Refactor away the need for some descr methods.

Instead we use `Display` impls and their `alternate` render scheme to
decide whether we want backticks or not.

compiler/rustc_const_eval/src/transform/check_consts/ops.rs

@@ -372,7 +372,7 @@ fn build_error(
         ccx: &ConstCx<'_, 'tcx>,
         span: Span,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-        let msg = format!("{}s are not allowed in {}s", self.0.descr(), ccx.const_kind());
+        let msg = format!("{:#}s are not allowed in {}s", self.0, ccx.const_kind());
         if let hir::CoroutineKind::Async(hir::CoroutineSource::Block) = self.0 {
             ccx.tcx.sess.create_feature_err(
                 errors::UnallowedOpInConstContext { span, msg },

compiler/rustc_hir/src/hir.rs

@@ -1520,21 +1520,19 @@ pub enum CoroutineKind {
 impl fmt::Display for CoroutineKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            CoroutineKind::Async(k) => fmt::Display::fmt(k, f),
+            CoroutineKind::Async(k) => {
+                if f.alternate() {
+                    f.write_str("`async` ")?;
+                } else {
+                    f.write_str("async ")?
+                }
+                k.fmt(f)
+            }
             CoroutineKind::Coroutine => f.write_str("coroutine"),
         }
     }
 }
 
-impl CoroutineKind {
-    pub fn descr(&self) -> &'static str {
-        match self {
-            CoroutineKind::Async(ask) => ask.descr(),
-            CoroutineKind::Coroutine => "coroutine",
-        }
-    }
-}
-
 /// In the case of a coroutine created as part of an async/gen construct,
 /// which kind of async/gen construct caused it to be created?
 ///
@@ -1555,21 +1553,12 @@ pub enum CoroutineSource {
 
 impl fmt::Display for CoroutineSource {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(match self {
-            CoroutineSource::Block => "async block",
-            CoroutineSource::Closure => "async closure body",
-            CoroutineSource::Fn => "async fn body",
-        })
-    }
-}
-
-impl CoroutineSource {
-    pub fn descr(&self) -> &'static str {
         match self {
-            CoroutineSource::Block => "`async` block",
+            CoroutineSource::Block => "block",
-            CoroutineSource::Closure => "`async` closure body",
+            CoroutineSource::Closure => "closure body",
-            CoroutineSource::Fn => "`async` fn body",
+            CoroutineSource::Fn => "fn body",
         }
+        .fmt(f)
     }
 }
 

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -1584,14 +1584,13 @@ fn add_labels_for_types(
                 target: &str,
                 types: &FxIndexMap<TyCategory, FxIndexSet<Span>>,
             ) {
-                for (key, values) in types.iter() {
+                for (kind, values) in types.iter() {
                     let count = values.len();
-                    let kind = key.descr();
                     for &sp in values {
                         err.span_label(
                             sp,
                             format!(
-                                "{}{} {}{}",
+                                "{}{} {:#}{}",
                                 if count == 1 { "the " } else { "one of the " },
                                 target,
                                 kind,
@@ -2952,17 +2951,19 @@ pub enum TyCategory {
     Foreign,
 }
 
-impl TyCategory {
+impl fmt::Display for TyCategory {
-    fn descr(&self) -> &'static str {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Self::Closure => "closure",
+            Self::Closure => "closure".fmt(f),
-            Self::Opaque => "opaque type",
+            Self::Opaque => "opaque type".fmt(f),
-            Self::OpaqueFuture => "future",
+            Self::OpaqueFuture => "future".fmt(f),
-            Self::Coroutine(gk) => gk.descr(),
+            Self::Coroutine(gk) => gk.fmt(f),
-            Self::Foreign => "foreign type",
+            Self::Foreign => "foreign type".fmt(f),
         }
     }
+}
 
+impl TyCategory {
     pub fn from_ty(tcx: TyCtxt<'_>, ty: Ty<'_>) -> Option<(Self, DefId)> {
         match *ty.kind() {
             ty::Closure(def_id, _) => Some((Self::Closure, def_id)),

compiler/rustc_middle/src/ty/error.rs

@@ -241,7 +241,9 @@ pub fn sort_string(self, tcx: TyCtxt<'tcx>) -> Cow<'static, str> {
             }
             ty::Dynamic(..) => "trait object".into(),
             ty::Closure(..) => "closure".into(),
-            ty::Coroutine(def_id, ..) => tcx.coroutine_kind(def_id).unwrap().descr().into(),
+            ty::Coroutine(def_id, ..) => {
+                format!("{:#}", tcx.coroutine_kind(def_id).unwrap()).into()
+            }
             ty::CoroutineWitness(..) => "coroutine witness".into(),
             ty::Infer(ty::TyVar(_)) => "inferred type".into(),
             ty::Infer(ty::IntVar(_)) => "integer".into(),
@@ -299,7 +301,9 @@ pub fn prefix_string(self, tcx: TyCtxt<'_>) -> Cow<'static, str> {
             ty::FnPtr(_) => "fn pointer".into(),
             ty::Dynamic(..) => "trait object".into(),
             ty::Closure(..) => "closure".into(),
-            ty::Coroutine(def_id, ..) => tcx.coroutine_kind(def_id).unwrap().descr().into(),
+            ty::Coroutine(def_id, ..) => {
+                format!("{:#}", tcx.coroutine_kind(def_id).unwrap()).into()
+            }
             ty::CoroutineWitness(..) => "coroutine witness".into(),
             ty::Tuple(..) => "tuple".into(),
             ty::Placeholder(..) => "higher-ranked type".into(),

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -2995,11 +2995,11 @@ fn note_obligation_cause_code<T>(
                                 let sp = self.tcx.def_span(def_id);
 
                                 // Special-case this to say "async block" instead of `[static coroutine]`.
-                                let kind = tcx.coroutine_kind(def_id).unwrap().descr();
+                                let kind = tcx.coroutine_kind(def_id).unwrap();
                                 err.span_note(
                                     sp,
                                     with_forced_trimmed_paths!(format!(
-                                        "required because it's used within this {kind}",
+                                        "required because it's used within this {kind:#}",
                                     )),
                                 )
                             }