[fpc-devel] Typed addresses, revisited

[Jonas Maebe]

On 07 Oct 2006, at 21:42, Micha Nelissen wrote:

> I propose to enable it for 2.3/2.9, i.e. after 2.2, because, as Jonas
> said, it breaks semantics for arithmetic on non-typecasted pointers  
> that
> point to something that is not size 1.

How will this change after 2.2?

> To that end, the compiler will now warn you of possible {$T+}-breaking
> code: when you do arithmetic on an untyped pointer. Tests tbf/tb0182,
> tbf/tb0183, and tbs/tb0504 test the proper working of this warning.

I don't like this. There is nothing wrong with pointer arithmetic on  
untyped pointers. At most it should be a hint, although even that is  
doubtful in my eyes since there really is no error. It's a bit  
similar to giving hints/warning for discarding function results in {$x 
+} mode, because doesn't work in {$x-} mode (but worse, since pointer  
arithmetic on untyped pointers in {$t-} mode is by no means always  
wrong in {$t+} mode and it forces people to add useless typecasts  
whenever they declare a plain variable as pointer and perform  
calculations on it).


Jonas