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Make it a fatal error if erasure cannot resolve a type #16373

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Merged
merged 1 commit into from
Dec 14, 2022
+18 −6
Merged

Make it a fatal error if erasure cannot resolve a type #16373

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24 changes: 18 additions & 6 deletions compiler/src/dotty/tools/dotc/core/TypeErasure.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -591,17 +591,17 @@ class TypeErasure(sourceLanguage: SourceLanguage, semiEraseVCs: Boolean, isConst
tp
case tp: TypeRef =>
val sym = tp.symbol
if (!sym.isClass) this(tp.translucentSuperType)
else if (semiEraseVCs && isDerivedValueClass(sym)) eraseDerivedValueClass(tp)
else if (defn.isSyntheticFunctionClass(sym)) defn.functionTypeErasure(sym)
if !sym.isClass then this(checkedSuperType(tp))
else if semiEraseVCs && isDerivedValueClass(sym) then eraseDerivedValueClass(tp)
else if defn.isSyntheticFunctionClass(sym) then defn.functionTypeErasure(sym)
else eraseNormalClassRef(tp)
case tp: AppliedType =>
val tycon = tp.tycon
if (tycon.isRef(defn.ArrayClass)) eraseArray(tp)
else if (tycon.isRef(defn.PairClass)) erasePair(tp)
else if (tp.isRepeatedParam) apply(tp.translateFromRepeated(toArray = sourceLanguage.isJava))
else if (semiEraseVCs && isDerivedValueClass(tycon.classSymbol)) eraseDerivedValueClass(tp)
else apply(tp.translucentSuperType)
else this(checkedSuperType(tp))
case tp: TermRef =>
this(underlyingOfTermRef(tp))
case _: ThisType =>
Expand Down Expand Up @@ -689,6 +689,18 @@ class TypeErasure(sourceLanguage: SourceLanguage, semiEraseVCs: Boolean, isConst
tp
}

/** Like translucentSuperType, but issue a fatal error if it does not exist. */
private def checkedSuperType(tp: TypeProxy)(using Context): Type =
val tp1 = tp.translucentSuperType
if !tp1.exists then
val msg = tp.typeConstructor match
case tycon: TypeRef =>
MissingType(tycon.prefix, tycon.name).toMessage.message
case _ =>
i"Cannot resolve reference to $tp"
throw FatalError(msg)
tp1

/** Widen term ref, skipping any `()` parameter of an eventual getter. Used to erase a TermRef.
* Since getters are introduced after erasure, one would think that erasing a TermRef
* could just use `widen`. However, it's possible that the TermRef got read from a class
Expand Down Expand Up @@ -815,7 +827,7 @@ class TypeErasure(sourceLanguage: SourceLanguage, semiEraseVCs: Boolean, isConst
throw new MissingType(tp.prefix, tp.name)
val sym = tp.symbol
if (!sym.isClass) {
val info = tp.translucentSuperType
val info = checkedSuperType(tp)
if (!info.exists) assert(false, i"undefined: $tp with symbol $sym")
return sigName(info)
}
Expand All @@ -841,7 +853,7 @@ class TypeErasure(sourceLanguage: SourceLanguage, semiEraseVCs: Boolean, isConst
sigName( // todo: what about repeatedParam?
if (erasureDependsOnArgs(sym)) this(tp)
else if (sym.isClass) tp.underlying
else tp.translucentSuperType)
else checkedSuperType(tp))
case ErasedValueType(_, underlying) =>
sigName(underlying)
case JavaArrayType(elem) =>
Expand Down