Migrate rustc_depr uses to use deprecation attribute

This should not be a change in behavior.

Author: Mark-Simulacrum

src/librustc_attr/builtin.rs

@@ -129,7 +129,6 @@ pub fn find_unwind_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> Op
 pub struct Stability {
     pub level: StabilityLevel,
     pub feature: Symbol,
-    pub rustc_depr: Option<RustcDeprecation>,
 }
 
 /// Represents the `#[rustc_const_unstable]` and `#[rustc_const_stable]` attributes.
@@ -162,15 +161,6 @@ impl StabilityLevel {
     }
 }
 
-#[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Copy, Clone, Debug, Eq, Hash)]
-#[derive(HashStable_Generic)]
-pub struct RustcDeprecation {
-    pub since: Symbol,
-    pub reason: Symbol,
-    /// A text snippet used to completely replace any use of the deprecated item in an expression.
-    pub suggestion: Option<Symbol>,
-}
-
 /// Checks if `attrs` contains an attribute like `#![feature(feature_name)]`.
 /// This will not perform any "sanity checks" on the form of the attributes.
 pub fn contains_feature_attr(attrs: &[Attribute], feature_name: Symbol) -> bool {
@@ -204,7 +194,6 @@ where
     use StabilityLevel::*;
 
     let mut stab: Option<Stability> = None;
-    let mut rustc_depr: Option<RustcDeprecation> = None;
     let mut const_stab: Option<ConstStability> = None;
     let mut promotable = false;
     let mut allow_const_fn_ptr = false;
@@ -256,45 +245,6 @@ where
                 }
             };
 
-            macro_rules! get_meta {
-                ($($name:ident),+) => {
-                    $(
-                        let mut $name = None;
-                    )+
-                    for meta in metas {
-                        if let Some(mi) = meta.meta_item() {
-                            match mi.name_or_empty() {
-                                $(
-                                    sym::$name => if !get(mi, &mut $name) { continue 'outer },
-                                )+
-                                _ => {
-                                    let expected = &[ $( stringify!($name) ),+ ];
-                                    handle_errors(
-                                        sess,
-                                        mi.span,
-                                        AttrError::UnknownMetaItem(
-                                            pprust::path_to_string(&mi.path),
-                                            expected,
-                                        ),
-                                    );
-                                    continue 'outer
-                                }
-                            }
-                        } else {
-                            handle_errors(
-                                sess,
-                                meta.span(),
-                                AttrError::UnsupportedLiteral(
-                                    "unsupported literal",
-                                    false,
-                                ),
-                            );
-                            continue 'outer
-                        }
-                    }
-                }
-            }
-
             let meta_name = meta.name_or_empty();
             match meta_name {
                 sym::rustc_const_unstable | sym::unstable => {
@@ -398,7 +348,7 @@ where
                         (Some(feature), reason, Some(_)) => {
                             let level = Unstable { reason, issue: issue_num, is_soft };
                             if sym::unstable == meta_name {
-                                stab = Some(Stability { level, feature, rustc_depr: None });
+                                stab = Some(Stability { level, feature });
                             } else {
                                 const_stab = Some(ConstStability {
                                     level,
@@ -470,7 +420,7 @@ where
                         (Some(feature), Some(since)) => {
                             let level = Stable { since };
                             if sym::stable == meta_name {
-                                stab = Some(Stability { level, feature, rustc_depr: None });
+                                stab = Some(Stability { level, feature });
                             } else {
                                 const_stab = Some(ConstStability {
                                     level,

src/librustc_middle/middle/stability.rs

@@ -5,7 +5,7 @@ pub use self::StabilityLevel::*;
 
 use crate::ty::{self, TyCtxt};
 use rustc_ast::ast::CRATE_NODE_ID;
-use rustc_attr::{self as attr, ConstStability, Deprecation, RustcDeprecation, Stability};
+use rustc_attr::{self as attr, ConstStability, Deprecation, Stability};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_errors::{Applicability, DiagnosticBuilder};
 use rustc_feature::GateIssue;
@@ -130,14 +130,26 @@ pub fn report_unstable(
 
 /// Checks whether an item marked with `deprecated(since="X")` is currently
 /// deprecated (i.e., whether X is not greater than the current rustc version).
-pub fn deprecation_in_effect(since: &str) -> bool {
+pub fn deprecation_in_effect(is_since_rustc_version: bool, since: Option<&str>) -> bool {
+    let since = if let Some(since) = since {
+        if is_since_rustc_version {
+            since
+        } else {
+            // We assume that the deprecation is in effect if it's not a
+            // rustc version.
+            return true;
+        }
+    } else {
+        // If since attribute is not set, then we're definitely in effect.
+        return true;
+    };
     fn parse_version(ver: &str) -> Vec<u32> {
         // We ignore non-integer components of the version (e.g., "nightly").
         ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
     }
 
     if let Some(rustc) = option_env!("CFG_RELEASE") {
-        let since: Vec<u32> = parse_version(since);
+        let since: Vec<u32> = parse_version(&since);
         let rustc: Vec<u32> = parse_version(rustc);
         // We simply treat invalid `since` attributes as relating to a previous
         // Rust version, thus always displaying the warning.
@@ -167,31 +179,27 @@ pub fn deprecation_suggestion(
     }
 }
 
-fn deprecation_message_common(message: String, reason: Option<Symbol>) -> String {
-    match reason {
-        Some(reason) => format!("{}: {}", message, reason),
-        None => message,
-    }
-}
-
 pub fn deprecation_message(depr: &Deprecation, path: &str) -> (String, &'static Lint) {
-    let message = format!("use of deprecated item '{}'", path);
-    (deprecation_message_common(message, depr.note), DEPRECATED)
-}
-
-pub fn rustc_deprecation_message(depr: &RustcDeprecation, path: &str) -> (String, &'static Lint) {
-    let (message, lint) = if deprecation_in_effect(&depr.since.as_str()) {
+    let (message, lint) = if deprecation_in_effect(
+        depr.is_since_rustc_version,
+        depr.since.map(Symbol::as_str).as_deref(),
+    ) {
         (format!("use of deprecated item '{}'", path), DEPRECATED)
     } else {
         (
             format!(
                 "use of item '{}' that will be deprecated in future version {}",
-                path, depr.since
+                path,
+                depr.since.unwrap()
             ),
             DEPRECATED_IN_FUTURE,
         )
     };
-    (deprecation_message_common(message, Some(depr.reason)), lint)
+    let message = match depr.note {
+        Some(reason) => format!("{}: {}", message, reason),
+        None => message,
+    };
+    (message, lint)
 }
 
 pub fn early_report_deprecation(
@@ -289,10 +297,23 @@ impl<'tcx> TyCtxt<'tcx> {
                     .lookup_deprecation_entry(parent_def_id.to_def_id())
                     .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
 
-                if !skip {
+                // #[deprecated] doesn't emit a notice if we're not on the
+                // topmost deprecation. For example, if a struct is deprecated,
+                // the use of a field won't be linted.
+                //
+                // #[rustc_deprecated] however wants to emit down the whole
+                // hierarchy.
+                if !skip || depr_entry.attr.is_since_rustc_version {
                     let (message, lint) =
                         deprecation_message(&depr_entry.attr, &self.def_path_str(def_id));
-                    late_report_deprecation(self, &message, None, lint, span, id);
+                    late_report_deprecation(
+                        self,
+                        &message,
+                        depr_entry.attr.suggestion,
+                        lint,
+                        span,
+                        id,
+                    );
                 }
             };
         }
@@ -310,16 +331,6 @@ impl<'tcx> TyCtxt<'tcx> {
             def_id, span, stability
         );
 
-        if let Some(id) = id {
-            if let Some(stability) = stability {
-                if let Some(depr) = &stability.rustc_depr {
-                    let (message, lint) =
-                        rustc_deprecation_message(depr, &self.def_path_str(def_id));
-                    late_report_deprecation(self, &message, depr.suggestion, lint, span, id);
-                }
-            }
-        }
-
         // Only the cross-crate scenario matters when checking unstable APIs
         let cross_crate = !def_id.is_local();
         if !cross_crate {