Re: Implementing Rust's borrow checked pointers

[Keith Thompson <kst-u@mib.org>]

Optikos <optikos@verizon.net> writes:
> On Tuesday, September 24, 2019 at 2:13:33 PM UTC-5, Keith Thompson wrote:
>> Lucretia <laguest9000@googlemail.com> writes:
[...]
>> > Yes, the compiler would raise that exception at compile time. This
>> > idea that all exceptions are raised at runtime is false and you should
>> > check the AARM.
>> 
>> Can you provide a specific citation?
>> 
>> Certainly a compiler can diagnose an error at compile time, but I've
>> never heard that referred to as an "exception".  And a compiler can
>> generate code that unconditionally raises an exception, but that code is
>> executed at run time.
>> 
>> (I've seen compile-time exceptions, but they were compiler bugs, not
>> diagnostics for the program being compiled.)
>
> Keith, I already did in a prior posting above, but you apparently
> blocked me, so your loss.

I have not blocked you.  It's entirely possible that I missed your
earlier article (I don't follow this newsgroup all that closely),
or that I read it but didn't think it supported the assertion.

>                            Here is the answer to your question again
> for all other readers: §1.1.5 Classification of •Errors “If such an
> •error• situation is certain to arise in every execution of a
> construct, then an implementation is •••allowed (although not
> required)••• to report this fact at •compilation• time.”

That doesn't describe raising an exception at compilation time.
It describes (optionally) *reporting* at compilation time that an
exception is certain to be raised at run time.

Again, the claim (from Lucretia, not from you) was:

    Yes, the compiler would raise that exception at compile
    time. This idea that all exceptions are raised at runtime is
    false and you should check the AARM.

Printing a warning message is not raising an exception.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */