error TS5055: Cannot write file 'a.d.ts' because it would overwrite input file.
  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.


!!! error TS5055: Cannot write file 'a.d.ts' because it would overwrite input file.
!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
==== a.ts (0 errors) ====
    class c {
    }
    
==== a.d.ts (0 errors) ====
    declare function isC(): boolean;