bjoernager/rust
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codegen_llvm: avoid Deref impls w/ extern type

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`rustc_codegen_llvm` relied on `Deref` impls where `Deref::Target` was
or contained an extern type - in my experimental implementation of
rust-lang/rfcs#3729, this isn't possible as the `Target` associated
type's `?Sized` bound cannot be relaxed backwards compatibly (unless we
come up with some way of doing this).

In later pull requests with the rust-lang/rfcs#3729 implementation,
breakage like this could only occur for nightly users relying on the
`extern_types` feature.

Upstreaming this to avoid needing to keep carrying this patch locally,
and I think it'll necessarily need to change eventually.
This commit is contained in:
David Wood 2025-02-04 12:20:09 +00:00
parent ad27045c31
commit a5615d3c62
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8 changed files with 31 additions and 30 deletions
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21
compiler/rustc_codegen_llvm/src/llvm/mod.rs
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@ -1,7 +1,6 @@
#![allow(non_snake_case)]
use std::ffi::{CStr, CString};
use std::ops::Deref;
use std::ptr;
use std::str::FromStr;
use std::string::FromUtf8Error;
@ -355,6 +354,16 @@ impl<'a> OperandBundleOwned<'a> {
};
OperandBundleOwned { raw: ptr::NonNull::new(raw).unwrap() }
}
/// Returns inner `OperandBundle` type.
///
/// This could be a `Deref` implementation, but `OperandBundle` contains an extern type and
/// `Deref::Target: ?Sized`.
pub(crate) fn raw(&self) -> &OperandBundle<'a> {
// SAFETY: The returned reference is opaque and can only used for FFI.
// It is valid for as long as `&self` is.
unsafe { self.raw.as_ref() }
}
}
impl Drop for OperandBundleOwned<'_> {
@ -365,16 +374,6 @@ impl Drop for OperandBundleOwned<'_> {
}
}
impl<'a> Deref for OperandBundleOwned<'a> {
type Target = OperandBundle<'a>;
fn deref(&self) -> &Self::Target {
// SAFETY: The returned reference is opaque and can only used for FFI.
// It is valid for as long as `&self` is.
unsafe { self.raw.as_ref() }
}
}
pub(crate) fn add_module_flag_u32(
module: &Module,
merge_behavior: ModuleFlagMergeBehavior,