https://github.com/rust-lang/rust http://git.dreamy.place/mirrors/rust/atom?h=1.86.0 2024-11-04T22:27:45+00:00 2024-11-04T22:27:45+00:00 Ralf Jung post@ralfj.de 2024-11-01T21:19:42+00:00 urn:sha1:10723c28964d582814ea8e07dbd8fa7367e0eaee 2024-10-25T18:31:40+00:00 Ralf Jung post@ralfj.de 2024-10-06T17:59:19+00:00 urn:sha1:a0215d8e46aab41219dea0bb1cbaaf97dafe2f89 Fundamentally, we have *three* disjoint categories of functions: 1. const-stable functions 2. private/unstable functions that are meant to be callable from const-stable functions 3. functions that can make use of unstable const features This PR implements the following system: - `#[rustc_const_stable]` puts functions in the first category. It may only be applied to `#[stable]` functions. - `#[rustc_const_unstable]` by default puts functions in the third category. The new attribute `#[rustc_const_stable_indirect]` can be added to such a function to move it into the second category. - `const fn` without a const stability marker are in the second category if they are still unstable. They automatically inherit the feature gate for regular calls, it can now also be used for const-calls. Also, several holes in recursive const stability checking are being closed. There's still one potential hole that is hard to avoid, which is when MIR building automatically inserts calls to a particular function in stable functions -- which happens in the panic machinery. Those need to *not* be `rustc_const_unstable` (or manually get a `rustc_const_stable_indirect`) to be sure they follow recursive const stability. But that's a fairly rare and special case so IMO it's fine. The net effect of this is that a `#[unstable]` or unmarked function can be constified simply by marking it as `const fn`, and it will then be const-callable from stable `const fn` and subject to recursive const stability requirements. If it is publicly reachable (which implies it cannot be unmarked), it will be const-unstable under the same feature gate. Only if the function ever becomes `#[stable]` does it need a `#[rustc_const_unstable]` or `#[rustc_const_stable]` marker to decide if this should also imply const-stability. Adding `#[rustc_const_unstable]` is only needed for (a) functions that need to use unstable const lang features (including intrinsics), or (b) `#[stable]` functions that are not yet intended to be const-stable. Adding `#[rustc_const_stable]` is only needed for functions that are actually meant to be directly callable from stable const code. `#[rustc_const_stable_indirect]` is used to mark intrinsics as const-callable and for `#[rustc_const_unstable]` functions that are actually called from other, exposed-on-stable `const fn`. No other attributes are required. 2024-09-10T02:39:43+00:00 Scott McMurray scottmcm@users.noreply.github.com 2024-08-22T08:28:20+00:00 urn:sha1:d2309c2a9d308ddcd94c0ee8f4d2a01d1bd93560 2024-02-25T07:15:44+00:00 Ralf Jung post@ralfj.de 2024-02-23T17:36:24+00:00 urn:sha1:c1d0e489e564049eae866d6beb5b192c36b3b835 2024-02-16T20:02:50+00:00 许杰友 Jieyou Xu (Joe) jieyouxu@outlook.com 2024-02-16T20:02:50+00:00 urn:sha1:ec2cc761bc7067712ecc7734502f703fe3b024c8 2023-01-11T09:32:08+00:00 Albert Larsan 74931857+albertlarsan68@users.noreply.github.com 2023-01-05T08:13:28+00:00 urn:sha1:cf2dff2b1e3fa55fa5415d524200070d0d7aacfe