@trusted attribute should be replaced with @trusted blocks
Joseph Rushton Wakeling
joseph.wakeling at webdrake.net
Thu Jan 23 11:40:20 UTC 2020
On Saturday, 18 January 2020 at 21:44:17 UTC, David Nadlinger
> On Thursday, 16 January 2020 at 00:21:21 UTC, Joseph Rushton
> Wakeling wrote:
>> The fact that in a similar situation D forces you to annotate
>> the function with `@trusted`, and alert users to the
>> _possibility_ that memory safety bugs could exist within the
>> code of this function, is useful information even if you can't
>> access the source code.
> Detail the scenario where this would be useful, please.
I'm honestly not sure what is useful to add to the existing
discussion. But I think the problem is that most folks are
looking for certainties, whereas I'm prepared to entertain a
certain amount of probability in certain contexts. (Please read
on to understand what I mean by that, rather than assuming that
I'm prepared to allow memory safety to be a roll of the dice:-)
Put it like this: for any given @safe function you see, odds are
that in practice it uses no @trusted code outside the standard
library/runtime. Is that a guarantee? No. But it's a
reasonable heuristic to use on a day-to-day "How concerned do I
have to be that this function might do something scary?" basis.
(Depending on what the function does, I might be able to make an
educated guess of the likelihood there's something @trusted
closer to home.)
OTOH if I see a function marked as @trusted I have a cast-iron
guarantee that the compiler did not do anything to verify the
memory safety of _this particular function_. Which gives me a
nudge that on the balance of probability, I might want to give a
bit more up-front scrutiny to exactly what it's doing -- either
by reading the source code if I can, or by playing with it a bit
to see if I can trip it up with some unexpected input.
Is that an _audit_? No. But it doesn't seem vastly different to
the kind of day to day trust-versus-verify judgement calls that
we all have to make, on a day to day basis, about all sorts of
matters of code correctness in the APIs that we use.
> If you want to audit a program to make sure there are no uses
> of potentially memory-unsafe code, you need access to all the
> source code
Yes, agreed. But that's the difference between doing a full
safety audit versus the typical day-to-day "Does it seem
reasonable to use this function for my use-case?" judgement calls
that we all make when writing code.
More information about the Digitalmars-d