Add more complete tests of possible rust-call cases

compiler/rustc_typeck/src/check/check.rs

@@ -104,7 +104,8 @@ pub(super) fn check_fn<'a, 'tcx>(
                     kind: hir::ImplItemKind::Fn(header, ..), ..
                 }) => Some(header),
                 Node::TraitItem(hir::TraitItem {
-                    kind: hir::TraitItemKind::Fn(header, .. ), ..
+                    kind: hir::TraitItemKind::Fn(header, ..),
+                    ..
                 }) => Some(header),
                 // Closures are RustCall, but they tuple their arguments, so shouldn't be checked
                 Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => None,

src/test/ui/abi/issues/issue-22565-rust-call.rs

@@ -3,6 +3,31 @@
 extern "rust-call" fn b(_i: i32) {}
 //~^ ERROR A function with the "rust-call" ABI must take a single non-self argument that is a tuple
 
+trait Tr {
+    extern "rust-call" fn a();
+    //~^ ERROR A function with the "rust-call" ABI must take a single non-self argument
+
+    extern "rust-call" fn b() {}
+    //~^ ERROR A function with the "rust-call" ABI must take a single non-self argument
+}
+
+struct Foo;
+
+impl Foo {
+    extern "rust-call" fn bar() {}
+    //~^ ERROR A function with the "rust-call" ABI must take a single non-self argument
+}
+
+impl Tr for Foo {
+    fn a() {}
+    //~^ ERROR A function with the "rust-call" ABI must take a single non-self argument
+}
+
 fn main () {
     b(10);
+
+    Foo::bar();
+
+    <Foo as Tr>::a();
+    <Foo as Tr>::b();
 }