From: Arthur Cohen <arthur.cohen@embecosm.com>
Date: Fri, 26 Jul 2024 09:04:46 +0000 (+0200)
Subject: gccrs: ffi-polonius: Remove usage of extern types.
X-Git-Tag: basepoints/gcc-16~1251
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c53ff58924fa162cef5a444dcc35db7da8037249;p=thirdparty%2Fgcc.git

gccrs: ffi-polonius: Remove usage of extern types.

This will allow us to revert our dependency on extern types, which would
help our godbolt build as well as our various builders.

gcc/rust/ChangeLog:

	* checks/errors/borrowck/ffi-polonius/src/gccrs_ffi.rs: Remove extern
	type feature.
	* checks/errors/borrowck/ffi-polonius/src/lib.rs: Define FFIVector
	per the nomicon's recommendation
	https://doc.rust-lang.org/nomicon/ffi.html#representing-opaque-structs
---

diff --git a/gcc/rust/checks/errors/borrowck/ffi-polonius/src/gccrs_ffi.rs b/gcc/rust/checks/errors/borrowck/ffi-polonius/src/gccrs_ffi.rs
index 0cb85078158..7377e3aaf85 100644
--- a/gcc/rust/checks/errors/borrowck/ffi-polonius/src/gccrs_ffi.rs
+++ b/gcc/rust/checks/errors/borrowck/ffi-polonius/src/gccrs_ffi.rs
@@ -30,11 +30,16 @@
 // ```
 include!("gccrs_ffi_generated.rs");
 
+use std::marker::{PhantomData, PhantomPinned};
+
 use crate::GccrsAtom;
 
-// Using opqaue types
-extern "C" {
-    pub type FFIVector;
+// We define an opaque C type per the nomicon's recommendation:
+// https://doc.rust-lang.org/nomicon/ffi.html#representing-opaque-structs
+#[repr(C)]
+pub struct FFIVector {
+    _empty: [u8; 0],
+    marker: PhantomData<(*mut u8, PhantomPinned)>,
 }
 
 impl<T1, T2> Into<(GccrsAtom, GccrsAtom)> for Pair<T1, T2>
diff --git a/gcc/rust/checks/errors/borrowck/ffi-polonius/src/lib.rs b/gcc/rust/checks/errors/borrowck/ffi-polonius/src/lib.rs
index 782a63f8078..c5c0ae9756e 100644
--- a/gcc/rust/checks/errors/borrowck/ffi-polonius/src/lib.rs
+++ b/gcc/rust/checks/errors/borrowck/ffi-polonius/src/lib.rs
@@ -16,8 +16,6 @@
 // along with GCC; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-#![feature(extern_types)]
-
 mod gccrs_ffi;
 
 use gccrs_ffi::FFIVector;