diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts index c40e43c871..74306ba287 100644 --- a/src/compiler/checker.ts +++ b/src/compiler/checker.ts @@ -4438,8 +4438,8 @@ module ts { maybeStack[depth][id] = RelationComparisonResult.Succeeded; depth++; let saveExpandingFlags = expandingFlags; - if (!(expandingFlags & 1) && isDeeplyNestedGeneric(source, sourceStack)) expandingFlags |= 1; - if (!(expandingFlags & 2) && isDeeplyNestedGeneric(target, targetStack)) expandingFlags |= 2; + if (!(expandingFlags & 1) && isDeeplyNestedGeneric(source, sourceStack, depth)) expandingFlags |= 1; + if (!(expandingFlags & 2) && isDeeplyNestedGeneric(target, targetStack, depth)) expandingFlags |= 2; let result: Ternary; if (expandingFlags === 3) { result = Ternary.Maybe; @@ -4475,27 +4475,6 @@ module ts { return result; } - // Return true if the given type is part of a deeply nested chain of generic instantiations. We consider this to be the case - // when structural type comparisons have been started for 10 or more instantiations of the same generic type. It is possible, - // though highly unlikely, for this test to be true in a situation where a chain of instantiations is not infinitely expanding. - // Effectively, we will generate a false positive when two types are structurally equal to at least 10 levels, but unequal at - // some level beyond that. - function isDeeplyNestedGeneric(type: ObjectType, stack: ObjectType[]): boolean { - // We track type references (created by createTypeReference) and instantiated types (created by instantiateType) - if (type.flags & (TypeFlags.Reference | TypeFlags.Instantiated) && depth >= 10) { - let symbol = type.symbol; - let count = 0; - for (let i = 0; i < depth; i++) { - let t = stack[i]; - if (t.flags & (TypeFlags.Reference | TypeFlags.Instantiated) && t.symbol === symbol) { - count++; - if (count >= 10) return true; - } - } - } - return false; - } - function propertiesRelatedTo(source: ObjectType, target: ObjectType, reportErrors: boolean): Ternary { if (relation === identityRelation) { return propertiesIdenticalTo(source, target); @@ -4814,6 +4793,27 @@ module ts { } } + // Return true if the given type is part of a deeply nested chain of generic instantiations. We consider this to be the case + // when structural type comparisons have been started for 10 or more instantiations of the same generic type. It is possible, + // though highly unlikely, for this test to be true in a situation where a chain of instantiations is not infinitely expanding. + // Effectively, we will generate a false positive when two types are structurally equal to at least 10 levels, but unequal at + // some level beyond that. + function isDeeplyNestedGeneric(type: Type, stack: Type[], depth: number): boolean { + // We track type references (created by createTypeReference) and instantiated types (created by instantiateType) + if (type.flags & (TypeFlags.Reference | TypeFlags.Instantiated) && depth >= 10) { + let symbol = type.symbol; + let count = 0; + for (let i = 0; i < depth; i++) { + let t = stack[i]; + if (t.flags & (TypeFlags.Reference | TypeFlags.Instantiated) && t.symbol === symbol) { + count++; + if (count >= 10) return true; + } + } + } + return false; + } + function isPropertyIdenticalTo(sourceProp: Symbol, targetProp: Symbol): boolean { return compareProperties(sourceProp, targetProp, compareTypes) !== Ternary.False; } @@ -5128,21 +5128,6 @@ module ts { return false; } - function isWithinDepthLimit(type: Type, stack: Type[]) { - if (depth >= 5) { - let target = (type).target; - let count = 0; - for (let i = 0; i < depth; i++) { - let t = stack[i]; - if (t.flags & TypeFlags.Reference && (t).target === target) { - count++; - } - } - return count < 5; - } - return true; - } - function inferFromTypes(source: Type, target: Type) { if (source === anyFunctionType) { return; @@ -5210,7 +5195,7 @@ module ts { else if (source.flags & TypeFlags.ObjectType && (target.flags & (TypeFlags.Reference | TypeFlags.Tuple) || (target.flags & TypeFlags.Anonymous) && target.symbol && target.symbol.flags & (SymbolFlags.Method | SymbolFlags.TypeLiteral))) { // If source is an object type, and target is a type reference, a tuple type, the type of a method, or a type literal, infer from members - if (!isInProcess(source, target) && isWithinDepthLimit(source, sourceStack) && isWithinDepthLimit(target, targetStack)) { + if (!isInProcess(source, target) && !(isDeeplyNestedGeneric(source, sourceStack, depth) && isDeeplyNestedGeneric(target, targetStack, depth))) { if (depth === 0) { sourceStack = []; targetStack = [];