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Support re-aliasing of type alias instantiations #42284

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Merged
ahejlsberg merged 5 commits into from
Jan 11, 2021
Merged

Support re-aliasing of type alias instantiations #42284

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a4a47db
New aliases for type alias instantiations
ahejlsberg Jan 9, 2021
0c6dfb7
New aliases for conditional, mapped, and anonymous object type instan…
ahejlsberg Jan 9, 2021
54da2a4
Accept new baselines
ahejlsberg Jan 9, 2021
1b0d12e
Fix issues with re-aliasing
ahejlsberg Jan 11, 2021
8ac7030
Accept new baselines
ahejlsberg Jan 11, 2021
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Fix issues with re-aliasing
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@ahejlsberg
ahejlsberg committed Jan 11, 2021
commit 1b0d12ea503ad8bc9d692137a3fdd2f300124784
36 changes: 19 additions & 17 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -12361,15 +12361,18 @@ namespace ts {
return type;
}

function createDeferredTypeReference(target: GenericType, node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, mapper?: TypeMapper): DeferredTypeReference {
const aliasSymbol = getAliasSymbolForTypeNode(node);
const aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol);
function createDeferredTypeReference(target: GenericType, node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, mapper?: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): DeferredTypeReference {
if (!aliasSymbol) {
aliasSymbol = getAliasSymbolForTypeNode(node);
const localAliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol);
aliasTypeArguments = mapper ? instantiateTypes(localAliasTypeArguments, mapper) : localAliasTypeArguments;
}
const type = <DeferredTypeReference>createObjectType(ObjectFlags.Reference, target.symbol);
type.target = target;
type.node = node;
type.mapper = mapper;
type.aliasSymbol = aliasSymbol;
type.aliasTypeArguments = mapper ? instantiateTypes(aliasTypeArguments, mapper) : aliasTypeArguments;
type.aliasTypeArguments = aliasTypeArguments;
return type;
}

Expand Down Expand Up @@ -15460,17 +15463,19 @@ namespace ts {
// instantiation cache key from the type IDs of the type arguments.
const combinedMapper = combineTypeMappers(type.mapper, mapper);
const typeArguments = map(typeParameters, t => getMappedType(t, combinedMapper));
const id = getTypeListId(typeArguments) + (aliasSymbol ? `@${getSymbolId(aliasSymbol)}` : "");
const newAliasSymbol = aliasSymbol || type.aliasSymbol;
const id = getTypeListId(typeArguments) + (newAliasSymbol ? `@${getSymbolId(newAliasSymbol)}` : "");
if (!target.instantiations) {
target.instantiations = new Map<string, Type>();
target.instantiations.set(getTypeListId(typeParameters), target);
target.instantiations.set(getTypeListId(typeParameters) + (target.aliasSymbol ? `@${getSymbolId(target.aliasSymbol)}` : ""), target);
}
let result = target.instantiations.get(id);
if (!result) {
const newMapper = createTypeMapper(typeParameters, typeArguments);
result = target.objectFlags & ObjectFlags.Reference ? createDeferredTypeReference((<DeferredTypeReference>type).target, (<DeferredTypeReference>type).node, newMapper) :
target.objectFlags & ObjectFlags.Mapped ? instantiateMappedType(<MappedType>target, newMapper, aliasSymbol, aliasTypeArguments) :
instantiateAnonymousType(target, newMapper, aliasSymbol, aliasTypeArguments);
const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper);
result = target.objectFlags & ObjectFlags.Reference ? createDeferredTypeReference((<DeferredTypeReference>type).target, (<DeferredTypeReference>type).node, newMapper, newAliasSymbol, newAliasTypeArguments) :
target.objectFlags & ObjectFlags.Mapped ? instantiateMappedType(<MappedType>target, newMapper, newAliasSymbol, newAliasTypeArguments) :
instantiateAnonymousType(target, newMapper, newAliasSymbol, newAliasTypeArguments);
target.instantiations.set(id, result);
}
return result;
Expand Down Expand Up @@ -15694,15 +15699,12 @@ namespace ts {
}
if (flags & TypeFlags.Object) {
const objectFlags = (<ObjectType>type).objectFlags;
if (objectFlags & ObjectFlags.Reference) {
if ((<TypeReference>type).node) {
return getObjectTypeInstantiation(<TypeReference | AnonymousType | MappedType>type, mapper);
if (objectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous | ObjectFlags.Mapped)) {
if (objectFlags & ObjectFlags.Reference && !(<TypeReference>type).node) {
const resolvedTypeArguments = (<TypeReference>type).resolvedTypeArguments;
const newTypeArguments = instantiateTypes(resolvedTypeArguments, mapper);
return newTypeArguments !== resolvedTypeArguments ? createNormalizedTypeReference((<TypeReference>type).target, newTypeArguments) : type;
}
const resolvedTypeArguments = (<TypeReference>type).resolvedTypeArguments;
const newTypeArguments = instantiateTypes(resolvedTypeArguments, mapper);
return newTypeArguments !== resolvedTypeArguments ? createNormalizedTypeReference((<TypeReference>type).target, newTypeArguments) : type;
}
if (objectFlags & (ObjectFlags.Anonymous | ObjectFlags.Mapped)) {
return getObjectTypeInstantiation(<TypeReference | AnonymousType | MappedType>type, mapper, aliasSymbol, aliasTypeArguments);
}
return type;
Expand Down