Represent absence of 'since' attribute as a variant of DeprecatedSince

compiler/rustc_attr/src/builtin.rs

@@ -720,7 +720,7 @@ pub fn eval_condition(
 
 #[derive(Copy, Debug, Encodable, Decodable, Clone, HashStable_Generic)]
 pub struct Deprecation {
-    pub since: Option<DeprecatedSince>,
+    pub since: DeprecatedSince,
     /// 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.
@@ -738,8 +738,10 @@ pub enum DeprecatedSince {
     /// `feature(staged_api)` is off. Deprecation versions outside the standard
     /// library are allowed to be arbitrary strings, for better or worse.
     Symbol(Symbol),
-    /// Failed to parse a deprecation version. An error has already been
-    /// emitted.
+    /// Deprecation version is unspecified but optional.
+    Unspecified,
+    /// Failed to parse a deprecation version, or the deprecation version is
+    /// unspecified and required. An error has already been emitted.
     Err,
 }
 
@@ -749,12 +751,12 @@ impl Deprecation {
     /// version).
     pub fn is_in_effect(&self) -> bool {
         match self.since {
-            Some(DeprecatedSince::RustcVersion(since)) => since <= RustcVersion::CURRENT,
-            Some(DeprecatedSince::Future) => false,
+            DeprecatedSince::RustcVersion(since) => since <= RustcVersion::CURRENT,
+            DeprecatedSince::Future => false,
             // The `since` field doesn't have semantic purpose without `#![staged_api]`.
-            Some(DeprecatedSince::Symbol(_)) => true,
+            DeprecatedSince::Symbol(_) => true,
             // Assume deprecation is in effect if "since" field is absent or invalid.
-            None | Some(DeprecatedSince::Err) => true,
+            DeprecatedSince::Unspecified | DeprecatedSince::Err => true,
         }
     }
 }
@@ -867,20 +869,20 @@ pub fn find_deprecation(
 
         let since = if let Some(since) = since {
             if since.as_str() == "TBD" {
-                Some(DeprecatedSince::Future)
+                DeprecatedSince::Future
             } else if !is_rustc {
-                Some(DeprecatedSince::Symbol(since))
+                DeprecatedSince::Symbol(since)
             } else if let Some(version) = parse_version(since) {
-                Some(DeprecatedSince::RustcVersion(version))
+                DeprecatedSince::RustcVersion(version)
             } else {
                 sess.emit_err(session_diagnostics::InvalidSince { span: attr.span });
-                Some(DeprecatedSince::Err)
+                DeprecatedSince::Err
             }
+        } else if is_rustc {
+            sess.emit_err(session_diagnostics::MissingSince { span: attr.span });
+            DeprecatedSince::Err
         } else {
-            if is_rustc {
-                sess.emit_err(session_diagnostics::MissingSince { span: attr.span });
-            }
-            None
+            DeprecatedSince::Unspecified
         };
 
         if is_rustc && note.is_none() {

compiler/rustc_middle/src/middle/stability.rs

@@ -147,7 +147,7 @@ fn deprecation_lint(is_in_effect: bool) -> &'static Lint {
 
 fn deprecation_message(
     is_in_effect: bool,
-    since: Option<DeprecatedSince>,
+    since: DeprecatedSince,
     note: Option<Symbol>,
     kind: &str,
     path: &str,
@@ -156,13 +156,13 @@ fn deprecation_message(
         format!("use of deprecated {kind} `{path}`")
     } else {
         match since {
-            Some(DeprecatedSince::RustcVersion(version)) => format!(
+            DeprecatedSince::RustcVersion(version) => format!(
                 "use of {kind} `{path}` that will be deprecated in future version {version}"
             ),
-            Some(DeprecatedSince::Future) => {
+            DeprecatedSince::Future => {
                 format!("use of {kind} `{path}` that will be deprecated in a future Rust version")
             }
-            Some(DeprecatedSince::Symbol(_)) | Some(DeprecatedSince::Err) | None => {
+            DeprecatedSince::Symbol(_) | DeprecatedSince::Unspecified | DeprecatedSince::Err => {
                 unreachable!("this deprecation is always in effect; {since:?}")
             }
         }
@@ -347,7 +347,7 @@ impl<'tcx> TyCtxt<'tcx> {
                 // With #![staged_api], we want to emit down the whole
                 // hierarchy.
                 let depr_attr = &depr_entry.attr;
-                if !skip || matches!(depr_attr.since, Some(DeprecatedSince::RustcVersion(_))) {
+                if !skip || matches!(depr_attr.since, DeprecatedSince::RustcVersion(_)) {
                     // Calculating message for lint involves calling `self.def_path_str`.
                     // Which by default to calculate visible path will invoke expensive `visible_parent_map` query.
                     // So we skip message calculation altogether, if lint is allowed.

compiler/rustc_passes/src/stability.rs

@@ -197,7 +197,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
         }
 
         if let Some((
-            rustc_attr::Deprecation { since: Some(DeprecatedSince::RustcVersion(_)), .. },
+            rustc_attr::Deprecation { since: DeprecatedSince::RustcVersion(_), .. },
             span,
         )) = &depr
         {
@@ -228,7 +228,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
             if let (
                 &Some(DeprecatedSince::RustcVersion(dep_since)),
                 &attr::Stable { since: stab_since, .. },
-            ) = (&depr.as_ref().and_then(|(d, _)| d.since), &stab.level)
+            ) = (&depr.as_ref().map(|(d, _)| d.since), &stab.level)
             {
                 match stab_since {
                     StableSince::Current => {

src/librustdoc/html/render/mod.rs

@@ -620,18 +620,18 @@ fn short_item_info(
         // We display deprecation messages for #[deprecated], but only display
         // the future-deprecation messages for rustc versions.
         let mut message = match since {
-            Some(DeprecatedSince::RustcVersion(version)) => {
+            DeprecatedSince::RustcVersion(version) => {
                 if depr.is_in_effect() {
                     format!("Deprecated since {version}")
                 } else {
                     format!("Deprecating in {version}")
                 }
             }
-            Some(DeprecatedSince::Future) => String::from("Deprecating in a future Rust version"),
-            Some(DeprecatedSince::Symbol(since)) => {
+            DeprecatedSince::Future => String::from("Deprecating in a future Rust version"),
+            DeprecatedSince::Symbol(since) => {
                 format!("Deprecated since {}", Escape(since.as_str()))
             }
-            Some(DeprecatedSince::Err) | None => String::from("Deprecated"),
+            DeprecatedSince::Unspecified | DeprecatedSince::Err => String::from("Deprecated"),
         };
 
         if let Some(note) = note {

src/librustdoc/json/conversions.rs

@@ -141,10 +141,10 @@ where
 pub(crate) fn from_deprecation(deprecation: rustc_attr::Deprecation) -> Deprecation {
     let rustc_attr::Deprecation { since, note, suggestion: _ } = deprecation;
     let since = match since {
-        Some(DeprecatedSince::RustcVersion(version)) => Some(version.to_string()),
-        Some(DeprecatedSince::Future) => Some("TBD".to_owned()),
-        Some(DeprecatedSince::Symbol(since)) => Some(since.to_string()),
-        Some(DeprecatedSince::Err) | None => None,
+        DeprecatedSince::RustcVersion(version) => Some(version.to_string()),
+        DeprecatedSince::Future => Some("TBD".to_owned()),
+        DeprecatedSince::Symbol(since) => Some(since.to_string()),
+        DeprecatedSince::Unspecified | DeprecatedSince::Err => None,
     };
     Deprecation { since, note: note.map(|s| s.to_string()) }
 }