package dotty.tools
package dotc
package typer
import core._
import ast.{Trees, untpd, tpd, TreeInfo}
import util.Positions._
import util.Stats.track
import Trees.Untyped
import Mode.ImplicitsEnabled
import Contexts._
import Flags._
import Denotations._
import NameOps._
import Symbols._
import Types._
import Decorators._
import ErrorReporting._
import Trees._
import config.Config
import Names._
import StdNames._
import ProtoTypes._
import EtaExpansion._
import Inferencing._
import collection.mutable
import config.Printers._
import TypeApplications._
import language.implicitConversions
object Applications {
import tpd._
def extractorMemberType(tp: Type, name: Name, errorPos: Position = NoPosition)(implicit ctx: Context) = {
val ref = tp.member(name).suchThat(_.info.isParameterless)
if (ref.isOverloaded)
errorType(i"Overloaded reference to $ref is not allowed in extractor", errorPos)
else if (ref.info.isInstanceOf[PolyType])
errorType(i"Reference to polymorphic $ref: ${ref.info} is not allowed in extractor", errorPos)
else
ref.info.widenExpr.dealias
}
def productSelectorTypes(tp: Type, errorPos: Position = NoPosition)(implicit ctx: Context): List[Type] = {
val sels = for (n <- Iterator.from(0)) yield extractorMemberType(tp, nme.selectorName(n), errorPos)
sels.takeWhile(_.exists).toList
}
def productSelectors(tp: Type)(implicit ctx: Context): List[Symbol] = {
val sels = for (n <- Iterator.from(0)) yield tp.member(nme.selectorName(n)).symbol
sels.takeWhile(_.exists).toList
}
def getUnapplySelectors(tp: Type, args: List[untpd.Tree], pos: Position = NoPosition)(implicit ctx: Context): List[Type] =
if (args.length > 1 && !(tp.derivesFrom(defn.SeqClass))) {
val sels = productSelectorTypes(tp, pos)
if (sels.length == args.length) sels
else tp :: Nil
} else tp :: Nil
def unapplyArgs(unapplyResult: Type, unapplyFn: Tree, args: List[untpd.Tree], pos: Position = NoPosition)(implicit ctx: Context): List[Type] = {
def seqSelector = defn.RepeatedParamType.appliedTo(unapplyResult.elemType :: Nil)
def getTp = extractorMemberType(unapplyResult, nme.get, pos)
// println(s"unapply $unapplyResult ${extractorMemberType(unapplyResult, nme.isDefined)}")
if (extractorMemberType(unapplyResult, nme.isDefined, pos) isRef defn.BooleanClass) {
if (getTp.exists)
if (unapplyFn.symbol.name == nme.unapplySeq) {
val seqArg = boundsToHi(getTp.elemType)
if (seqArg.exists) return args map Function.const(seqArg)
}
else return getUnapplySelectors(getTp, args, pos)
else if (defn.isProductSubType(unapplyResult)) return productSelectorTypes(unapplyResult, pos)
}
if (unapplyResult derivesFrom defn.SeqClass) seqSelector :: Nil
else if (unapplyResult isRef defn.BooleanClass) Nil
else {
ctx.error(i"$unapplyResult is not a valid result type of an unapply method of an extractor", pos)
Nil
}
}
def wrapDefs(defs: mutable.ListBuffer[Tree], tree: Tree)(implicit ctx: Context): Tree =
if (defs != null && defs.nonEmpty) tpd.Block(defs.toList, tree) else tree
}
import Applications._
trait Applications extends Compatibility { self: Typer with Dynamic =>
import Applications._
import tpd.{ cpy => _, _ }
import untpd.cpy
import Dynamic.isDynamicMethod
/** @tparam Arg the type of arguments, could be tpd.Tree, untpd.Tree, or Type
* @param methRef the reference to the method of the application
* @param funType the type of the function part of the application
* @param args the arguments of the application
* @param resultType the expected result type of the application
*/
abstract class Application[Arg](methRef: TermRef, funType: Type, args: List[Arg], resultType: Type)(implicit ctx: Context) {
/** The type of typed arguments: either tpd.Tree or Type */
type TypedArg
/** Given an original argument and the type of the corresponding formal
* parameter, produce a typed argument.
*/
protected def typedArg(arg: Arg, formal: Type): TypedArg
/** Turn a typed tree into an argument */
protected def treeToArg(arg: Tree): Arg
/** Check that argument corresponds to type `formal` and
* possibly add it to the list of adapted arguments
*/
protected def addArg(arg: TypedArg, formal: Type): Unit
/** Is this an argument of the form `expr: _*` or a RepeatedParamType
* derived from such an argument?
*/
protected def isVarArg(arg: Arg): Boolean
/** If constructing trees, turn last `n` processed arguments into a
* `SeqLiteral` tree with element type `elemFormal`.
*/
protected def makeVarArg(n: Int, elemFormal: Type): Unit
/** If all `args` have primitive numeric types, make sure it's the same one */
protected def harmonizeArgs(args: List[TypedArg]): List[TypedArg]
/** Signal failure with given message at position of given argument */
protected def fail(msg: => String, arg: Arg): Unit
/** Signal failure with given message at position of the application itself */
protected def fail(msg: => String): Unit
protected def appPos: Position
/** The current function part, which might be affected by lifting.
*/
protected def normalizedFun: Tree
/** If constructing trees, pull out all parts of the function
* which are not idempotent into separate prefix definitions
*/
protected def liftFun(): Unit = ()
/** A flag signalling that the typechecking the application was so far successful */
private[this] var _ok = true
def ok = _ok
def ok_=(x: Boolean) = {
assert(x || ctx.reporter.errorsReported || !ctx.typerState.isCommittable) // !!! DEBUG
_ok = x
}
/** The function's type after widening and instantiating polytypes
* with polyparams in constraint set
*/
val methType = funType.widen match {
case funType: MethodType => funType
case funType: PolyType => constrained(funType).resultType
case tp => tp //was: funType
}
/** The arguments re-ordered so that each named argument matches the
* same-named formal parameter.
*/
lazy val orderedArgs =
if (hasNamedArg(args))
reorder(args.asInstanceOf[List[untpd.Tree]]).asInstanceOf[List[Arg]]
else
args
protected def init() = methType match {
case methType: MethodType =>
// apply the result type constraint, unless method type is dependent
if (!methType.isDependent) {
val savedConstraint = ctx.typerState.constraint
if (!constrainResult(methType.resultType, resultType))
if (ctx.typerState.isCommittable)
// defer the problem until after the application;
// it might be healed by an implicit conversion
assert(ctx.typerState.constraint eq savedConstraint)
else
fail(err.typeMismatchStr(methType.resultType, resultType))
}
// match all arguments with corresponding formal parameters
matchArgs(orderedArgs, methType.paramTypes, 0)
case _ =>
if (methType.isError) ok = false
else fail(s"$methString does not take parameters")
}
/** The application was successful */
def success = ok
protected def methodType = methType.asInstanceOf[MethodType]
private def methString: String = i"${methRef.symbol}: ${methType.show}"
/** Re-order arguments to correctly align named arguments */
def reorder[T >: Untyped](args: List[Trees.Tree[T]]): List[Trees.Tree[T]] = {
/** @param pnames The list of parameter names that are missing arguments
* @param args The list of arguments that are not yet passed, or that are waiting to be dropped
* @param nameToArg A map from as yet unseen names to named arguments
* @param toDrop A set of names that have already be passed as named arguments
*
* For a well-typed application we have the invariants
*
* 1. `(args diff toDrop)` can be reordered to match `pnames`
* 2. For every `(name -> arg)` in `nameToArg`, `arg` is an element of `args`
*/
def recur(pnames: List[Name], args: List[Trees.Tree[T]],
nameToArg: Map[Name, Trees.NamedArg[T]], toDrop: Set[Name]): List[Trees.Tree[T]] = pnames match {
case pname :: pnames1 if nameToArg contains pname =>
// there is a named argument for this parameter; pick it
nameToArg(pname) :: recur(pnames1, args, nameToArg - pname, toDrop + pname)
case _ =>
def pnamesRest = if (pnames.isEmpty) pnames else pnames.tail
args match {
case (arg @ NamedArg(aname, _)) :: args1 =>
if (toDrop contains aname) // argument is already passed
recur(pnames, args1, nameToArg, toDrop - aname)
else if ((nameToArg contains aname) && pnames.nonEmpty) // argument is missing, pass an empty tree
genericEmptyTree :: recur(pnames.tail, args, nameToArg, toDrop)
else { // name not (or no longer) available for named arg
def msg =
if (methodType.paramNames contains aname)
s"parameter $aname of $methString is already instantiated"
else
s"$methString does not have a parameter $aname"
fail(msg, arg.asInstanceOf[Arg])
arg :: recur(pnamesRest, args1, nameToArg, toDrop)
}
case arg :: args1 =>
arg :: recur(pnamesRest, args1, nameToArg, toDrop) // unnamed argument; pick it
case Nil => // no more args, continue to pick up any preceding named args
if (pnames.isEmpty) Nil
else recur(pnamesRest, args, nameToArg, toDrop)
}
}
val nameAssocs = for (arg @ NamedArg(name, _) <- args) yield (name, arg)
recur(methodType.paramNames, args, nameAssocs.toMap, Set())
}
/** Splice new method reference into existing application */
def spliceMeth(meth: Tree, app: Tree): Tree = app match {
case Apply(fn, args) => Apply(spliceMeth(meth, fn), args)
case TypeApply(fn, targs) => TypeApply(spliceMeth(meth, fn), targs)
case _ => meth
}
/** Find reference to default parameter getter for parameter #n in current
* parameter list, or NoType if none was found
*/
def findDefaultGetter(n: Int)(implicit ctx: Context): Tree = {
val meth = methRef.symbol.asTerm
val receiver: Tree = methPart(normalizedFun) match {
case Select(receiver, _) => receiver
case mr => mr.tpe.normalizedPrefix match {
case mr: TermRef => ref(mr)
case mr =>
if (this.isInstanceOf[TestApplication[_]])
// In this case it is safe to skolemize now; we will produce a stable prefix for the actual call.
ref(mr.narrow)
else
EmptyTree
}
}
val getterPrefix =
if ((meth is Synthetic) && meth.name == nme.apply) nme.CONSTRUCTOR else meth.name
def getterName = getterPrefix.defaultGetterName(n)
if (!meth.hasDefaultParams)
EmptyTree
else if (receiver.isEmpty) {
def findGetter(cx: Context): Tree = {
if (cx eq NoContext) EmptyTree
else if (cx.scope != cx.outer.scope &&
cx.denotNamed(meth.name).hasAltWith(_.symbol == meth)) {
val denot = cx.denotNamed(getterName)
assert(denot.exists, s"non-existent getter denotation ($denot) for getter($getterName)")
ref(TermRef(cx.owner.thisType, getterName, denot))
} else findGetter(cx.outer)
}
findGetter(ctx)
}
else {
def selectGetter(qual: Tree): Tree = {
val getterDenot = qual.tpe.member(getterName)
if (getterDenot.exists) qual.select(TermRef(qual.tpe, getterName, getterDenot))
else EmptyTree
}
if (!meth.isClassConstructor)
selectGetter(receiver)
else {
// default getters for class constructors are found in the companion object
val cls = meth.owner
val companion = cls.companionModule
receiver.tpe.baseTypeRef(cls) match {
case tp: TypeRef if companion.isTerm =>
selectGetter(ref(TermRef(tp.prefix, companion.asTerm)))
case _ =>
EmptyTree
}
}
}
}
/** Match re-ordered arguments against formal parameters
* @param n The position of the first parameter in formals in `methType`.
*/
def matchArgs(args: List[Arg], formals: List[Type], n: Int): Unit = {
if (success) formals match {
case formal :: formals1 =>
def addTyped(arg: Arg, formal: Type) =
addArg(typedArg(arg, formal), formal)
def missingArg(n: Int): Unit = {
val pname = methodType.paramNames(n)
fail(
if (pname contains '$') s"not enough arguments for $methString"
else s"missing argument for parameter $pname of $methString")
}
def tryDefault(n: Int, args1: List[Arg]): Unit = {
liftFun()
val getter = findDefaultGetter(n + numArgs(normalizedFun))
if (getter.isEmpty) missingArg(n)
else {
addTyped(treeToArg(spliceMeth(getter withPos appPos, normalizedFun)), formal)
matchArgs(args1, formals1, n + 1)
}
}
if (formal.isRepeatedParam)
args match {
case arg :: Nil if isVarArg(arg) =>
addTyped(arg, formal)
case _ =>
val elemFormal = formal.widenExpr.argTypesLo.head
val origConstraint = ctx.typerState.constraint
var typedArgs = args.map(typedArg(_, elemFormal))
val harmonizedArgs = harmonizeArgs(typedArgs)
if (harmonizedArgs ne typedArgs) {
ctx.typerState.constraint = origConstraint
typedArgs = harmonizedArgs
}
typedArgs.foreach(addArg(_, elemFormal))
makeVarArg(args.length, elemFormal)
}
else args match {
case EmptyTree :: args1 =>
tryDefault(n, args1)
case arg :: args1 =>
addTyped(arg, formal)
matchArgs(args1, formals1, n + 1)
case nil =>
tryDefault(n, args)
}
case nil =>
args match {
case arg :: args1 => fail(s"too many arguments for $methString", arg)
case nil =>
}
}
}
}
/** Subclass of Application for the cases where we are interested only
* in a "can/cannot apply" answer, without needing to construct trees or
* issue error messages.
*/
abstract class TestApplication[Arg](methRef: TermRef, funType: Type, args: List[Arg], resultType: Type)(implicit ctx: Context)
extends Application[Arg](methRef, funType, args, resultType) {
type TypedArg = Arg
type Result = Unit
/** The type of the given argument */
protected def argType(arg: Arg, formal: Type): Type
def typedArg(arg: Arg, formal: Type): Arg = arg
def addArg(arg: TypedArg, formal: Type) =
ok = ok & isCompatible(argType(arg, formal), formal)
def makeVarArg(n: Int, elemFormal: Type) = {}
def fail(msg: => String, arg: Arg) =
ok = false
def fail(msg: => String) =
ok = false
def appPos = NoPosition
lazy val normalizedFun = ref(methRef)
init()
}
/** Subclass of Application for applicability tests with type arguments and value
* argument trees.
*/
class ApplicableToTrees(methRef: TermRef, targs: List[Type], args: List[Tree], resultType: Type)(implicit ctx: Context)
extends TestApplication(methRef, methRef.widen.appliedTo(targs), args, resultType) {
def argType(arg: Tree, formal: Type): Type = normalize(arg.tpe, formal)
def treeToArg(arg: Tree): Tree = arg
def isVarArg(arg: Tree): Boolean = tpd.isWildcardStarArg(arg)
def harmonizeArgs(args: List[Tree]) = harmonize(args)
}
/** Subclass of Application for applicability tests with type arguments and value
* argument trees.
*/
class ApplicableToTreesDirectly(methRef: TermRef, targs: List[Type], args: List[Tree], resultType: Type)(implicit ctx: Context) extends ApplicableToTrees(methRef, targs, args, resultType)(ctx) {
override def addArg(arg: TypedArg, formal: Type) =
ok = ok & (argType(arg, formal) <:< formal)
}
/** Subclass of Application for applicability tests with value argument types. */
class ApplicableToTypes(methRef: TermRef, args: List[Type], resultType: Type)(implicit ctx: Context)
extends TestApplication(methRef, methRef, args, resultType) {
def argType(arg: Type, formal: Type): Type = arg
def treeToArg(arg: Tree): Type = arg.tpe
def isVarArg(arg: Type): Boolean = arg.isRepeatedParam
def harmonizeArgs(args: List[Type]) = harmonizeTypes(args)
}
/** Subclass of Application for type checking an Apply node, where
* types of arguments are either known or unknown.
*/
abstract class TypedApply[T >: Untyped](
app: untpd.Apply, fun: Tree, methRef: TermRef, args: List[Trees.Tree[T]], resultType: Type)(implicit ctx: Context)
extends Application(methRef, fun.tpe, args, resultType) {
type TypedArg = Tree
def isVarArg(arg: Trees.Tree[T]): Boolean = untpd.isWildcardStarArg(arg)
private var typedArgBuf = new mutable.ListBuffer[Tree]
private var liftedDefs: mutable.ListBuffer[Tree] = null
private var myNormalizedFun: Tree = fun
init()
def addArg(arg: Tree, formal: Type): Unit =
typedArgBuf += adaptInterpolated(arg, formal.widenExpr, EmptyTree)
def makeVarArg(n: Int, elemFormal: Type): Unit = {
val args = typedArgBuf.takeRight(n).toList
typedArgBuf.trimEnd(n)
val elemtpt = TypeTree(elemFormal)
val seqLit =
if (methodType.isJava) JavaSeqLiteral(args, elemtpt)
else SeqLiteral(args, elemtpt)
typedArgBuf += seqToRepeated(seqLit)
}
def harmonizeArgs(args: List[TypedArg]) = harmonize(args)
override def appPos = app.pos
def fail(msg: => String, arg: Trees.Tree[T]) = {
ctx.error(msg, arg.pos)
ok = false
}
def fail(msg: => String) = {
ctx.error(msg, app.pos)
ok = false
}
def normalizedFun = myNormalizedFun
override def liftFun(): Unit =
if (liftedDefs == null) {
liftedDefs = new mutable.ListBuffer[Tree]
myNormalizedFun = liftApp(liftedDefs, myNormalizedFun)
}
/** The index of the first difference between lists of trees `xs` and `ys`,
* where `EmptyTree`s in the second list are skipped.
* -1 if there are no differences.
*/
private def firstDiff[T <: Trees.Tree[_]](xs: List[T], ys: List[T], n: Int = 0): Int = xs match {
case x :: xs1 =>
ys match {
case EmptyTree :: ys1 => firstDiff(xs1, ys1, n)
case y :: ys1 => if (x ne y) n else firstDiff(xs1, ys1, n + 1)
case nil => n
}
case nil =>
ys match {
case EmptyTree :: ys1 => firstDiff(xs, ys1, n)
case y :: ys1 => n
case nil => -1
}
}
private def sameSeq[T <: Trees.Tree[_]](xs: List[T], ys: List[T]): Boolean = firstDiff(xs, ys) < 0
val result = {
var typedArgs = typedArgBuf.toList
def app0 = cpy.Apply(app)(normalizedFun, typedArgs) // needs to be a `def` because typedArgs can change later
val app1 =
if (!success) app0.withType(ErrorType)
else {
if (!sameSeq(args, orderedArgs)) {
// need to lift arguments to maintain evaluation order in the
// presence of argument reorderings.
liftFun()
val eqSuffixLength = firstDiff(app.args.reverse, orderedArgs.reverse)
val (liftable, rest) = typedArgs splitAt (typedArgs.length - eqSuffixLength)
typedArgs = liftArgs(liftedDefs, methType, liftable) ++ rest
}
if (sameSeq(typedArgs, args)) // trick to cut down on tree copying
typedArgs = args.asInstanceOf[List[Tree]]
assignType(app0, normalizedFun, typedArgs)
}
wrapDefs(liftedDefs, app1)
}
}
/** Subclass of Application for type checking an Apply node with untyped arguments. */
class ApplyToUntyped(app: untpd.Apply, fun: Tree, methRef: TermRef, proto: FunProto, resultType: Type)(implicit ctx: Context)
extends TypedApply(app, fun, methRef, proto.args, resultType) {
def typedArg(arg: untpd.Tree, formal: Type): TypedArg = proto.typedArg(arg, formal.widenExpr)
def treeToArg(arg: Tree): untpd.Tree = untpd.TypedSplice(arg)
}
/** Subclass of Application for type checking an Apply node with typed arguments. */
class ApplyToTyped(app: untpd.Apply, fun: Tree, methRef: TermRef, args: List[Tree], resultType: Type)(implicit ctx: Context)
extends TypedApply[Type](app, fun, methRef, args, resultType) {
// Dotty deviation: Dotc infers Untyped for the supercall. This seems to be according to the rules
// (of both Scala and Dotty). Untyped is legal, and a subtype of Typed, whereas TypeApply
// is invariant in the type parameter, so the minimal type should be inferred. But then typedArg does
// not match the abstract method in Application and an abstract class error results.
def typedArg(arg: tpd.Tree, formal: Type): TypedArg = arg
def treeToArg(arg: Tree): Tree = arg
}
/** If `app` is a `this(...)` constructor call, the this-call argument context,
* otherwise the current context.
*/
def argCtx(app: untpd.Tree)(implicit ctx: Context): Context =
if (untpd.isSelfConstrCall(app)) ctx.thisCallArgContext else ctx
def typedApply(tree: untpd.Apply, pt: Type)(implicit ctx: Context): Tree = {
def realApply(implicit ctx: Context): Tree = track("realApply") {
val originalProto = new FunProto(tree.args, IgnoredProto(pt), this)(argCtx(tree))
val fun1 = typedExpr(tree.fun, originalProto)
// Warning: The following lines are dirty and fragile. We record that auto-tupling was demanded as
// a side effect in adapt. If it was, we assume the tupled proto-type in the rest of the application,
// until, possibly, we have to fall back to insert an implicit on the qualifier.
// This crucially relies on he fact that `proto` is used only in a single call of `adapt`,
// otherwise we would get possible cross-talk between different `adapt` calls using the same
// prototype. A cleaner alternative would be to return a modified prototype from `adapt` together with
// a modified tree but this would be more convoluted and less efficient.
val proto = if (originalProto.isTupled) originalProto.tupled else originalProto
// If some of the application's arguments are function literals without explicitly declared
// parameter types, relate the normalized result type of the application with the
// expected type through `constrainResult`. This can add more constraints which
// help sharpen the inferred parameter types for the argument function literal(s).
// This tweak is needed to make i1378 compile.
if (tree.args.exists(untpd.isFunctionWithUnknownParamType(_)))
if (!constrainResult(fun1.tpe.widen, proto.derivedFunProto(resultType = pt)))
typr.println(i"result failure for $tree with type ${fun1.tpe.widen}, expected = $pt")
/** Type application where arguments come from prototype, and no implicits are inserted */
def simpleApply(fun1: Tree, proto: FunProto)(implicit ctx: Context): Tree =
methPart(fun1).tpe match {
case funRef: TermRef =>
val app =
if (proto.allArgTypesAreCurrent())
new ApplyToTyped(tree, fun1, funRef, proto.typedArgs, pt)
else
new ApplyToUntyped(tree, fun1, funRef, proto, pt)(argCtx(tree))
convertNewGenericArray(ConstFold(app.result))
case _ =>
handleUnexpectedFunType(tree, fun1)
}
/** Try same application with an implicit inserted around the qualifier of the function
* part. Return an optional value to indicate success.
*/
def tryWithImplicitOnQualifier(fun1: Tree, proto: FunProto)(implicit ctx: Context): Option[Tree] =
tryInsertImplicitOnQualifier(fun1, proto) flatMap { fun2 =>
tryEither {
implicit ctx => Some(simpleApply(fun2, proto)): Option[Tree]
} {
(_, _) => None
}
}
fun1.tpe match {
case ErrorType => tree.withType(ErrorType)
case TryDynamicCallType =>
tree match {
case tree @ Apply(Select(qual, name), args) if !isDynamicMethod(name) =>
typedDynamicApply(qual, name, args, pt)(tree)
case _ =>
handleUnexpectedFunType(tree, fun1)
}
case _ =>
tryEither {
implicit ctx => simpleApply(fun1, proto)
} {
(failedVal, failedState) =>
def fail = { failedState.commit(); failedVal }
// Try once with original prototype and once (if different) with tupled one.
// The reason we need to try both is that the decision whether to use tupled
// or not was already taken but might have to be revised when an implicit
// is inserted on the qualifier.
tryWithImplicitOnQualifier(fun1, originalProto).getOrElse(
if (proto eq originalProto) fail
else tryWithImplicitOnQualifier(fun1, proto).getOrElse(fail))
}
}
}
/** Convert expression like
*
* e += (args)
*
* where the lifted-for-assignment version of e is { val xs = es; e' } to
*
* { val xs = es; e' = e' + args }
*/
def typedOpAssign: Tree = track("typedOpAssign") {
val Apply(Select(lhs, name), rhss) = tree
val lhs1 = typedExpr(lhs)
val liftedDefs = new mutable.ListBuffer[Tree]
val lhs2 = untpd.TypedSplice(liftAssigned(liftedDefs, lhs1))
val assign = untpd.Assign(lhs2, untpd.Apply(untpd.Select(lhs2, name.init), rhss))
wrapDefs(liftedDefs, typed(assign))
}
if (untpd.isOpAssign(tree))
tryEither {
implicit ctx => realApply
} { (failedVal, failedState) =>
tryEither {
implicit ctx => typedOpAssign
} { (_, _) =>
failedState.commit()
failedVal
}
}
else {
val app = realApply
app match {
case Apply(fn @ Select(left, _), right :: Nil) if fn.hasType =>
val op = fn.symbol
if (op == defn.Any_== || op == defn.Any_!=)
checkCanEqual(left.tpe.widen, right.tpe.widen, app.pos)
case _ =>
}
app
}
}
/** Overridden in ReTyper to handle primitive operations that can be generated after erasure */
protected def handleUnexpectedFunType(tree: untpd.Apply, fun: Tree)(implicit ctx: Context): Tree =
throw new Error(s"unexpected type.\n fun = $fun,\n methPart(fun) = ${methPart(fun)},\n methPart(fun).tpe = ${methPart(fun).tpe},\n tpe = ${fun.tpe}")
def typedNamedArgs(args: List[untpd.Tree])(implicit ctx: Context) =
for (arg @ NamedArg(id, argtpt) <- args) yield {
val argtpt1 = typedType(argtpt)
cpy.NamedArg(arg)(id, argtpt1).withType(argtpt1.tpe)
}
def typedTypeApply(tree: untpd.TypeApply, pt: Type)(implicit ctx: Context): Tree = track("typedTypeApply") {
val isNamed = hasNamedArg(tree.args)
val typedArgs = if (isNamed) typedNamedArgs(tree.args) else tree.args.mapconserve(typedType(_))
val typedFn = typedExpr(tree.fun, PolyProto(typedArgs.tpes, pt))
typedFn.tpe.widen match {
case pt: PolyType =>
if (typedArgs.length <= pt.paramBounds.length && !isNamed)
if (typedFn.symbol == defn.Predef_classOf && typedArgs.nonEmpty) {
val arg = typedArgs.head
checkClassType(arg.tpe, arg.pos, traitReq = false, stablePrefixReq = false)
}
case _ =>
}
assignType(cpy.TypeApply(tree)(typedFn, typedArgs), typedFn, typedArgs)
}
/** Rewrite `new Array[T](....)` if T is an unbounded generic to calls to newGenericArray.
* It is performed during typer as creation of generic arrays needs a classTag.
* we rely on implicit search to find one.
*/
def convertNewGenericArray(tree: tpd.Tree)(implicit ctx: Context): tpd.Tree = tree match {
case Apply(TypeApply(tycon, targs@(targ :: Nil)), args) if tycon.symbol == defn.ArrayConstructor =>
fullyDefinedType(tree.tpe, "array", tree.pos)
def newGenericArrayCall =
ref(defn.DottyArraysModule)
.select(defn.newGenericArrayMethod).withPos(tree.pos)
.appliedToTypeTrees(targs).appliedToArgs(args)
if (TypeErasure.isUnboundedGeneric(targ.tpe))
newGenericArrayCall
else tree
case _ =>
tree
}
def typedUnApply(tree: untpd.Apply, selType: Type)(implicit ctx: Context): Tree = track("typedUnApply") {
val Apply(qual, args) = tree
def notAnExtractor(tree: Tree) =
errorTree(tree, s"${qual.show} cannot be used as an extractor in a pattern because it lacks an unapply or unapplySeq method")
/** If this is a term ref tree, try to typecheck with its type name.
* If this refers to a type alias, follow the alias, and if
* one finds a class, reference the class companion module.
*/
def followTypeAlias(tree: untpd.Tree): untpd.Tree = {
tree match {
case tree: untpd.RefTree =>
val ttree = typedType(untpd.rename(tree, tree.name.toTypeName))
ttree.tpe match {
case alias: TypeRef if alias.info.isAlias =>
companionRef(alias) match {
case companion: TermRef => return untpd.ref(companion) withPos tree.pos
case _ =>
}
case _ =>
}
case _ =>
}
untpd.EmptyTree
}
/** A typed qual.unapply or qual.unapplySeq tree, if this typechecks.
* Otherwise fallBack with (maltyped) qual.unapply as argument
* Note: requires special handling for overloaded occurrences of
* unapply or unapplySeq. We first try to find a non-overloaded
* method which matches any type. If that fails, we try to find an
* overloaded variant which matches one of the argument types.
* In fact, overloaded unapply's are problematic because a non-
* overloaded unapply does *not* need to be applicable to its argument
* whereas overloaded variants need to have a conforming variant.
*/
def trySelectUnapply(qual: untpd.Tree)(fallBack: Tree => Tree): Tree = {
val genericProto = new UnapplyFunProto(WildcardType, this)
def specificProto = new UnapplyFunProto(selType, this)
// try first for non-overloaded, then for overloaded ocurrences
def tryWithName(name: TermName)(fallBack: Tree => Tree)(implicit ctx: Context): Tree =
tryEither {
implicit ctx => typedExpr(untpd.Select(qual, name), specificProto)
} {
(sel, _) =>
tryEither {
implicit ctx => typedExpr(untpd.Select(qual, name), genericProto)
} {
(_, _) => fallBack(sel)
}
}
// try first for unapply, then for unapplySeq
tryWithName(nme.unapply) {
sel => tryWithName(nme.unapplySeq)(_ => fallBack(sel)) // for backwards compatibility; will be dropped
}
}
/** Produce a typed qual.unapply or qual.unapplySeq tree, or
* else if this fails follow a type alias and try again.
*/
val unapplyFn = trySelectUnapply(qual) { sel =>
val qual1 = followTypeAlias(qual)
if (qual1.isEmpty) notAnExtractor(sel)
else trySelectUnapply(qual1)(_ => notAnExtractor(sel))
}
def fromScala2x = unapplyFn.symbol.exists && (unapplyFn.symbol.owner is Scala2x)
/** Is `subtp` a subtype of `tp` or of some generalization of `tp`?
* The generalizations of a type T are the smallest set G such that
*
* - T is in G
* - If a typeref R in G represents a class or trait, R's superclass is in G.
* - If a type proxy P is not a reference to a class, P's supertype is in G
*/
def isSubTypeOfParent(subtp: Type, tp: Type)(implicit ctx: Context): Boolean =
if (subtp <:< tp) true
else tp match {
case tp: TypeRef if tp.symbol.isClass => isSubTypeOfParent(subtp, tp.firstParent)
case tp: TypeProxy => isSubTypeOfParent(subtp, tp.superType)
case _ => false
}
unapplyFn.tpe.widen match {
case mt: MethodType if mt.paramTypes.length == 1 =>
val unapplyArgType = mt.paramTypes.head
unapp.println(i"unapp arg tpe = $unapplyArgType, pt = $selType")
val ownType =
if (selType <:< unapplyArgType) {
unapp.println(i"case 1 $unapplyArgType ${ctx.typerState.constraint}")
selType
} else if (isSubTypeOfParent(unapplyArgType, selType)(ctx.addMode(Mode.GADTflexible))) {
maximizeType(unapplyArgType) match {
case Some(tvar) =>
def msg =
ex"""There is no best instantiation of pattern type $unapplyArgType
|that makes it a subtype of selector type $selType.
|Non-variant type variable ${tvar.origin} cannot be uniquely instantiated."""
if (fromScala2x) {
// We can't issue an error here, because in Scala 2, ::[B] is invariant
// whereas List[+T] is covariant. According to the strict rule, a pattern
// match of a List[C] against a case x :: xs is illegal, because
// B cannot be uniquely instantiated. Of course :: should have been
// covariant in the first place, but in the Scala libraries it isn't.
// So for now we allow these kinds of patterns, even though they
// can open unsoundness holes. See SI-7952 for an example of the hole this opens.
if (ctx.settings.verbose.value) ctx.warning(msg, tree.pos)
} else {
unapp.println(s" ${unapplyFn.symbol.owner} ${unapplyFn.symbol.owner is Scala2x}")
ctx.strictWarning(msg, tree.pos)
}
case _ =>
}
unapp.println(i"case 2 $unapplyArgType ${ctx.typerState.constraint}")
unapplyArgType
} else {
unapp.println("Neither sub nor super")
unapp.println(TypeComparer.explained(implicit ctx => unapplyArgType <:< selType))
errorType(
ex"Pattern type $unapplyArgType is neither a subtype nor a supertype of selector type $selType",
tree.pos)
}
val dummyArg = dummyTreeOfType(ownType)
val unapplyApp = typedExpr(untpd.TypedSplice(Apply(unapplyFn, dummyArg :: Nil)))
val unapplyImplicits = unapplyApp match {
case Apply(Apply(unapply, `dummyArg` :: Nil), args2) => assert(args2.nonEmpty); args2
case Apply(unapply, `dummyArg` :: Nil) => Nil
}
var argTypes = unapplyArgs(unapplyApp.tpe, unapplyFn, args, tree.pos)
for (argType <- argTypes) assert(!argType.isInstanceOf[TypeBounds], unapplyApp.tpe.show)
val bunchedArgs = argTypes match {
case argType :: Nil =>
if (argType.isRepeatedParam) untpd.SeqLiteral(args, untpd.TypeTree()) :: Nil
else if (args.lengthCompare(1) > 0 && ctx.canAutoTuple) untpd.Tuple(args) :: Nil
else args
case _ => args
}
if (argTypes.length != bunchedArgs.length) {
ctx.error(em"wrong number of argument patterns for $qual; expected: ($argTypes%, %)", tree.pos)
argTypes = argTypes.take(args.length) ++
List.fill(argTypes.length - args.length)(WildcardType)
}
val unapplyPatterns = (bunchedArgs, argTypes).zipped map (typed(_, _))
val result = assignType(cpy.UnApply(tree)(unapplyFn, unapplyImplicits, unapplyPatterns), ownType)
unapp.println(s"unapply patterns = $unapplyPatterns")
if ((ownType eq selType) || ownType.isError) result
else Typed(result, TypeTree(ownType))
case tp =>
val unapplyErr = if (tp.isError) unapplyFn else notAnExtractor(unapplyFn)
val typedArgsErr = args mapconserve (typed(_, defn.AnyType))
cpy.UnApply(tree)(unapplyErr, Nil, typedArgsErr) withType ErrorType
}
}
/** A typed unapply hook, can be overridden by re any-typers between frontend
* and pattern matcher.
*/
def typedUnApply(tree: untpd.UnApply, selType: Type)(implicit ctx: Context) =
throw new UnsupportedOperationException("cannot type check an UnApply node")
/** Is given method reference applicable to type arguments `targs` and argument trees `args`?
* @param resultType The expected result type of the application
*/
def isApplicable(methRef: TermRef, targs: List[Type], args: List[Tree], resultType: Type)(implicit ctx: Context): Boolean = {
val nestedContext = ctx.fresh.setExploreTyperState
new ApplicableToTrees(methRef, targs, args, resultType)(nestedContext).success
}
/** Is given method reference applicable to type arguments `targs` and argument trees `args` without inferring views?
* @param resultType The expected result type of the application
*/
def isDirectlyApplicable(methRef: TermRef, targs: List[Type], args: List[Tree], resultType: Type)(implicit ctx: Context): Boolean = {
val nestedContext = ctx.fresh.setExploreTyperState
new ApplicableToTreesDirectly(methRef, targs, args, resultType)(nestedContext).success
}
/** Is given method reference applicable to argument types `args`?
* @param resultType The expected result type of the application
*/
def isApplicable(methRef: TermRef, args: List[Type], resultType: Type)(implicit ctx: Context): Boolean = {
val nestedContext = ctx.fresh.setExploreTyperState
new ApplicableToTypes(methRef, args, resultType)(nestedContext).success
}
/** Is given type applicable to type arguments `targs` and argument trees `args`,
* possibly after inserting an `apply`?
* @param resultType The expected result type of the application
*/
def isApplicable(tp: Type, targs: List[Type], args: List[Tree], resultType: Type)(implicit ctx: Context): Boolean =
onMethod(tp, isApplicable(_, targs, args, resultType))
/** Is given type applicable to argument types `args`, possibly after inserting an `apply`?
* @param resultType The expected result type of the application
*/
def isApplicable(tp: Type, args: List[Type], resultType: Type)(implicit ctx: Context): Boolean =
onMethod(tp, isApplicable(_, args, resultType))
private def onMethod(tp: Type, p: TermRef => Boolean)(implicit ctx: Context): Boolean = tp match {
case methRef: TermRef if methRef.widenSingleton.isInstanceOf[MethodicType] =>
p(methRef)
case mt: MethodicType =>
p(mt.narrow)
case _ =>
tp.member(nme.apply).hasAltWith(d => p(TermRef(tp, nme.apply, d)))
}
/** In a set of overloaded applicable alternatives, is `alt1` at least as good as
* `alt2`? `alt1` and `alt2` are non-overloaded references.
*/
def isAsGood(alt1: TermRef, alt2: TermRef)(implicit ctx: Context): Boolean = track("isAsGood") { ctx.traceIndented(i"isAsGood($alt1, $alt2)", overload) {
assert(alt1 ne alt2)
/** Is class or module class `sym1` derived from class or module class `sym2`?
* Module classes also inherit the relationship from their companions.
*/
def isDerived(sym1: Symbol, sym2: Symbol): Boolean =
if (sym1 isSubClass sym2) true
else if (sym2 is Module) isDerived(sym1, sym2.companionClass)
else (sym1 is Module) && isDerived(sym1.companionClass, sym2)
/** Is alternative `alt1` with type `tp1` as specific as alternative
* `alt2` with type `tp2` ?
*
* 1. A method `alt1` of type (p1: T1, ..., pn: Tn)U is as specific as `alt2`
* if `alt2` is applicable to arguments (p1, ..., pn) of types T1,...,Tn
* or if `alt1` is nullary.
* 2. A polymorphic member of type [a1 >: L1 <: U1, ..., an >: Ln <: Un]T is as
* specific as `alt2` of type `tp2` if T is as specific as `tp2` under the
* assumption that for i = 1,...,n each ai is an abstract type name bounded
* from below by Li and from above by Ui.
* 3. A member of any other type `tp1` is:
* a. always as specific as a method or a polymorphic method.
* b. as specific as a member of any other type `tp2` if `tp1` is compatible
* with `tp2`.
*/
def isAsSpecific(alt1: TermRef, tp1: Type, alt2: TermRef, tp2: Type): Boolean = ctx.traceIndented(i"isAsSpecific $tp1 $tp2", overload) { tp1 match {
case tp1: MethodType => // (1)
def repeatedToSingle(tp: Type): Type = tp match {
case tp @ ExprType(tp1) => tp.derivedExprType(repeatedToSingle(tp1))
case _ => if (tp.isRepeatedParam) tp.argTypesHi.head else tp
}
val formals1 =
if (tp1.isVarArgsMethod && tp2.isVarArgsMethod) tp1.paramTypes map repeatedToSingle
else tp1.paramTypes
isApplicable(alt2, formals1, WildcardType) ||
tp1.paramTypes.isEmpty && tp2.isInstanceOf[MethodOrPoly]
case tp1: PolyType => // (2)
val tparams = ctx.newTypeParams(alt1.symbol, tp1.paramNames, EmptyFlags, tp1.instantiateBounds)
isAsSpecific(alt1, tp1.instantiate(tparams map (_.typeRef)), alt2, tp2)
case _ => // (3)
tp2 match {
case tp2: MethodType => true // (3a)
case tp2: PolyType if tp2.isPolymorphicMethodType => true // (3a)
case tp2: PolyType => // (3b)
val nestedCtx = ctx.fresh.setExploreTyperState
{
implicit val ctx: Context = nestedCtx
isAsSpecificValueType(tp1, constrained(tp2).resultType)
}
case _ => // (3b)
isAsSpecificValueType(tp1, tp2)
}
}}
/** Test whether value type `tp1` is as specific as value type `tp2`.
* Let's abbreviate this to `tp1 <:s tp2`.
* Previously, `<:s` was the same as `<:`. This behavior is still
* available under mode `Mode.OldOverloadingResolution`. The new behavior
* is different, however. Here, `T <:s U` iff
*
* flip(T) <: flip(U)
*
* where `flip` changes top-level contravariant type aliases to covariant ones.
* Intuitively `<:s` means subtyping `<:`, except that all top-level arguments
* to contravariant parameters are compared as if they were covariant. E.g. given class
*
* class Cmp[-X]
*
* `Cmp[T] <:s Cmp[U]` if `T <: U`. On the other hand, nested occurrences
* of parameters are not affected.
* So `T <: U` would imply `List[Cmp[U]] <:s List[Cmp[T]]`, as usual.
*
* This relation might seem strange, but it models closely what happens for methods.
* Indeed, if we integrate the existing rules for methods into `<:s` we have now that
*
* (T)R <:s (U)R
*
* iff
*
* T => R <:s U => R
*/
def isAsSpecificValueType(tp1: Type, tp2: Type)(implicit ctx: Context) =
if (ctx.mode.is(Mode.OldOverloadingResolution))
isCompatible(tp1, tp2)
else {
val flip = new TypeMap {
def apply(t: Type) = t match {
case t: TypeAlias if variance > 0 && t.variance < 0 => t.derivedTypeAlias(t.alias, 1)
case t: TypeBounds => t
case _ => mapOver(t)
}
}
isCompatible(flip(tp1), flip(tp2))
}
/** Drop any implicit parameter section */
def stripImplicit(tp: Type): Type = tp match {
case mt: ImplicitMethodType if !mt.isDependent =>
mt.resultType
// todo: make sure implicit method types are not dependent?
// but check test case in /tests/pos/depmet_implicit_chaining_zw.scala
case pt: PolyType =>
pt.derivedPolyType(pt.paramNames, pt.paramBounds, stripImplicit(pt.resultType))
case _ =>
tp
}
val owner1 = if (alt1.symbol.exists) alt1.symbol.owner else NoSymbol
val owner2 = if (alt2.symbol.exists) alt2.symbol.owner else NoSymbol
val tp1 = stripImplicit(alt1.widen)
val tp2 = stripImplicit(alt2.widen)
def winsOwner1 = isDerived(owner1, owner2)
def winsType1 = isAsSpecific(alt1, tp1, alt2, tp2)
def winsOwner2 = isDerived(owner2, owner1)
def winsType2 = isAsSpecific(alt2, tp2, alt1, tp1)
overload.println(i"isAsGood($alt1, $alt2)? $tp1 $tp2 $winsOwner1 $winsType1 $winsOwner2 $winsType2")
// Assume the following probabilities:
//
// P(winsOwnerX) = 2/3
// P(winsTypeX) = 1/3
//
// Then the call probabilities of the 4 basic operations are as follows:
//
// winsOwner1: 1/1
// winsOwner2: 1/1
// winsType1 : 7/9
// winsType2 : 4/9
if (winsOwner1) /* 6/9 */ !winsOwner2 || /* 4/9 */ winsType1 || /* 8/27 */ !winsType2
else if (winsOwner2) /* 2/9 */ winsType1 && /* 2/27 */ !winsType2
else /* 1/9 */ winsType1 || /* 2/27 */ !winsType2
}}
def narrowMostSpecific(alts: List[TermRef])(implicit ctx: Context): List[TermRef] = track("narrowMostSpecific") {
alts match {
case Nil => alts
case _ :: Nil => alts
case alt :: alts1 =>
def winner(bestSoFar: TermRef, alts: List[TermRef]): TermRef = alts match {
case alt :: alts1 =>
winner(if (isAsGood(alt, bestSoFar)) alt else bestSoFar, alts1)
case nil =>
bestSoFar
}
val best = winner(alt, alts1)
def asGood(alts: List[TermRef]): List[TermRef] = alts match {
case alt :: alts1 =>
if ((alt eq best) || !isAsGood(alt, best)) asGood(alts1)
else alt :: asGood(alts1)
case nil =>
Nil
}
best :: asGood(alts)
}
}
/** Resolve overloaded alternative `alts`, given expected type `pt` and
* possibly also type argument `targs` that need to be applied to each alternative
* to form the method type.
* todo: use techniques like for implicits to pick candidates quickly?
*/
def resolveOverloaded(alts: List[TermRef], pt: Type)(implicit ctx: Context): List[TermRef] = track("resolveOverloaded") {
/** Is `alt` a method or polytype whose result type after the first value parameter
* section conforms to the expected type `resultType`? If `resultType`
* is a `IgnoredProto`, pick the underlying type instead.
*/
def resultConforms(alt: Type, resultType: Type)(implicit ctx: Context): Boolean = resultType match {
case IgnoredProto(ignored) => resultConforms(alt, ignored)
case _: ValueType =>
alt.widen match {
case tp: PolyType => resultConforms(constrained(tp).resultType, resultType)
case tp: MethodType => constrainResult(tp.resultType, resultType)
case _ => true
}
case _ => true
}
/** If the `chosen` alternative has a result type incompatible with the expected result
* type `pt`, run overloading resolution again on all alternatives that do match `pt`.
* If the latter succeeds with a single alternative, return it, otherwise
* fallback to `chosen`.
*
* Note this order of events is done for speed. One might be tempted to
* preselect alternatives by result type. But is slower, because it discriminates
* less. The idea is when searching for a best solution, as is the case in overloading
* resolution, we should first try criteria which are cheap and which have a high
* probability of pruning the search. result type comparisons are neither cheap nor
* do they prune much, on average.
*/
def adaptByResult(chosen: TermRef) = {
def nestedCtx = ctx.fresh.setExploreTyperState
pt match {
case pt: FunProto if !resultConforms(chosen, pt.resultType)(nestedCtx) =>
alts.filter(alt =>
(alt ne chosen) && resultConforms(alt, pt.resultType)(nestedCtx)) match {
case Nil => chosen
case alt2 :: Nil => alt2
case alts2 =>
resolveOverloaded(alts2, pt) match {
case alt2 :: Nil => alt2
case _ => chosen
}
}
case _ => chosen
}
}
var found = resolveOverloaded(alts, pt, Nil)(ctx.retractMode(Mode.ImplicitsEnabled))
if (found.isEmpty && ctx.mode.is(Mode.ImplicitsEnabled))
found = resolveOverloaded(alts, pt, Nil)
found match {
case alt :: Nil => adaptByResult(alt) :: Nil
case _ => found
}
}
/** This private version of `resolveOverloaded` does the bulk of the work of
* overloading resolution, but does not do result adaptation. It might be
* called twice from the public `resolveOverloaded` method, once with
* implicits enabled, and once without.
*/
private def resolveOverloaded(alts: List[TermRef], pt: Type, targs: List[Type])(implicit ctx: Context): List[TermRef] = track("resolveOverloaded") {
def isDetermined(alts: List[TermRef]) = alts.isEmpty || alts.tail.isEmpty
/** The shape of given tree as a type; cannot handle named arguments. */
def typeShape(tree: untpd.Tree): Type = tree match {
case untpd.Function(args, body) =>
defn.FunctionOf(args map Function.const(defn.AnyType), typeShape(body))
case _ =>
defn.NothingType
}
/** The shape of given tree as a type; is more expensive than
* typeShape but can can handle named arguments.
*/
def treeShape(tree: untpd.Tree): Tree = tree match {
case NamedArg(name, arg) =>
val argShape = treeShape(arg)
cpy.NamedArg(tree)(name, argShape).withType(argShape.tpe)
case _ =>
dummyTreeOfType(typeShape(tree))
}
def narrowByTypes(alts: List[TermRef], argTypes: List[Type], resultType: Type): List[TermRef] =
alts filter (isApplicable(_, argTypes, resultType))
val candidates = pt match {
case pt @ FunProto(args, resultType, _) =>
val numArgs = args.length
val normArgs = args.mapConserve {
case Block(Nil, expr) => expr
case x => x
}
def sizeFits(alt: TermRef, tp: Type): Boolean = tp match {
case tp: PolyType => sizeFits(alt, tp.resultType)
case MethodType(_, ptypes) =>
val numParams = ptypes.length
def isVarArgs = ptypes.nonEmpty && ptypes.last.isRepeatedParam
def hasDefault = alt.symbol.hasDefaultParams
if (numParams == numArgs) true
else if (numParams < numArgs) isVarArgs
else if (numParams > numArgs + 1) hasDefault
else isVarArgs || hasDefault
case _ =>
numArgs == 0
}
def narrowBySize(alts: List[TermRef]): List[TermRef] =
alts filter (alt => sizeFits(alt, alt.widen))
def narrowByShapes(alts: List[TermRef]): List[TermRef] = {
if (normArgs exists (_.isInstanceOf[untpd.Function]))
if (hasNamedArg(args)) narrowByTrees(alts, args map treeShape, resultType)
else narrowByTypes(alts, normArgs map typeShape, resultType)
else
alts
}
def narrowByTrees(alts: List[TermRef], args: List[Tree], resultType: Type): List[TermRef] = {
val alts2 = alts.filter(alt =>
isDirectlyApplicable(alt, targs, args, resultType)
)
if (alts2.isEmpty && !ctx.isAfterTyper)
alts.filter(alt =>
isApplicable(alt, targs, args, resultType)
)
else
alts2
}
val alts1 = narrowBySize(alts)
//ctx.log(i"narrowed by size: ${alts1.map(_.symbol.showDcl)}%, %")
if (isDetermined(alts1)) alts1
else {
val alts2 = narrowByShapes(alts1)
//ctx.log(i"narrowed by shape: ${alts1.map(_.symbol.showDcl)}%, %")
if (isDetermined(alts2)) alts2
else {
pretypeArgs(alts2, pt)
narrowByTrees(alts2, pt.typedArgs, resultType)
}
}
case pt @ PolyProto(targs1, pt1) =>
assert(targs.isEmpty)
val alts1 = alts filter pt.isMatchedBy
resolveOverloaded(alts1, pt1, targs1)
case defn.FunctionOf(args, resultType) =>
narrowByTypes(alts, args, resultType)
case pt =>
alts filter (normalizedCompatible(_, pt))
}
val found = narrowMostSpecific(candidates)
if (found.length <= 1) found
else {
val noDefaults = alts.filter(!_.symbol.hasDefaultParams)
if (noDefaults.length == 1) noDefaults // return unique alternative without default parameters if it exists
else {
val deepPt = pt.deepenProto
if (deepPt ne pt) resolveOverloaded(alts, deepPt, targs)
else alts
}
}
}
/** Try to typecheck any arguments in `pt` that are function values missing a
* parameter type. The expected type for these arguments is the lub of the
* corresponding formal parameter types of all alternatives. Type variables
* in formal parameter types are replaced by wildcards. The result of the
* typecheck is stored in `pt`, to be retrieved when its `typedArgs` are selected.
* The benefit of doing this is to allow idioms like this:
*
* def map(f: Char => Char): String = ???
* def map[U](f: Char => U): Seq[U] = ???
* map(x => x.toUpper)
*
* Without `pretypeArgs` we'd get a "missing parameter type" error for `x`.
* With `pretypeArgs`, we use the union of the two formal parameter types
* `Char => Char` and `Char => ?` as the expected type of the closure `x => x.toUpper`.
* That union is `Char => Char`, so we have an expected parameter type `Char`
* for `x`, and the code typechecks.
*/
private def pretypeArgs(alts: List[TermRef], pt: FunProto)(implicit ctx: Context): Unit = {
def recur(altFormals: List[List[Type]], args: List[untpd.Tree]): Unit = args match {
case arg :: args1 if !altFormals.exists(_.isEmpty) =>
def isUnknownParamType(t: untpd.Tree) = t match {
case ValDef(_, tpt, _) => tpt.isEmpty
case _ => false
}
arg match {
case arg: untpd.Function if arg.args.exists(isUnknownParamType) =>
def isUniform[T](xs: List[T])(p: (T, T) => Boolean) = xs.forall(p(_, xs.head))
val formalsForArg: List[Type] = altFormals.map(_.head)
// For alternatives alt_1, ..., alt_n, test whether formal types for current argument are of the form
// (p_1_1, ..., p_m_1) => r_1
// ...
// (p_1_n, ..., p_m_n) => r_n
val decomposedFormalsForArg: List[Option[(List[Type], Type)]] =
formalsForArg.map(defn.FunctionOf.unapply)
if (decomposedFormalsForArg.forall(_.isDefined)) {
val formalParamTypessForArg: List[List[Type]] =
decomposedFormalsForArg.map(_.get._1)
if (isUniform(formalParamTypessForArg)((x, y) => x.length == y.length)) {
val commonParamTypes = formalParamTypessForArg.transpose.map(ps =>
// Given definitions above, for i = 1,...,m,
// ps(i) = List(p_i_1, ..., p_i_n) -- i.e. a column
// If all p_i_k's are the same, assume the type as formal parameter
// type of the i'th parameter of the closure.
if (isUniform(ps)(ctx.typeComparer.isSameTypeWhenFrozen(_, _))) ps.head
else WildcardType)
val commonFormal = defn.FunctionOf(commonParamTypes, WildcardType)
overload.println(i"pretype arg $arg with expected type $commonFormal")
pt.typedArg(arg, commonFormal)
}
}
case _ =>
}
recur(altFormals.map(_.tail), args1)
case _ =>
}
def paramTypes(alt: Type): List[Type] = alt match {
case mt: MethodType => mt.paramTypes
case mt: PolyType => paramTypes(mt.resultType)
case _ => Nil
}
recur(alts.map(alt => paramTypes(alt.widen)), pt.args)
}
private def harmonizeWith[T <: AnyRef](ts: List[T])(tpe: T => Type, adapt: (T, Type) => T)(implicit ctx: Context): List[T] = {
def numericClasses(ts: List[T], acc: Set[Symbol]): Set[Symbol] = ts match {
case t :: ts1 =>
val sym = tpe(t).widen.classSymbol
if (sym.isNumericValueClass) numericClasses(ts1, acc + sym)
else Set()
case Nil =>
acc
}
val clss = numericClasses(ts, Set())
if (clss.size > 1) {
val lub = defn.ScalaNumericValueTypeList.find(lubTpe =>
clss.forall(cls => defn.isValueSubType(cls.typeRef, lubTpe))).get
ts.mapConserve(adapt(_, lub))
}
else ts
}
/** If `trees` all have numeric value types, and they do not have all the same type,
* pick a common numeric supertype and convert all trees to this type.
*/
def harmonize(trees: List[Tree])(implicit ctx: Context): List[Tree] = {
def adapt(tree: Tree, pt: Type): Tree = tree match {
case cdef: CaseDef => tpd.cpy.CaseDef(cdef)(body = adapt(cdef.body, pt))
case _ => adaptInterpolated(tree, pt, tree)
}
if (ctx.isAfterTyper) trees else harmonizeWith(trees)(_.tpe, adapt)
}
/** If all `types` are numeric value types, and they are not all the same type,
* pick a common numeric supertype and return it instead of every original type.
*/
def harmonizeTypes(tpes: List[Type])(implicit ctx: Context): List[Type] =
harmonizeWith(tpes)(identity, (tp, pt) => pt)
}