tests/cases/compiler/recursiveBaseCheck6.ts(1,7): error TS2310: Type 'S18' recursively references itself as a base type. tests/cases/compiler/recursiveBaseCheck6.ts(2,13): error TS2339: Property 'blah' does not exist on type 'S18<{}>'. ==== tests/cases/compiler/recursiveBaseCheck6.ts (2 errors) ==== class S18 extends S18<{ S19: A; }>{ } ~~~ !!! error TS2310: Type 'S18' recursively references itself as a base type. (new S18()).blah; ~~~~ !!! error TS2339: Property 'blah' does not exist on type 'S18<{}>'.