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by liquidify 2232 days ago
wish gcc 10 was built into ubuntu 20.04
11 comments

You want a bleeding edge release in your non-bleeding edge LTS distribution?
it does not make sense to pair development toolchain versions with operating system versions.
What do you think LTS entails, exactly?

One of the core ideas of working with LTS is that you can build your software on an LTS release and ship it to somebody else on the same LTS release, either as a source or as a binary.

If you want the latest GCC, that's fine, you're not forced to use the default compiler distributed with your OS. But it doesn't make sense to update the default compiler used in an LTS release. If you want that, then you don't want LTS.

eh, no. the OS package manager is for sysadmins. LTS is for sysadmins to not have to worry about versions changing under their feet rapidly when they apply security updates.

If you want to develop an application, you use your own toolchain. But yes I know most C++ people don't d this because C++ tools don't easily support it. But that's on C++ for not having pyenv, rustup, multiruby, etc equivalent.

C++ lets you statically link the standard library though, right? Or am I missing your point?
Yes, but I'm quite sure GP is talking about using LTS so the installed libraries are the same as you built with.

IIRC there's still an issue with gethostname which must be dynamically linked.

> it doesn't make sense to update the default compiler used in an LTS release. If you want that, then you don't want LTS

This needs to be emphasized.

> One of the core ideas of working with LTS is that you can build your software on an LTS release and ship it to somebody else on the same LTS release, either as a source or as a binary.

Yes, and updating compilers don't prevent that at all. You can use GCC 10 to ship code that will build and run on Ubuntu 12.04 without issues. Xcode 11 can ship code that works back to macOS 10.6 and Visual Studio 2019 can still optionally target windows fucking XP !

> [...] and updating compilers don't prevent that at all.

This is incorrect. In practice, for larger code bases, upgrading to a newer version of GCC or Clang is something that must be done purposefully, and you must test.

Sometimes it turns out that your code relies on some compiler behavior which has changed. Sometimes newer compilers are stricter than older compilers. There are plenty of real-world cases of these problems!

> Xcode 11 can ship code that works back to macOS 10.6 [...]

There are a number of features that are specific to the macOS toolchain which make this possible. Take a look at the "-mmacosx-version-min" flag on the macOS compiler. This selectively enables and disables various APIs. These features don't solve all the compatibility problems, either.

> Visual Studio 2019 can still optionally target windows fucking XP !

We're talking about Linux here. The Windows toolchain is radically different.

> Sometimes it turns out that your code relies on some compiler behavior which has changed.

In practice this can be "undefined behavior" like dangling pointers or data races. Maybe the new version of the compiler happens to reorder a couple of instructions (which it's perfectly within it's rights to do) which turns a "benign" race into a crash or an exploitable security issue. Is it your fault for writing these bugs? Sure. But if you're a big organization, and you know you have bugs like this, is this a reason not to upgrade your compiler? Absolutely. All the real world testing you've done on your current binaries has value, and losing some of that value needs to be weighed against the benefits of upgrading.

> This is incorrect. In practice, for larger code bases, upgrading to a newer version of GCC or Clang is something that must be done purposefully, and you must test. Sometimes it turns out that your code relies on some compiler behavior which has changed. Sometimes newer compilers are stricter than older compilers. There are plenty of real-world cases of these problems!

So if you hit issues, do what you do on every other system which is "installing older Xcode / Visual Studio" ? That would not be an issue at all if the toolchain wasn't vendored as part of the distro, you'd just have something like rustup that allows you to use whatever version of the toolchain your project requires.

> There are a number of features that are specific to the macOS toolchain which make this possible. Take a look at the "-mmacosx-version-min" flag on the macOS compiler. This selectively enables and disables various APIs.

yes ? https://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Dialect-Optio...

> We're talking about Linux here. The Windows toolchain is radically different.

what I'm saying is exactly that the Linux desktop world would be in a far better place if Linux followed the Windows / macOS way of vendoring toolchains.

The only thing that is an actual issue on Linux if you want backward compatibility is glibc which does not have an easy way (AFAIK) to say "I want to target this old glibc version". But that's not the issue for what we are talking about which is "getting newer compilers on a given distro" - Red Hat & derivatives manage this without issue with the various devtoolsets for instance.

> Yes, and updating compilers don't prevent that at all.

You do understand that ABI backward compabitility is not ensured, don't you?

https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html

Some software packages even break between distro releases.

The primary value of a distro is to provide a fixed platform that application developers and users can safely target. Risking ABI breakups just because a rare number of users wish to be on the bleeding edge without wanting to do any of the work to install their own software is something that's very hard to justify.

Let me quote exactly the page you linked :

> The GNU C++ compiler, g++, has a compiler command line option to switch between various different C++ ABIs. This explicit version switch is the flag -fabi-version.

If you want to target a given distro, you -fabi-version this distro's ABI, just like you set -mmacosx-version-min on mac or set _WIN32_WINNT on windows

It is available in the repos it just isn't the default
Compiling gcc is actually not so bad (and sometimes necessary if you want to e.g. use drd to debug openmp, so you can make libgomp use pthreads primitives that drd knows how to do deal with).
It's nice when they're built in, sure. But gcc is pretty easy to build on its own.
If you want the newest version of software, Ubuntu does not cater to that.
If you are a dev then you can prefer using an LTS flavor of Ubuntu with a PPA for whatever you need to be newer. For important stuff this PPA are provided by Canonical so I run newer kernel and nvidia drivers on an older LTS.
Well, you might want to run a newer/non-lts release via lxd/lxc. It's probably a much better idea than pulling in willy-nilly ppa's.
But at this point, why not simply run Arch Linux?
You might want LTS and upgrade some packages when needed/forced and not play the "update" lottery. New updates not only bring you cool new feature and fixes , they bring new bugs and sometimes features are removed or GUIs are moved around. At least with my LTS I worked around for existing bugs , upgraded from PPA the things I needed to, browsers are latest versions and my IDE is auto-updating too.
Stable base. I'm pretty fond of Ubuntu LTS as the OS running the bare metal, then [docker] containers on top of that to run applications, which means I can have as new of apps as I want while keeping a nice boring stable kernel/bootloader/sshd/whatever.
I'm not sure I understand. You want a stable host system without the need for forced, sometimes breaking, upgrades - so an lts release "on the outside".

You want to develop with new tooling, so a newer release under lxd/lxc. But you probably want to deploy on an lts release - maybe the one comming in a year?

You could of course develop under arch in lxd/lxc - then validate for an lts release once your code is "done".

But I don't think you'd generally would want to deploy to arch - as you'd have to play catch-up in order to keep up with security patches (or backport yourself)?

Just use docker and you can have any toolchain you want any time you want
Just use Fedora, which targets developers.
They still may have a snap for it....
just add it in as a ppa!