Rollup merge of rust-lang#94635 - jhpratt:merge-deprecated-attrs, r=davidtwco

Merge `#[deprecated]` and `#[rustc_deprecated]`

The first commit makes "reason" an alias for "note" in `#[rustc_deprecated]`, while still prohibiting it in `#[deprecated]`.

The second commit changes "suggestion" to not just be a feature of `#[rustc_deprecated]`. This is placed behind the new `deprecated_suggestion` feature. This needs a tracking issue; let me know if this PR will be approved and I can create one.

The third commit is what permits `#[deprecated]` to be used when `#![feature(staged_api)]` is enabled. This isn't yet used in stdlib (only tests), as it would require duplicating all deprecation attributes until a bootstrap occurs. I intend to submit a follow-up PR that replaces all uses and removes the remaining `#[rustc_deprecated]` code after the next bootstrap.

`@rustbot` label +T-libs-api +C-feature-request +A-attributes +S-waiting-on-review

Author: matthiaskrgr

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -437,13 +437,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 )
                 .emit();
             }
-        } else {
-            if attr.has_name(sym::deprecated) {
-                self.sess
-                    .struct_span_err(attr.span, "`#[deprecated]` cannot be used in staged API")
-                    .span_label(attr.span, "use `#[rustc_deprecated]` instead")
-                    .emit();
-            }
         }
     }
 

compiler/rustc_attr/src/builtin.rs

@@ -664,6 +664,7 @@ where
 {
     let mut depr: Option<(Deprecation, Span)> = None;
     let diagnostic = &sess.parse_sess.span_diagnostic;
+    let is_rustc = sess.features_untracked().staged_api;
 
     'outer: for attr in attrs_iter {
         if !(attr.has_name(sym::deprecated) || attr.has_name(sym::rustc_deprecated)) {
@@ -728,17 +729,31 @@ where
                                     continue 'outer;
                                 }
                             }
-                            sym::note if attr.has_name(sym::deprecated) => {
+                            sym::note => {
                                 if !get(mi, &mut note) {
                                     continue 'outer;
                                 }
                             }
+                            // FIXME(jhpratt) remove this after a bootstrap occurs. Emitting an
+                            // error specific to the renaming would be a good idea as well.
                             sym::reason if attr.has_name(sym::rustc_deprecated) => {
                                 if !get(mi, &mut note) {
                                     continue 'outer;
                                 }
                             }
-                            sym::suggestion if attr.has_name(sym::rustc_deprecated) => {
+                            sym::suggestion => {
+                                if !sess.features_untracked().deprecated_suggestion {
+                                    let mut diag = sess.struct_span_err(
+                                        mi.span,
+                                        "suggestions on deprecated items are unstable",
+                                    );
+                                    if sess.is_nightly_build() {
+                                        diag.help("add `#![feature(deprecated_suggestion)]` to the crate root");
+                                    }
+                                    // FIXME(jhpratt) change this to an actual tracking issue
+                                    diag.note("see #XXX for more details").emit();
+                                }
+
                                 if !get(mi, &mut suggestion) {
                                     continue 'outer;
                                 }
@@ -752,7 +767,7 @@ where
                                         if attr.has_name(sym::deprecated) {
                                             &["since", "note"]
                                         } else {
-                                            &["since", "reason", "suggestion"]
+                                            &["since", "note", "suggestion"]
                                         },
                                     ),
                                 );
@@ -775,24 +790,22 @@ where
             }
         }
 
-        if suggestion.is_some() && attr.has_name(sym::deprecated) {
-            unreachable!("only allowed on rustc_deprecated")
-        }
-
-        if attr.has_name(sym::rustc_deprecated) {
+        if is_rustc {
             if since.is_none() {
                 handle_errors(&sess.parse_sess, attr.span, AttrError::MissingSince);
                 continue;
             }
 
             if note.is_none() {
-                struct_span_err!(diagnostic, attr.span, E0543, "missing 'reason'").emit();
+                struct_span_err!(diagnostic, attr.span, E0543, "missing 'note'").emit();
                 continue;
             }
         }
 
-        let is_since_rustc_version = attr.has_name(sym::rustc_deprecated);
-        depr = Some((Deprecation { since, note, suggestion, is_since_rustc_version }, attr.span));
+        depr = Some((
+            Deprecation { since, note, suggestion, is_since_rustc_version: is_rustc },
+            attr.span,
+        ));
     }
 
     depr

compiler/rustc_feature/src/active.rs

@@ -362,6 +362,8 @@ declare_features! (
     (active, default_alloc_error_handler, "1.48.0", Some(66741), None),
     /// Allows default type parameters to influence type inference.
     (active, default_type_parameter_fallback, "1.3.0", Some(27336), None),
+    /// Allows having using `suggestion` in the `#[deprecated]` attribute.
+    (active, deprecated_suggestion, "1.61.0", Some(94785), None),
     /// Allows `#[derive(Default)]` and `#[default]` on enums.
     (active, derive_default_enum, "1.56.0", Some(86985), None),
     /// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.

compiler/rustc_feature/src/builtin_attrs.rs

@@ -461,7 +461,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     // DuplicatesOk since it has its own validation
     ungated!(
         rustc_deprecated, Normal,
-        template!(List: r#"since = "version", reason = "...""#), DuplicatesOk // See E0550
+        template!(List: r#"since = "version", note = "...""#), DuplicatesOk // See E0550
     ),
     // DuplicatesOk since it has its own validation
     ungated!(

compiler/rustc_passes/src/stability.rs

@@ -202,7 +202,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
                     self.tcx.sess,
                     *span,
                     E0549,
-                    "rustc_deprecated attribute must be paired with \
+                    "deprecated attribute must be paired with \
                     either stable or unstable attribute"
                 )
                 .emit();

compiler/rustc_span/src/symbol.rs

@@ -562,6 +562,7 @@ symbols! {
         delay_span_bug_from_inside_query,
         deny,
         deprecated,
+        deprecated_suggestion,
         deref,
         deref_method,
         deref_mut,

library/core/src/lib.rs

@@ -167,6 +167,7 @@
 #![feature(const_refs_to_cell)]
 #![feature(decl_macro)]
 #![feature(derive_default_enum)]
+#![cfg_attr(not(bootstrap), feature(deprecated_suggestion))]
 #![feature(doc_cfg)]
 #![feature(doc_notable_trait)]
 #![feature(rustdoc_internals)]

library/std/src/lib.rs

@@ -263,6 +263,7 @@
 #![feature(doc_cfg)]
 #![feature(doc_cfg_hide)]
 #![feature(rustdoc_internals)]
+#![cfg_attr(not(bootstrap), feature(deprecated_suggestion))]
 #![feature(doc_masked)]
 #![feature(doc_notable_trait)]
 #![feature(dropck_eyepatch)]