Add default trait implementations for "c-unwind" ABI function pointers

Following up on #92964, only add default trait implementations for the
`c-unwind` family of function pointers. The previous attempt in #92964
added trait implementations for many more ABIs and ran into concerns
regarding the increase in size of the libcore rlib.

An attempt to abstract away function pointer types behind a unified
trait to reduce the duplication of trait impls is being discussed in #99531
but this change looks to be blocked on a lang MCP.

Following @RalfJung's suggestion in
https://github.com/rust-lang/rust/pull/99531#issuecomment-1233440142,
this commit is another cut at #92964 but it _only_ adds the impls for
`extern "C-unwind" fn` and `unsafe extern "C-unwind" fn`.

I am interested in landing this patch to unblock the stabilization of
the `c_unwind` feature.

RFC: https://github.com/rust-lang/rfcs/pull/2945
Tracking Issue: https://github.com/rust-lang/rust/issues/74990

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 2fd8180f8b2a29a829c028a03dfe02fad512b1f4..9cbfbbb9f399c67432f8243d2dd218509d3eec21 100644 (file)
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -174,6 +174,7 @@
 #![feature(allow_internal_unstable)]
 #![feature(associated_type_bounds)]
 #![feature(auto_traits)]
+#![feature(c_unwind)]
 #![feature(cfg_sanitize)]
 #![feature(cfg_target_has_atomic)]
 #![feature(cfg_target_has_atomic_equal_alignment)]

diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index 1f7cf6e5d052ca6f1e33b1f5a0580f811f4bcd4e..eb95651973738ec0072d640ec42961f05929ea94 100644 (file)
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -1938,16 +1938,22 @@ macro_rules! fnptr_impls_args {
         fnptr_impls_safety_abi! { extern "Rust" fn($($Arg),+) -> Ret, $($Arg),+ }
         fnptr_impls_safety_abi! { extern "C" fn($($Arg),+) -> Ret, $($Arg),+ }
         fnptr_impls_safety_abi! { extern "C" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
+        fnptr_impls_safety_abi! { extern "C-unwind" fn($($Arg),+) -> Ret, $($Arg),+ }
+        fnptr_impls_safety_abi! { extern "C-unwind" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
         fnptr_impls_safety_abi! { unsafe extern "Rust" fn($($Arg),+) -> Ret, $($Arg),+ }
         fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),+) -> Ret, $($Arg),+ }
         fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
+        fnptr_impls_safety_abi! { unsafe extern "C-unwind" fn($($Arg),+) -> Ret, $($Arg),+ }
+        fnptr_impls_safety_abi! { unsafe extern "C-unwind" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
     };
     () => {
         // No variadic functions with 0 parameters
         fnptr_impls_safety_abi! { extern "Rust" fn() -> Ret, }
         fnptr_impls_safety_abi! { extern "C" fn() -> Ret, }
+        fnptr_impls_safety_abi! { extern "C-unwind" fn() -> Ret, }
         fnptr_impls_safety_abi! { unsafe extern "Rust" fn() -> Ret, }
         fnptr_impls_safety_abi! { unsafe extern "C" fn() -> Ret, }
+        fnptr_impls_safety_abi! { unsafe extern "C-unwind" fn() -> Ret, }
     };
 }