AaronBallman

6 ms·

1.
What's New in C in 2023?(blog.aaronballman.com)
38 points by AaronBallman 3y ago|3 comments
2.
by AaronBallman 6y ago
I could imagine misguided readings of some coding standard advice that would lead to that interpretation, but it's still not an interpretation that makes sense to me. Implementations define undefined behavior all the time and users r
3.
by AaronBallman 6y ago
Ah! No, those just predate my joining the committee and haven't really come up since they were presented. Basically, every paper that gets submitted by an author will get some amount of discussion time at the next available meeting as
4.
by AaronBallman 6y ago
I don't think it's a myth so much as a misunderstanding of terminology. If an implementation defines some undefined behavior from the standard, it stops being undefined behavior at that point (for that implementation) and is no lo
5.
by AaronBallman 6y ago
I think this is correct, assuming that locale is supported by the implementation and wchar_t is wide enough, but I am by no means an expert on character encodings.
6.
by AaronBallman 6y ago
> 1. Will the Apple's Blocks extension, which allows creation of Closures and Lambda functions, be included in C2X? We haven't seen a proposal to add them to C2x, yet. However, there has been some interest within the committee
7.
by AaronBallman 6y ago
I must be remembering incorrectly then, thank you!
8.
by AaronBallman 6y ago
If that macro is defined, then wchar_t is able to represent every character from the Unicode required character set with the same value as the short code for that character. Which version of Unicode is supported is determined by the date va
9.
by AaronBallman 6y ago
I don't think the book covers strict aliasing, at least not in detail.
10.
by AaronBallman 6y ago
Not off the top of my head, but as an example along similar lines, when talking about whether we could realistically specify twos complement integer representations for C2x, we had to determine whether this would require an implementation t
11.
by AaronBallman 6y ago
When the committee considers proposals, we do consider the implementation burden of the proposal as part of the feature. If parts of the proposal would be an undue burden for an implementation, the committee may request modifications to the
12.
by AaronBallman 6y ago
Not really -- vendors are free to ignore newer releases of the standard that do not meet their customers needs and the committee can't do much about it. However, as a user, you can help apply pressure on the vendor to support newer sta
13.
by AaronBallman 6y ago
You couldn't in that parameter order. However, you could do this: int f(size_t n, int a[n][n]) { return a[n-1][n-1]; } ( https://godbolt.org/z/DV9c-C ) Btw, that definition was obsolescent in C89 too.
14.
by AaronBallman 6y ago
If you're interested in the final TR, I would imagine we'd list it on that page you linked. If you're interested in following the drafts before it becomes published, you'd fine them on http://www.open-std.org&
15.
by AaronBallman 6y ago
> Alternatively, please keep it going for a few hours if you would be able to be so generous with your time! We're remaining active while there are still people asking questions, so the west coast folks should hopefully have the cha
16.
by AaronBallman 6y ago
I'd ask them if they really meant "impossible" or just "harder than I wish it was". I've typically found that the tradeoffs between security, performance, and implementation efforts are usually more to blame fo
17.
by AaronBallman 6y ago
The MISRA committee is a separate organization from the C standards committee, but there is overlap between the two groups and an official liaison process for the committees to collaborate. So there's a bit of bidirectional influence b
18.
by AaronBallman 6y ago
I'd put it this way -- as someone who writes both C and C++ and has for a long while, I find that the difference between "best practice" C89 and C17 code is not as wide as the difference between "best practice" C++9
19.
by AaronBallman 6y ago
There's not an official collaboration between the committee and the kernel developers (that I'm aware of), but we do have people on the committee who need to support Linux kernel development (such as GCC maintainers), so there is
20.
by AaronBallman 6y ago
The usual argument is: once you've verified some piece of code is correct, changing it (even when there should be no functional change in the semantics) carries risk. Some customers have C89-era code that compiles in C17 mode and they
21.
by AaronBallman 6y ago
I think that may be inaccurate -- IIRC, in C, you can do type punning via a union but not memcpy, and in C++ you can do type punning via memcpy but not a union and this incompatibility drives me nuts because it makes inline functions in a h
22.
by AaronBallman 6y ago
We've started doing some things in this area, but I don't think the committee would abandon legacy code bases entirely. Instead, we try to make a migration path for code bases. For instance, we added the '_Bool' data typ
23.
by AaronBallman 6y ago
> In general, how is one supposed to approach wg14 with ideas or need for clarification on the standard's wording / interpretation? I'm currently working on an update to the committee website to clarify exactly this sort o
24.
by AaronBallman 6y ago
> Does the committee have any plans to document the rationale for each kind of Undefined Behavior? In the C99 timeframe, we had a rationale document that was separately maintained. My understanding (this predates my joining the committee
25.
by AaronBallman 6y ago
> Do you think Annex K of C11 will be widely adopted by programmers or unused? Why aren't people adopting it? So far, it's not been widely adopted. Part of the issue is that there are specification issues relating to threads an
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by AaronBallman 6y ago
> When deciding on standardized behavior for C operations or data representation that may favor some hardware over others [1], who argues the side of the various hardware vendors, if they have no members on the standardization committee?
27.
by AaronBallman 6y ago
I would love to see more open interactions between the broader C community and the WG14 committee. One of the plans I am currently working on is an update to the committee's webpage to at least make it more obvious as to how you can ge
28.
by AaronBallman 6y ago
We've been discussing a paper on this ( http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2466.pdf ) at recent meetings and it's been fairly well-received each time, but not adopted for C2x a
29.
by AaronBallman 6y ago
Correct -- it would be nice if the glibc maintainers would reconsider their opinion of supporting the optional Annex K functionality. There is definitely user demand for the feature.
30.
by AaronBallman 6y ago
> - Which differences between the C abstract machine and actual modern CPUs/hardware have proven most difficult to deal with in the language? For me, I think it's 'volatile' because, by its nature, you can't desc

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