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Avoid "missing parameter type" error when checking isMatchedBy #4165

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merged 2 commits into from
Mar 24, 2018
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Avoid "missing parameter type" error when checking isMatchedBy #4165

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9b32b8a
Avoid "missing parameter type" error when checking `isMatchedBy`
odersky Mar 23, 2018
3889333
Fix typo
odersky Mar 23, 2018
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30 changes: 21 additions & 9 deletions compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -212,7 +212,7 @@ object ProtoTypes {
private[this] var evalState: SimpleIdentityMap[untpd.Tree, (TyperState, Constraint)] = SimpleIdentityMap.Empty

def isMatchedBy(tp: Type)(implicit ctx: Context) =
typer.isApplicable(tp, Nil, typedArgs, resultType)
typer.isApplicable(tp, Nil, unforcedTypedArgs, resultType)

def derivedFunProto(args: List[untpd.Tree] = this.args, resultType: Type, typer: Typer = this.typer) =
if ((args eq this.args) && (resultType eq this.resultType) && (typer eq this.typer)) this
Expand Down Expand Up @@ -240,33 +240,45 @@ object ProtoTypes {
myTypedArg.size == args.length
}

private def cacheTypedArg(arg: untpd.Tree, typerFn: untpd.Tree => Tree)(implicit ctx: Context): Tree = {
private def cacheTypedArg(arg: untpd.Tree, typerFn: untpd.Tree => Tree, force: Boolean)(implicit ctx: Context): Tree = {
var targ = myTypedArg(arg)
if (targ == null) {
targ = typerFn(arg)
if (!ctx.reporter.hasPending) {
myTypedArg = myTypedArg.updated(arg, targ)
evalState = evalState.updated(arg, (ctx.typerState, ctx.typerState.constraint))
if (!force && untpd.functionWithUnknownParamType(arg).isDefined)
// If force = false, assume ? rather than reporting an error.
// That way we don't cause a "missing parameter" error in `typerFn(arg)`
targ = arg.withType(WildcardType)
else {
targ = typerFn(arg)
if (!ctx.reporter.hasPending) {
myTypedArg = myTypedArg.updated(arg, targ)
evalState = evalState.updated(arg, (ctx.typerState, ctx.typerState.constraint))
}
}
}
targ
}

/** The typed arguments. This takes any arguments already typed using
* `typedArg` into account.
* @param force if true try to typecheck arguments even if they are functions
* with unknown parameter types - this will then cause a
* "missing parameter type" error
*/
def typedArgs: List[Tree] = {
private def typedArgs(force: Boolean): List[Tree] = {
if (myTypedArgs.size != args.length)
myTypedArgs = args.mapconserve(cacheTypedArg(_, typer.typed(_)))
myTypedArgs = args.mapconserve(cacheTypedArg(_, typer.typed(_), force))
myTypedArgs
}

def typedArgs: List[Tree] = typedArgs(force = true)
def unforcedTypedArgs: List[Tree] = typedArgs(force = false)

/** Type single argument and remember the unadapted result in `myTypedArg`.
* used to avoid repeated typings of trees when backtracking.
*/
def typedArg(arg: untpd.Tree, formal: Type)(implicit ctx: Context): Tree = {
val locked = ctx.typerState.ownedVars
val targ = cacheTypedArg(arg, typer.typedUnadapted(_, formal, locked))
val targ = cacheTypedArg(arg, typer.typedUnadapted(_, formal, locked), force = true)
typer.adapt(targ, formal, locked)
}

Expand Down