Rollup merge of #91002 - petrochenkov:nosynth, r=davidtwco

rustc: Remove `#[rustc_synthetic]`

This function parameter attribute was introduced in https://github.com/rust-lang/rust/pull/44866 as an intermediate step in implementing `impl Trait`, it's not necessary or used anywhere by itself.

Noticed while reviewing https://github.com/rust-lang/rust/pull/90947.

2 files changed, 6 insertions, 19 deletions

diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 5ca532198f4..959dc545337 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -459,9 +459,7 @@ impl Clean<Generics> for hir::Generics<'_> {
         // scans them first.
         fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
             match param.kind {
-                hir::GenericParamKind::Type { synthetic, .. } => {
-                    synthetic == Some(hir::SyntheticTyParamKind::ImplTrait)
-                }
+                hir::GenericParamKind::Type { synthetic, .. } => synthetic,
                 _ => false,
             }
         }
@@ -560,7 +558,7 @@ impl<'a, 'tcx> Clean<Generics> for (&'a ty::Generics, ty::GenericPredicates<'tcx
                         assert_eq!(param.index, 0);
                         return None;
                     }
-                    if synthetic == Some(hir::SyntheticTyParamKind::ImplTrait) {
+                    if synthetic {
                         impl_trait.insert(param.index.into(), vec![]);
                         return None;
                     }
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 2dba52afcd9..fb08ced205d 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -1238,20 +1238,9 @@ impl WherePredicate {
 
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 crate enum GenericParamDefKind {
-    Lifetime {
-        outlives: Vec<Lifetime>,
-    },
-    Type {
-        did: DefId,
-        bounds: Vec<GenericBound>,
-        default: Option<Box<Type>>,
-        synthetic: Option<hir::SyntheticTyParamKind>,
-    },
-    Const {
-        did: DefId,
-        ty: Box<Type>,
-        default: Option<Box<String>>,
-    },
+    Lifetime { outlives: Vec<Lifetime> },
+    Type { did: DefId, bounds: Vec<GenericBound>, default: Option<Box<Type>>, synthetic: bool },
+    Const { did: DefId, ty: Box<Type>, default: Option<Box<String>> },
 }
 
 impl GenericParamDefKind {
@@ -1285,7 +1274,7 @@ impl GenericParamDef {
     crate fn is_synthetic_type_param(&self) -> bool {
         match self.kind {
             GenericParamDefKind::Lifetime { .. } | GenericParamDefKind::Const { .. } => false,
-            GenericParamDefKind::Type { ref synthetic, .. } => synthetic.is_some(),
+            GenericParamDefKind::Type { synthetic, .. } => synthetic,
         }
     }