Function resolveReverseMappedTypeMembers

test/fixtures/snapshot/typescript.js:58457–58489

(type)

            return instantiateType(instantiable, createTypeMapper([type.indexType, type.objectType], [getNumberLiteralType(0), createTupleType([replacement])]));
        }
        function resolveReverseMappedTypeMembers(type) {
            var indexInfo = getIndexInfoOfType(type.source, stringType);
            var modifiers = getMappedTypeModifiers(type.mappedType);
            var readonlyMask = modifiers & 1 /* MappedTypeModifiers.IncludeReadonly */ ? false : true;
            var optionalMask = modifiers & 4 /* MappedTypeModifiers.IncludeOptional */ ? 0 : 16777216 /* SymbolFlags.Optional */;
            var indexInfos = indexInfo ? [createIndexInfo(stringType, inferReverseMappedType(indexInfo.type, type.mappedType, type.constraintType), readonlyMask && indexInfo.isReadonly)] : ts.emptyArray;
            var members = ts.createSymbolTable();
            for (var _i = 0, _a = getPropertiesOfType(type.source); _i < _a.length; _i++) {
                var prop = _a[_i];
                var checkFlags = 8192 /* CheckFlags.ReverseMapped */ | (readonlyMask && isReadonlySymbol(prop) ? 8 /* CheckFlags.Readonly */ : 0);
                var inferredProp = createSymbol(4 /* SymbolFlags.Property */ | prop.flags & optionalMask, prop.escapedName, checkFlags);
                inferredProp.declarations = prop.declarations;
                inferredProp.nameType = getSymbolLinks(prop).nameType;
                inferredProp.propertyType = getTypeOfSymbol(prop);
                if (type.constraintType.type.flags & 8388608 /* TypeFlags.IndexedAccess */
                    && type.constraintType.type.objectType.flags & 262144 /* TypeFlags.TypeParameter */
                    && type.constraintType.type.indexType.flags & 262144 /* TypeFlags.TypeParameter */) {
                    // A reverse mapping of `{[K in keyof T[K_1]]: T[K_1]}` is the same as that of `{[K in keyof T]: T}`, since all we care about is
                    // inferring to the "type parameter" (or indexed access) shared by the constraint and template. So, to reduce the number of
                    // type identities produced, we simplify such indexed access occurences
                    var newTypeParam = type.constraintType.type.objectType;
                    var newMappedType = replaceIndexedAccess(type.mappedType, type.constraintType.type, newTypeParam);
                    inferredProp.mappedType = newMappedType;
                    inferredProp.constraintType = getIndexType(newTypeParam);
                }
                else {
                    inferredProp.mappedType = type.mappedType;
                    inferredProp.constraintType = type.constraintType;
                }
                members.set(prop.escapedName, inferredProp);
            }
            setStructuredTypeMembers(type, members, ts.emptyArray, ts.emptyArray, indexInfos);
        }
        // Return the lower bound of the key type in a mapped type. Intuitively, the lower
        // bound includes those keys that are known to always be present, for example because
        // because of constraints on type parameters (e.g. 'keyof T' for a constrained T).