tests/cases/compiler/indexSignatureTypeCheck2.ts(10,8): error TS1019: An index signature parameter cannot have a question mark. tests/cases/compiler/indexSignatureTypeCheck2.ts(11,6): error TS1017: An index signature cannot have a rest parameter. tests/cases/compiler/indexSignatureTypeCheck2.ts(12,6): error TS1096: An index signature must have exactly one parameter. tests/cases/compiler/indexSignatureTypeCheck2.ts(13,6): error TS1096: An index signature must have exactly one parameter. ==== tests/cases/compiler/indexSignatureTypeCheck2.ts (4 errors) ==== class IPropertySet { [index: string]: any } var ps: IPropertySet = null; var index: any = "hello"; ps[index] = 12; interface indexErrors { [p2?: string]; ~ !!! error TS1019: An index signature parameter cannot have a question mark. [...p3: any[]]; ~~~ !!! error TS1017: An index signature cannot have a rest parameter. [p4: string, p5?: string]; ~~ !!! error TS1096: An index signature must have exactly one parameter. [p6: string, ...p7: any[]]; ~~ !!! error TS1096: An index signature must have exactly one parameter. }