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Merge pull request #32558 from microsoft/fix32247
Infer between closely matching types in unions and intersections
This commit is contained in:
Anders Hejlsberg
@@ -15308,7 +15308,7 @@ namespace ts {
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objectFlags & ObjectFlags.Reference && forEach((<TypeReference>type).typeArguments, couldContainTypeVariables) ||
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objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral) && type.symbol.declarations ||
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objectFlags & ObjectFlags.Mapped ||
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type.flags & TypeFlags.UnionOrIntersection && couldUnionOrIntersectionContainTypeVariables(<UnionOrIntersectionType>type));
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type.flags & TypeFlags.UnionOrIntersection && !(type.flags & TypeFlags.EnumLiteral) && couldUnionOrIntersectionContainTypeVariables(<UnionOrIntersectionType>type));
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}
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function couldUnionOrIntersectionContainTypeVariables(type: UnionOrIntersectionType): boolean {
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@@ -15460,7 +15460,7 @@ namespace ts {
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let visited: Map<number>;
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let bivariant = false;
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let propagationType: Type;
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let inferenceCount = 0;
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let inferenceMatch = false;
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let inferenceIncomplete = false;
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let allowComplexConstraintInference = true;
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inferFromTypes(originalSource, originalTarget);
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@@ -15485,46 +15485,50 @@ namespace ts {
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inferFromTypeArguments(source.aliasTypeArguments, target.aliasTypeArguments!, getAliasVariances(source.aliasSymbol));
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return;
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}
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if (source.flags & TypeFlags.Union && target.flags & TypeFlags.Union && !(source.flags & TypeFlags.EnumLiteral && target.flags & TypeFlags.EnumLiteral) ||
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source.flags & TypeFlags.Intersection && target.flags & TypeFlags.Intersection) {
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// Source and target are both unions or both intersections. If source and target
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// are the same type, just relate each constituent type to itself.
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if (source === target) {
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for (const t of (<UnionOrIntersectionType>source).types) {
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inferFromTypes(t, t);
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}
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return;
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}
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// Find each source constituent type that has an identically matching target constituent
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// type, and for each such type infer from the type to itself. When inferring from a
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// type to itself we effectively find all type parameter occurrences within that type
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// and infer themselves as their type arguments. We have special handling for numeric
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// and string literals because the number and string types are not represented as unions
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// of all their possible values.
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let matchingTypes: Type[] | undefined;
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if (source === target && source.flags & TypeFlags.UnionOrIntersection) {
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// When source and target are the same union or intersection type, just relate each constituent
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// type to itself.
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for (const t of (<UnionOrIntersectionType>source).types) {
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const matched = findMatchedType(t, <UnionOrIntersectionType>target);
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if (matched) {
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(matchingTypes || (matchingTypes = [])).push(matched);
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inferFromTypes(matched, matched);
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}
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inferFromTypes(t, t);
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}
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// Next, to improve the quality of inferences, reduce the source and target types by
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// removing the identically matched constituents. For example, when inferring from
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// 'string | string[]' to 'string | T' we reduce the types to 'string[]' and 'T'.
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if (matchingTypes) {
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const s = removeTypesFromUnionOrIntersection(<UnionOrIntersectionType>source, matchingTypes);
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const t = removeTypesFromUnionOrIntersection(<UnionOrIntersectionType>target, matchingTypes);
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if (!(s && t)) return;
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source = s;
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target = t;
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return;
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}
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if (target.flags & TypeFlags.Union) {
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if (source.flags & TypeFlags.Union) {
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// First, infer between identically matching source and target constituents and remove the
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// matching types.
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const [tempSources, tempTargets] = inferFromMatchingTypes((<UnionType>source).types, (<UnionType>target).types, isTypeOrBaseIdenticalTo);
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// Next, infer between closely matching source and target constituents and remove
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// the matching types. Types closely match when they are instantiations of the same
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// object type or instantiations of the same type alias.
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const [sources, targets] = inferFromMatchingTypes(tempSources, tempTargets, isTypeCloselyMatchedBy);
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if (sources.length === 0 || targets.length === 0) {
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return;
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}
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source = getUnionType(sources);
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target = getUnionType(targets);
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}
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else {
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if (inferFromMatchingType(source, (<UnionType>target).types, isTypeOrBaseIdenticalTo)) return;
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if (inferFromMatchingType(source, (<UnionType>target).types, isTypeCloselyMatchedBy)) return;
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}
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}
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else if (target.flags & TypeFlags.Union && !(target.flags & TypeFlags.EnumLiteral) || target.flags & TypeFlags.Intersection) {
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const matched = findMatchedType(source, <UnionOrIntersectionType>target);
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if (matched) {
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inferFromTypes(matched, matched);
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return;
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else if (target.flags & TypeFlags.Intersection && some((<IntersectionType>target).types, t => !!getInferenceInfoForType(t))) {
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// We reduce intersection types only when they contain naked type parameters. For example, when
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// inferring from 'string[] & { extra: any }' to 'string[] & T' we want to remove string[] and
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// infer { extra: any } for T. But when inferring to 'string[] & Iterable<T>' we want to keep the
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// string[] on the source side and infer string for T.
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if (source.flags & TypeFlags.Intersection) {
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// Infer between identically matching source and target constituents and remove the matching types.
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const [sources, targets] = inferFromMatchingTypes((<IntersectionType>source).types, (<IntersectionType>target).types, isTypeIdenticalTo);
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if (sources.length === 0 || targets.length === 0) {
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return;
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}
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source = getIntersectionType(sources);
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target = getIntersectionType(targets);
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}
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else if (!(source.flags & TypeFlags.Union)) {
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if (inferFromMatchingType(source, (<IntersectionType>target).types, isTypeIdenticalTo)) return;
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}
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}
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else if (target.flags & (TypeFlags.IndexedAccess | TypeFlags.Substitution)) {
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@@ -15570,7 +15574,7 @@ namespace ts {
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clearCachedInferences(inferences);
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}
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}
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inferenceCount++;
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inferenceMatch = true;
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return;
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}
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else {
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@@ -15662,15 +15666,50 @@ namespace ts {
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function invokeOnce(source: Type, target: Type, action: (source: Type, target: Type) => void) {
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const key = source.id + "," + target.id;
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const count = visited && visited.get(key);
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if (count !== undefined) {
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inferenceCount += count;
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const status = visited && visited.get(key);
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if (status !== undefined) {
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if (status & 1) inferenceMatch = true;
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if (status & 2) inferenceIncomplete = true;
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return;
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}
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(visited || (visited = createMap<number>())).set(key, 0);
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const startCount = inferenceCount;
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const saveInferenceMatch = inferenceMatch;
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const saveInferenceIncomplete = inferenceIncomplete;
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inferenceMatch = false;
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inferenceIncomplete = false;
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action(source, target);
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visited.set(key, inferenceCount - startCount);
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visited.set(key, (inferenceMatch ? 1 : 0) | (inferenceIncomplete ? 2 : 0));
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inferenceMatch = inferenceMatch || saveInferenceMatch;
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inferenceIncomplete = inferenceIncomplete || saveInferenceIncomplete;
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}
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function inferFromMatchingType(source: Type, targets: Type[], matches: (s: Type, t: Type) => boolean) {
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let matched = false;
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for (const t of targets) {
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if (matches(source, t)) {
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inferFromTypes(source, t);
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matched = true;
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}
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}
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return matched;
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}
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function inferFromMatchingTypes(sources: Type[], targets: Type[], matches: (s: Type, t: Type) => boolean): [Type[], Type[]] {
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let matchedSources: Type[] | undefined;
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let matchedTargets: Type[] | undefined;
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for (const t of targets) {
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for (const s of sources) {
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if (matches(s, t)) {
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inferFromTypes(s, t);
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matchedSources = appendIfUnique(matchedSources, s);
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matchedTargets = appendIfUnique(matchedTargets, t);
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}
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}
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}
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return [
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matchedSources ? filter(sources, t => !contains(matchedSources, t)) : sources,
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matchedTargets ? filter(targets, t => !contains(matchedTargets, t)) : targets,
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];
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}
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function inferFromTypeArguments(sourceTypes: readonly Type[], targetTypes: readonly Type[], variances: readonly VarianceFlags[]) {
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@@ -15724,9 +15763,11 @@ namespace ts {
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}
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else {
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for (let i = 0; i < sources.length; i++) {
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const count = inferenceCount;
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const saveInferenceMatch = inferenceMatch;
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inferenceMatch = false;
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inferFromTypes(sources[i], t);
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if (count !== inferenceCount) matched[i] = true;
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if (inferenceMatch) matched[i] = true;
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inferenceMatch = inferenceMatch || saveInferenceMatch;
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}
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}
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}
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@@ -15953,47 +15994,13 @@ namespace ts {
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}
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}
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function isMatchableType(type: Type) {
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// We exclude non-anonymous object types because some frameworks (e.g. Ember) rely on the ability to
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// infer between types that don't witness their type variables. Such types would otherwise be eliminated
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// because they appear identical.
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return !(type.flags & TypeFlags.Object) || !!(getObjectFlags(type) & ObjectFlags.Anonymous);
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function isTypeOrBaseIdenticalTo(s: Type, t: Type) {
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return isTypeIdenticalTo(s, t) || !!(s.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) && isTypeIdenticalTo(getBaseTypeOfLiteralType(s), t);
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}
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function typeMatchedBySomeType(type: Type, types: Type[]): boolean {
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for (const t of types) {
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if (t === type || isMatchableType(t) && isMatchableType(type) && isTypeIdenticalTo(t, type)) {
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return true;
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}
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}
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return false;
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}
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function findMatchedType(type: Type, target: UnionOrIntersectionType) {
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if (typeMatchedBySomeType(type, target.types)) {
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return type;
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}
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if (type.flags & (TypeFlags.NumberLiteral | TypeFlags.StringLiteral) && target.flags & TypeFlags.Union) {
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const base = getBaseTypeOfLiteralType(type);
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if (typeMatchedBySomeType(base, target.types)) {
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return base;
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}
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}
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return undefined;
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}
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/**
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* Return a new union or intersection type computed by removing a given set of types
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* from a given union or intersection type.
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*/
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function removeTypesFromUnionOrIntersection(type: UnionOrIntersectionType, typesToRemove: Type[]) {
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const reducedTypes: Type[] = [];
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for (const t of type.types) {
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if (!typeMatchedBySomeType(t, typesToRemove)) {
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reducedTypes.push(t);
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}
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}
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return reducedTypes.length ? type.flags & TypeFlags.Union ? getUnionType(reducedTypes) : getIntersectionType(reducedTypes) : undefined;
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function isTypeCloselyMatchedBy(s: Type, t: Type) {
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return !!(s.flags & TypeFlags.Object && t.flags & TypeFlags.Object && s.symbol && s.symbol === t.symbol ||
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s.aliasSymbol && s.aliasTypeArguments && s.aliasSymbol === t.aliasSymbol);
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}
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function hasPrimitiveConstraint(type: TypeParameter): boolean {
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