Rollup merge of #140617 - Urgau:unsafe_attr-lint-allow, r=jieyouxu

Report the `unsafe_attr_outside_unsafe` lint at the closest node

This PR have `AstValidation` track a linting node id and then uses it when reporting the `unsafe_attr_outside_unsafe` lint, so that instead of being bound at the crate-root, `#[allow]` of the lint works at any node.

Fixes rust-lang/rust#140602
r? `@jieyouxu`

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -82,6 +82,8 @@ struct AstValidator<'a> {
     /// Used to ban explicit safety on foreign items when the extern block is not marked as unsafe.
     extern_mod_safety: Option<Safety>,
 
+    lint_node_id: NodeId,
+
     lint_buffer: &'a mut LintBuffer,
 }
 
@@ -826,7 +828,7 @@ fn validate_generic_param_order(dcx: DiagCtxtHandle<'_>, generics: &[GenericPara
 
 impl<'a> Visitor<'a> for AstValidator<'a> {
     fn visit_attribute(&mut self, attr: &Attribute) {
-        validate_attr::check_attr(&self.sess.psess, attr);
+        validate_attr::check_attr(&self.sess.psess, attr, self.lint_node_id);
     }
 
     fn visit_ty(&mut self, ty: &'a Ty) {
@@ -839,6 +841,8 @@ fn visit_item(&mut self, item: &'a Item) {
             self.has_proc_macro_decls = true;
         }
 
+        let previous_lint_node_id = mem::replace(&mut self.lint_node_id, item.id);
+
         if let Some(ident) = item.kind.ident()
             && attr::contains_name(&item.attrs, sym::no_mangle)
         {
@@ -1128,6 +1132,8 @@ fn visit_item(&mut self, item: &'a Item) {
             }
             _ => visit::walk_item(self, item),
         }
+
+        self.lint_node_id = previous_lint_node_id;
     }
 
     fn visit_foreign_item(&mut self, fi: &'a ForeignItem) {
@@ -1694,6 +1700,7 @@ pub fn check_crate(
         outer_impl_trait_span: None,
         disallow_tilde_const: Some(TildeConstReason::Item),
         extern_mod_safety: None,
+        lint_node_id: CRATE_NODE_ID,
         lint_buffer: lints,
     };
     visit::walk_crate(&mut validator, krate);

compiler/rustc_expand/src/config.rs

@@ -274,7 +274,12 @@ fn process_cfg_attr(&self, attr: &Attribute) -> Vec<Attribute> {
     /// is in the original source file. Gives a compiler error if the syntax of
     /// the attribute is incorrect.
     pub(crate) fn expand_cfg_attr(&self, cfg_attr: &Attribute, recursive: bool) -> Vec<Attribute> {
-        validate_attr::check_attribute_safety(&self.sess.psess, AttributeSafety::Normal, &cfg_attr);
+        validate_attr::check_attribute_safety(
+            &self.sess.psess,
+            AttributeSafety::Normal,
+            &cfg_attr,
+            ast::CRATE_NODE_ID,
+        );
 
         // A trace attribute left in AST in place of the original `cfg_attr` attribute.
         // It can later be used by lints or other diagnostics.

compiler/rustc_expand/src/expand.rs

@@ -1983,7 +1983,11 @@ fn check_attributes(&self, attrs: &[ast::Attribute], call: &ast::MacCall) {
         let mut span: Option<Span> = None;
         while let Some(attr) = attrs.next() {
             rustc_ast_passes::feature_gate::check_attribute(attr, self.cx.sess, features);
-            validate_attr::check_attr(&self.cx.sess.psess, attr);
+            validate_attr::check_attr(
+                &self.cx.sess.psess,
+                attr,
+                self.cx.current_expansion.lint_node_id,
+            );
 
             let current_span = if let Some(sp) = span { sp.to(attr.span) } else { attr.span };
             span = Some(current_span);

compiler/rustc_parse/src/validate_attr.rs

@@ -3,7 +3,8 @@
 use rustc_ast::token::Delimiter;
 use rustc_ast::tokenstream::DelimSpan;
 use rustc_ast::{
-    self as ast, AttrArgs, Attribute, DelimArgs, MetaItem, MetaItemInner, MetaItemKind, Safety,
+    self as ast, AttrArgs, Attribute, DelimArgs, MetaItem, MetaItemInner, MetaItemKind, NodeId,
+    Safety,
 };
 use rustc_errors::{Applicability, FatalError, PResult};
 use rustc_feature::{AttributeSafety, AttributeTemplate, BUILTIN_ATTRIBUTE_MAP, BuiltinAttribute};
@@ -15,7 +16,7 @@
 
 use crate::{errors, parse_in};
 
-pub fn check_attr(psess: &ParseSess, attr: &Attribute) {
+pub fn check_attr(psess: &ParseSess, attr: &Attribute, id: NodeId) {
     if attr.is_doc_comment() || attr.has_name(sym::cfg_trace) || attr.has_name(sym::cfg_attr_trace)
     {
         return;
@@ -26,7 +27,7 @@ pub fn check_attr(psess: &ParseSess, attr: &Attribute) {
 
     // All non-builtin attributes are considered safe
     let safety = attr_info.map(|x| x.safety).unwrap_or(AttributeSafety::Normal);
-    check_attribute_safety(psess, safety, attr);
+    check_attribute_safety(psess, safety, attr, id);
 
     // Check input tokens for built-in and key-value attributes.
     match attr_info {
@@ -154,7 +155,12 @@ fn is_attr_template_compatible(template: &AttributeTemplate, meta: &ast::MetaIte
     }
 }
 
-pub fn check_attribute_safety(psess: &ParseSess, safety: AttributeSafety, attr: &Attribute) {
+pub fn check_attribute_safety(
+    psess: &ParseSess,
+    safety: AttributeSafety,
+    attr: &Attribute,
+    id: NodeId,
+) {
     let attr_item = attr.get_normal_item();
 
     if let AttributeSafety::Unsafe { unsafe_since } = safety {
@@ -185,7 +191,7 @@ pub fn check_attribute_safety(psess: &ParseSess, safety: AttributeSafety, attr:
                 psess.buffer_lint(
                     UNSAFE_ATTR_OUTSIDE_UNSAFE,
                     path_span,
-                    ast::CRATE_NODE_ID,
+                    id,
                     BuiltinLintDiag::UnsafeAttrOutsideUnsafe {
                         attribute_name_span: path_span,
                         sugg_spans: (diag_span.shrink_to_lo(), diag_span.shrink_to_hi()),

tests/ui/rust-2024/unsafe-attributes/unsafe-attributes-allow.rs

@@ -0,0 +1,16 @@
+//@ check-pass
+//@ edition: 2021
+//
+// Anti-regression test for https://github.com/rust-lang/rust/issues/140602
+// where the generated warning couldn't be allowed due too being attached to
+// the wrong AST node.
+
+#![deny(unsafe_attr_outside_unsafe)]
+
+#[allow(unsafe_attr_outside_unsafe)]
+mod generated {
+    #[no_mangle]
+    fn _generated_foo() {}
+}
+
+fn main() {}