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C++ has Schrödinger's ABI: some will say that it has a too stable ABI and others will say that its ABI is not stable at all. Which one is it ? https://stackove

C++ has Schrödinger's ABI: some will say that it has a too stable ABI and others will say that its ABI is not stable at all. Which one is it ? https://stackoverflow.com/questions/67839008/please-explain-the-c-abi https://stackoverflow.com/questions/67839008/please-explain-... Can one link two rust static libraries communicating with actual rust symbols (not just C ones), one built with gcc-rs (assuming that this is possible yet), the other built with rustc with its default x86_64-pc-windows-msvc abi ? if not, it's at the exact same state ABI-wise than C++

woodruffw 4y ago
Well, it's a multiparadigm language, so both :-) I'm being facetious, but it really is both: it's too unstable in ways that are bad, and also too stable in other ways that are bad. Edit: since you updated your comment: Rust is not in the same position as C++. C++ has an unstable ABI that it cannot break; Rust has an unstable ABI that it can (and regularly does break). Rust works around this with developer tooling; C++ largely ignores the problem and requires developers to learn the secret rules through blood and tears.
- jcelerier 4y ago
  > Rust works around this with developer tooling; how does that work for companies that may use proprietary rust libraries? the proprietary lib authors won't recompile their shit for you just because you upgraded to the latest rustc
  - woodruffw 4y ago
    As pointed out, the C ABI is stable. If companies absolutely feel the need to distribute Rust shared libraries and cannot guarantee the compiler being used, then it's a reasonable choice. I suspect that isn't very common, however. More realistically, the answer is to change the interface: Rust is pretty popular in software architectures where the unit of operation is a networked or IPC'd service; vendors can distribute binaries that communicate at that layer instead.
    - jcelerier 4y ago
      > vendors can distribute binaries that communicate at that layer instead. they could do this in C++ also but they overwhelmingly don't, I don't see why they would in any other language for the same target applications
      - woodruffw 4y ago
        For one, because it's easier in Rust (this goes back to the developer experience and tooling again). But we've now gone from "here's how Rust and C++'s ABI guarantees differ" to "proprietary vendors might not have the easiest time in either language," which is a significant deviation.
    - saagarjha 4y ago
      The real answer is that Rust doesn’t really seek a solution for this problem. That’s fine, but C++ does and it pays an appropriate price for doing so. That’s just how things are.

woodruffw 4y ago

Well, it's a multiparadigm language, so both :-) I'm being facetious, but it really is both: it's too unstable in ways that are bad, and also too stable in other ways that are bad. Edit: since you updated your comment: Rust is not in the same position as C++. C++ has an unstable ABI that it cannot break; Rust has an unstable ABI that it can (and regularly does break). Rust works around this with developer tooling; C++ largely ignores the problem and requires developers to learn the secret rules through blood and tears.

jcelerier 4y ago
> Rust works around this with developer tooling; how does that work for companies that may use proprietary rust libraries? the proprietary lib authors won't recompile their shit for you just because you upgraded to the latest rustc
- woodruffw 4y ago
  As pointed out, the C ABI is stable. If companies absolutely feel the need to distribute Rust shared libraries and cannot guarantee the compiler being used, then it's a reasonable choice. I suspect that isn't very common, however. More realistically, the answer is to change the interface: Rust is pretty popular in software architectures where the unit of operation is a networked or IPC'd service; vendors can distribute binaries that communicate at that layer instead.
  - jcelerier 4y ago
    > vendors can distribute binaries that communicate at that layer instead. they could do this in C++ also but they overwhelmingly don't, I don't see why they would in any other language for the same target applications
    - woodruffw 4y ago
      For one, because it's easier in Rust (this goes back to the developer experience and tooling again). But we've now gone from "here's how Rust and C++'s ABI guarantees differ" to "proprietary vendors might not have the easiest time in either language," which is a significant deviation.
  - saagarjha 4y ago
    The real answer is that Rust doesn’t really seek a solution for this problem. That’s fine, but C++ does and it pays an appropriate price for doing so. That’s just how things are.