import dotty.tools.dotc.core.DenotTransformers.DenotTransformer
+import StdNames._
+
+/** Replace member references as follows:
+  *
+  * - `x == y` for == in class Any becomes `x equals y` with equals in class Object.
+  * - `x != y` for != in class Any becomes `!(x equals y)` with equals in class Object.
+  * - `x.##` for ## in other classes becomes calls to ScalaRunTime.hash,
+  *     using the most precise overload available
+  * - `x.getClass` for getClass in primitives becomes `x.getClass` with getClass in class Object.
+  */
+class InterceptedMethods extends TreeTransform {
+
+  import tpd._
+
+  override def name: String = "intercepted"
+
+  private var getClassMethods: Set[Symbol] = _
+  private var poundPoundMethods: Set[Symbol] = _
+  private var Any_comparisons: Set[Symbol] = _
+  private var interceptedMethods: Set[Symbol] = _
+  private var primitiveGetClassMethods: Set[Symbol] = _
+
+  /** perform context-dependant initialization */
+  override def init(implicit ctx: Context, info: TransformerInfo): Unit = {
+    getClassMethods =  Set(defn.Any_getClass, defn.AnyVal_getClass)
+    poundPoundMethods = Set(defn.Any_##, defn.Object_##)
+    Any_comparisons = Set(defn.Any_==, defn.Any_!=)
+    interceptedMethods = getClassMethods ++ poundPoundMethods ++ Any_comparisons
+    primitiveGetClassMethods = Set[Symbol](defn.Any_getClass, defn.AnyVal_getClass) ++
+      defn.ScalaValueClasses.map(x => x.requiredMethod(nme.getClass_))
+  }
+
+  // this should be removed if we have guarantee that ## will get Apply node
+  override def transformSelect(tree: tpd.Select)(implicit ctx: Context, info: TransformerInfo): Tree = {
+    if (tree.symbol.isTerm && poundPoundMethods.contains(tree.symbol.asTerm)) {
+      val rewrite = PoundPoundValue(tree.qualifier)
+      ctx.log(s"$name rewrote $tree to $rewrite")
+      rewrite
+    }
+    else tree
+  }
+
+  private def PoundPoundValue(tree: Tree)(implicit ctx: Context) = {
+    val s = tree.tpe.widen.typeSymbol
+    if (s == defn.NullClass) Literal(Constant(0))
+    else {
+      // Since we are past typer, we need to avoid creating trees carrying
+      // overloaded types.  This logic is custom (and technically incomplete,
+      // although serviceable) for def hash.  What is really needed is for
+      // the overloading logic presently hidden away in a few different
+      // places to be properly exposed so we can just call "resolveOverload"
+      // after typer.  Until then:
+
+      def alts = defn.ScalaRuntimeModule.info.member(nme.hash_)
+
+      // if tpe is a primitive value type, alt1 will match on the exact value,
+      // taking in account that null.asInstanceOf[Int] == 0
+      def alt1 = alts.suchThat(_.info.firstParamTypes.head =:= tree.tpe.widen)
+
+      // otherwise alt2 will match. alt2 also knows how to handle 'null' runtime value
+      def alt2 = defn.ScalaRuntimeModule.info.member(nme.hash_)
+        .suchThat(_.info.firstParamTypes.head.typeSymbol == defn.AnyClass)
+
+      if (defn.ScalaNumericValueClasses contains s) {
+        tpd.Apply(Ident(alt1.termRef), List(tree))
+      } else tpd.Apply(Ident(alt2.termRef), List(tree))
+    }
+  }
+
+  override def transformApply(tree: Apply)(implicit ctx: Context, info: TransformerInfo): Tree = {
+    def unknown = {
+      assert(false, s"The symbol '${tree.fun.symbol}' was interecepted but didn't match any cases, " +
+        s"that means the intercepted methods set doesn't match the code")
+      tree
+    }
+    if (tree.fun.symbol.isTerm && tree.args.isEmpty &&
+        (interceptedMethods contains tree.fun.symbol.asTerm)) {
+      val rewrite: Tree = tree.fun match {
+        case Select(qual, name) =>
+          if (poundPoundMethods contains tree.fun.symbol.asTerm) {
+            PoundPoundValue(qual)
+          } else if (Any_comparisons contains tree.fun.symbol.asTerm) {
+            if (tree.fun.symbol eq defn.Any_==) {
+              Apply(Select(qual, defn.Object_equals.termRef), tree.args)
+            } else if (tree.fun.symbol eq defn.Any_!=) {
+              Select(Apply(Select(qual, defn.Object_equals.termRef), tree.args), defn.Boolean_!.termRef)
+            } else unknown
+          } /* else if (isPrimitiveValueClass(qual.tpe.typeSymbol)) {
+            // todo: this is needed to support value classes
+            // Rewrite 5.getClass to ScalaRunTime.anyValClass(5)
+            global.typer.typed(gen.mkRuntimeCall(nme.anyValClass,
+              List(qual, typer.resolveClassTag(tree.pos, qual.tpe.widen))))
+          }*/
+          else if (primitiveGetClassMethods.contains(tree.fun.symbol)) {
+            // if we got here then we're trying to send a primitive getClass method to either
+            // a) an Any, in which cage Object_getClass works because Any erases to object. Or
+            //
+            // b) a non-primitive, e.g. because the qualifier's type is a refinement type where one parent
+            //    of the refinement is a primitive and another is AnyRef. In that case
+            //    we get a primitive form of _getClass trying to target a boxed value
+            //    so we need replace that method name with Object_getClass to get correct behavior.
+            //    See SI-5568.
+            Apply(Select(qual, defn.Object_getClass.termRef), Nil)
+          } else {
+            unknown
+          }
+        case _ =>
+          unknown
+      }
+      ctx.log(s"$name rewrote $tree to $rewrite")
+      rewrite
+    }
+    else tree
+  }
+}
diff --git a/src/dotty/tools/dotc/transform/TypeTestsCasts.scala b/src/dotty/tools/dotc/transform/TypeTestsCasts.scala
index cbd521210..aba674d1c 100644
--- a/src/dotty/tools/dotc/transform/TypeTestsCasts.scala
+++ b/src/dotty/tools/dotc/transform/TypeTestsCasts.scala
@@ -15,7 +15,8 @@ import typer.ErrorReporting._
 import ast.Trees._
 import Erasure.Boxing.box
 
-/** This transform normalizes type tests and type casts.
+/** This transform normalizes type tests and type casts,
+ *  also replacing type tests with singleton argument type with refference equality check
  *  Any remaining type tests
  *   - use the object methods $isInstanceOf and $asInstanceOf
  *   - have a reference type as receiver