It's worth mentioning that for some reason, Solaris doesn't protect the entire first page of memory--only the zero address. For accesses the where the compiler pre-computes the offset and reads that location directly, you won't get a segfault if the pointer is null (at least with GCC--haven't tested with Sun's compiler). This makes no sense to me and it's been the source of a ton of problems in C apps I've found. I'm just mentioning this because it's made me leery of relying on the hardware to flag null accesses.
Sent from my iPhone On Aug 30, 2011, at 4:19 PM, Walter Bright <[email protected]> wrote: > On 8/30/2011 4:07 PM, Timon Gehr wrote: >> You mean, in release mode the assert gets compiled out, and it seg faults in >> the >> code sequence that depends on the assertion, right? > > Yes. Any dereference of a null class ref would cause a seg fault. > >> I am not afraid of seg faults so much, but in debug mode it is certainly an >> annoyance, because you don't get the source line and stack trace. I'd say it >> would be really nice if assert(classreference); would never seg fault during >> debugging. > > Why? I rely on that for debugging. I run it under the debugger, seg fault, > bing the debugger shows where it faulted and a stack trace. It's about 98% of > what a debugger is good for. > > Andrei will reply that there are some environments where you cannot use a > debugger, and he's right. But there are other workarounds for that - D > doesn't *prevent* you from doing soft debugging. > > >> Is there any practical use for manually running the class invariant? > > Looking for corruption of the data. >
