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package dotty.tools
package dotc
package ast
import core._
import util.Positions._, Types._, Contexts._, Constants._, Names._, Flags._
import SymDenotations._, Symbols._, StdNames._, Annotations._, Trees._
// TODO: revise, integrate in a checking phase.
object CheckTrees {
import tpd._
def check(p: Boolean, msg: => String = "")(implicit ctx: Context): Unit = assert(p, msg)
def checkTypeArg(arg: Tree, bounds: TypeBounds)(implicit ctx: Context): Unit = {
check(arg.isValueType)
check(bounds contains arg.tpe)
}
def escapingRefs(block: Block)(implicit ctx: Context): collection.Set[NamedType] = {
var hoisted: Set[Symbol] = Set()
lazy val locals = ctx.typeAssigner.localSyms(block.stats).toSet
def isLocal(sym: Symbol): Boolean =
(locals contains sym) && !isHoistableClass(sym)
def isHoistableClass(sym: Symbol) =
sym.isClass && {
(hoisted contains sym) || {
hoisted += sym
!classLeaks(sym.asClass)
}
}
def leakingTypes(tp: Type): collection.Set[NamedType] =
tp namedPartsWith (tp => isLocal(tp.symbol))
def typeLeaks(tp: Type): Boolean = leakingTypes(tp).nonEmpty
def classLeaks(sym: ClassSymbol): Boolean =
(ctx.owner is Method) || // can't hoist classes out of method bodies
(sym.info.parents exists typeLeaks) ||
(sym.decls.toList exists (t => typeLeaks(t.info)))
leakingTypes(block.tpe)
}
def checkType(tree: Tree)(implicit ctx: Context): Unit = tree match {
case Ident(name) =>
case Select(qualifier, name) =>
check(qualifier.isValue)
check(qualifier.tpe =:= tree.tpe.normalizedPrefix)
val denot = qualifier.tpe.member(name)
check(denot.exists)
check(denot.hasAltWith(_.symbol == tree.symbol))
case This(cls) =>
case Super(qual, mixin) =>
check(qual.isValue)
val cls = qual.tpe.typeSymbol
check(cls.isClass)
case Apply(fn, args) =>
def checkArg(arg: Tree, name: Name, formal: Type): Unit = {
arg match {
case NamedArg(argName, _) =>
check(argName == name)
case _ =>
check(arg.isValue)
}
check(arg.tpe <:< formal)
}
val MethodType(paramNames, paramTypes) = fn.tpe.widen // checked already at construction
(args, paramNames, paramTypes).zipped foreach checkArg
case TypeApply(fn, args) =>
val pt @ PolyType(_) = fn.tpe.widen // checked already at construction
(args, pt.instantiateBounds(args map (_.tpe))).zipped foreach checkTypeArg
case Literal(const: Constant) =>
case New(tpt) =>
check(tpt.isValueType)
val cls = tpt.tpe.typeSymbol
check(cls.isClass)
check(!(cls is AbstractOrTrait))
case Pair(left, right) =>
check(left.isValue)
check(right.isValue)
case Typed(expr, tpt) =>
check(tpt.isValueType)
expr.tpe.widen match {
case tp: MethodType =>
val cls = tpt.tpe.typeSymbol
check(cls.isClass)
check((cls is Trait) ||
cls.primaryConstructor.info.paramTypess.flatten.isEmpty)
val absMembers = tpt.tpe.abstractTermMembers
check(absMembers.size == 1)
check(tp <:< absMembers.head.info)
case _ =>
check(expr.isValueOrPattern)
check(expr.tpe <:< tpt.tpe.translateParameterized(defn.RepeatedParamClass, defn.SeqClass))
}
case NamedArg(name, arg) =>
case Assign(lhs, rhs) =>
check(lhs.isValue); check(rhs.isValue)
lhs.tpe match {
case ltpe: TermRef =>
check(ltpe.symbol is Mutable)
case _ =>
check(false)
}
check(rhs.tpe <:< lhs.tpe.widen)
case tree @ Block(stats, expr) =>
check(expr.isValue)
check(escapingRefs(tree).isEmpty)
case If(cond, thenp, elsep) =>
check(cond.isValue); check(thenp.isValue); check(elsep.isValue)
check(cond.tpe isRef defn.BooleanClass)
case Closure(env, meth, target) =>
meth.tpe.widen match {
case mt @ MethodType(_, paramTypes) =>
if (target.isEmpty) {
check(env.length < paramTypes.length)
for ((arg, formal) <- env zip paramTypes)
check(arg.tpe <:< formal)
}
else
// env is stored in class, not method
target.tpe match {
case SAMType(targetMeth) =>
check(mt <:< targetMeth.info)
}
}
case Match(selector, cases) =>
check(selector.isValue)
// are any checks that relate selector and patterns desirable?
case CaseDef(pat, guard, body) =>
check(pat.isValueOrPattern); check(guard.isValue); check(body.isValue)
check(guard.tpe.derivesFrom(defn.BooleanClass))
case Return(expr, from) =>
check(expr.isValue); check(from.isTerm)
check(from.tpe.termSymbol.isRealMethod)
case Try(block, handler, finalizer) =>
check(block.isTerm)
check(finalizer.isTerm)
check(handler.isTerm)
check(handler.tpe derivesFrom defn.FunctionClass(1))
check(handler.tpe.baseArgInfos(defn.FunctionClass(1)).head <:< defn.ThrowableType)
case Throw(expr) =>
check(expr.isValue)
check(expr.tpe.derivesFrom(defn.ThrowableClass))
case SeqLiteral(elems) =>
val elemtp = tree.tpe.elemType
for (elem <- elems) {
check(elem.isValue)
check(elem.tpe <:< elemtp)
}
case TypeTree(original) =>
if (!original.isEmpty) {
check(original.isValueType)
check(original.tpe == tree.tpe)
}
case SingletonTypeTree(ref) =>
check(ref.isValue)
check(ref.symbol.isStable)
case SelectFromTypeTree(qualifier, name) =>
check(qualifier.isValueType)
check(qualifier.tpe =:= tree.tpe.normalizedPrefix)
val denot = qualifier.tpe.member(name)
check(denot.exists)
check(denot.symbol == tree.symbol)
case AndTypeTree(left, right) =>
check(left.isValueType); check(right.isValueType)
case OrTypeTree(left, right) =>
check(left.isValueType); check(right.isValueType)
case RefinedTypeTree(tpt, refinements) =>
check(tpt.isValueType)
def checkRefinements(forbidden: Set[Symbol], rs: List[Tree]): Unit = rs match {
case r :: rs1 =>
val rsym = r.symbol
check(rsym.isTerm || rsym.isAbstractOrAliasType)
if (rsym.isAbstractType) check(tpt.tpe.member(rsym.name).exists)
check(rsym.info forallParts {
case nt: NamedType => !(forbidden contains nt.symbol)
case _ => true
})
checkRefinements(forbidden - rsym, rs1)
case nil =>
}
checkRefinements(ctx.typeAssigner.localSyms(refinements).toSet, refinements)
case AppliedTypeTree(tpt, args) =>
check(tpt.isValueType)
val tparams = tpt.tpe.typeParams
check(sameLength(tparams, args))
(args, tparams map (_.info.bounds)).zipped foreach checkTypeArg
case TypeBoundsTree(lo, hi) =>
check(lo.isValueType); check(hi.isValueType)
check(lo.tpe <:< hi.tpe)
case Bind(sym, body) =>
check(body.isValueOrPattern)
check(!(tree.symbol is Method))
body match {
case Ident(nme.WILDCARD) =>
case _ => check(body.tpe.widen =:= tree.symbol.info)
}
case Alternative(alts) =>
for (alt <- alts) check(alt.isValueOrPattern)
case UnApply(fun, implicits, args) => // todo: review
check(fun.isTerm)
for (arg <- args) check(arg.isValueOrPattern)
val funtpe @ MethodType(_, _) = fun.tpe.widen
fun.symbol.name match { // check arg arity
case nme.unapplySeq =>
// args need to be wrapped in (...: _*)
check(args.length == 1)
check(args.head.isInstanceOf[SeqLiteral])
case nme.unapply =>
val rtp = funtpe.resultType
if (rtp isRef defn.BooleanClass)
check(args.isEmpty)
else {
check(rtp isRef defn.OptionClass)
val normArgs = rtp.argTypesHi match {
case optionArg :: Nil =>
optionArg.argTypesHi match {
case Nil =>
optionArg :: Nil
case tupleArgs if defn.isTupleType(optionArg) =>
tupleArgs
}
case _ =>
check(false)
Nil
}
check(sameLength(normArgs, args))
}
}
case ValDef(mods, name, tpt, rhs) =>
check(!(tree.symbol is Method))
if (!rhs.isEmpty) {
check(rhs.isValue)
check(rhs.tpe <:< tpt.tpe)
}
case DefDef(mods, name, tparams, vparamss, tpt, rhs) =>
check(tree.symbol is Method)
if (!rhs.isEmpty) {
check(rhs.isValue)
check(rhs.tpe <:< tpt.tpe)
}
case TypeDef(mods, name, tpt) =>
check(tpt.isInstanceOf[Template] || tpt.tpe.isInstanceOf[TypeBounds])
case Template(constr, parents, selfType, body) =>
case Import(expr, selectors) =>
check(expr.isValue)
check(expr.tpe.termSymbol.isStable)
case PackageDef(pid, stats) =>
check(pid.isTerm)
check(pid.symbol is Package)
case Annotated(annot, arg) =>
check(annot.isInstantiation)
check(annot.symbol.owner.isSubClass(defn.AnnotationClass))
check(arg.isValueType || arg.isValue)
case EmptyTree =>
}
}
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