[mustache_kimono]

> I don't want to be able compile some source only with "rustc-v_ancient-company_name-internal_fork-no_you_cant_have_its_source" version.

Yeah, it's not like Google (and dozens of others) has/have an internal fork of Linux, which never gets merged back. I'm not certain the GPL butters any parsnips here.

> Hence, I'd rather have multiple compatible, yet independently implemented compilers, per language.

You identified it. The problem is compatibility, and again Linux is a good negative example where ostensibly we have a language spec and multiple compilers, but Linux for years would only compile on one compiler.

Multiple compilers and "competition" doesn't solve compatibility. It makes it more difficult. Although I'm sure there will be benefits, I'm not certain the GPL/GCC will make compatibility any easier. It hasn't so far.

[bayindirh]

> Yeah, it's not like Google (and dozens of others) has an internal fork of Linux...

Doesn't matter for completely internal stuff. My concern is public code requiring non-public toolchains to compile. I have experienced this enough during the decades. I don't want to fight with this again.

Google doesn't want to touch Linux for their devices anymore, so they're building Fuchsia, but let's not digress...

> Multiple compilers and "competition" doesn't solve compatibility. It makes it more difficult. Although I'm sure there will be benefits, I'm not certain GPL will make compatibility easier. It hasn't so far.

What GPL brings to the table is strict openness, not compatibility. I can share my code and say that "It builds right on this $GPLd_Compiler", and people can get it and build it. This is what I like to bring to the table for anything I release.

I also wonder whether people would be this reactive to this issue if $company announced a closed source compiler with strict rustc compatibility.

[mustache_kimono]

> What GPL brings to the table is strict openness, not compatibility.

I kinda wonder where this has been an issue with LLVM re: non-public toolchains, and public code where it wouldn't also be an issue with GCC. FWIW I definitely could see it being an issue in HPC/graphics/ML.

> I also wonder whether people would be this reactive to this issue if $company announced a closed source compiler with strict rustc compatibility.

Call me dense -- I guess I don't understand precisely what you're getting at. I don't think anyone would use a closed source compiler with strict rustc compatibility without a pretty big carrot. I think the issue here is strictly compatibility/divergence. Although I'm personally less of a fan of GCC/GPL/FSF, I think a new compiler is great so long as it doesn't (completely) ruin some of the nice things about a single implementation system, and why rust_codegen_gcc seems much more appealing.

Many Rust people don't want to live in the C/C++ compiler world, because they don't have to. "Oops this code won't build with GCC" is a battle they'd just as soon avoid.

[bayindirh]

In the past I have downloaded kernel modules & SDKs for Linux, which were partially open (i.e. had binaries, compiled libraries, etc. alongside open parts), and they were intentionally compiled for highly specific environments, tying the modules or SDKs to (archaic) OS releases which are very hard to obtain, or cannot be obtained from anyone except the hardware vendor.

We wanted to use these thing in newer systems, but it was not always possible, and made our lives way harder than it should be. At the end of the day, you buy vendor's hardware and want to couple it with more modern software, but the vendor doesn't want this for some unknown reason. Planned obsolescence, maybe.

Now, consider that a company pulls the same shenanigans, but by moving the magic to the compiler. All source is open, but can't be compiled because, while the code valid, its correct compilation needs a specific compiler behavior, and the vendor who opened the source cannot share the compiler in source form due to "trade secrets". They may require you to send the code in to "make sure that it's fine", or "sign an agreement" to get the compiler, for a fee, maybe.

I don't want to live in this world, or leave anyone accidentally in that state.

> Many Rust people don't want to live in the C/C++ compiler world, because they don't have to. "Oops this code won't build with GCC" is a battle they'd just as soon avoid.

As someone else noted, gccrs people say that "We strive for rustc compatibility. We will not extend or mangle the language, and consider rustc as our test suite." This is a pretty strong commitment to "many implementations, single behavior" promise.

I started my computing journey in a very open and flexible ecosystem, and with every stopgap put as in the name of security, this openness and flexibility eroded step by step. With this pace, programming and development will be confined to corporations which design the hardware and OS running on them, and PCs will be consoles with keyboards.

I don't want to live in such future. This is why FSF/GPL is important, for me.