Rollup merge of #124214 - carbotaniuman:parse_unsafe_attrs, r=michaelwoerister

Parse unsafe attributes

Initial parse implementation for #123757

This is the initial work to parse unsafe attributes, which is represented as an extra `unsafety` field in `MetaItem` and `AttrItem`. There's two areas in the code where it appears that parsing is done manually and not using the parser stuff, and I'm not sure how I'm supposed to thread the change there.

compiler/rustc_ast/src/ast.rs

@@ -488,6 +488,7 @@ pub struct Crate {
 /// E.g., `#[test]`, `#[derive(..)]`, `#[rustfmt::skip]` or `#[feature = "foo"]`.
 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
 pub struct MetaItem {
+    pub unsafety: Safety,
     pub path: Path,
     pub kind: MetaItemKind,
     pub span: Span,
@@ -2823,7 +2824,12 @@ pub struct NormalAttr {
 impl NormalAttr {
     pub fn from_ident(ident: Ident) -> Self {
         Self {
-            item: AttrItem { path: Path::from_ident(ident), args: AttrArgs::Empty, tokens: None },
+            item: AttrItem {
+                unsafety: Safety::Default,
+                path: Path::from_ident(ident),
+                args: AttrArgs::Empty,
+                tokens: None,
+            },
             tokens: None,
         }
     }
@@ -2831,6 +2837,7 @@ impl NormalAttr {
 
 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
 pub struct AttrItem {
+    pub unsafety: Safety,
     pub path: Path,
     pub args: AttrArgs,
     // Tokens for the meta item, e.g. just the `foo` within `#[foo]` or `#![foo]`.

compiler/rustc_ast/src/attr/mod.rs

@@ -1,6 +1,8 @@
 //! Functions dealing with attributes and meta items.
 
-use crate::ast::{AttrArgs, AttrArgsEq, AttrId, AttrItem, AttrKind, AttrStyle, AttrVec, Attribute};
+use crate::ast::{
+    AttrArgs, AttrArgsEq, AttrId, AttrItem, AttrKind, AttrStyle, AttrVec, Attribute, Safety,
+};
 use crate::ast::{DelimArgs, Expr, ExprKind, LitKind, MetaItemLit};
 use crate::ast::{MetaItem, MetaItemKind, NestedMetaItem, NormalAttr};
 use crate::ast::{Path, PathSegment, DUMMY_NODE_ID};
@@ -238,7 +240,12 @@ impl AttrItem {
     }
 
     pub fn meta(&self, span: Span) -> Option<MetaItem> {
-        Some(MetaItem { path: self.path.clone(), kind: self.meta_kind()?, span })
+        Some(MetaItem {
+            unsafety: Safety::Default,
+            path: self.path.clone(),
+            kind: self.meta_kind()?,
+            span,
+        })
     }
 
     pub fn meta_kind(&self) -> Option<MetaItemKind> {
@@ -371,7 +378,10 @@ impl MetaItem {
             _ => path.span.hi(),
         };
         let span = path.span.with_hi(hi);
-        Some(MetaItem { path, kind, span })
+        // FIXME: This parses `unsafe()` not as unsafe attribute syntax in `MetaItem`,
+        // but as a parenthesized list. This (and likely `MetaItem`) should be changed in
+        // such a way that builtin macros don't accept extraneous `unsafe()`.
+        Some(MetaItem { unsafety: Safety::Default, path, kind, span })
     }
 }
 
@@ -555,11 +565,12 @@ pub fn mk_doc_comment(
 pub fn mk_attr(
     g: &AttrIdGenerator,
     style: AttrStyle,
+    unsafety: Safety,
     path: Path,
     args: AttrArgs,
     span: Span,
 ) -> Attribute {
-    mk_attr_from_item(g, AttrItem { path, args, tokens: None }, None, style, span)
+    mk_attr_from_item(g, AttrItem { unsafety, path, args, tokens: None }, None, style, span)
 }
 
 pub fn mk_attr_from_item(
@@ -577,15 +588,22 @@ pub fn mk_attr_from_item(
     }
 }
 
-pub fn mk_attr_word(g: &AttrIdGenerator, style: AttrStyle, name: Symbol, span: Span) -> Attribute {
+pub fn mk_attr_word(
+    g: &AttrIdGenerator,
+    style: AttrStyle,
+    unsafety: Safety,
+    name: Symbol,
+    span: Span,
+) -> Attribute {
     let path = Path::from_ident(Ident::new(name, span));
     let args = AttrArgs::Empty;
-    mk_attr(g, style, path, args, span)
+    mk_attr(g, style, unsafety, path, args, span)
 }
 
 pub fn mk_attr_nested_word(
     g: &AttrIdGenerator,
     style: AttrStyle,
+    unsafety: Safety,
     outer: Symbol,
     inner: Symbol,
     span: Span,
@@ -601,12 +619,13 @@ pub fn mk_attr_nested_word(
         delim: Delimiter::Parenthesis,
         tokens: inner_tokens,
     });
-    mk_attr(g, style, path, attr_args, span)
+    mk_attr(g, style, unsafety, path, attr_args, span)
 }
 
 pub fn mk_attr_name_value_str(
     g: &AttrIdGenerator,
     style: AttrStyle,
+    unsafety: Safety,
     name: Symbol,
     val: Symbol,
     span: Span,
@@ -621,7 +640,7 @@ pub fn mk_attr_name_value_str(
     });
     let path = Path::from_ident(Ident::new(name, span));
     let args = AttrArgs::Eq(span, AttrArgsEq::Ast(expr));
-    mk_attr(g, style, path, args, span)
+    mk_attr(g, style, unsafety, path, args, span)
 }
 
 pub fn filter_by_name(attrs: &[Attribute], name: Symbol) -> impl Iterator<Item = &Attribute> {

compiler/rustc_ast/src/mut_visit.rs

@@ -647,8 +647,10 @@ fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
     let Attribute { kind, id: _, style: _, span } = attr;
     match kind {
         AttrKind::Normal(normal) => {
-            let NormalAttr { item: AttrItem { path, args, tokens }, tokens: attr_tokens } =
-                &mut **normal;
+            let NormalAttr {
+                item: AttrItem { unsafety: _, path, args, tokens },
+                tokens: attr_tokens,
+            } = &mut **normal;
             vis.visit_path(path);
             visit_attr_args(args, vis);
             visit_lazy_tts(tokens, vis);
@@ -678,7 +680,7 @@ fn noop_visit_meta_list_item<T: MutVisitor>(li: &mut NestedMetaItem, vis: &mut T
 }
 
 fn noop_visit_meta_item<T: MutVisitor>(mi: &mut MetaItem, vis: &mut T) {
-    let MetaItem { path: _, kind, span } = mi;
+    let MetaItem { unsafety: _, path: _, kind, span } = mi;
     match kind {
         MetaItemKind::Word => {}
         MetaItemKind::List(mis) => visit_thin_vec(mis, |mi| vis.visit_meta_list_item(mi)),
@@ -840,7 +842,7 @@ fn visit_nonterminal<T: MutVisitor>(nt: &mut token::Nonterminal, vis: &mut T) {
         token::NtTy(ty) => vis.visit_ty(ty),
         token::NtLiteral(expr) => vis.visit_expr(expr),
         token::NtMeta(item) => {
-            let AttrItem { path, args, tokens } = item.deref_mut();
+            let AttrItem { unsafety: _, path, args, tokens } = item.deref_mut();
             vis.visit_path(path);
             visit_attr_args(args, vis);
             visit_lazy_tts(tokens, vis);