Remove dead code stemming from an old effects desugaring

rust-lang · jhpratt · Aug 23, 2025 · Aug 28, 2025 · Aug 28, 2025 · Aug 28, 2025
commit 6fc0cf428885a4939fc3b6f60f638ce09e48339f
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
@@ -2028,7 +2028,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
                 (
                     hir::ParamName::Plain(self.lower_ident(param.ident)),
-                    hir::GenericParamKind::Const { ty, default, synthetic: false },
+                    hir::GenericParamKind::Const { ty, default },
                 )
             }
         }

diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
@@ -784,7 +784,6 @@ pub enum GenericParamKind<'hir> {
         ty: &'hir Ty<'hir>,
         /// Optional default value for the const generic param
         default: Option<&'hir ConstArg<'hir>>,
-        synthetic: bool,
     },
 }
 

diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs
@@ -1085,7 +1085,7 @@ pub fn walk_generic_param<'v, V: Visitor<'v>>(
         GenericParamKind::Type { ref default, .. } => {
             visit_opt!(visitor, visit_ty_unambig, default)
         }
-        GenericParamKind::Const { ref ty, ref default, synthetic: _ } => {
+        GenericParamKind::Const { ref ty, ref default } => {
             try_visit!(visitor.visit_ty_unambig(ty));
             if let Some(default) = default {
                 try_visit!(visitor.visit_const_param_default(*hir_id, default));

diff --git a/compiler/rustc_hir_analysis/src/collect/generics_of.rs b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
@@ -305,7 +305,7 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
 
                 ty::GenericParamDefKind::Type { has_default: default.is_some(), synthetic }
             }
-            GenericParamKind::Const { ty: _, default, synthetic } => {
+            GenericParamKind::Const { ty: _, default } => {
                 if default.is_some() {
                     match param_default_policy.expect("no policy for generic param default") {
                         ParamDefaultPolicy::Allowed => {}
@@ -316,7 +316,7 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
                     }
                 }
 
-                ty::GenericParamDefKind::Const { has_default: default.is_some(), synthetic }
+                ty::GenericParamDefKind::Const { has_default: default.is_some() }
             }
         };
         Some(ty::GenericParamDef {
@@ -523,7 +523,7 @@ impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
     type Result = ControlFlow<()>;
 
     fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) -> Self::Result {
-        if let GenericParamKind::Const { ty, default: _, synthetic: _ } = p.kind {
+        if let GenericParamKind::Const { ty, default: _ } = p.kind {
             let prev = self.in_param_ty;
             self.in_param_ty = true;
             let res = self.visit_ty_unambig(ty);

diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/generics.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/generics.rs
@@ -419,14 +419,7 @@ pub(crate) fn check_generic_arg_count(
         .filter(|param| matches!(param.kind, ty::GenericParamDefKind::Type { synthetic: true, .. }))
         .count();
     let named_type_param_count = param_counts.types - has_self as usize - synth_type_param_count;
-    let synth_const_param_count = gen_params
-        .own_params
-        .iter()
-        .filter(|param| {
-            matches!(param.kind, ty::GenericParamDefKind::Const { synthetic: true, .. })
-        })
-        .count();
-    let named_const_param_count = param_counts.consts - synth_const_param_count;
+    let named_const_param_count = param_counts.consts;
     let infer_lifetimes =
         (gen_pos != GenericArgPosition::Type || seg.infer_args) && !gen_args.has_lifetime_params();
 

diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
@@ -2379,7 +2379,7 @@ impl<'a> State<'a> {
                     self.print_type(default);
                 }
             }
-            GenericParamKind::Const { ty, ref default, synthetic: _ } => {
+            GenericParamKind::Const { ty, ref default } => {
                 self.word_space(":");
                 self.print_type(ty);
                 if let Some(default) = default {

diff --git a/compiler/rustc_middle/src/ty/generics.rs b/compiler/rustc_middle/src/ty/generics.rs
@@ -13,7 +13,7 @@ use crate::ty::{EarlyBinder, GenericArgsRef};
 pub enum GenericParamDefKind {
     Lifetime,
     Type { has_default: bool, synthetic: bool },
-    Const { has_default: bool, synthetic: bool },
+    Const { has_default: bool },
 }
 
 impl GenericParamDefKind {

diff --git a/compiler/rustc_public/src/unstable/convert/stable/ty.rs b/compiler/rustc_public/src/unstable/convert/stable/ty.rs
@@ -656,13 +656,13 @@ impl<'tcx> Stable<'tcx> for rustc_middle::ty::GenericParamDefKind {
 
     fn stable(&self, _: &mut Tables<'_, BridgeTys>, _: &CompilerCtxt<'_, BridgeTys>) -> Self::T {
         use crate::ty::GenericParamDefKind;
-        match self {
+        match *self {
             ty::GenericParamDefKind::Lifetime => GenericParamDefKind::Lifetime,
             ty::GenericParamDefKind::Type { has_default, synthetic } => {
-                GenericParamDefKind::Type { has_default: *has_default, synthetic: *synthetic }
+                GenericParamDefKind::Type { has_default, synthetic }
             }
-            ty::GenericParamDefKind::Const { has_default, synthetic: _ } => {
-                GenericParamDefKind::Const { has_default: *has_default }
+            ty::GenericParamDefKind::Const { has_default } => {
+                GenericParamDefKind::Const { has_default }
             }
         }
     }

diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
@@ -557,7 +557,7 @@ fn clean_generic_param_def(
                 },
             )
         }
-        ty::GenericParamDefKind::Const { has_default, synthetic } => (
+        ty::GenericParamDefKind::Const { has_default } => (
             def.name,
             GenericParamDefKind::Const {
                 ty: Box::new(clean_middle_ty(
@@ -580,7 +580,6 @@ fn clean_generic_param_def(
                 } else {
                     None
                 },
-                synthetic,
             },
         ),
     };
@@ -636,14 +635,13 @@ fn clean_generic_param<'tcx>(
                 },
             )
         }
-        hir::GenericParamKind::Const { ty, default, synthetic } => (
+        hir::GenericParamKind::Const { ty, default } => (
             param.name.ident().name,
             GenericParamDefKind::Const {
                 ty: Box::new(clean_ty(ty, cx)),
                 default: default.map(|ct| {
                     Box::new(lower_const_arg_for_rustdoc(cx.tcx, ct, FeedConstTy::No).to_string())
                 }),
-                synthetic,
             },
         ),
     };

diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
@@ -1396,7 +1396,7 @@ pub(crate) enum GenericParamDefKind {
     Lifetime { outlives: ThinVec<Lifetime> },
     Type { bounds: ThinVec<GenericBound>, default: Option<Box<Type>>, synthetic: bool },
     // Option<Box<String>> makes this type smaller than `Option<String>` would.
-    Const { ty: Box<Type>, default: Option<Box<String>>, synthetic: bool },
+    Const { ty: Box<Type>, default: Option<Box<String>> },
 }
 
 impl GenericParamDefKind {

diff --git a/src/librustdoc/json/conversions.rs b/src/librustdoc/json/conversions.rs
@@ -466,7 +466,7 @@ impl FromClean<clean::GenericParamDefKind> for GenericParamDefKind {
                 default: default.into_json(renderer),
                 is_synthetic: *synthetic,
             },
-            Const { ty, default, synthetic: _ } => GenericParamDefKind::Const {
+            Const { ty, default } => GenericParamDefKind::Const {
                 type_: ty.into_json(renderer),
                 default: default.as_ref().map(|x| x.as_ref().clone()),
             },
-Original file line number
+Diff line change
@@ Expand Up / @@ -2028,7 +2028,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { @@
                     (
                         hir::ParamName::Plain(self.lower_ident(param.ident)),
-                        hir::GenericParamKind::Const { ty, default, synthetic: false },
+                        hir::GenericParamKind::Const { ty, default },
                     )
                 }
             }
@@ Expand Down @@