Rollup merge of #139001 - folkertdev:naked-function-rustic-abi, r=traviscross,compiler-errors

add `naked_functions_rustic_abi` feature gate

tracking issue: https://github.com/rust-lang/rust/issues/138997

Because the details of the rust abi are unstable, and a naked function must match its stated ABI, this feature gate keeps naked functions with a rustic abi ("Rust", "rust-cold", "rust-call" and "rust-intrinsic") unstable.

r? ````@traviscross````

compiler/rustc_passes/messages.ftl

@@ -742,9 +742,6 @@ passes_trait_impl_const_stable =
 passes_transparent_incompatible =
     transparent {$target} cannot have other repr hints
 
-passes_undefined_naked_function_abi =
-    Rust ABI is unsupported in naked functions
-
 passes_unknown_external_lang_item =
     unknown external lang item: `{$lang_item}`
 

compiler/rustc_passes/src/check_attr.rs

@@ -624,6 +624,21 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         match target {
             Target::Fn
             | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => {
+                let fn_sig = self.tcx.hir_node(hir_id).fn_sig().unwrap();
+                let abi = fn_sig.header.abi;
+                if abi.is_rustic_abi() && !self.tcx.features().naked_functions_rustic_abi() {
+                    feature_err(
+                        &self.tcx.sess,
+                        sym::naked_functions_rustic_abi,
+                        fn_sig.span,
+                        format!(
+                            "`#[naked]` is currently unstable on `extern \"{}\"` functions",
+                            abi.as_str()
+                        ),
+                    )
+                    .emit();
+                }
+
                 for other_attr in attrs {
                     // this covers "sugared doc comments" of the form `/// ...`
                     // it does not cover `#[doc = "..."]`, which is handled below

compiler/rustc_passes/src/errors.rs

@@ -1197,10 +1197,6 @@ pub(crate) struct UnlabeledCfInWhileCondition<'a> {
     pub cf_type: &'a str,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(passes_undefined_naked_function_abi)]
-pub(crate) struct UndefinedNakedFunctionAbi;
-
 #[derive(Diagnostic)]
 #[diag(passes_no_patterns)]
 pub(crate) struct NoPatterns {

compiler/rustc_passes/src/naked_functions.rs

@@ -1,6 +1,5 @@
 //! Checks validity of naked functions.
 
-use rustc_abi::ExternAbi;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{LocalDefId, LocalModDefId};
@@ -10,12 +9,11 @@ use rustc_middle::hir::nested_filter::OnlyBodies;
 use rustc_middle::query::Providers;
 use rustc_middle::span_bug;
 use rustc_middle::ty::TyCtxt;
-use rustc_session::lint::builtin::UNDEFINED_NAKED_FUNCTION_ABI;
 use rustc_span::{Span, sym};
 
 use crate::errors::{
     NakedAsmOutsideNakedFn, NakedFunctionsAsmBlock, NakedFunctionsMustNakedAsm, NoPatterns,
-    ParamsNotAllowed, UndefinedNakedFunctionAbi,
+    ParamsNotAllowed,
 };
 
 pub(crate) fn provide(providers: &mut Providers) {
@@ -29,26 +27,21 @@ fn check_mod_naked_functions(tcx: TyCtxt<'_>, module_def_id: LocalModDefId) {
             continue;
         }
 
-        let (fn_header, body_id) = match tcx.hir_node_by_def_id(def_id) {
+        let body = match tcx.hir_node_by_def_id(def_id) {
             hir::Node::Item(hir::Item {
-                kind: hir::ItemKind::Fn { sig, body: body_id, .. },
-                ..
+                kind: hir::ItemKind::Fn { body: body_id, .. }, ..
             })
             | hir::Node::TraitItem(hir::TraitItem {
-                kind: hir::TraitItemKind::Fn(sig, hir::TraitFn::Provided(body_id)),
+                kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(body_id)),
                 ..
             })
             | hir::Node::ImplItem(hir::ImplItem {
-                kind: hir::ImplItemKind::Fn(sig, body_id),
-                ..
-            }) => (sig.header, *body_id),
+                kind: hir::ImplItemKind::Fn(_, body_id), ..
+            }) => tcx.hir_body(*body_id),
             _ => continue,
         };
 
-        let body = tcx.hir_body(body_id);
-
         if tcx.has_attr(def_id, sym::naked) {
-            check_abi(tcx, def_id, fn_header.abi);
             check_no_patterns(tcx, body.params);
             check_no_parameters_use(tcx, body);
             check_asm(tcx, def_id, body);
@@ -60,20 +53,6 @@ fn check_mod_naked_functions(tcx: TyCtxt<'_>, module_def_id: LocalModDefId) {
     }
 }
 
-/// Checks that function uses non-Rust ABI.
-fn check_abi(tcx: TyCtxt<'_>, def_id: LocalDefId, abi: ExternAbi) {
-    if abi == ExternAbi::Rust {
-        let hir_id = tcx.local_def_id_to_hir_id(def_id);
-        let span = tcx.def_span(def_id);
-        tcx.emit_node_span_lint(
-            UNDEFINED_NAKED_FUNCTION_ABI,
-            hir_id,
-            span,
-            UndefinedNakedFunctionAbi,
-        );
-    }
-}
-
 /// Checks that parameters don't use patterns. Mirrors the checks for function declarations.
 fn check_no_patterns(tcx: TyCtxt<'_>, params: &[hir::Param<'_>]) {
     for param in params {