This is the default calling convention used by C++ member functions that do not use variable arguments. The callee cleans the stack, so the compiler makes vararg functions __cdecl, and pushes the this pointer on the stack last. The thiscall calling convention cannot be explicitly specified in a program, because thiscall is not a keyword.
All function arguments are pushed on the stack. Because this calling convention applies only to C++, there is no C name decoration scheme.