Auto merge of rust-lang#106075 - nbdd0121:ffi-unwind, r=joshtriplett

Partial stabilisation of `c_unwind`

The stabilisation report is at rust-lang#74990 (comment)

cc `@rust-lang/wg-ffi-unwind`

Author: bors

compiler/rustc_feature/src/active.rs

@@ -311,7 +311,7 @@ declare_features! (
     (active, async_closure, "1.37.0", Some(62290), None),
     /// Allows async functions to be declared, implemented, and used in traits.
     (incomplete, async_fn_in_trait, "1.66.0", Some(91611), None),
-    /// Allows `extern "C-unwind" fn` to enable unwinding across ABI boundaries.
+    /// Treat `extern "C"` function as nounwind.
     (active, c_unwind, "1.52.0", Some(74990), None),
     /// Allows using C-variadics.
     (active, c_variadic, "1.34.0", Some(44930), None),

compiler/rustc_lint_defs/src/builtin.rs

@@ -4014,7 +4014,6 @@ declare_lint! {
     /// ### Example
     ///
     /// ```rust
-    /// #![feature(c_unwind)]
     /// #![warn(ffi_unwind_calls)]
     ///
     /// extern "C-unwind" {
@@ -4037,8 +4036,7 @@ declare_lint! {
     /// that desire this ability it is therefore necessary to avoid such calls.
     pub FFI_UNWIND_CALLS,
     Allow,
-    "call to foreign functions or function pointers with FFI-unwind ABI",
-    @feature_gate = sym::c_unwind;
+    "call to foreign functions or function pointers with FFI-unwind ABI"
 }
 
 declare_lint! {

compiler/rustc_target/src/spec/abi.rs

@@ -148,8 +148,9 @@ pub fn is_enabled(
 pub fn is_stable(name: &str) -> Result<(), AbiDisabled> {
     match name {
         // Stable
-        "Rust" | "C" | "cdecl" | "stdcall" | "fastcall" | "aapcs" | "win64" | "sysv64"
-        | "system" | "efiapi" => Ok(()),
+        "Rust" | "C" | "C-unwind" | "cdecl" | "cdecl-unwind" | "stdcall" | "stdcall-unwind"
+        | "fastcall" | "fastcall-unwind" | "aapcs" | "aapcs-unwind" | "win64" | "win64-unwind"
+        | "sysv64" | "sysv64-unwind" | "system" | "system-unwind" | "efiapi" => Ok(()),
         "rust-intrinsic" => Err(AbiDisabled::Unstable {
             feature: sym::intrinsics,
             explain: "intrinsics are subject to change",
@@ -162,10 +163,18 @@ pub fn is_stable(name: &str) -> Result<(), AbiDisabled> {
             feature: sym::abi_vectorcall,
             explain: "vectorcall is experimental and subject to change",
         }),
+        "vectorcall-unwind" => Err(AbiDisabled::Unstable {
+            feature: sym::abi_vectorcall,
+            explain: "vectorcall-unwind ABI is experimental and subject to change",
+        }),
         "thiscall" => Err(AbiDisabled::Unstable {
             feature: sym::abi_thiscall,
             explain: "thiscall is experimental and subject to change",
         }),
+        "thiscall-unwind" => Err(AbiDisabled::Unstable {
+            feature: sym::abi_thiscall,
+            explain: "thiscall-unwind ABI is experimental and subject to change",
+        }),
         "rust-call" => Err(AbiDisabled::Unstable {
             feature: sym::unboxed_closures,
             explain: "rust-call ABI is subject to change",
@@ -202,46 +211,6 @@ pub fn is_stable(name: &str) -> Result<(), AbiDisabled> {
             feature: sym::abi_c_cmse_nonsecure_call,
             explain: "C-cmse-nonsecure-call ABI is experimental and subject to change",
         }),
-        "C-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "C-unwind ABI is experimental and subject to change",
-        }),
-        "stdcall-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "stdcall-unwind ABI is experimental and subject to change",
-        }),
-        "system-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "system-unwind ABI is experimental and subject to change",
-        }),
-        "thiscall-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "thiscall-unwind ABI is experimental and subject to change",
-        }),
-        "cdecl-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "cdecl-unwind ABI is experimental and subject to change",
-        }),
-        "fastcall-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "fastcall-unwind ABI is experimental and subject to change",
-        }),
-        "vectorcall-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "vectorcall-unwind ABI is experimental and subject to change",
-        }),
-        "aapcs-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "aapcs-unwind ABI is experimental and subject to change",
-        }),
-        "win64-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "win64-unwind ABI is experimental and subject to change",
-        }),
-        "sysv64-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::c_unwind,
-            explain: "sysv64-unwind ABI is experimental and subject to change",
-        }),
         "wasm" => Err(AbiDisabled::Unstable {
             feature: sym::wasm_abi,
             explain: "wasm ABI is experimental and subject to change",

library/panic_unwind/src/emcc.rs

@@ -47,7 +47,7 @@ static EXCEPTION_TYPE_INFO: TypeInfo = TypeInfo {
     name: b"rust_panic\0".as_ptr(),
 };
 
-// NOTE(nbdd0121): The `canary` field will be part of stable ABI after `c_unwind` stabilization.
+// NOTE(nbdd0121): The `canary` field is part of stable ABI.
 #[repr(C)]
 struct Exception {
     // See `gcc.rs` on why this is present. We already have a static here so just use it.

library/panic_unwind/src/gcc.rs

@@ -48,8 +48,8 @@ use unwind as uw;
 static CANARY: u8 = 0;
 
 // NOTE(nbdd0121)
-// Once `c_unwind` feature is stabilized, there will be ABI stability requirement
-// on this struct. The first two field must be `_Unwind_Exception` and `canary`,
+// There is an ABI stability requirement on this struct.
+// The first two field must be `_Unwind_Exception` and `canary`,
 // as it may be accessed by a different version of the std with a different compiler.
 #[repr(C)]
 struct Exception {

library/panic_unwind/src/seh.rs

@@ -52,7 +52,7 @@ use core::mem::{self, ManuallyDrop};
 use core::ptr;
 use libc::{c_int, c_uint, c_void};
 
-// NOTE(nbdd0121): The `canary` field will be part of stable ABI after `c_unwind` stabilization.
+// NOTE(nbdd0121): The `canary` field is part of stable ABI.
 #[repr(C)]
 struct Exception {
     // See `gcc.rs` on why this is present. We already have a static here so just use it.

tests/run-make/c-unwind-abi-catch-lib-panic/main.rs

@@ -2,7 +2,6 @@
 //!
 //! This test triggers a panic in a Rust library that our foreign function invokes. This shows
 //! that we can unwind through the C code in that library, and catch the underlying panic.
-#![feature(c_unwind)]
 
 use std::panic::{catch_unwind, AssertUnwindSafe};
 

tests/run-make/c-unwind-abi-catch-lib-panic/panic.rs

@@ -1,5 +1,4 @@
 #![crate_type = "staticlib"]
-#![feature(c_unwind)]
 
 /// This function will panic if `x` is greater than 10.
 ///

tests/run-make/c-unwind-abi-catch-panic/main.rs

@@ -1,7 +1,6 @@
 //! A test for calling `C-unwind` functions across foreign function boundaries.
 //!
 //! This test triggers a panic when calling a foreign function that calls *back* into Rust.
-#![feature(c_unwind)]
 
 use std::panic::{catch_unwind, AssertUnwindSafe};
 

tests/run-make/foreign-double-unwind/foo.rs

@@ -1,8 +1,6 @@
 // Tests that C++ double unwinding through Rust code will be properly guarded
 // against instead of exhibiting undefined behaviour.
 
-#![feature(c_unwind)]
-
 extern "C-unwind" {
     fn throw_cxx_exception();
     fn cxx_catch_callback(cb: extern "C-unwind" fn());