Merge ref '29b7717de23f' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: 29b7717
Filtered ref: fb4b6388017a4b5fa9806863ffe33ed23df840d4
Upstream diff: rust-lang/rust@f957826...29b7717

This merge was created using https://github.com/rust-lang/josh-sync.

Author: The Miri Cronjob Bot

compiler/rustc_abi/src/layout.rs

@@ -1167,7 +1167,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                 // To allow unsizing `&Foo<Type>` -> `&Foo<dyn Trait>`, the layout of the struct must
                 // not depend on the layout of the tail.
                 let max_field_align =
-                    fields_excluding_tail.iter().map(|f| f.align.abi.bytes()).max().unwrap_or(1);
+                    fields_excluding_tail.iter().map(|f| f.align.bytes()).max().unwrap_or(1);
                 let largest_niche_size = fields_excluding_tail
                     .iter()
                     .filter_map(|f| f.largest_niche)
@@ -1187,7 +1187,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                     } else {
                         // Returns `log2(effective-align)`. The calculation assumes that size is an
                         // integer multiple of align, except for ZSTs.
-                        let align = layout.align.abi.bytes();
+                        let align = layout.align.bytes();
                         let size = layout.size.bytes();
                         let niche_size = layout.largest_niche.map(|n| n.available(dl)).unwrap_or(0);
                         // Group [u8; 4] with align-4 or [u8; 6] with align-2 fields.
@@ -1485,7 +1485,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         for i in layout.fields.index_by_increasing_offset() {
             let offset = layout.fields.offset(i);
             let f = &fields[FieldIdx::new(i)];
-            write!(s, "[o{}a{}s{}", offset.bytes(), f.align.abi.bytes(), f.size.bytes()).unwrap();
+            write!(s, "[o{}a{}s{}", offset.bytes(), f.align.bytes(), f.size.bytes()).unwrap();
             if let Some(n) = f.largest_niche {
                 write!(
                     s,

compiler/rustc_abi/src/lib.rs

@@ -2156,7 +2156,7 @@ impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
 
     /// Returns `true` if the type is sized and a 1-ZST (meaning it has size 0 and alignment 1).
     pub fn is_1zst(&self) -> bool {
-        self.is_sized() && self.size.bytes() == 0 && self.align.abi.bytes() == 1
+        self.is_sized() && self.size.bytes() == 0 && self.align.bytes() == 1
     }
 
     /// Returns `true` if the type is a ZST and not unsized.

compiler/rustc_ast/src/ast.rs

@@ -114,8 +114,7 @@ impl PartialEq<Symbol> for Path {
 impl PartialEq<&[Symbol]> for Path {
     #[inline]
     fn eq(&self, names: &&[Symbol]) -> bool {
-        self.segments.len() == names.len()
-            && self.segments.iter().zip(names.iter()).all(|(s1, s2)| s1 == s2)
+        self.segments.iter().eq(*names)
     }
 }
 

compiler/rustc_ast/src/lib.rs

@@ -15,6 +15,7 @@
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
+#![feature(iter_order_by)]
 #![feature(macro_metavar_expr)]
 #![feature(rustdoc_internals)]
 #![recursion_limit = "256"]

compiler/rustc_ast/src/tokenstream.rs

@@ -48,9 +48,7 @@ impl TokenTree {
         match (self, other) {
             (TokenTree::Token(token, _), TokenTree::Token(token2, _)) => token.kind == token2.kind,
             (TokenTree::Delimited(.., delim, tts), TokenTree::Delimited(.., delim2, tts2)) => {
-                delim == delim2
-                    && tts.len() == tts2.len()
-                    && tts.iter().zip(tts2.iter()).all(|(a, b)| a.eq_unspanned(b))
+                delim == delim2 && tts.iter().eq_by(tts2.iter(), |a, b| a.eq_unspanned(b))
             }
             _ => false,
         }

compiler/rustc_attr_parsing/messages.ftl

@@ -8,7 +8,15 @@ attr_parsing_deprecated_item_suggestion =
 
 attr_parsing_empty_attribute =
     unused attribute
-    .suggestion = remove this attribute
+    .suggestion = {$valid_without_list ->
+        [true] remove these parentheses
+        *[other] remove this attribute
+    }
+    .note = {$valid_without_list ->
+        [true] using `{$attr_path}` with an empty list is equivalent to not using a list at all
+        *[other] using `{$attr_path}` with an empty list has no effect
+    }
+
 
 attr_parsing_invalid_target = `#[{$name}]` attribute cannot be used on {$target}
     .help = `#[{$name}]` can {$only}be applied to {$applied}

compiler/rustc_attr_parsing/src/context.rs

@@ -597,7 +597,12 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
     }
 
     pub(crate) fn warn_empty_attribute(&mut self, span: Span) {
-        self.emit_lint(AttributeLintKind::EmptyAttribute { first_span: span }, span);
+        let attr_path = self.attr_path.clone();
+        let valid_without_list = self.template.word;
+        self.emit_lint(
+            AttributeLintKind::EmptyAttribute { first_span: span, attr_path, valid_without_list },
+            span,
+        );
     }
 }
 

compiler/rustc_attr_parsing/src/lints.rs

@@ -43,12 +43,18 @@ pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<L::Id>, lint_emi
                     ),
                 },
             ),
-        AttributeLintKind::EmptyAttribute { first_span } => lint_emitter.emit_node_span_lint(
-            rustc_session::lint::builtin::UNUSED_ATTRIBUTES,
-            *id,
-            *first_span,
-            session_diagnostics::EmptyAttributeList { attr_span: *first_span },
-        ),
+        AttributeLintKind::EmptyAttribute { first_span, attr_path, valid_without_list } => {
+            lint_emitter.emit_node_span_lint(
+                rustc_session::lint::builtin::UNUSED_ATTRIBUTES,
+                *id,
+                *first_span,
+                session_diagnostics::EmptyAttributeList {
+                    attr_span: *first_span,
+                    attr_path: attr_path.clone(),
+                    valid_without_list: *valid_without_list,
+                },
+            )
+        }
         AttributeLintKind::InvalidTarget { name, target, applied, only } => lint_emitter
             .emit_node_span_lint(
                 // This check is here because `deprecated` had its own lint group and removing this would be a breaking change

compiler/rustc_attr_parsing/src/parser.rs

@@ -49,7 +49,7 @@ impl<'a> PathParser<'a> {
     }
 
     pub fn segments_is(&self, segments: &[Symbol]) -> bool {
-        self.len() == segments.len() && self.segments().zip(segments).all(|(a, b)| a.name == *b)
+        self.segments().map(|segment| &segment.name).eq(segments)
     }
 
     pub fn word(&self) -> Option<Ident> {

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -503,9 +503,12 @@ pub(crate) struct EmptyConfusables {
 
 #[derive(LintDiagnostic)]
 #[diag(attr_parsing_empty_attribute)]
+#[note]
 pub(crate) struct EmptyAttributeList {
     #[suggestion(code = "", applicability = "machine-applicable")]
     pub attr_span: Span,
+    pub attr_path: AttrPath,
+    pub valid_without_list: bool,
 }
 
 #[derive(LintDiagnostic)]