d-programming-language.org

[bearophile]

What I meant:

Run-time: I have written an enhancement request for LLVM about optimizing much better the simple operations needed to spot and use the overflows. LLVM dev team has implemented it in 2.8 or 2.9. Such optimizations are not optional, if you want people to use overflow tests they need to be efficient. Even the advanced optimizations done by LLVM weren't good enough until few months ago.

Compile-time: D is able to run code at compile-time too, but only where you ask it explicitly, using or assigning the result where a compile-time constant is required. I think this means compile-time overflow tests will usually not happen.

There are routines for run-time overflow tests in C and C++, but I am not seeing them used. While in Delphi I use overflow tests all the time and I see code written by other people that have runtime overflow tests switched on. I think that to catch integral overflow bugs in programs you can't just add a SafeInt struct, you need a compiler-wide switch. Otherwise most people will not use it. Array bound tests are able to catch bugs in normal D code written by everybody because you don't need to use a SafeArray instead of the built in arrays and because array bound tests are active on default, you need a switch to disable them. A bit more syntax is needed to disable tests locally, where needed.

Bye,
bearophile