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AAPCS ABI is accepted for x86 target #57182
Description
Currently the following code compiles fine when targetting x86_64.
pub extern "aapcs" fn foo() {}This code is non-sensical because AAPCS calling convention is only defined for ARM. An example of non-sensical ABI being disallowed is
pub extern "fastcall" fn foo() {}when compiling with --target=armv7-unknown-linux-gnueabihf which fails with:
error[E0570]: The ABI `"fastcall"` is not supported for the current target
--> <source>:6:1
|
6 | / extern "fastcall" fn foo() {
7 | | }
| |_^
Targets should be reviewed for such nonsensical ABIs and their blacklists updated. I feel that to avoid this issue in the future we should rather prefer a whitelist of ABIs, rather than a blacklist, and by default put no ABIs, so that the compilation fails until the ABI list is properly populated for the target.
Reacted by Kyle J Strand and gnzlbg
Activity
nagisa commentedon Dec 28, 2018
Compiling
extern "aapcs"on aarch64 will explode in LLVM withLLVM ERROR: Unsupported calling convention..gnzlbg commentedon Oct 16, 2019
I ran into these same issues in #65443 .
One thing that I mentioned there, that is not mentioned here, is that because these errors can happen on stable safe Rust code, this is actually a soundness bug (safe Rust code has UB). Note also that for some ABIs, like
stdcall, we don't error on tier-1 targets.I agree. There are some ABIs that the reference says are available on all targets (e.g.
"C","system","Rust", etc.) but except for those, each target should have a white-list that explicitly allows using an ABI on the target.Replace per-target ABI denylist with an allowlist
Auto merge of rust-lang#86231 - nagisa:nagisa/abi-allowlist, r=petroc…