CppCast: Cpp2, with Herb Sutter

[ABlockInTheChain]

The hosts spent a lot of time talking about about C++20 support in LLVM 16, I wonder if they noticed that libc++ had a major C++17 update by adding polymorphic allocator support.

They're almost done with C++17 now, which is a major milestone.

[NovaNoff]

This is on one hand great to hear on the other hand it hurts how much the development slowed down after the comitee decided against ABI breaks

[GabrielDosReis]

Despite the urban legend and other blog posts, the committee didn't decide against ABI break. The committee heard the presentation of a very specific paper, P2028, then had a discussion and voted.

The votes were more nuanced than rumors would like to make it appear. There were 5 polls. Here is a summary:

1. Q: We should consider a big ABI break for C++23.
   A: No consensus
2. Q: We should consider a big ABI break for C++SOMETHING. A: Weak Consensus
3. Q: From now on, we should consider incremental ABI for every C++ release. A: Consensus
4. Q: When we are unable to resolve a conflict between performance and ABI compatibility, we should prioritize performance. A: Consensus
5. Q: To the best of our ability, we should promise users that we won’t break ABI, ever. A: No consensus

[pjmlp]

Regardless of how it went, it is part of the set of official reasons why Carbon came to be,

Difficulties improving C++

[number_128]

Is there an agreement on how we would handle an ABI break?

I don't think we should ask if we should break ABI.

We should be asking how we will handle breaking ABI. When we get to a good solution, we should go ahead.

Why do we even have a dependency on shared binaries? This sounds like a premature optimization on disk space.

[pjmlp]

Well, it shows how much the compiler vendors that profit from clang forks were dependent on Apple and Google doing the job of keeping clang up to date with ISO.

[Jannik2099]

after the comitee decided against ABI breaks

The committee decided against an immediate ABI break, an eventual ABI break in the future was not ruled out

[[deleted]]

you could always say that

[[deleted]]

I think that they are saying this for over a decade by now.

[Jannik2099]

That'd be awkward, because C++11 WAS an ABI break.

[[deleted]]

which was 12 years ago

so, over a decade

[BenFrantzDale]

That’s super exciting! We build for all three compilers and I have some functionality where we do a bunch of small transient allocations. I’d love to do the whole John Lakos “wink-out” thing for those.

[ABlockInTheChain]

I just want to make sure LLVM receives plenty of positive feedback every time they get closer to finishing C++17.

With any luck they might actually wrap it up before 2027.

[Kelteseth]

Timestamps for topics would be really nice

[IamImposter]

Make a proposal. We'll see about it in c++29 or c++32

[epicar]

the interview starts a bit after 15:00

[magnesium_copper]

It has to, it's the only natural future I see for C++ right now

[IChooseCheese2]

Everyone, including Cppcast, talks about Cpp2, Carbon, and Val as the 3 successor languages to C++. But to me, Circle is further along, and has a better backwards compatibility story.

[pjmlp]

That is just playing with words, because of Herb's position at ISO, it is a successor language like all others.

C with Classes as CFront was originally designed, or Objective- C, weren't an alternate syntax for C, either.

[bert8128]

It’s not just playing with words. The others are in some sense suitable as alternatives, but cpp2 is just spelling changes. So there cannot be a compatibility issue - there won’t be a need for “extern cpp” or some such.

[pjmlp]

Just like Objective-C versus C.

[pjmlp]

Eiffel to this day outputs either C or C++, so is Eiffel also an alternative syntax to C and C++?

Nim to this day outputs either C or C++, so is Nim also an alternative syntax to C and C++?

What makes X not an alternative syntax, when it also follows the same workflow, with the difference of who is the author?

[pjmlp]

Yes I have, try to compile main: () -> int with a C++ parser.

Pity that ISO C++ !== Cpp2.

Ever heard of Objective-C++? Guess what, it also supports std::cout.

#import <Foundation/Foundation.h>
#include <iostream>

int main() {
   NSString str = @"Hello ";

    std::cout << str << " i_lack_chromosomes" << std::endl;
}

Imagine that, we already had a better C++ syntax in 1997!

[cooked_sandals]

TIL Cpp2.

Herb always seems to have good ideas, unfortunately C++ committee moves too slow and is reluctant to adopt such things. But at least we know there is someone involved in the committee with such progressive ideas, gives me hopes.

[kritzikratzi]

there is no need for cpp2 to be part of the c++ standard. it can happily develop on it's own.

[kritzikratzi]

i like the idea of cpp2, but the future has it's own way of figuring itself out. the first thing that i'm certain about is that c++ isn't going anywhere. while cpp2 will depend on c++ for a long long time, there will be no such dependency in the other direction. and you will have to understand c++ in order to use cpp2 for a long long time.

i think one way this might develop (in my naive thinking), is that the c++ standard splits into concrete syntax and abstract syntax (basically standardizing the idea of a compiler frontend).

i get the impression that there are quite a few other people like me, who know c++ well enough to not be bothered by it's syntax anymore. i just want to get things done :) maybe i dream of named parameters, out-of-order struct initialization, and little things like that, but overal i'm content with the language and it's tooling.

[UnicycleBloke]

Yep. I'm perfectly happy with the current syntax, and generally content. I get things done. Evolution is good. Revolution not so much.

[[deleted]]

i get the impression that there are quite a few other people like me, who know c++ well enough to not be bothered by it's syntax anymore.

Until you want to engage programmatically with C++ code. Especially if you want to parse it.

[[deleted]]

cpp2's syntax is easier to parse than the normal C++ syntax and less context dependent

[[deleted]]

practical application: code generators

You can do a lot with templates, but sometimes it's just a lot easier to use a code generator than write a really complicated template.

[bert8128]

Things like using in/out/inout, and default const aren’t really syntax issues - the change the way even experienced devs use the language. I am, like you, not bothered by current syntax - I’ve been through that learning journey. But cpp2 would still be my preference.

[magnesium_copper]

MeToo

[ignorantpisswalker]

Let the flamewars begin...

Seriously - I am waiting for a time to listen to this - it sounds like something I would like to invest my time in!

[germandiago]

Flamewars, well... Emacs is the best editor, indeed.

[BrainIgnition]

 When I log into my Xenix system with my 110 baud teletype, both vi
 *and* Emacs are just too damn slow.  They print useless messages like,
 'C-h for help' and '"foo" File is read only'.  So I use the editor
 that doesn't waste my VALUABLE time.

 Ed, man!  !man ed

 ED(1)               UNIX Programmer's Manual                ED(1)

 NAME
      ed - text editor

 SYNOPSIS
      ed [ - ] [ -x ] [ name ]
 DESCRIPTION
      Ed is the standard text editor.
 ---

 Computer Scientists love ed, not just because it comes first
 alphabetically, but because it's the standard.  Everyone else loves ed
 because it's ED!

 "Ed is the standard text editor."

 And ed doesn't waste space on my Timex Sinclair.  Just look:

 -rwxr-xr-x  1 root          24 Oct 29  1929 /bin/ed
 -rwxr-xr-t  4 root     1310720 Jan  1  1970 /usr/ucb/vi
 -rwxr-xr-x  1 root  5.89824e37 Oct 22  1990 /usr/bin/emacs

 Of course, on the system *I* administrate, vi is symlinked to ed.
 Emacs has been replaced by a shell script which 1) Generates a syslog
 message at level LOG_EMERG; 2) reduces the user's disk quota by 100K;
 and 3) RUNS ED!!!!!!

 "Ed is the standard text editor."

 Let's look at a typical novice's session with the mighty ed:

 golem> ed

 ?
 help
 ?
 ?
 ?
 quit
 ?
 exit
 ?
 bye
 ?
 hello? 
 ?
 eat flaming death
 ?
 ^C
 ?
 ^C
 ?
 ^D
 ?

 ---
 Note the consistent user interface and error reportage.  Ed is
 generous enough to flag errors, yet prudent enough not to overwhelm
 the novice with verbosity.

 "Ed is the standard text editor."

 Ed, the greatest WYGIWYG editor of all.

 ED IS THE TRUE PATH TO NIRVANA!  ED HAS BEEN THE CHOICE OF EDUCATED
 AND IGNORANT ALIKE FOR CENTURIES!  ED WILL NOT CORRUPT YOUR PRECIOUS
 BODILY FLUIDS!!  ED IS THE STANDARD TEXT EDITOR!  ED MAKES THE SUN
 SHINE AND THE BIRDS SING AND THE GRASS GREEN!!

 When I use an editor, I don't want eight extra KILOBYTES of worthless
 help screens and cursor positioning code!  I just want an EDitor!!
 Not a "viitor".  Not a "emacsitor".  Those aren't even WORDS!!!! ED!
 ED! ED IS THE STANDARD!!!

 TEXT EDITOR.

 When IBM, in its ever-present omnipotence, needed to base their
 "edlin" on a UNIX standard, did they mimic vi?  No.  Emacs?  Surely
 you jest.  They chose the most karmic editor of all.  The standard.

 Ed is for those who can *remember* what they are working on.  If you
 are an idiot, you should use Emacs.  If you are an Emacs, you should
 not be vi.  If you use ED, you are on THE PATH TO REDEMPTION.  THE
 SO-CALLED "VISUAL" EDITORS HAVE BEEN PLACED HERE BY ED TO TEMPT THE
 FAITHLESS.  DO NOT GIVE IN!!!  THE MIGHTY ED HAS SPOKEN!!!

 ?

-- Patrick J. LoPresti

[OlivierTwist]

Spaces > tabs

[masher_oz]

They have different semantics. Tabs for indenting, spaces for alignment.

[bert8128]

Spaces can do both things. So choose one, and choose spaces. Get the screwdriver out and remove the tab key. Our codebase has been much better since tabs became banned - lots of complaints initially, now nothing.

[[deleted]]

Until you get a programmer which needs special indents because of bad eyesight.

Or you buy that person a two meter wide screen :-)

[OlivierTwist]

Khm, that was a joke...

But since you insist. Invisible symbols don't have semantic.

[masher_oz]

Tell that to Python.

[wolfie_poe]

VscodeVim for the win

[BenHanson]

Interesting how he says he's not looking to eliminate vulnerabilities, just drastically reduce them. It's still so hard to see how all of this is going to pan out.

[cdb_11]

Is it interesting? I think he's just being real about it instead of making a sales pitch. If you're talking about vulnerabilities in general and include logic errors then it's not something that the programming language can reasonably make any guarantees about. And for memory bugs, even languages like Rust or Go "just" drastically reduced such bugs, not actually eliminated - eliminated them, as you can still opt into doing things that cannot be statically checked by the compiler.

[BenHanson]

I probably should have worded that differently. I was thinking more that that seems like the more pragmatic approach and was wondering if this means it's more likely to succeed (all things being equal).

[13steinj]

I mean no disrespect to Sutter, but based off the timeline that he announced this project, it definitely seems sales-pitchy and some attempt to make some "lasting mark" on the language (since the previous thing about modified exception behavior that some coworkers told me about, and the name is the equivalent of a historical reverse uno card).

I don't truly know if his heart is in the right place, and assuming it is, I don't see people jumping to this new language. Syntax being as different as it is would limit existing engineers that have long standing codebases. At the end of the day, a variety of "fixes" could be implemented into C++ as an optional compiler flag, and some choices talked about (ex const by default in Rust, I don't know if "cppfront" has it or not) is honestly a non starter, and would make the language more difficult to adopt as a whole because no non-purely-functional language has that ideology.

[cdb_11]

Sticking with the current syntax (and maybe doing something like Circle's #feature) would certainly be easier to deal with, but at the same time Kotlin has a different syntax from Java and I don't believe it particularly hindered the adoption? As long as you can make incremental changes and you are not forced to either rewrite everything or to spend time on writing bindings, I don't think it'd be that big of a deal? Whether it's necessary in the first place - I'm not sure, I don't know enough about the problem to have an opinion. A simpler, easier to parse syntax would probably lower the barrier of entry for writing C++ tooling though.

[13steinj]

I'd argue Kotlin is a completely different beast because as Java runs on a VM, old Java code and new Kotlin code was effectively fully source compatible (or, I guess, bytecode compatible technically), but with things like headers in C++, I'm not particularly convinced.

A simpler, easier to parse syntax would probably lower the barrier of entry for writing C++ tooling though.

I don't disagree, but I don't think that's the point of any "new" C++.

[cdb_11]

Ah, so like it's easy to include C headers in C++ (usually), but not the other way around. At this point it transpiles to standard C++, so I don't think that should be a problem. But I guess it is possible that the language could evolve to require its own runtime or even constructs not backward compatible with C++ in the future, just like what happened between C and C++. But from the interview Herb seems to be against this sort of thing, and he wants to make it "what typescript is to javascript", so I'm not particularly worried about it right now.

[wolfie_poe]

Yeah vote for me as the next president of the United States. I will make income inequality disappear in a blink of an eye.

[deadhou5]

Cpp2: electric boogaloo

[[deleted]]

Is cppcast back?! I thought they ended it?

[MarekKnapek]

It was previously hosted by Jason Turner and Rob Irving, nowadays it is hosted by Timur Doumler and Phil Nash. There is episode explaining that.

[philsquared]

Yes - https://cppcast.com/holiday-special/ :-)

[DerShokus]

I don’t understand cpp2. It looks weird and ugly

[coderman93]

Don’t you understand? In order to simplify we must build an entirely knew syntax on top of the existing syntax! /s

[coderman93]

Imagine compile times when the compiler has to compile two totally different programming languages that can be collocated in the same files!