Multiple versions of GTK or QT can coexist on the same system. GTK2 is still packaged on most distros, I think for example GIMP only switched to GTK3 last year or so.
GTK update schedule is very slow, and you can run multiple major versions of GTK on the same computer, it's not the right argument. When people says GTK backwards compatibility is bad, they are referring in particular to its breaking changes between minor versions. It was common for themes and apps to break (or work differently) between minor versions of GTK+ 3, as deprecations were sometimes accompanied with the breaking of the deprecated code. (anyway, before Wayland support became important people stuck to GTK+ 2 which was simple, stable, and still supported at the time; and everyone had it installed on their computer alongside GTK+ 3).
Breaking between major versions is annoying (2 to 3, 3 to 4), but for the most part it's renaming work and some slight API modifications, reminiscent of the Python 2 to 3 switch, and it only happened twice since 2000.
The difference is that you can statically link GTK+, and it'll work. You can't statically link glibc, if you want to be able to resolve hostnames or users, because of NSS modules.
We definitely can, because almost every other POSIX libc doesn’t have symbol versioning (or MSVC-style multi-version support). It’s not like the behavior of “open” changes radically all the time, and you need to know exactly what source symbol it linked against. It’s really just an artifact of decisions from decades ago, and the cure is way worse than the disease.
The problem is not the APIs, it's symbol versions. You will routinely get loader errors when running software compiled against a newer glibc than what a system provides, even if the caller does not use any "new" APIs.
glibc-based toolchains are ultimately missing a GLIBC_MIN_DEPLOYMENT_TARGET definition that gets passed to the linker so it knows which minimum version of glibc your software supports, similar to how Apple's toolchain lets you target older MacOS from a newer toolchain.
Yes, so that's why freezing the glibc symbol versions would help. If everybody uses the same version, you cannot get conflicts (at least after it has rippled through and everybody is on the same version). The downside is that we can't add anything new to glibc, but I'd say given all the trouble it produces, that's worth accepting. We can still add bugfixes and security fixes to glibc, we just don't change the APIs of the symbols.
In principle you can patch your binary to accept the old local version, though I don't remember ever getting it to work right. Anyway here it is for the brave or foolhardy, here's the gist:
It's really just not. GTK is on its fourth major version. Wayland broke backwards compatibility with tons of apps.
Multiple versions of GTK or QT can coexist on the same system. GTK2 is still packaged on most distros, I think for example GIMP only switched to GTK3 last year or so.
GTK update schedule is very slow, and you can run multiple major versions of GTK on the same computer, it's not the right argument. When people says GTK backwards compatibility is bad, they are referring in particular to its breaking changes between minor versions. It was common for themes and apps to break (or work differently) between minor versions of GTK+ 3, as deprecations were sometimes accompanied with the breaking of the deprecated code. (anyway, before Wayland support became important people stuck to GTK+ 2 which was simple, stable, and still supported at the time; and everyone had it installed on their computer alongside GTK+ 3).
Breaking between major versions is annoying (2 to 3, 3 to 4), but for the most part it's renaming work and some slight API modifications, reminiscent of the Python 2 to 3 switch, and it only happened twice since 2000.
The difference is that you can statically link GTK+, and it'll work. You can't statically link glibc, if you want to be able to resolve hostnames or users, because of NSS modules.
Static linking itself doesn't prevent modules. There's https://github.com/pikhq/musl-nscd for example
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Can't we just freeze glibc, at least from an API version perspective?
We definitely can, because almost every other POSIX libc doesn’t have symbol versioning (or MSVC-style multi-version support). It’s not like the behavior of “open” changes radically all the time, and you need to know exactly what source symbol it linked against. It’s really just an artifact of decisions from decades ago, and the cure is way worse than the disease.
The problem is not the APIs, it's symbol versions. You will routinely get loader errors when running software compiled against a newer glibc than what a system provides, even if the caller does not use any "new" APIs.
glibc-based toolchains are ultimately missing a GLIBC_MIN_DEPLOYMENT_TARGET definition that gets passed to the linker so it knows which minimum version of glibc your software supports, similar to how Apple's toolchain lets you target older MacOS from a newer toolchain.
Yes, so that's why freezing the glibc symbol versions would help. If everybody uses the same version, you cannot get conflicts (at least after it has rippled through and everybody is on the same version). The downside is that we can't add anything new to glibc, but I'd say given all the trouble it produces, that's worth accepting. We can still add bugfixes and security fixes to glibc, we just don't change the APIs of the symbols.
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In principle you can patch your binary to accept the old local version, though I don't remember ever getting it to work right. Anyway here it is for the brave or foolhardy, here's the gist:
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That's exactly what apgcc from Autopackage provided (20 years ago). https://github.com/DeaDBeeF-Player/apbuild
But compiling in a container is easier and also solves other problems.
Or just pre-install all the versions on each distro and pick the right one at load-time