Function getVariancesWorker

test/fixtures/snapshot/typescript.js:66982–67033

(symbol, typeParameters)

        // instantiations of the generic type for type arguments with known relations. The function
        // returns the emptyArray singleton when invoked recursively for the given generic type.
        function getVariancesWorker(symbol, typeParameters) {
            if (typeParameters === void 0) { typeParameters = ts.emptyArray; }
            var links = getSymbolLinks(symbol);
            if (!links.variances) {
                ts.tracing === null || ts.tracing === void 0 ? void 0 : ts.tracing.push("checkTypes" /* tracing.Phase.CheckTypes */, "getVariancesWorker", { arity: typeParameters.length, id: getTypeId(getDeclaredTypeOfSymbol(symbol)) });
                links.variances = ts.emptyArray;
                var variances = [];
                var _loop_22 = function (tp) {
                    var modifiers = getVarianceModifiers(tp);
                    var variance = modifiers & 65536 /* ModifierFlags.Out */ ?
                        modifiers & 32768 /* ModifierFlags.In */ ? 0 /* VarianceFlags.Invariant */ : 1 /* VarianceFlags.Covariant */ :
                        modifiers & 32768 /* ModifierFlags.In */ ? 2 /* VarianceFlags.Contravariant */ : undefined;
                    if (variance === undefined) {
                        var unmeasurable_1 = false;
                        var unreliable_1 = false;
                        var oldHandler = outofbandVarianceMarkerHandler;
                        outofbandVarianceMarkerHandler = function (onlyUnreliable) { return onlyUnreliable ? unreliable_1 = true : unmeasurable_1 = true; };
                        // We first compare instantiations where the type parameter is replaced with
                        // marker types that have a known subtype relationship. From this we can infer
                        // invariance, covariance, contravariance or bivariance.
                        var typeWithSuper = createMarkerType(symbol, tp, markerSuperType);
                        var typeWithSub = createMarkerType(symbol, tp, markerSubType);
                        variance = (isTypeAssignableTo(typeWithSub, typeWithSuper) ? 1 /* VarianceFlags.Covariant */ : 0) |
                            (isTypeAssignableTo(typeWithSuper, typeWithSub) ? 2 /* VarianceFlags.Contravariant */ : 0);
                        // If the instantiations appear to be related bivariantly it may be because the
                        // type parameter is independent (i.e. it isn't witnessed anywhere in the generic
                        // type). To determine this we compare instantiations where the type parameter is
                        // replaced with marker types that are known to be unrelated.
                        if (variance === 3 /* VarianceFlags.Bivariant */ && isTypeAssignableTo(createMarkerType(symbol, tp, markerOtherType), typeWithSuper)) {
                            variance = 4 /* VarianceFlags.Independent */;
                        }
                        outofbandVarianceMarkerHandler = oldHandler;
                        if (unmeasurable_1 || unreliable_1) {
                            if (unmeasurable_1) {
                                variance |= 8 /* VarianceFlags.Unmeasurable */;
                            }
                            if (unreliable_1) {
                                variance |= 16 /* VarianceFlags.Unreliable */;
                            }
                        }
                    }
                    variances.push(variance);
                };
                for (var _i = 0, typeParameters_1 = typeParameters; _i < typeParameters_1.length; _i++) {
                    var tp = typeParameters_1[_i];
                    _loop_22(tp);
                }
                links.variances = variances;
                ts.tracing === null || ts.tracing === void 0 ? void 0 : ts.tracing.pop();
            }
            return links.variances;
        }
        function createMarkerType(symbol, source, target) {
            var mapper = makeUnaryTypeMapper(source, target);
            var type = getDeclaredTypeOfSymbol(symbol);