On Fri, 17 Feb 2023, 13:15 Helmut Zeisel via Gcc, <gcc@gcc.gnu.org> wrote:
> Recently I read about Value-Oriented Programming > ( https://accu.org/journals/overload/31/173/teodorescu/ ) > There it is pointed out that sharing mutable data. i. e., code like > > my_push_back(vec, vec[0]); > > can lead to subtle errors. Of course GCC cannot change C++ to a language > like Val that forbids such code. > From my understanding, however, sharing of mutable data can be detected by > the compiler on caller side > (looking at the prototype of the function - are all shared arguments const > or is there some mutable argument?) > and it might be possible to add a warning "shared mutable data". > > How difficult is it to implement such a warning? > What exactly are you suggesting for the semantics of the warning? You haven't described what you want it to do, for anybody to say how difficult it would be. > If we have such a warning, it will be possible to get some information > > .) How often such code occurs in real programs? > .) Is it difficult to fix such code (e.g. by making a copy of the data > before passing it to the function) > .) Is it possible to find all such possbible errors when the complete > program is compiled with this warning enabled? > > Even if it were not possible to detect all cases, also detecting some > cases might prevent some bugs. > > What do you think about adding a warning "shared mutable data" to GCC? > > Helmut Zeisel > > >
