It is not a bug, it's a feature :-) http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Pointer-Arith.html#Pointer-Arith >>> 5.17 Arithmetic on void- and Function-Pointers In GNU C, addition and subtraction operations are supported on pointers to void and on pointers to functions. This is done by treating the size of a void or of a function as 1. A consequence of this is that sizeof is also allowed on void and on function types, and returns 1. The option -Wpointer-arith requests a warning if these extensions are used. <<< Daniel Duft Markus wrote: > Hi > > I'm porting lots of stuff to windows (i know, *arg*...) and while doing > so i found something interesting in a C Source file: > > void* myptr = (void*)otherptr + 1; > > Which doesn't compile with the microsoft compiler (error: void*: unknown > size). Now i think, that microsoft is right in that case, and that void > really has an unknown size. > > Since the "+ 1" should add something like "one times sizeof type" to the > pointer, what should the compiler add when void is encountered? I think > the above is wrong and dangerous. Should the compiler catch this? With > C++ gcc prints an error and exits, but because of type conversions, not > because of the addition. > > I attached a small test program, which demonstrates this (maybe bug... > ;o)). > > Should i officially report this issue? > > Cheers, Markus
