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TY: infer type of default type parameters for known stdlib items #6643

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merged 1 commit into from
Jan 13, 2021
Merged

TY: infer type of default type parameters for known stdlib items #6643

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4 changes: 2 additions & 2 deletions src/main/kotlin/org/rust/lang/core/types/infer/PatternMatching.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -98,7 +98,7 @@ fun RsPat.extractBindings(fcx: RsTypeInferenceWalker, type: Ty, defBm: RsBinding
}
is RsPatFieldKind.Shorthand -> {
val bindingType = if (fieldType is TyAdt && kind.isBox) {
fieldType.typeArguments.singleOrNull() ?: return
fieldType.typeArguments.firstOrNull() ?: return
} else {
fieldType
}
Expand All @@ -116,7 +116,7 @@ fun RsPat.extractBindings(fcx: RsTypeInferenceWalker, type: Ty, defBm: RsBinding
val (expected, bm) = type.stripReferences(defBm)
fcx.writePatTy(this, expected)
if (expected is TyAdt && expected.isBox) {
val boxed = expected.typeArguments.singleOrNull() ?: return
val boxed = expected.typeArguments.firstOrNull() ?: return
pat.extractBindings(fcx, boxed, bm)
}
}
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44 changes: 28 additions & 16 deletions src/main/kotlin/org/rust/lang/core/types/infer/TypeInferenceWalker.kt
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Expand Up @@ -1438,19 +1438,9 @@ val RsFunction.type: TyFunction
private fun Sequence<Ty>.infiniteWithTyUnknown(): Sequence<Ty> =
this + generateSequence { TyUnknown }

private fun KnownItems.findVecForElementTy(elementTy: Ty): Ty {
val ty = Vec?.declaredType ?: TyUnknown
private fun KnownItems.findVecForElementTy(elementTy: Ty): Ty = Vec.makeTy("T", elementTy)

val typeParameter = ty.getTypeParameter("T") ?: return ty
return ty.substitute(mapOf(typeParameter to elementTy).toTypeSubst())
}

private fun KnownItems.findOptionForElementTy(elementTy: Ty): Ty {
val ty = Option?.declaredType ?: TyUnknown

val typeParameter = ty.getTypeParameter("T") ?: return ty
return ty.substitute(mapOf(typeParameter to elementTy).toTypeSubst())
}
private fun KnownItems.findOptionForElementTy(elementTy: Ty): Ty = Option.makeTy("T", elementTy)

private fun KnownItems.findRangeTy(rangeName: String, indexType: Ty?): Ty {
val ty = findItem<RsNamedElement>("core::ops::$rangeName")?.asTy() ?: TyUnknown
Expand All @@ -1461,10 +1451,32 @@ private fun KnownItems.findRangeTy(rangeName: String, indexType: Ty?): Ty {
return ty.substitute(mapOf(typeParameter to indexType).toTypeSubst())
}

private fun KnownItems.makeBox(innerTy: Ty): Ty {
val box = Box ?: return TyUnknown
val boxTy = TyAdt.valueOf(box)
return boxTy.substitute(mapOf(boxTy.typeArguments[0] as TyTypeParameter to innerTy).toTypeSubst())
private fun KnownItems.makeBox(innerTy: Ty): Ty = Box.makeTy("T", innerTy)

private fun <T> T?.makeTy(typeParamName: String, innerTy: Ty): Ty where T : RsTypeDeclarationElement,
T : RsGenericDeclaration {
if (this == null) return TyUnknown
val itemTy = declaredType

val typeParameter = itemTy.getTypeParameter(typeParamName) ?: return itemTy
val substitutionMap = mutableMapOf(typeParameter to innerTy)

val typeParameters = typeParameters
if (typeParameters.size > 1) {
// Potentially, it's O(n^2) if item contains O(n) type parameters with default value.
// But all known stdlib items contain at most one type parameter with default value
// so it doesn't matter
for (param in typeParameters) {
val name = param.name ?: continue
val typeReference = param.typeReference ?: continue
if (name != typeParamName) {
val typeParam = itemTy.getTypeParameter(name) ?: continue
substitutionMap[typeParam] = typeReference.type
}
}
}

return itemTy.substitute(substitutionMap.toTypeSubst())
}

private fun KnownItems.makeGenerator(yieldTy: Ty, returnTy: Ty): Ty {
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