bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Auto merge of #129753 - folkertdev:stabilize-const-extern-fn, r=RalfJung

Browse source 
stabilize `const_extern_fn`

closes https://github.com/rust-lang/rust/issues/64926

tracking issue: https://github.com/rust-lang/rust/issues/64926
reference PR: https://github.com/rust-lang/reference/pull/1596

## Stabilizaton Report

### Summary

Using `const extern "Rust"` and `const extern "C"` was already stabilized (since version 1.62.0, see https://github.com/rust-lang/rust/pull/95346). This PR stabilizes the other calling conventions: it is now possible to write  `const unsafe extern "calling-convention" fn` and `const extern "calling-convention" fn` for any supported calling convention:

```rust
const extern "C-unwind" fn foo1(val: u8) -> u8 { val + 1}
const extern "stdcall" fn foo2(val: u8) -> u8 { val + 1}
const unsafe extern "C-unwind" fn bar1(val: bool) -> bool { !val }
const unsafe extern "stdcall" fn bar2(val: bool) -> bool { !val }
```

This can be used to const-ify an `extern fn`, or conversely, to make a `const fn` callable from external code.

r? T-lang

cc `@RalfJung`
This commit is contained in:
bors 2024-09-14 23:47:59 +00:00
commit 4f1be92153
29 changed files with 186 additions and 235 deletions
Download patch file Download diff file Expand all files Collapse all files

3
compiler/rustc_parse/src/parser/ty.rs
View file

@ -607,9 +607,6 @@ impl<'a> Parser<'a> {
let decl = self.parse_fn_decl(|_| false, AllowPlus::No, recover_return_sign)?;
let whole_span = lo.to(self.prev_token.span);
if let ast::Const::Yes(span) = constness {
// If we ever start to allow `const fn()`, then update
// feature gating for `#![feature(const_extern_fn)]` to
// cover it.
self.dcx().emit_err(FnPointerCannotBeConst { span: whole_span, qualifier: span });
}
if let Some(ast::CoroutineKind::Async { span, .. }) = coroutine_kind {