Add additional information to note for referencing packed field diagnostic

compiler/rustc_ast/src/ast.rs

@@ -2976,7 +2976,7 @@ pub enum ItemKind {
 }
 
 impl ItemKind {
-    pub fn article(&self) -> &str {
+    pub fn article(&self) -> &'static str {
         use ItemKind::*;
         match self {
             Use(..) | Static(..) | Const(..) | Fn(..) | Mod(..) | GlobalAsm(..) | TyAlias(..)
@@ -2985,7 +2985,7 @@ impl ItemKind {
         }
     }
 
-    pub fn descr(&self) -> &str {
+    pub fn descr(&self) -> &'static str {
         match self {
             ItemKind::ExternCrate(..) => "extern crate",
             ItemKind::Use(..) => "`use` import",

compiler/rustc_ast_lowering/src/format.rs

@@ -186,7 +186,7 @@ enum ArgumentType {
 /// Generates:
 ///
 /// ```text
-///     <core::fmt::ArgumentV1>::new_…(arg)
+///     <core::fmt::Argument>::new_…(arg)
 /// ```
 fn make_argument<'hir>(
     ctx: &mut LoweringContext<'_, 'hir>,
@@ -327,7 +327,7 @@ fn make_format_spec<'hir>(
             None => sym::Unknown,
         },
     );
-    // This needs to match `FlagV1` in library/core/src/fmt/mod.rs.
+    // This needs to match `Flag` in library/core/src/fmt/rt.rs.
     let flags: u32 = ((sign == Some(FormatSign::Plus)) as u32)
         | ((sign == Some(FormatSign::Minus)) as u32) << 1
         | (alternate as u32) << 2
@@ -438,7 +438,7 @@ fn expand_format_args<'hir>(
     // If the args array contains exactly all the original arguments once,
     // in order, we can use a simple array instead of a `match` construction.
     // However, if there's a yield point in any argument except the first one,
-    // we don't do this, because an ArgumentV1 cannot be kept across yield points.
+    // we don't do this, because an Argument cannot be kept across yield points.
     //
     // This is an optimization, speeding up compilation about 1-2% in some cases.
     // See https://github.com/rust-lang/rust/pull/106770#issuecomment-1380790609
@@ -449,9 +449,9 @@ fn expand_format_args<'hir>(
     let args = if use_simple_array {
         // Generate:
         //     &[
-        //         <core::fmt::ArgumentV1>::new_display(&arg0),
-        //         <core::fmt::ArgumentV1>::new_lower_hex(&arg1),
-        //         <core::fmt::ArgumentV1>::new_debug(&arg2),
+        //         <core::fmt::Argument>::new_display(&arg0),
+        //         <core::fmt::Argument>::new_lower_hex(&arg1),
+        //         <core::fmt::Argument>::new_debug(&arg2),
         //         …
         //     ]
         let elements: Vec<_> = arguments
@@ -477,9 +477,9 @@ fn expand_format_args<'hir>(
         // Generate:
         //     &match (&arg0, &arg1, &…) {
         //         args => [
-        //             <core::fmt::ArgumentV1>::new_display(args.0),
-        //             <core::fmt::ArgumentV1>::new_lower_hex(args.1),
-        //             <core::fmt::ArgumentV1>::new_debug(args.0),
+        //             <core::fmt::Argument>::new_display(args.0),
+        //             <core::fmt::Argument>::new_lower_hex(args.1),
+        //             <core::fmt::Argument>::new_debug(args.0),
         //             …
         //         ]
         //     }

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

@@ -819,8 +819,15 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     .builtin_deref(true)
                     .unwrap_or_else(|| bug!("deref of non-pointer {:?}", input_ty))
                     .ty;
-                let llty = bx.cx().backend_type(bx.cx().layout_of(pointee_type));
-                bx.inbounds_gep(llty, lhs, &[rhs])
+                let pointee_layout = bx.cx().layout_of(pointee_type);
+                if pointee_layout.is_zst() {
+                    // `Offset` works in terms of the size of pointee,
+                    // so offsetting a pointer to ZST is a noop.
+                    lhs
+                } else {
+                    let llty = bx.cx().backend_type(pointee_layout);
+                    bx.inbounds_gep(llty, lhs, &[rhs])
+                }
             }
             mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs),
             mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, lhs, rhs),

compiler/rustc_const_eval/src/transform/check_consts/ops.rs

@@ -296,7 +296,7 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
                 diag_trait(&mut err, self_ty, tcx.require_lang_item(LangItem::Deref, Some(span)));
                 err
             }
-            _ if tcx.opt_parent(callee) == tcx.get_diagnostic_item(sym::ArgumentV1Methods) => ccx
+            _ if tcx.opt_parent(callee) == tcx.get_diagnostic_item(sym::ArgumentMethods) => ccx
                 .tcx
                 .sess
                 .create_err(errors::NonConstFmtMacroCall { span, kind: ccx.const_kind() }),

compiler/rustc_feature/src/builtin_attrs.rs

@@ -344,7 +344,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     ),
     ungated!(link_name, Normal, template!(NameValueStr: "name"), FutureWarnPreceding),
     ungated!(no_link, Normal, template!(Word), WarnFollowing),
-    ungated!(repr, Normal, template!(List: "C"), DuplicatesOk, @only_local: true),
+    ungated!(repr, Normal, template!(List: "C"), DuplicatesOk),
     ungated!(export_name, Normal, template!(NameValueStr: "name"), FutureWarnPreceding),
     ungated!(link_section, Normal, template!(NameValueStr: "name"), FutureWarnPreceding),
     ungated!(no_mangle, Normal, template!(Word), WarnFollowing, @only_local: true),

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -215,7 +215,8 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
 
             sym::type_name => (1, Vec::new(), tcx.mk_static_str()),
             sym::type_id => (1, Vec::new(), tcx.types.u64),
-            sym::offset | sym::arith_offset => (
+            sym::offset => (2, vec![param(0), param(1)], param(0)),
+            sym::arith_offset => (
                 1,
                 vec![
                     tcx.mk_ptr(ty::TypeAndMut { ty: param(0), mutbl: hir::Mutability::Not }),

compiler/rustc_hir_typeck/src/lib.rs

@@ -221,12 +221,6 @@ fn typeck_with_fallback<'tcx>(
             }))
         } else if let Node::AnonConst(_) = node {
             match tcx.hir().get(tcx.hir().parent_id(id)) {
-                Node::Expr(&hir::Expr {
-                    kind: hir::ExprKind::ConstBlock(ref anon_const), ..
-                }) if anon_const.hir_id == id => Some(fcx.next_ty_var(TypeVariableOrigin {
-                    kind: TypeVariableOriginKind::TypeInference,
-                    span,
-                })),
                 Node::Ty(&hir::Ty { kind: hir::TyKind::Typeof(ref anon_const), .. })
                     if anon_const.hir_id == id =>
                 {

compiler/rustc_lint_defs/src/builtin.rs

@@ -3273,110 +3273,115 @@ declare_lint_pass! {
     /// Does nothing as a lint pass, but registers some `Lint`s
     /// that are used by other parts of the compiler.
     HardwiredLints => [
-        FORBIDDEN_LINT_GROUPS,
-        ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
+        // tidy-alphabetical-start
+        ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
+        AMBIGUOUS_ASSOCIATED_ITEMS,
+        AMBIGUOUS_GLOB_REEXPORTS,
         ARITHMETIC_OVERFLOW,
-        UNCONDITIONAL_PANIC,
-        UNUSED_IMPORTS,
-        UNUSED_EXTERN_CRATES,
-        UNUSED_CRATE_DEPENDENCIES,
-        UNUSED_QUALIFICATIONS,
-        UNKNOWN_LINTS,
-        UNFULFILLED_LINT_EXPECTATIONS,
-        UNUSED_VARIABLES,
-        UNUSED_ASSIGNMENTS,
-        DEAD_CODE,
-        UNREACHABLE_CODE,
-        UNREACHABLE_PATTERNS,
-        OVERLAPPING_RANGE_ENDPOINTS,
+        ASM_SUB_REGISTER,
+        BAD_ASM_STYLE,
+        BARE_TRAIT_OBJECTS,
         BINDINGS_WITH_VARIANT_NAME,
-        UNUSED_MACROS,
-        UNUSED_MACRO_RULES,
-        WARNINGS,
-        UNUSED_FEATURES,
-        STABLE_FEATURES,
-        UNKNOWN_CRATE_TYPES,
-        TRIVIAL_CASTS,
-        TRIVIAL_NUMERIC_CASTS,
-        PRIVATE_IN_PUBLIC,
-        EXPORTED_PRIVATE_DEPENDENCIES,
-        PUB_USE_OF_PRIVATE_EXTERN_CRATE,
-        INVALID_TYPE_PARAM_DEFAULT,
-        RENAMED_AND_REMOVED_LINTS,
-        CONST_ITEM_MUTATION,
-        PATTERNS_IN_FNS_WITHOUT_BODY,
-        MISSING_FRAGMENT_SPECIFIER,
-        LATE_BOUND_LIFETIME_ARGUMENTS,
-        ORDER_DEPENDENT_TRAIT_OBJECTS,
+        BREAK_WITH_LABEL_AND_LOOP,
+        BYTE_SLICE_IN_PACKED_STRUCT_WITH_DERIVE,
+        CENUM_IMPL_DROP_CAST,
         COHERENCE_LEAK_CHECK,
+        CONFLICTING_REPR_HINTS,
+        CONST_EVALUATABLE_UNCHECKED,
+        CONST_ITEM_MUTATION,
+        DEAD_CODE,
         DEPRECATED,
-        UNUSED_UNSAFE,
-        UNUSED_MUT,
-        UNCONDITIONAL_RECURSION,
-        SINGLE_USE_LIFETIMES,
-        UNUSED_LIFETIMES,
-        UNUSED_LABELS,
-        TYVAR_BEHIND_RAW_POINTER,
+        DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
+        DEPRECATED_IN_FUTURE,
+        DEPRECATED_WHERE_CLAUSE_LOCATION,
+        DUPLICATE_MACRO_ATTRIBUTES,
         ELIDED_LIFETIMES_IN_PATHS,
-        BARE_TRAIT_OBJECTS,
-        ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
-        UNSTABLE_NAME_COLLISIONS,
-        IRREFUTABLE_LET_PATTERNS,
-        WHERE_CLAUSES_OBJECT_SAFETY,
-        PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
-        MACRO_USE_EXTERN_CRATE,
-        MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
+        EXPORTED_PRIVATE_DEPENDENCIES,
+        FFI_UNWIND_CALLS,
+        FORBIDDEN_LINT_GROUPS,
+        FUNCTION_ITEM_REFERENCES,
+        FUZZY_PROVENANCE_CASTS,
         ILL_FORMED_ATTRIBUTE_INPUT,
-        CONFLICTING_REPR_HINTS,
-        META_VARIABLE_MISUSE,
-        DEPRECATED_IN_FUTURE,
-        AMBIGUOUS_ASSOCIATED_ITEMS,
-        INDIRECT_STRUCTURAL_MATCH,
-        POINTER_STRUCTURAL_MATCH,
-        NONTRIVIAL_STRUCTURAL_MATCH,
-        SOFT_UNSTABLE,
-        UNSTABLE_SYNTAX_PRE_EXPANSION,
-        INLINE_NO_SANITIZE,
-        BAD_ASM_STYLE,
-        ASM_SUB_REGISTER,
-        UNSAFE_OP_IN_UNSAFE_FN,
+        ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
+        IMPLIED_BOUNDS_ENTAILMENT,
         INCOMPLETE_INCLUDE,
-        CENUM_IMPL_DROP_CAST,
-        FUZZY_PROVENANCE_CASTS,
-        LOSSY_PROVENANCE_CASTS,
-        CONST_EVALUATABLE_UNCHECKED,
+        INDIRECT_STRUCTURAL_MATCH,
         INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
-        MUST_NOT_SUSPEND,
-        UNINHABITED_STATIC,
-        FUNCTION_ITEM_REFERENCES,
-        USELESS_DEPRECATED,
-        MISSING_ABI,
+        INLINE_NO_SANITIZE,
+        INVALID_ALIGNMENT,
         INVALID_DOC_ATTRIBUTES,
-        SEMICOLON_IN_EXPRESSIONS_FROM_MACROS,
-        RUST_2021_INCOMPATIBLE_CLOSURE_CAPTURES,
+        INVALID_MACRO_EXPORT_ARGUMENTS,
+        INVALID_TYPE_PARAM_DEFAULT,
+        IRREFUTABLE_LET_PATTERNS,
+        LARGE_ASSIGNMENTS,
+        LATE_BOUND_LIFETIME_ARGUMENTS,
         LEGACY_DERIVE_HELPERS,
+        LOSSY_PROVENANCE_CASTS,
+        MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
+        MACRO_USE_EXTERN_CRATE,
+        META_VARIABLE_MISUSE,
+        MISSING_ABI,
+        MISSING_FRAGMENT_SPECIFIER,
+        MUST_NOT_SUSPEND,
+        NAMED_ARGUMENTS_USED_POSITIONALLY,
+        NON_EXHAUSTIVE_OMITTED_PATTERNS,
+        NONTRIVIAL_STRUCTURAL_MATCH,
+        ORDER_DEPENDENT_TRAIT_OBJECTS,
+        OVERLAPPING_RANGE_ENDPOINTS,
+        PATTERNS_IN_FNS_WITHOUT_BODY,
+        POINTER_STRUCTURAL_MATCH,
+        PRIVATE_IN_PUBLIC,
         PROC_MACRO_BACK_COMPAT,
+        PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
+        PUB_USE_OF_PRIVATE_EXTERN_CRATE,
+        RENAMED_AND_REMOVED_LINTS,
+        REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
+        RUST_2021_INCOMPATIBLE_CLOSURE_CAPTURES,
         RUST_2021_INCOMPATIBLE_OR_PATTERNS,
-        LARGE_ASSIGNMENTS,
-        RUST_2021_PRELUDE_COLLISIONS,
         RUST_2021_PREFIXES_INCOMPATIBLE_SYNTAX,
+        RUST_2021_PRELUDE_COLLISIONS,
+        SEMICOLON_IN_EXPRESSIONS_FROM_MACROS,
+        SINGLE_USE_LIFETIMES,
+        SOFT_UNSTABLE,
+        STABLE_FEATURES,
+        SUSPICIOUS_AUTO_TRAIT_IMPLS,
+        TEST_UNSTABLE_LINT,
+        TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
+        TRIVIAL_CASTS,
+        TRIVIAL_NUMERIC_CASTS,
+        TYVAR_BEHIND_RAW_POINTER,
+        UNCONDITIONAL_PANIC,
+        UNCONDITIONAL_RECURSION,
+        UNDEFINED_NAKED_FUNCTION_ABI,
+        UNFULFILLED_LINT_EXPECTATIONS,
+        UNINHABITED_STATIC,
+        UNKNOWN_CRATE_TYPES,
+        UNKNOWN_LINTS,
+        UNREACHABLE_CODE,
+        UNREACHABLE_PATTERNS,
+        UNSAFE_OP_IN_UNSAFE_FN,
+        UNSTABLE_NAME_COLLISIONS,
+        UNSTABLE_SYNTAX_PRE_EXPANSION,
         UNSUPPORTED_CALLING_CONVENTIONS,
-        BREAK_WITH_LABEL_AND_LOOP,
+        UNUSED_ASSIGNMENTS,
         UNUSED_ATTRIBUTES,
+        UNUSED_CRATE_DEPENDENCIES,
+        UNUSED_EXTERN_CRATES,
+        UNUSED_FEATURES,
+        UNUSED_IMPORTS,
+        UNUSED_LABELS,
+        UNUSED_LIFETIMES,
+        UNUSED_MACRO_RULES,
+        UNUSED_MACROS,
+        UNUSED_MUT,
+        UNUSED_QUALIFICATIONS,
         UNUSED_TUPLE_STRUCT_FIELDS,
-        NON_EXHAUSTIVE_OMITTED_PATTERNS,
-        TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
-        DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
-        DUPLICATE_MACRO_ATTRIBUTES,
-        SUSPICIOUS_AUTO_TRAIT_IMPLS,
-        DEPRECATED_WHERE_CLAUSE_LOCATION,
-        TEST_UNSTABLE_LINT,
-        FFI_UNWIND_CALLS,
-        REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
-        NAMED_ARGUMENTS_USED_POSITIONALLY,
-        IMPLIED_BOUNDS_ENTAILMENT,
-        BYTE_SLICE_IN_PACKED_STRUCT_WITH_DERIVE,
-        AMBIGUOUS_GLOB_REEXPORTS,
+        UNUSED_UNSAFE,
+        UNUSED_VARIABLES,
+        USELESS_DEPRECATED,
+        WARNINGS,
+        WHERE_CLAUSES_OBJECT_SAFETY,
+        // tidy-alphabetical-end
     ]
 }
 

compiler/rustc_mir_transform/src/check_packed_ref.rs

@@ -56,9 +56,11 @@ impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> {
                         "reference to packed field is unaligned"
                     )
                     .note(
-                        "fields of packed structs are not properly aligned, and creating \
-                        a misaligned reference is undefined behavior (even if that \
-                        reference is never dereferenced)",
+                        "packed structs are only aligned by one byte. therefore, fields of packed \
+                        structs are not properly aligned and many modern architectures may penalize this."
+                    ).note(
+                        "creating a misaligned reference is undefined behavior (even if that \
+                        reference is never dereferenced)"
                     ).help(
                         "copy the field contents to a local variable, or replace the \
                         reference with a raw pointer and use `read_unaligned`/`write_unaligned` \