From 87380cbc0c967f7ffb714c01e02c48fb6daf6eee Mon Sep 17 00:00:00 2001
From: Jake Goulding <jake.goulding@gmail.com>
Date: Sat, 25 Nov 2023 15:45:44 -0500
Subject: [PATCH] Address unused tuple struct fields in the compiler

---
 compiler/rustc_borrowck/src/lib.rs                 | 3 ++-
 compiler/rustc_mir_transform/src/check_unsafety.rs | 6 +++---
 compiler/rustc_resolve/src/def_collector.rs        | 6 ++----
 compiler/rustc_resolve/src/lib.rs                  | 2 +-
 4 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 7d6e15839c508..6e44f44dc18b0 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -42,6 +42,7 @@ use rustc_target::abi::FieldIdx;
 use smallvec::SmallVec;
 use std::cell::RefCell;
 use std::collections::BTreeMap;
+use std::marker::PhantomData;
 use std::ops::Deref;
 use std::rc::Rc;
 
@@ -100,7 +101,7 @@ use renumber::RegionCtxt;
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
 /// Associate some local constants with the `'tcx` lifetime
-struct TyCtxtConsts<'tcx>(TyCtxt<'tcx>);
+struct TyCtxtConsts<'tcx>(PhantomData<&'tcx ()>);
 impl<'tcx> TyCtxtConsts<'tcx> {
     const DEREF_PROJECTION: &'tcx [PlaceElem<'tcx>; 1] = &[ProjectionElem::Deref];
 }
diff --git a/compiler/rustc_mir_transform/src/check_unsafety.rs b/compiler/rustc_mir_transform/src/check_unsafety.rs
index 85447887cb0ec..c63b24b194fc2 100644
--- a/compiler/rustc_mir_transform/src/check_unsafety.rs
+++ b/compiler/rustc_mir_transform/src/check_unsafety.rs
@@ -385,7 +385,7 @@ pub(crate) fn provide(providers: &mut Providers) {
 enum Context {
     Safe,
     /// in an `unsafe fn`
-    UnsafeFn(HirId),
+    UnsafeFn,
     /// in a *used* `unsafe` block
     /// (i.e. a block without unused-unsafe warning)
     UnsafeBlock(HirId),
@@ -407,7 +407,7 @@ impl<'tcx> intravisit::Visitor<'tcx> for UnusedUnsafeVisitor<'_, 'tcx> {
             };
             let unused_unsafe = match (self.context, used) {
                 (_, false) => UnusedUnsafe::Unused,
-                (Context::Safe, true) | (Context::UnsafeFn(_), true) => {
+                (Context::Safe, true) | (Context::UnsafeFn, true) => {
                     let previous_context = self.context;
                     self.context = Context::UnsafeBlock(block.hir_id);
                     intravisit::walk_block(self, block);
@@ -454,7 +454,7 @@ fn check_unused_unsafe(
     let body = tcx.hir().body(body_id);
     let hir_id = tcx.local_def_id_to_hir_id(def_id);
     let context = match tcx.hir().fn_sig_by_hir_id(hir_id) {
-        Some(sig) if sig.header.unsafety == hir::Unsafety::Unsafe => Context::UnsafeFn(hir_id),
+        Some(sig) if sig.header.unsafety == hir::Unsafety::Unsafe => Context::UnsafeFn,
         _ => Context::Safe,
     };
 
diff --git a/compiler/rustc_resolve/src/def_collector.rs b/compiler/rustc_resolve/src/def_collector.rs
index b1ee7f438d296..c52450e11d642 100644
--- a/compiler/rustc_resolve/src/def_collector.rs
+++ b/compiler/rustc_resolve/src/def_collector.rs
@@ -223,7 +223,7 @@ impl<'a, 'b, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'b, 'tcx> {
         // ```
         //
         // In that case, the impl-trait is lowered as an additional generic parameter.
-        self.with_impl_trait(ImplTraitContext::Universal(self.parent_def), |this| {
+        self.with_impl_trait(ImplTraitContext::Universal, |this| {
             visit::walk_generic_param(this, param)
         });
     }
@@ -310,9 +310,7 @@ impl<'a, 'b, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'b, 'tcx> {
         if p.is_placeholder {
             self.visit_macro_invoc(p.id)
         } else {
-            self.with_impl_trait(ImplTraitContext::Universal(self.parent_def), |this| {
-                visit::walk_param(this, p)
-            })
+            self.with_impl_trait(ImplTraitContext::Universal, |this| visit::walk_param(this, p))
         }
     }
 
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 590bbfc3df1a1..d15e245868325 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -172,7 +172,7 @@ impl<'a> ParentScope<'a> {
 #[derive(Copy, Debug, Clone)]
 enum ImplTraitContext {
     Existential,
-    Universal(LocalDefId),
+    Universal,
 }
 
 #[derive(Debug)]