Add #[unsafe_eii].

Author: m-ou-se

compiler/rustc_builtin_macros/src/eii.rs

@@ -6,32 +6,49 @@ use rustc_ast_pretty::pprust::path_to_string;
 use rustc_expand::base::{Annotatable, ExtCtxt};
 use rustc_span::{Ident, Span, kw, sym};
 
-/* ```rust
-
-#[eii]
-fn panic_handler();
-
-#[eii(panic_handler)]
-fn panic_handler();
-
-#[eii(panic_handler, unsafe)]
-fn panic_handler();
-
-// expansion:
-
-extern "Rust" {
-    fn panic_handler();
+// ```rust
+// #[eii]
+// fn panic_handler();
+//
+// // or:
+//
+// #[eii(panic_handler)]
+// fn panic_handler();
+//
+// // expansion:
+//
+// extern "Rust" {
+//     fn panic_handler();
+// }
+//
+// #[rustc_builtin_macro(eii_macro)]
+// #[eii_macro_for(panic_handler)]
+// macro panic_handler() {}
+// ```
+pub(crate) fn eii(
+    ecx: &mut ExtCtxt<'_>,
+    span: Span,
+    meta_item: &ast::MetaItem,
+    item: Annotatable,
+) -> Vec<Annotatable> {
+    eii_(ecx, span, meta_item, item, false)
 }
 
-#[rustc_builtin_macro(eii_macro)] // eii_macro_for: panic_handler
-macro panic_handler() {}
+pub(crate) fn unsafe_eii(
+    ecx: &mut ExtCtxt<'_>,
+    span: Span,
+    meta_item: &ast::MetaItem,
+    item: Annotatable,
+) -> Vec<Annotatable> {
+    eii_(ecx, span, meta_item, item, true)
+}
 
-``` */
-pub(crate) fn eii(
+fn eii_(
     ecx: &mut ExtCtxt<'_>,
     span: Span,
     meta_item: &ast::MetaItem,
     item: Annotatable,
+    impl_unsafe: bool,
 ) -> Vec<Annotatable> {
     let span = ecx.with_def_site_ctxt(span);
 
@@ -73,8 +90,6 @@ pub(crate) fn eii(
         return vec![Annotatable::Item(P(item))];
     };
 
-    let impl_unsafe = false; // TODO
-
     let abi = match func.sig.header.ext {
         // extern "X" fn  =>  extern "X" {}
         ast::Extern::Explicit(lit, _) => Some(lit),
@@ -124,28 +139,6 @@ pub(crate) fn eii(
 
     let macro_def = Annotatable::Item(P(ast::Item {
         attrs: ast::AttrVec::from_iter([
-            // #[eii_macro_for(item_name)]
-            ast::Attribute {
-                kind: ast::AttrKind::Normal(P(ast::NormalAttr {
-                    item: ast::AttrItem {
-                        unsafety: ast::Safety::Default,
-                        path: ast::Path::from_ident(Ident::new(sym::eii_macro_for, span)),
-                        args: ast::AttrArgs::Delimited(ast::DelimArgs {
-                            dspan: DelimSpan::from_single(span),
-                            delim: Delimiter::Parenthesis,
-                            tokens: TokenStream::new(vec![tokenstream::TokenTree::Token(
-                                token::Token::from_ast_ident(item_name),
-                                Spacing::Alone,
-                            )]),
-                        }),
-                        tokens: None,
-                    },
-                    tokens: None,
-                })),
-                id: ecx.sess.psess.attr_id_generator.mk_attr_id(),
-                style: ast::AttrStyle::Outer,
-                span,
-            },
             // #[builtin_macro(eii_macro)]
             ast::Attribute {
                 kind: ast::AttrKind::Normal(P(ast::NormalAttr {
@@ -197,7 +190,11 @@ pub(crate) fn eii(
                 ]),
             }),
             macro_rules: false,
-            eii_macro_for: None,
+            // #[eii_macro_for(item_name)]
+            eii_macro_for: Some(ast::EIIMacroFor {
+                extern_item_path: ast::Path::from_ident(item_name),
+                impl_unsafe,
+            }),
         }),
         tokens: None,
     }));

compiler/rustc_builtin_macros/src/lib.rs

@@ -125,6 +125,7 @@ pub fn register_builtin_macros(resolver: &mut dyn ResolverExpand) {
         test: test::expand_test,
         test_case: test::expand_test_case,
         eii: eii::eii,
+        unsafe_eii: eii::unsafe_eii,
         eii_macro_for: eii::eii_macro_for,
         eii_macro: eii::eii_macro,
     }

compiler/rustc_span/src/symbol.rs

@@ -2202,6 +2202,7 @@ symbols! {
         unsafe_block_in_unsafe_fn,
         unsafe_cell,
         unsafe_cell_raw_get,
+        unsafe_eii,
         unsafe_extern_blocks,
         unsafe_fields,
         unsafe_no_drop_flag,

library/core/src/macros/mod.rs

@@ -1791,6 +1791,16 @@ pub(crate) mod builtin {
         /* compiler built-in */
     }
 
+    /// Unsafely Externally Implementable Item: Defines an unsafe attribute macro that can override
+    /// the item this is applied to.
+    #[cfg(not(bootstrap))]
+    #[unstable(feature = "eii", issue = "none")]
+    #[rustc_builtin_macro]
+    #[allow_internal_unstable(eii_internals, decl_macro, rustc_attrs)]
+    pub macro unsafe_eii($item:item) {
+        /* compiler built-in */
+    }
+
     /// Impl detail of EII
     #[cfg(not(bootstrap))]
     #[unstable(feature = "eii_internals", issue = "none")]

library/core/src/prelude/v1.rs

@@ -122,7 +122,7 @@ pub use crate::macros::builtin::define_opaque;
 
 #[unstable(feature = "eii", issue = "none")]
 #[cfg(not(bootstrap))]
-pub use crate::macros::builtin::eii;
+pub use crate::macros::builtin::{eii, unsafe_eii};
 
 #[unstable(feature = "eii_internals", issue = "none")]
 #[cfg(not(bootstrap))]