Only store a span in ConstArgKind::Infer

Author: voidc

compiler/rustc_ast_lowering/src/lib.rs

@@ -2034,10 +2034,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         match c.value.kind {
             ExprKind::Underscore => {
                 if self.tcx.features().generic_arg_infer() {
-                    let ct_kind = hir::ConstArgKind::Infer(hir::InferArg {
-                        hir_id: self.lower_node_id(c.id),
-                        span: self.lower_span(c.value.span),
-                    });
+                    let ct_kind = hir::ConstArgKind::Infer(self.lower_span(c.value.span));
                     self.arena.alloc(hir::ConstArg { hir_id: self.next_id(), kind: ct_kind })
                 } else {
                     feature_err(

compiler/rustc_hir/src/hir.rs

@@ -275,7 +275,7 @@ impl<'hir> ConstArg<'hir> {
         match self.kind {
             ConstArgKind::Path(path) => path.span(),
             ConstArgKind::Anon(anon) => anon.span,
-            ConstArgKind::Infer(infer) => infer.span,
+            ConstArgKind::Infer(span) => span,
         }
     }
 }
@@ -294,7 +294,7 @@ pub enum ConstArgKind<'hir> {
     /// `ConstArgKind::Infer`. In cases where it is ambiguous whether
     /// a generic arg is a type or a const, inference variables are
     /// represented as `GenericArg::Infer` instead.
-    Infer(InferArg),
+    Infer(Span),
 }
 
 #[derive(Clone, Copy, Debug, HashStable_Generic)]

compiler/rustc_hir/src/intravisit.rs

@@ -728,7 +728,7 @@ pub fn walk_const_arg<'v, V: Visitor<'v>>(
     match &const_arg.kind {
         ConstArgKind::Path(qpath) => visitor.visit_qpath(qpath, const_arg.hir_id, qpath.span()),
         ConstArgKind::Anon(anon) => visitor.visit_anon_const(*anon),
-        ConstArgKind::Infer(infer) => visitor.visit_infer(infer),
+        ConstArgKind::Infer(..) => V::Result::output(),
     }
 }
 

compiler/rustc_hir_analysis/src/collect.rs

@@ -151,8 +151,8 @@ impl<'v> Visitor<'v> for HirPlaceholderCollector {
         }
     }
     fn visit_const_arg(&mut self, const_arg: &'v hir::ConstArg<'v>) {
-        if let hir::ConstArgKind::Infer(infer) = const_arg.kind {
-            self.0.push(infer.span);
+        if let hir::ConstArgKind::Infer(span) = const_arg.kind {
+            self.0.push(span);
         }
         intravisit::walk_const_arg(self, const_arg)
     }

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -2089,7 +2089,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 format!("Const::lower_const_arg: invalid qpath {qpath:?}"),
             ),
             hir::ConstArgKind::Anon(anon) => Const::from_anon_const(tcx, anon.def_id),
-            hir::ConstArgKind::Infer(infer) => self.ct_infer(None, infer.span),
+            hir::ConstArgKind::Infer(span) => self.ct_infer(None, span),
         }
     }