8000 Support re-aliasing of type alias instantiations by ahejlsberg · Pull Request #42284 · microsoft/TypeScript · GitHub
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Support re-aliasing of type alias instantiations #42284

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Merged
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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New aliases for type alias instantiations
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@ahejlsberg
ahejlsberg committed Jan 9, 2021
commit a4a47dbb0a4bdde77a47ce949566d53336029bdc
36 changes: 23 additions & 13 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -12443,17 +12443,20 @@ namespace ts {
return checkNoTypeArguments(node, symbol) ? type : errorType;
}

function getTypeAliasInstantiation(symbol: Symbol, typeArguments: readonly Type[] | undefined): Type {
function getTypeAliasInstantiation(symbol: Symbol, typeArguments: readonly Type[] | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type {
const type = getDeclaredTypeOfSymbol(symbol);
if (type === intrinsicMarkerType && intrinsicTypeKinds.has(symbol.escapedName as string) && typeArguments && typeArguments.length === 1) {
return getStringMappingType(symbol, typeArguments[0]);
}
const links = getSymbolLinks(symbol);
const typeParameters = links.typeParameters!;
const id = getTypeListId(typeArguments);
const id = getTypeListId(typeArguments) + (aliasSymbol ? `@${getSymbolId(aliasSymbol)}` : "");
let instantiation = links.instantiations!.get(id);
if (!instantiation) {
links.instantiations!.set(id, instantiation = instantiateType(type, createTypeMapper(typeParameters, fillMissingTypeArguments(typeArguments, typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(symbol.valueDeclaration)))));
links.instantiations!.set(id, instantiation = instantiateType(type,
createTypeMapper(typeParameters, fillMissingTypeArguments(typeArguments, typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(symbol.valueDeclaration))),
aliasSymbol, aliasTypeArguments));
}
return instantiation;
}
Expand All @@ -12479,7 +12482,8 @@ namespace ts {
typeParameters.length);
return errorType;
}
return getTypeAliasInstantiation(symbol, typeArgumentsFromTypeReferenceNode(node));
const aliasSymbol = getAliasSymbolForTypeNode(node);
return getTypeAliasInstantiation(symbol, typeArgumentsFromTypeReferenceNode(node), aliasSymbol, getTypeArgumentsForAliasSymbol(aliasSymbol));
}
return checkNoTypeArguments(node, symbol) ? type : errorType;
}
Expand Down Expand Up @@ -15658,9 +15662,9 @@ namespace ts {
return getConditionalType(root, mapper);
}

function instantiateType(type: Type, mapper: TypeMapper | undefined): Type;
function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined;
function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined {
function instantiateType(type: Type, mapper: TypeMapper | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type;
function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type | undefined;
function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type | undefined {
if (!(type && mapper && couldContainTypeVariables(type))) {
return type;
}
Expand All @@ -15675,12 +15679,12 @@ namespace ts {
totalInstantiationCount++;
instantiationCount++;
instantiationDepth++;
const result = instantiateTypeWorker(type, mapper);
const result = instantiateTypeWorker(type, mapper, aliasSymbol, aliasTypeArguments);
instantiationDepth--;
return result;
}

function instantiateTypeWorker(type: Type, mapper: TypeMapper): Type {
function instantiateTypeWorker(type: Type, mapper: TypeMapper, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined): Type {
const flags = type.flags;
if (flags & TypeFlags.TypeParameter) {
return getMappedType(type, mapper);
Expand All @@ -15701,10 +15705,14 @@ namespace ts {
const origin = type.flags & TypeFlags.Union ? (<UnionType>type).origin : undefined;
const types = origin && origin.flags & TypeFlags.UnionOrIntersection ? (<UnionOrIntersectionType>origin).types : (<UnionOrIntersectionType>type).types;
const newTypes = instantiateTypes(types, mapper);
return newTypes === types ? type :
flags & TypeFlags.Intersection || origin && origin.flags & TypeFlags.Intersection ?
getIntersectionType(newTypes, type.aliasSymbol, instantiateTypes(type.aliasTypeArguments, mapper)) :
getUnionType(newTypes, UnionReduction.Literal, type.aliasSymbol, instantiateTypes(type.aliasTypeArguments, mapper));
if (newTypes === types && aliasSymbol === type.aliasSymbol) {
return type;
}
const newAliasSymbol = aliasSymbol || type.aliasSymbol;
const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper);
return flags & TypeFlags.Intersection || origin && origin.flags & TypeFlags.Intersection ?
getIntersectionType(newTypes, newAliasSymbol, newAliasTypeArguments) :
getUnionType(newTypes, UnionReduction.Literal, newAliasSymbol, newAliasTypeArguments);
}
if (flags & TypeFlags.Index) {
return getIndexType(instantiateType((<IndexType>type).type, mapper));
Expand All @@ -15716,7 +15724,9 @@ namespace ts {
return getStringMappingType((<StringMappingType>type).symbol, instantiateType((<StringMappingType>type).type, mapper));
}
if (flags & TypeFlags.IndexedAccess) {
return getIndexedAccessType(instantiateType((<IndexedAccessType>type).objectType, mapper), instantiateType((<IndexedAccessType>type).indexType, mapper), (<IndexedAccessType>type).noUncheckedIndexedAccessCandidate, /*accessNode*/ undefined, type.aliasSymbol, instantiateTypes(type.aliasTypeArguments, mapper));
const newAliasSymbol = aliasSymbol || type.aliasSymbol;
const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper);
return getIndexedAccessType(instantiateType((<IndexedAccessType>type).objectType, mapper), instantiateType((<IndexedAccessType>type).indexType, mapper), (<IndexedAccessType>type).noUncheckedIndexedAccessCandidate, /*accessNode*/ undefined, newAliasSymbol, newAliasTypeArguments);
}
if (flags & TypeFlags.Conditional) {
return getConditionalTypeInstantiation(<ConditionalType>type, combineTypeMappers((<ConditionalType>type).mapper, mapper));
Expand Down
2 changes: 2 additions & 0 deletions src/compiler/types.ts
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Expand Up @@ -4745,6 +4745,8 @@ namespace ts {
typeParameters?: TypeParameter[]; // Type parameters of type alias (undefined if non-generic)
outerTypeParameters?: TypeParameter[]; // Outer type parameters of anonymous object type
instantiations?: ESMap<string, Type>; // Instantiations of generic type alias (undefined if non-generic)
aliasSymbol?: Symbol; // Alias associated with generic type alias instantiation
aliasTypeArguments?: readonly Type[] // Alias type arguments (if any)
inferredClassSymbol?: ESMap<SymbolId, TransientSymbol>; // Symbol of an inferred ES5 constructor function
mapper?: TypeMapper; // Type mapper for instantiation alias
referenced?: boolean; // True if alias symbol has been referenced as a value that can be emitted
Expand Down
0