Parse rustc_deprecated as deprecated attribute

Author: Mark-Simulacrum

src/librustc_attr/builtin.rs

@@ -124,7 +124,6 @@ pub fn find_unwind_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> Op
 ///
 /// - `#[stable]`
 /// - `#[unstable]`
-/// - `#[rustc_deprecated]`
 #[derive(RustcEncodable, RustcDecodable, Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[derive(HashStable_Generic)]
 pub struct Stability {
@@ -213,7 +212,6 @@ where
 
     'outer: for attr in attrs_iter {
         if ![
-            sym::rustc_deprecated,
             sym::rustc_const_unstable,
             sym::rustc_const_stable,
             sym::unstable,
@@ -299,35 +297,6 @@ where
 
             let meta_name = meta.name_or_empty();
             match meta_name {
-                sym::rustc_deprecated => {
-                    if rustc_depr.is_some() {
-                        struct_span_err!(
-                            diagnostic,
-                            item_sp,
-                            E0540,
-                            "multiple rustc_deprecated attributes"
-                        )
-                        .emit();
-                        continue 'outer;
-                    }
-
-                    get_meta!(since, reason, suggestion);
-
-                    match (since, reason) {
-                        (Some(since), Some(reason)) => {
-                            rustc_depr = Some(RustcDeprecation { since, reason, suggestion })
-                        }
-                        (None, _) => {
-                            handle_errors(sess, attr.span, AttrError::MissingSince);
-                            continue;
-                        }
-                        _ => {
-                            struct_span_err!(diagnostic, attr.span, E0543, "missing 'reason'")
-                                .emit();
-                            continue;
-                        }
-                    }
-                }
                 sym::rustc_const_unstable | sym::unstable => {
                     if meta_name == sym::unstable && stab.is_some() {
                         handle_errors(sess, attr.span, AttrError::MultipleStabilityLevels);
@@ -714,7 +683,16 @@ pub fn eval_condition(
 #[derive(RustcEncodable, RustcDecodable, Clone, HashStable_Generic)]
 pub struct Deprecation {
     pub since: Option<Symbol>,
+    /// The note to issue a reason.
     pub note: Option<Symbol>,
+    /// A text snippet used to completely replace any use of the deprecated item in an expression.
+    ///
+    /// This is currently unstable.
+    pub suggestion: Option<Symbol>,
+
+    /// Whether to treat the since attribute as being a Rust version identifier
+    /// (rather than an opaque string).
+    pub is_since_rustc_version: bool,
 }
 
 /// Finds the deprecation attribute. `None` if none exists.
@@ -738,7 +716,7 @@ where
     let diagnostic = &sess.span_diagnostic;
 
     'outer: for attr in attrs_iter {
-        if !attr.check_name(sym::deprecated) {
+        if !(attr.check_name(sym::deprecated) || attr.check_name(sym::rustc_deprecated)) {
             continue;
         }
 
@@ -751,11 +729,12 @@ where
             Some(meta) => meta,
             None => continue,
         };
-        depr = match &meta.kind {
-            MetaItemKind::Word => Some(Deprecation { since: None, note: None }),
-            MetaItemKind::NameValue(..) => {
-                meta.value_str().map(|note| Deprecation { since: None, note: Some(note) })
-            }
+        let mut since = None;
+        let mut note = None;
+        let mut suggestion = None;
+        match &meta.kind {
+            MetaItemKind::Word => {}
+            MetaItemKind::NameValue(..) => note = meta.value_str(),
             MetaItemKind::List(list) => {
                 let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
                     if item.is_some() {
@@ -789,8 +768,6 @@ where
                     }
                 };
 
-                let mut since = None;
-                let mut note = None;
                 for meta in list {
                     match meta {
                         NestedMetaItem::MetaItem(mi) => match mi.name_or_empty() {
@@ -799,18 +776,32 @@ where
                                     continue 'outer;
                                 }
                             }
-                            sym::note => {
+                            sym::note if attr.check_name(sym::deprecated) => {
+                                if !get(mi, &mut note) {
+                                    continue 'outer;
+                                }
+                            }
+                            sym::reason if attr.check_name(sym::rustc_deprecated) => {
                                 if !get(mi, &mut note) {
                                     continue 'outer;
                                 }
                             }
+                            sym::suggestion if attr.check_name(sym::rustc_deprecated) => {
+                                if !get(mi, &mut suggestion) {
+                                    continue 'outer;
+                                }
+                            }
                             _ => {
                                 handle_errors(
                                     sess,
                                     meta.span(),
                                     AttrError::UnknownMetaItem(
                                         pprust::path_to_string(&mi.path),
-                                        &["since", "note"],
+                                        if attr.check_name(sym::deprecated) {
+                                            &["since", "note"]
+                                        } else {
+                                            &["since", "reason", "suggestion"]
+                                        },
                                     ),
                                 );
                                 continue 'outer;
@@ -829,10 +820,29 @@ where
                         }
                     }
                 }
+            }
+        }
+
+        if suggestion.is_some() && attr.check_name(sym::deprecated) {
+            unreachable!("only allowed on rustc_deprecated")
+        }
 
-                Some(Deprecation { since, note })
+        if attr.check_name(sym::rustc_deprecated) {
+            if since.is_none() {
+                handle_errors(sess, attr.span, AttrError::MissingSince);
+                continue;
             }
-        };
+
+            if note.is_none() {
+                struct_span_err!(diagnostic, attr.span, E0543, "missing 'reason'").emit();
+                continue;
+            }
+        }
+
+        mark_used(&attr);
+
+        let is_since_rustc_version = attr.check_name(sym::rustc_deprecated);
+        depr = Some(Deprecation { since, note, suggestion, is_since_rustc_version });
     }
 
     depr

src/librustc_error_codes/error_codes.rs

@@ -588,7 +588,7 @@ E0770: include_str!("./error_codes/E0770.md"),
     E0521, // borrowed data escapes outside of closure
     E0523,
 //  E0526, // shuffle indices are not constant
-    E0540, // multiple rustc_deprecated attributes
+//  E0540, // multiple rustc_deprecated attributes
     E0542, // missing 'since'
     E0543, // missing 'reason'
     E0544, // multiple stability levels

src/test/ui/stability-attribute/stability-attribute-sanity.rs

@@ -62,7 +62,7 @@ fn multiple3() { }
 #[rustc_deprecated(since = "b", reason = "text")]
 #[rustc_const_unstable(feature = "c", issue = "none")]
 #[rustc_const_unstable(feature = "d", issue = "none")] //~ ERROR multiple stability levels
-pub const fn multiple4() { } //~ ERROR multiple rustc_deprecated attributes [E0540]
+pub const fn multiple4() { } //~ ERROR multiple deprecated attributes
 //~^ ERROR Invalid stability or deprecation version found
 
 #[rustc_deprecated(since = "a", reason = "text")]

src/test/ui/stability-attribute/stability-attribute-sanity.stderr

@@ -82,7 +82,7 @@ error[E0544]: multiple stability levels
 LL | #[stable(feature = "a", since = "b")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0540]: multiple rustc_deprecated attributes
+error[E0550]: multiple deprecated attributes
   --> $DIR/stability-attribute-sanity.rs:65:1
    |
 LL | pub const fn multiple4() { }
@@ -108,5 +108,5 @@ LL | fn deprecated_without_unstable_or_stable() { }
 
 error: aborting due to 18 previous errors
 
-Some errors have detailed explanations: E0539, E0541.
+Some errors have detailed explanations: E0539, E0541, E0550.
 For more information about an error, try `rustc --explain E0539`.