-mng_error_proc(mng_handle mng, mng_int32 error, mng_int8 severity, mng_chunkid chunkname,
- mng_uint32 chunkseq, mng_int32 extra1, mng_int32 extra2, mng_pchar errortext)
+mng_error_proc(mng_handle mng __attribute__ ((unused)), mng_int32 error __attribute__ ((unused)),
+ mng_int8 severity __attribute__ ((unused)), mng_chunkid chunkname __attribute__ ((unused)),
+ mng_uint32 chunkseq __attribute__ ((unused)), mng_int32 extra1 __attribute__ ((unused)),
+ mng_int32 extra2 __attribute__ ((unused)), mng_pchar errortext)