Ignore automatically derived impls of `Clone` and `Debug` in dead code analysis

54 files changed, 225 insertions, 107 deletions

diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
index 725f8b8763a..61e27d2e4cd 100644
--- a/compiler/rustc_feature/src/accepted.rs
+++ b/compiler/rustc_feature/src/accepted.rs
@@ -16,7 +16,6 @@ macro_rules! declare_features {
                     since: $ver,
                     issue: to_nonzero($issue),
                     edition: None,
-                    description: concat!($($doc,)*),
                 }
             ),+
         ];
diff --git a/compiler/rustc_feature/src/active.rs b/compiler/rustc_feature/src/active.rs
index a3807a2bb9f..366ed715434 100644
--- a/compiler/rustc_feature/src/active.rs
+++ b/compiler/rustc_feature/src/active.rs
@@ -37,7 +37,6 @@ macro_rules! declare_features {
                     since: $ver,
                     issue: to_nonzero($issue),
                     edition: $edition,
-                    description: concat!($($doc,)*),
                 }
             ),+];
 
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
index e2aa54a59b2..f74ea0e0c4d 100644
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -453,6 +453,9 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     ),
     // Enumerates "identity-like" conversion methods to suggest on type mismatch.
     rustc_attr!(rustc_conversion_suggestion, Normal, template!(Word), INTERNAL_UNSTABLE),
+    // Prevents field reads in the marked trait or method to be considered
+    // during dead code analysis.
+    rustc_attr!(rustc_trivial_field_reads, Normal, template!(Word), INTERNAL_UNSTABLE),
 
     // ==========================================================================
     // Internal attributes, Const related:
diff --git a/compiler/rustc_feature/src/lib.rs b/compiler/rustc_feature/src/lib.rs
index cf102aa16e0..b25aab21e49 100644
--- a/compiler/rustc_feature/src/lib.rs
+++ b/compiler/rustc_feature/src/lib.rs
@@ -51,7 +51,6 @@ pub struct Feature {
     pub since: &'static str,
     issue: Option<NonZeroU32>,
     pub edition: Option<Edition>,
-    description: &'static str,
 }
 
 #[derive(Copy, Clone, Debug)]
diff --git a/compiler/rustc_feature/src/removed.rs b/compiler/rustc_feature/src/removed.rs
index efab0200ff5..7b9b68268ea 100644
--- a/compiler/rustc_feature/src/removed.rs
+++ b/compiler/rustc_feature/src/removed.rs
@@ -16,7 +16,6 @@ macro_rules! declare_features {
                     since: $ver,
                     issue: to_nonzero($issue),
                     edition: None,
-                    description: concat!($($doc,)*),
                 }
             ),+
         ];
@@ -34,7 +33,6 @@ macro_rules! declare_features {
                     since: $ver,
                     issue: to_nonzero($issue),
                     edition: None,
-                    description: concat!($($doc,)*),
                 }
             ),+
         ];
diff --git a/compiler/rustc_middle/src/hir/map/collector.rs b/compiler/rustc_middle/src/hir/map/collector.rs
index 1351b4950f1..082948eba41 100644
--- a/compiler/rustc_middle/src/hir/map/collector.rs
+++ b/compiler/rustc_middle/src/hir/map/collector.rs
@@ -62,13 +62,6 @@ fn hash_body(
     stable_hasher.finish()
 }
 
-/// Represents an entry and its parent `HirId`.
-#[derive(Copy, Clone, Debug)]
-pub struct Entry<'hir> {
-    parent: HirId,
-    node: Node<'hir>,
-}
-
 impl<'a, 'hir> NodeCollector<'a, 'hir> {
     pub(super) fn root(
         sess: &'a Session,
diff --git a/compiler/rustc_middle/src/ich/hcx.rs b/compiler/rustc_middle/src/ich/hcx.rs
index 32ccdafaeb4..1c7e022673d 100644
--- a/compiler/rustc_middle/src/ich/hcx.rs
+++ b/compiler/rustc_middle/src/ich/hcx.rs
@@ -28,7 +28,6 @@ fn compute_ignored_attr_names() -> FxHashSet<Symbol> {
 /// things (e.g., each `DefId`/`DefPath` is only hashed once).
 #[derive(Clone)]
 pub struct StableHashingContext<'a> {
-    sess: &'a Session,
     definitions: &'a Definitions,
     cstore: &'a dyn CrateStore,
     pub(super) body_resolver: BodyResolver<'a>,
@@ -78,7 +77,6 @@ impl<'a> StableHashingContext<'a> {
             !always_ignore_spans && !sess.opts.debugging_opts.incremental_ignore_spans;
 
         StableHashingContext {
-            sess,
             body_resolver: BodyResolver(krate),
             definitions,
             cstore,
diff --git a/compiler/rustc_mir_build/src/build/matches/mod.rs b/compiler/rustc_mir_build/src/build/matches/mod.rs
index ba94e15444a..0ff3fc60995 100644
--- a/compiler/rustc_mir_build/src/build/matches/mod.rs
+++ b/compiler/rustc_mir_build/src/build/matches/mod.rs
@@ -900,10 +900,7 @@ fn traverse_candidate<'pat, 'tcx: 'pat, C, T, I>(
 struct Binding<'tcx> {
     span: Span,
     source: Place<'tcx>,
-    name: Symbol,
     var_id: HirId,
-    var_ty: Ty<'tcx>,
-    mutability: Mutability,
     binding_mode: BindingMode,
 }
 
diff --git a/compiler/rustc_mir_build/src/build/matches/simplify.rs b/compiler/rustc_mir_build/src/build/matches/simplify.rs
index 1feb8b0d7a0..4ce26cc8dff 100644
--- a/compiler/rustc_mir_build/src/build/matches/simplify.rs
+++ b/compiler/rustc_mir_build/src/build/matches/simplify.rs
@@ -176,17 +176,22 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 Ok(())
             }
 
-            PatKind::Binding { name, mutability, mode, var, ty, ref subpattern, is_primary: _ } => {
+            PatKind::Binding {
+                name: _,
+                mutability: _,
+                mode,
+                var,
+                ty: _,
+                ref subpattern,
+                is_primary: _,
+            } => {
                 if let Ok(place_resolved) =
                     match_pair.place.clone().try_upvars_resolved(self.tcx, self.typeck_results)
                 {
                     candidate.bindings.push(Binding {
-                        name,
-                        mutability,
                         span: match_pair.pattern.span,
                         source: place_resolved.into_place(self.tcx, self.typeck_results),
                         var_id: var,
-                        var_ty: ty,
                         binding_mode: mode,
                     });
                 }
diff --git a/compiler/rustc_mir_build/src/build/scope.rs b/compiler/rustc_mir_build/src/build/scope.rs
index bd8d14fcd01..b74208edafe 100644
--- a/compiler/rustc_mir_build/src/build/scope.rs
+++ b/compiler/rustc_mir_build/src/build/scope.rs
@@ -118,9 +118,6 @@ struct Scope {
     /// the region span of this scope within source code.
     region_scope: region::Scope,
 
-    /// the span of that region_scope
-    region_scope_span: Span,
-
     /// set of places to drop when exiting this scope. This starts
     /// out empty but grows as variables are declared during the
     /// building process. This is a stack, so we always drop from the
@@ -420,7 +417,6 @@ impl<'tcx> Scopes<'tcx> {
         self.scopes.push(Scope {
             source_scope: vis_scope,
             region_scope: region_scope.0,
-            region_scope_span: region_scope.1.span,
             drops: vec![],
             moved_locals: vec![],
             cached_unwind_block: None,
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 6043606c379..b9e3c058ad7 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -263,7 +263,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
         }
 
         if let Err(e) = result {
-            bug!("Error processing: {:?}: {:?}", self.mir_body.source.def_id(), e)
+            bug!("Error processing: {:?}: {:?}", self.mir_body.source.def_id(), e.message)
         };
 
         // Depending on current `debug_options()`, `alert_on_unused_expressions()` could panic, so
diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs
index 25ad00aaf1f..0a309375716 100644
--- a/compiler/rustc_passes/src/dead.rs
+++ b/compiler/rustc_passes/src/dead.rs
@@ -239,7 +239,69 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
         }
     }
 
+    /// Automatically generated items marked with `rustc_trivial_field_reads`
+    /// will be ignored for the purposes of dead code analysis (see PR #85200
+    /// for discussion).
+    fn should_ignore_item(&self, def_id: DefId) -> bool {
+        if !self.tcx.has_attr(def_id, sym::automatically_derived)
+            && !self
+                .tcx
+                .impl_of_method(def_id)
+                .map_or(false, |impl_id| self.tcx.has_attr(impl_id, sym::automatically_derived))
+        {
+            return false;
+        }
+
+        let has_attr = |def_id| self.tcx.has_attr(def_id, sym::rustc_trivial_field_reads);
+
+        if has_attr(def_id) {
+            return true;
+        }
+
+        if let Some(impl_of) = self.tcx.impl_of_method(def_id) {
+            if has_attr(impl_of) {
+                return true;
+            }
+
+            if let Some(trait_of) = self.tcx.trait_id_of_impl(impl_of) {
+                if has_attr(trait_of) {
+                    return true;
+                }
+
+                if let Some(method_ident) = self.tcx.opt_item_name(def_id) {
+                    if let Some(trait_method) = self
+                        .tcx
+                        .associated_items(trait_of)
+                        .find_by_name_and_kind(self.tcx, method_ident, ty::AssocKind::Fn, trait_of)
+                    {
+                        if has_attr(trait_method.def_id) {
+                            return true;
+                        }
+                    }
+                }
+            }
+        } else if let Some(trait_of) = self.tcx.trait_of_item(def_id) {
+            if has_attr(trait_of) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     fn visit_node(&mut self, node: Node<'tcx>) {
+        if let Some(item_def_id) = match node {
+            Node::Item(hir::Item { def_id, .. })
+            | Node::ForeignItem(hir::ForeignItem { def_id, .. })
+            | Node::TraitItem(hir::TraitItem { def_id, .. })
+            | Node::ImplItem(hir::ImplItem { def_id, .. }) => Some(def_id.to_def_id()),
+            _ => None,
+        } {
+            if self.should_ignore_item(item_def_id) {
+                return;
+            }
+        }
+
         let had_repr_c = self.repr_has_repr_c;
         let had_inherited_pub_visibility = self.inherited_pub_visibility;
         let had_pub_visibility = self.pub_visibility;
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 24023163cc3..c816d060456 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1134,6 +1134,7 @@ symbols! {
         rustc_synthetic,
         rustc_test_marker,
         rustc_then_this_would_need,
+        rustc_trivial_field_reads,
         rustc_unsafe_specialization_marker,
         rustc_variance,
         rustdoc,
diff --git a/library/core/src/clone.rs b/library/core/src/clone.rs
index 19faf9cddac..b02333b0288 100644
--- a/library/core/src/clone.rs
+++ b/library/core/src/clone.rs
@@ -105,6 +105,7 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 #[lang = "clone"]
 #[rustc_diagnostic_item = "Clone"]
+#[cfg_attr(not(bootstrap), rustc_trivial_field_reads)]
 pub trait Clone: Sized {
     /// Returns a copy of the value.
     ///
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 0a29843c9cf..166a8e3f28a 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -582,6 +582,7 @@ impl Display for Arguments<'_> {
 )]
 #[doc(alias = "{:?}")]
 #[rustc_diagnostic_item = "debug_trait"]
+#[cfg_attr(not(bootstrap), rustc_trivial_field_reads)]
 pub trait Debug {
     /// Formats the value using the given formatter.
     ///
diff --git a/library/core/tests/fmt/builders.rs b/library/core/tests/fmt/builders.rs
index 7580010a28b..9567479c813 100644
--- a/library/core/tests/fmt/builders.rs
+++ b/library/core/tests/fmt/builders.rs
@@ -653,6 +653,7 @@ mod debug_list {
 fn test_formatting_parameters_are_forwarded() {
     use std::collections::{BTreeMap, BTreeSet};
     #[derive(Debug)]
+    #[allow(dead_code)]
     struct Foo {
         bar: u32,
         baz: u32,
diff --git a/library/std/src/io/buffered/tests.rs b/library/std/src/io/buffered/tests.rs
index f6c2b499567..d290c3c4660 100644
--- a/library/std/src/io/buffered/tests.rs
+++ b/library/std/src/io/buffered/tests.rs
@@ -468,9 +468,6 @@ struct ProgrammableSink {
     // Writes append to this slice
     pub buffer: Vec<u8>,
 
-    // Flush sets this flag
-    pub flushed: bool,
-
     // If true, writes will always be an error
     pub always_write_error: bool,
 
@@ -520,7 +517,6 @@ impl Write for ProgrammableSink {
         if self.always_flush_error {
             Err(io::Error::new(io::ErrorKind::Other, "test - always_flush_error"))
         } else {
-            self.flushed = true;
             Ok(())
         }
     }
diff --git a/library/test/src/term/terminfo/mod.rs b/library/test/src/term/terminfo/mod.rs
index f4c5a05d1e2..694473f52c1 100644
--- a/library/test/src/term/terminfo/mod.rs
+++ b/library/test/src/term/terminfo/mod.rs
@@ -16,6 +16,7 @@ use parser::compiled::{msys_terminfo, parse};
 use searcher::get_dbpath_for_term;
 
 /// A parsed terminfo database entry.
+#[allow(unused)]
 #[derive(Debug)]
 pub(crate) struct TermInfo {
     /// Names for the terminal
diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
index 0c81a558430..78e4e4ec116 100644
--- a/src/librustdoc/clean/inline.rs
+++ b/src/librustdoc/clean/inline.rs
@@ -557,7 +557,6 @@ fn build_macro(
     name: Symbol,
     import_def_id: Option<DefId>,
 ) -> clean::ItemKind {
-    let imported_from = cx.tcx.crate_name(def_id.krate);
     match CStore::from_tcx(cx.tcx).load_macro_untracked(def_id, cx.sess()) {
         LoadedMacro::MacroDef(item_def, _) => {
             if let ast::ItemKind::MacroDef(ref def) = item_def.kind {
@@ -569,7 +568,6 @@ fn build_macro(
                         def_id,
                         cx.tcx.visibility(import_def_id.unwrap_or(def_id)),
                     ),
-                    imported_from: Some(imported_from),
                 })
             } else {
                 unreachable!()
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index e2ad21bba21..7ece2acac7a 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1859,7 +1859,6 @@ impl Clean<Vec<Item>> for (&hir::Item<'_>, Option<Symbol>) {
                 }
                 ItemKind::Macro(ref macro_def) => MacroItem(Macro {
                     source: display_macro_source(cx, name, &macro_def, def_id, &item.vis),
-                    imported_from: None,
                 }),
                 ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref item_ids) => {
                     let items = item_ids
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 5eff56a2200..5f09e6ced96 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -2202,7 +2202,6 @@ crate struct ImportSource {
 #[derive(Clone, Debug)]
 crate struct Macro {
     crate source: String,
-    crate imported_from: Option<Symbol>,
 }
 
 #[derive(Clone, Debug)]
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 172fe5d164b..f71660c4b2a 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -224,7 +224,6 @@ struct AllTypes {
     opaque_tys: FxHashSet<ItemEntry>,
     statics: FxHashSet<ItemEntry>,
     constants: FxHashSet<ItemEntry>,
-    keywords: FxHashSet<ItemEntry>,
     attributes: FxHashSet<ItemEntry>,
     derives: FxHashSet<ItemEntry>,
     trait_aliases: FxHashSet<ItemEntry>,
@@ -245,7 +244,6 @@ impl AllTypes {
             opaque_tys: new_set(100),
             statics: new_set(100),
             constants: new_set(100),
-            keywords: new_set(100),
             attributes: new_set(100),
             derives: new_set(100),
             trait_aliases: new_set(100),
diff --git a/src/test/ui/array-slice-vec/slice_binary_search.rs b/src/test/ui/array-slice-vec/slice_binary_search.rs
index 12236960179..4d8022ecba7 100644
--- a/src/test/ui/array-slice-vec/slice_binary_search.rs
+++ b/src/test/ui/array-slice-vec/slice_binary_search.rs
@@ -2,6 +2,7 @@
 
 // Test binary_search_by_key lifetime. Issue #34683
 
+#[allow(dead_code)]
 #[derive(Debug)]
 struct Assignment {
     topic: String,
diff --git a/src/test/ui/borrowck/borrowck-unused-mut-locals.rs b/src/test/ui/borrowck/borrowck-unused-mut-locals.rs
index fd0e346e2b4..23ef975cbbc 100644
--- a/src/test/ui/borrowck/borrowck-unused-mut-locals.rs
+++ b/src/test/ui/borrowck/borrowck-unused-mut-locals.rs
@@ -1,4 +1,5 @@
 // run-pass
+#![allow(dead_code)]
 #![deny(unused_mut)]
 
 #[derive(Debug)]
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness.rs b/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness.rs
index 1cc22fac352..3399bc0018e 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness.rs
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness.rs
@@ -3,6 +3,7 @@
 // check-pass
 #![allow(unreachable_code)]
 #![warn(unused)]
+#![allow(dead_code)]
 
 #[derive(Debug)]
 struct Point {
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness.stderr b/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness.stderr
index 4eac5a2d282..74109772724 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness.stderr
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness.stderr
@@ -1,5 +1,5 @@
 warning: value captured by `a` is never read
-  --> $DIR/liveness.rs:23:9
+  --> $DIR/liveness.rs:24:9
    |
 LL |         a = 1;
    |         ^
@@ -13,7 +13,7 @@ LL | #![warn(unused)]
    = help: did you mean to capture by reference instead?
 
 warning: unused variable: `a`
-  --> $DIR/liveness.rs:32:9
+  --> $DIR/liveness.rs:33:9
    |
 LL |         a += 1;
    |         ^
@@ -27,7 +27,7 @@ LL | #![warn(unused)]
    = help: did you mean to capture by reference instead?
 
 warning: value assigned to `a` is never read
-  --> $DIR/liveness.rs:52:9
+  --> $DIR/liveness.rs:53:9
    |
 LL |         a += 1;
    |         ^
@@ -35,7 +35,7 @@ LL |         a += 1;
    = help: maybe it is overwritten before being read?
 
 warning: value assigned to `a` is never read
-  --> $DIR/liveness.rs:76:13
+  --> $DIR/liveness.rs:77:13
    |
 LL |             a = Some("d1");
    |             ^
@@ -43,7 +43,7 @@ LL |             a = Some("d1");
    = help: maybe it is overwritten before being read?
 
 warning: value assigned to `b` is never read
-  --> $DIR/liveness.rs:84:13
+  --> $DIR/liveness.rs:85:13
    |
 LL |             b = Some("e1");
    |             ^
@@ -51,7 +51,7 @@ LL |             b = Some("e1");
    = help: maybe it is overwritten before being read?
 
 warning: value assigned to `b` is never read
-  --> $DIR/liveness.rs:86:13
+  --> $DIR/liveness.rs:87:13
    |
 LL |             b = Some("e2");
    |             ^
@@ -59,7 +59,7 @@ LL |             b = Some("e2");
    = help: maybe it is overwritten before being read?
 
 warning: unused variable: `b`
-  --> $DIR/liveness.rs:84:13
+  --> $DIR/liveness.rs:85:13
    |
 LL |             b = Some("e1");
    |             ^
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness_unintentional_copy.rs b/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness_unintentional_copy.rs
index 10a7d07a1df..465c9476ba6 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness_unintentional_copy.rs
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness_unintentional_copy.rs
@@ -2,6 +2,7 @@
 
 // check-pass
 #![warn(unused)]
+#![allow(dead_code)]
 
 #[derive(Debug)]
 struct MyStruct {
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness_unintentional_copy.stderr b/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness_unintentional_copy.stderr
index f74303e3dd6..11a440554f7 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness_unintentional_copy.stderr
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/liveness_unintentional_copy.stderr
@@ -1,5 +1,5 @@
 warning: value assigned to `a` is never read
-  --> $DIR/liveness_unintentional_copy.rs:19:9
+  --> $DIR/liveness_unintentional_copy.rs:20:9
    |
 LL |         a = s;
    |         ^
@@ -13,7 +13,7 @@ LL | #![warn(unused)]
    = help: maybe it is overwritten before being read?
 
 warning: unused variable: `a`
-  --> $DIR/liveness_unintentional_copy.rs:19:9
+  --> $DIR/liveness_unintentional_copy.rs:20:9
    |
 LL |         a = s;
    |         ^
@@ -27,7 +27,7 @@ LL | #![warn(unused)]
    = help: did you mean to capture by reference instead?
 
 warning: unused variable: `a`
-  --> $DIR/liveness_unintentional_copy.rs:35:9
+  --> $DIR/liveness_unintentional_copy.rs:36:9
    |
 LL |         a += x;
    |         ^
diff --git a/src/test/ui/closures/2229_closure_analysis/run_pass/struct-pattern-matching-with-methods.rs b/src/test/ui/closures/2229_closure_analysis/run_pass/struct-pattern-matching-with-methods.rs
index 045fe78040a..ed222b3148f 100644
--- a/src/test/ui/closures/2229_closure_analysis/run_pass/struct-pattern-matching-with-methods.rs
+++ b/src/test/ui/closures/2229_closure_analysis/run_pass/struct-pattern-matching-with-methods.rs
@@ -1,6 +1,7 @@
 // edition:2021
 //check-pass
 #![warn(unused)]
+#![allow(dead_code)]
 #![feature(rustc_attrs)]
 
 #[derive(Debug, Clone, Copy)]
diff --git a/src/test/ui/closures/2229_closure_analysis/run_pass/unsafe_ptr.rs b/src/test/ui/closures/2229_closure_analysis/run_pass/unsafe_ptr.rs
index 8e4f91c27e2..3f7ddf93f06 100644
--- a/src/test/ui/closures/2229_closure_analysis/run_pass/unsafe_ptr.rs
+++ b/src/test/ui/closures/2229_closure_analysis/run_pass/unsafe_ptr.rs
@@ -3,6 +3,8 @@
 
 // Test that we can use raw ptrs when using `capture_disjoint_fields`.
 
+#![allow(dead_code)]
+
 #[derive(Debug)]
 struct S {
     s: String,
diff --git a/src/test/ui/const-generics/broken-mir-2.rs b/src/test/ui/const-generics/broken-mir-2.rs
index f9e03151374..9d62281178c 100644
--- a/src/test/ui/const-generics/broken-mir-2.rs
+++ b/src/test/ui/const-generics/broken-mir-2.rs
@@ -1,4 +1,7 @@
 // run-pass
+
+#![allow(dead_code)]
+
 use std::fmt::Debug;
 
 #[derive(Debug)]
diff --git a/src/test/ui/derives/clone-debug-dead-code.rs b/src/test/ui/derives/clone-debug-dead-code.rs
new file mode 100644
index 00000000000..80e91320939
--- /dev/null
+++ b/src/test/ui/derives/clone-debug-dead-code.rs
@@ -0,0 +1,45 @@
+// Checks that derived implementations of Clone and Debug do not
+// contribute to dead code analysis (issue #84647).
+
+#![forbid(dead_code)]
+
+struct A { f: () }
+//~^ ERROR: field is never read: `f`
+
+#[derive(Clone)]
+struct B { f: () }
+//~^ ERROR: field is never read: `f`
+
+#[derive(Debug)]
+struct C { f: () }
+//~^ ERROR: field is never read: `f`
+
+#[derive(Debug,Clone)]
+struct D { f: () }
+//~^ ERROR: field is never read: `f`
+
+struct E { f: () }
+//~^ ERROR: field is never read: `f`
+// Custom impl, still doesn't read f
+impl Clone for E {
+    fn clone(&self) -> Self {
+        Self { f: () }
+    }
+}
+
+struct F { f: () }
+// Custom impl that actually reads f
+impl Clone for F {
+    fn clone(&self) -> Self {
+        Self { f: self.f }
+    }
+}
+
+fn main() {
+    let _ = A { f: () };
+    let _ = B { f: () };
+    let _ = C { f: () };
+    let _ = D { f: () };
+    let _ = E { f: () };
+    let _ = F { f: () };
+}
diff --git a/src/test/ui/derives/clone-debug-dead-code.stderr b/src/test/ui/derives/clone-debug-dead-code.stderr
new file mode 100644
index 00000000000..226007f3647
--- /dev/null
+++ b/src/test/ui/derives/clone-debug-dead-code.stderr
@@ -0,0 +1,38 @@
+error: field is never read: `f`
+  --> $DIR/clone-debug-dead-code.rs:6:12
+   |
+LL | struct A { f: () }
+   |            ^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/clone-debug-dead-code.rs:4:11
+   |
+LL | #![forbid(dead_code)]
+   |           ^^^^^^^^^
+
+error: field is never read: `f`
+  --> $DIR/clone-debug-dead-code.rs:10:12
+   |
+LL | struct B { f: () }
+   |            ^^^^^
+
+error: field is never read: `f`
+  --> $DIR/clone-debug-dead-code.rs:14:12
+   |
+LL | struct C { f: () }
+   |            ^^^^^
+
+error: field is never read: `f`
+  --> $DIR/clone-debug-dead-code.rs:18:12
+   |
+LL | struct D { f: () }
+   |            ^^^^^
+
+error: field is never read: `f`
+  --> $DIR/clone-debug-dead-code.rs:21:12
+   |
+LL | struct E { f: () }
+   |            ^^^^^
+
+error: aborting due to 5 previous errors
+
diff --git a/src/test/ui/deriving/deriving-clone-generic-struct.rs b/src/test/ui/deriving/deriving-clone-generic-struct.rs
index f6e105555fd..4374d1594e4 100644
--- a/src/test/ui/deriving/deriving-clone-generic-struct.rs
+++ b/src/test/ui/deriving/deriving-clone-generic-struct.rs
@@ -1,6 +1,8 @@
 // run-pass
 // pretty-expanded FIXME #23616
 
+#![allow(dead_code)]
+
 #[derive(Clone)]
 struct S<T> {
     foo: (),
diff --git a/src/test/ui/deriving/deriving-clone-struct.rs b/src/test/ui/deriving/deriving-clone-struct.rs
index 7b0a1d20260..b93cbe5f8b6 100644
--- a/src/test/ui/deriving/deriving-clone-struct.rs
+++ b/src/test/ui/deriving/deriving-clone-struct.rs
@@ -1,6 +1,8 @@
 // run-pass
 // pretty-expanded FIXME #23616
 
+#![allow(dead_code)]
+
 #[derive(Clone)]
 struct S {
     _int: isize,
diff --git a/src/test/ui/deriving/deriving-clone-tuple-struct.rs b/src/test/ui/deriving/deriving-clone-tuple-struct.rs
index 166f1be55e0..7ad3f034713 100644
--- a/src/test/ui/deriving/deriving-clone-tuple-struct.rs
+++ b/src/test/ui/deriving/deriving-clone-tuple-struct.rs
@@ -1,6 +1,8 @@
 // run-pass
 // pretty-expanded FIXME #23616
 
+#![allow(dead_code)]
+
 #[derive(Clone)]
 struct S((), ());
 
diff --git a/src/test/ui/deriving/deriving-in-fn.rs b/src/test/ui/deriving/deriving-in-fn.rs
index 8931e94a4f8..07f91d05973 100644
--- a/src/test/ui/deriving/deriving-in-fn.rs
+++ b/src/test/ui/deriving/deriving-in-fn.rs
@@ -1,4 +1,7 @@
 // run-pass
+
+#![allow(dead_code)]
+
 pub fn main() {
     #[derive(Debug)]
     struct Foo {
diff --git a/src/test/ui/issues/issue-19358.rs b/src/test/ui/issues/issue-19358.rs
index f66e0a1c078..3970a4155e9 100644
--- a/src/test/ui/issues/issue-19358.rs
+++ b/src/test/ui/issues/issue-19358.rs
@@ -1,4 +1,7 @@
 // run-pass
+
+#![allow(dead_code)]
+
 trait Trait { fn dummy(&self) { } }
 
 #[derive(Debug)]
diff --git a/src/test/ui/issues/issue-3794.rs b/src/test/ui/issues/issue-3794.rs
index 408d8d866d8..1809e822c54 100644
--- a/src/test/ui/issues/issue-3794.rs
+++ b/src/test/ui/issues/issue-3794.rs
@@ -1,5 +1,6 @@
 // run-pass
 #![feature(box_syntax)]
+#![allow(dead_code)]
 
 trait T {
     fn print(&self);
diff --git a/src/test/ui/monomorphize-abi-alignment.rs b/src/test/ui/monomorphize-abi-alignment.rs
index 637b09fc04e..a8d8bd1d5fd 100644
--- a/src/test/ui/monomorphize-abi-alignment.rs
+++ b/src/test/ui/monomorphize-abi-alignment.rs
@@ -1,6 +1,7 @@
 // run-pass
 
 #![allow(non_upper_case_globals)]
+#![allow(dead_code)]
 /*!
  * On x86_64-linux-gnu and possibly other platforms, structs get 8-byte "preferred" alignment,
  * but their "ABI" alignment (i.e., what actually matters for data layout) is the largest alignment
diff --git a/src/test/ui/moves/move-1-unique.rs b/src/test/ui/moves/move-1-unique.rs
index 48baead074a..7d3987f6560 100644
--- a/src/test/ui/moves/move-1-unique.rs
+++ b/src/test/ui/moves/move-1-unique.rs
@@ -1,5 +1,6 @@
 // run-pass
 #![allow(unused_mut)]
+#![allow(dead_code)]
 #![feature(box_syntax)]
 
 #[derive(Clone)]
diff --git a/src/test/ui/moves/move-3-unique.rs b/src/test/ui/moves/move-3-unique.rs
index 55b10e057d8..d23a852433f 100644
--- a/src/test/ui/moves/move-3-unique.rs
+++ b/src/test/ui/moves/move-3-unique.rs
@@ -1,5 +1,6 @@
 // run-pass
 #![allow(unused_mut)]
+#![allow(dead_code)]
 #![feature(box_syntax)]
 
 #[derive(Clone)]
diff --git a/src/test/ui/overloaded/overloaded-autoderef-order.rs b/src/test/ui/overloaded/overloaded-autoderef-order.rs
index 1ae16d2a7fc..f48bae55f5f 100644
--- a/src/test/ui/overloaded/overloaded-autoderef-order.rs
+++ b/src/test/ui/overloaded/overloaded-autoderef-order.rs
@@ -1,5 +1,7 @@
 // run-pass
 
+#![allow(dead_code)]
+
 use std::rc::Rc;
 use std::ops::Deref;
 
diff --git a/src/test/ui/self/ufcs-explicit-self.rs b/src/test/ui/self/ufcs-explicit-self.rs
index 4e2405504f0..0aaaa7d47c3 100644
--- a/src/test/ui/self/ufcs-explicit-self.rs
+++ b/src/test/ui/self/ufcs-explicit-self.rs
@@ -1,5 +1,6 @@
 // run-pass
 #![feature(box_syntax)]
+#![allow(dead_code)]
 
 #[derive(Copy, Clone)]
 struct Foo {
diff --git a/src/test/ui/structs-enums/class-cast-to-trait-multiple-types.rs b/src/test/ui/structs-enums/class-cast-to-trait-multiple-types.rs
index 55975cbdb53..ca35a615d21 100644
--- a/src/test/ui/structs-enums/class-cast-to-trait-multiple-types.rs
+++ b/src/test/ui/structs-enums/class-cast-to-trait-multiple-types.rs
@@ -1,5 +1,6 @@
 // run-pass
 #![allow(non_camel_case_types)]
+#![allow(dead_code)]
 
 trait noisy {
   fn speak(&mut self) -> isize;
diff --git a/src/test/ui/structs-enums/class-implement-traits.rs b/src/test/ui/structs-enums/class-implement-traits.rs
index c9e98e21b9e..732aa146ce4 100644
--- a/src/test/ui/structs-enums/class-implement-traits.rs
+++ b/src/test/ui/structs-enums/class-implement-traits.rs
@@ -1,5 +1,6 @@
 // run-pass
 #![allow(non_camel_case_types)]
+#![allow(dead_code)]
 
 trait noisy {
     fn speak(&mut self);
diff --git a/src/test/ui/structs-enums/functional-struct-upd.rs b/src/test/ui/structs-enums/functional-struct-upd.rs
index 51c6b6d7e4f..68ff73a0805 100644
--- a/src/test/ui/structs-enums/functional-struct-upd.rs
+++ b/src/test/ui/structs-enums/functional-struct-upd.rs
@@ -1,4 +1,7 @@
 // run-pass
+
+#![allow(dead_code)]
+
 #[derive(Debug)]
 struct Foo {
     x: isize,
diff --git a/src/test/ui/structs-enums/tag-align-shape.rs b/src/test/ui/structs-enums/tag-align-shape.rs
index 87282ddbcca..ce599582378 100644
--- a/src/test/ui/structs-enums/tag-align-shape.rs
+++ b/src/test/ui/structs-enums/tag-align-shape.rs
@@ -1,5 +1,6 @@
 // run-pass
 #![allow(non_camel_case_types)]
+#![allow(dead_code)]
 
 #[derive(Debug)]
 enum a_tag {
diff --git a/src/tools/clippy/clippy_lints/src/macro_use.rs b/src/tools/clippy/clippy_lints/src/macro_use.rs
index 7627e0fb289..41e6ad12d05 100644
--- a/src/tools/clippy/clippy_lints/src/macro_use.rs
+++ b/src/tools/clippy/clippy_lints/src/macro_use.rs
@@ -29,36 +29,21 @@ declare_clippy_lint! {
     "#[macro_use] is no longer needed"
 }
 
-const BRACKETS: &[char] = &['<', '>'];
-
 #[derive(Clone, Debug, PartialEq, Eq)]
 struct PathAndSpan {
     path: String,
     span: Span,
 }
 
-/// `MacroRefData` includes the name of the macro
-/// and the path from `SourceMap::span_to_filename`.
+/// `MacroRefData` includes the name of the macro.
 #[derive(Debug, Clone)]
 pub struct MacroRefData {
     name: String,
-    path: String,
 }
 
 impl MacroRefData {
-    pub fn new(name: String, callee: Span, cx: &LateContext<'_>) -> Self {
-        let sm = cx.sess().source_map();
-        let mut path = sm.filename_for_diagnostics(&sm.span_to_filename(callee)).to_string();
-
-        // std lib paths are <::std::module::file type>
-        // so remove brackets, space and type.
-        if path.contains('<') {
-            path = path.replace(BRACKETS, "");
-        }
-        if path.contains(' ') {
-            path = path.split(' ').next().unwrap().to_string();
-        }
-        Self { name, path }
+    pub fn new(name: String) -> Self {
+        Self { name }
     }
 }
 
@@ -78,7 +63,7 @@ impl MacroUseImports {
     fn push_unique_macro(&mut self, cx: &LateContext<'_>, span: Span) {
         let call_site = span.source_callsite();
         let name = snippet(cx, cx.sess().source_map().span_until_char(call_site, '!'), "_");
-        if let Some(callee) = span.source_callee() {
+        if let Some(_callee) = span.source_callee() {
             if !self.collected.contains(&call_site) {
                 let name = if name.contains("::") {
                     name.split("::").last().unwrap().to_string()
@@ -86,7 +71,7 @@ impl MacroUseImports {
                     name.to_string()
                 };
 
-                self.mac_refs.push(MacroRefData::new(name, callee.def_site, cx));
+                self.mac_refs.push(MacroRefData::new(name));
                 self.collected.insert(call_site);
             }
         }
@@ -95,10 +80,10 @@ impl MacroUseImports {
     fn push_unique_macro_pat_ty(&mut self, cx: &LateContext<'_>, span: Span) {
         let call_site = span.source_callsite();
         let name = snippet(cx, cx.sess().source_map().span_until_char(call_site, '!'), "_");
-        if let Some(callee) = span.source_callee() {
+        if let Some(_callee) = span.source_callee() {
             if !self.collected.contains(&call_site) {
                 self.mac_refs
-                    .push(MacroRefData::new(name.to_string(), callee.def_site, cx));
+                    .push(MacroRefData::new(name.to_string()));
                 self.collected.insert(call_site);
             }
         }
diff --git a/src/tools/clippy/clippy_lints/src/regex.rs b/src/tools/clippy/clippy_lints/src/regex.rs
index eab09733730..89be7bf844f 100644
--- a/src/tools/clippy/clippy_lints/src/regex.rs
+++ b/src/tools/clippy/clippy_lints/src/regex.rs
@@ -3,8 +3,7 @@ use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
 use clippy_utils::{match_def_path, paths};
 use if_chain::if_chain;
 use rustc_ast::ast::{LitKind, StrStyle};
-use rustc_data_structures::fx::FxHashSet;
-use rustc_hir::{BorrowKind, Expr, ExprKind, HirId};
+use rustc_hir::{BorrowKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::{BytePos, Span};
@@ -53,10 +52,7 @@ declare_clippy_lint! {
 }
 
 #[derive(Clone, Default)]
-pub struct Regex {
-    spans: FxHashSet<Span>,
-    last: Option<HirId>,
-}
+pub struct Regex {}
 
 impl_lint_pass!(Regex => [INVALID_REGEX, TRIVIAL_REGEX]);
 
diff --git a/src/tools/clippy/tests/ui/default_trait_access.fixed b/src/tools/clippy/tests/ui/default_trait_access.fixed
index 4c80cabc723..f1f9c123dc8 100644
--- a/src/tools/clippy/tests/ui/default_trait_access.fixed
+++ b/src/tools/clippy/tests/ui/default_trait_access.fixed
@@ -1,6 +1,6 @@
 // run-rustfix
 
-#![allow(unused_imports)]
+#![allow(unused_imports,dead_code)]
 #![deny(clippy::default_trait_access)]
 
 use std::default;
diff --git a/src/tools/clippy/tests/ui/default_trait_access.rs b/src/tools/clippy/tests/ui/default_trait_access.rs
index a68b6455c04..7f3dfc7f013 100644
--- a/src/tools/clippy/tests/ui/default_trait_access.rs
+++ b/src/tools/clippy/tests/ui/default_trait_access.rs
@@ -1,6 +1,6 @@
 // run-rustfix
 
-#![allow(unused_imports)]
+#![allow(unused_imports,dead_code)]
 #![deny(clippy::default_trait_access)]
 
 use std::default;
diff --git a/src/tools/rustfmt/src/macros.rs b/src/tools/rustfmt/src/macros.rs
index a9bc89544d8..779a1149f41 100644
--- a/src/tools/rustfmt/src/macros.rs
+++ b/src/tools/rustfmt/src/macros.rs
@@ -762,7 +762,6 @@ impl MacroArgKind {
 #[derive(Debug, Clone)]
 struct ParsedMacroArg {
     kind: MacroArgKind,
-    span: Span,
 }
 
 impl ParsedMacroArg {
@@ -780,14 +779,10 @@ impl ParsedMacroArg {
 struct MacroArgParser {
     /// Either a name of the next metavariable, a separator, or junk.
     buf: String,
-    /// The start position on the current buffer.
-    lo: BytePos,
     /// The first token of the current buffer.
     start_tok: Token,
     /// `true` if we are parsing a metavariable or a repeat.
     is_meta_var: bool,
-    /// The position of the last token.
-    hi: BytePos,
     /// The last token parsed.
     last_tok: Token,
     /// Holds the parsed arguments.
@@ -807,8 +802,6 @@ fn last_tok(tt: &TokenTree) -> Token {
 impl MacroArgParser {
     fn new() -> MacroArgParser {
         MacroArgParser {
-            lo: BytePos(0),
-            hi: BytePos(0),
             buf: String::new(),
             is_meta_var: false,
             last_tok: Token {
@@ -824,7 +817,6 @@ impl MacroArgParser {
     }
 
     fn set_last_tok(&mut self, tok: &TokenTree) {
-        self.hi = tok.span().hi();
         self.last_tok = last_tok(tok);
     }
 
@@ -836,7 +828,6 @@ impl MacroArgParser {
         };
         self.result.push(ParsedMacroArg {
             kind: MacroArgKind::Separator(self.buf.clone(), prefix),
-            span: mk_sp(self.lo, self.hi),
         });
         self.buf.clear();
     }
@@ -849,7 +840,6 @@ impl MacroArgParser {
         };
         self.result.push(ParsedMacroArg {
             kind: MacroArgKind::Other(self.buf.clone(), prefix),
-            span: mk_sp(self.lo, self.hi),
         });
         self.buf.clear();
     }
@@ -858,11 +848,10 @@ impl MacroArgParser {
         match iter.next() {
             Some(TokenTree::Token(Token {
                 kind: TokenKind::Ident(name, _),
-                span,
+                ..
             })) => {
                 self.result.push(ParsedMacroArg {
                     kind: MacroArgKind::MetaVariable(name, self.buf.clone()),
-                    span: mk_sp(self.lo, span.hi()),
                 });
 
                 self.buf.clear();
@@ -873,10 +862,9 @@ impl MacroArgParser {
         }
     }
 
-    fn add_delimited(&mut self, inner: Vec<ParsedMacroArg>, delim: DelimToken, span: Span) {
+    fn add_delimited(&mut self, inner: Vec<ParsedMacroArg>, delim: DelimToken) {
         self.result.push(ParsedMacroArg {
             kind: MacroArgKind::Delimited(delim, inner),
-            span,
         });
     }
 
@@ -886,19 +874,15 @@ impl MacroArgParser {
         inner: Vec<ParsedMacroArg>,
         delim: DelimToken,
         iter: &mut Cursor,
-        span: Span,
     ) -> Option<()> {
         let mut buffer = String::new();
         let mut first = true;
-        let mut lo = span.lo();
-        let mut hi = span.hi();
 
         // Parse '*', '+' or '?.
         for tok in iter {
             self.set_last_tok(&tok);
             if first {
                 first = false;
-                lo = tok.span().lo();
             }
 
             match tok {
@@ -918,7 +902,6 @@ impl MacroArgParser {
                 }
                 TokenTree::Token(ref t) => {
                     buffer.push_str(&pprust::token_to_string(&t));
-                    hi = t.span.hi();
                 }
                 _ => return None,
             }
@@ -930,20 +913,17 @@ impl MacroArgParser {
         } else {
             Some(Box::new(ParsedMacroArg {
                 kind: MacroArgKind::Other(buffer, "".to_owned()),
-                span: mk_sp(lo, hi),
             }))
         };
 
         self.result.push(ParsedMacroArg {
             kind: MacroArgKind::Repeat(delim, inner, another, self.last_tok.clone()),
-            span: mk_sp(self.lo, self.hi),
         });
         Some(())
     }
 
     fn update_buffer(&mut self, t: &Token) {
         if self.buf.is_empty() {
-            self.lo = t.span.lo();
             self.start_tok = t.clone();
         } else {
             let needs_space = match next_space(&self.last_tok.kind) {
@@ -999,7 +979,6 @@ impl MacroArgParser {
 
                     // Start keeping the name of this metavariable in the buffer.
                     self.is_meta_var = true;
-                    self.lo = span.lo();
                     self.start_tok = Token {
                         kind: TokenKind::Dollar,
                         span,
@@ -1012,7 +991,7 @@ impl MacroArgParser {
                     self.add_meta_variable(&mut iter)?;
                 }
                 TokenTree::Token(ref t) => self.update_buffer(t),
-                TokenTree::Delimited(delimited_span, delimited, ref tts) => {
+                TokenTree::Delimited(_delimited_span, delimited, ref tts) => {
                     if !self.buf.is_empty() {
                         if next_space(&self.last_tok.kind) == SpaceState::Always {
                             self.add_separator();
@@ -1022,16 +1001,14 @@ impl MacroArgParser {
                     }
 
                     // Parse the stuff inside delimiters.
-                    let mut parser = MacroArgParser::new();
-                    parser.lo = delimited_span.open.lo();
+                    let parser = MacroArgParser::new();
                     let delimited_arg = parser.parse(tts.clone())?;
 
-                    let span = delimited_span.entire();
                     if self.is_meta_var {
-                        self.add_repeat(delimited_arg, delimited, &mut iter, span)?;
+                        self.add_repeat(delimited_arg, delimited, &mut iter)?;
                         self.is_meta_var = false;
                     } else {
-                        self.add_delimited(delimited_arg, delimited, span);
+                        self.add_delimited(delimited_arg, delimited);
                     }
                 }
             }
diff --git a/src/tools/rustfmt/src/modules.rs b/src/tools/rustfmt/src/modules.rs
index 5de0575b5cd..ded34d9032f 100644
--- a/src/tools/rustfmt/src/modules.rs
+++ b/src/tools/rustfmt/src/modules.rs
@@ -27,7 +27,6 @@ type FileModMap<'ast> = BTreeMap<FileName, Module<'ast>>;
 pub(crate) struct Module<'a> {
     ast_mod_kind: Option<Cow<'a, ast::ModKind>>,
     pub(crate) items: Cow<'a, Vec<rustc_ast::ptr::P<ast::Item>>>,
-    attrs: Cow<'a, Vec<ast::Attribute>>,
     inner_attr: Vec<ast::Attribute>,
     pub(crate) span: Span,
 }
@@ -46,7 +45,6 @@ impl<'a> Module<'a> {
             .collect();
         Module {
             items: mod_items,
-            attrs: mod_attrs,
             inner_attr,
             span: mod_span,
             ast_mod_kind,