Rollup of 11 pull requests

Cargo.lock

@@ -3364,9 +3364,9 @@ dependencies = [
 
 [[package]]
 name = "rustc-build-sysroot"
-version = "0.4.5"
+version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a26170e1d79ea32f7ccec3188dd13cfc1f18c82764a9cbc1071667c0f865a4ea"
+checksum = "a9bf37423495cd3a6a9ef8c75fc4566de0d26de0ab75f36f67a426e58df5768c"
 dependencies = [
  "anyhow",
  "rustc_version",

compiler/rustc_const_eval/src/interpret/machine.rs

@@ -347,8 +347,6 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
     /// allocation (because a copy had to be done to adjust things), machine memory will
     /// cache the result. (This relies on `AllocMap::get_or` being able to add the
     /// owned allocation to the map even when the map is shared.)
-    ///
-    /// This must only fail if `alloc` contains provenance.
     fn adjust_allocation<'b>(
         ecx: &InterpCx<'mir, 'tcx, Self>,
         id: AllocId,
@@ -427,6 +425,7 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
         _prov: (AllocId, Self::ProvenanceExtra),
         _size: Size,
         _align: Align,
+        _kind: MemoryKind<Self::MemoryKind>,
     ) -> InterpResult<'tcx> {
         Ok(())
     }

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -227,7 +227,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         self.allocate_raw_ptr(alloc, kind)
     }
 
-    /// This can fail only if `alloc` contains provenance.
     pub fn allocate_raw_ptr(
         &mut self,
         alloc: Allocation,
@@ -355,6 +354,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             (alloc_id, prov),
             size,
             alloc.align,
+            kind,
         )?;
 
         // Don't forget to remember size and align of this now-dead allocation

compiler/rustc_feature/src/unstable.rs

@@ -533,6 +533,8 @@ declare_features! (
     (unstable, more_qualified_paths, "1.54.0", Some(86935)),
     /// Allows the `#[must_not_suspend]` attribute.
     (unstable, must_not_suspend, "1.57.0", Some(83310)),
+    /// Make `mut` not reset the binding mode on edition >= 2024.
+    (incomplete, mut_preserve_binding_mode_2024, "CURRENT_RUSTC_VERSION", Some(123076)),
     /// Allows `mut ref` and `mut ref mut` identifier patterns.
     (incomplete, mut_ref, "CURRENT_RUSTC_VERSION", Some(123076)),
     /// Allows using `#[naked]` on functions.

compiler/rustc_hir_typeck/messages.ftl

@@ -46,6 +46,10 @@ hir_typeck_ctor_is_private = tuple struct constructor `{$def}` is private
 
 hir_typeck_deref_is_empty = this expression `Deref`s to `{$deref_ty}` which implements `is_empty`
 
+hir_typeck_dereferencing_mut_binding = dereferencing `mut` binding
+    .label = `mut` dereferences the type of this binding
+    .help = this will change in edition 2024
+
 hir_typeck_expected_default_return_type = expected `()` because of default return type
 
 hir_typeck_expected_return_type = expected `{$expected}` because of return type

compiler/rustc_hir_typeck/src/errors.rs

@@ -632,3 +632,11 @@ pub enum SuggestBoxingForReturnImplTrait {
         ends: Vec<Span>,
     },
 }
+
+#[derive(LintDiagnostic)]
+#[diag(hir_typeck_dereferencing_mut_binding)]
+pub struct DereferencingMutBinding {
+    #[label]
+    #[help]
+    pub span: Span,
+}

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -1696,7 +1696,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 if let ProbeResult::Match = result
                     && self
                         .at(&ObligationCause::dummy(), self.param_env)
-                        .sup(DefineOpaqueTypes::No, return_ty, xform_ret_ty)
+                        .sup(DefineOpaqueTypes::Yes, return_ty, xform_ret_ty)
                         .is_err()
                 {
                     result = ProbeResult::BadReturnType;

compiler/rustc_hir_typeck/src/pat.rs

@@ -10,6 +10,7 @@ use rustc_hir::pat_util::EnumerateAndAdjustIterator;
 use rustc_hir::{self as hir, BindingAnnotation, ByRef, HirId, Mutability, Pat, PatKind};
 use rustc_infer::infer;
 use rustc_infer::infer::type_variable::TypeVariableOrigin;
+use rustc_lint as lint;
 use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::ty::{self, Adt, Ty, TypeVisitableExt};
 use rustc_session::lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS;
@@ -629,12 +630,26 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected: Ty<'tcx>,
         pat_info: PatInfo<'tcx, '_>,
     ) -> Ty<'tcx> {
-        let PatInfo { binding_mode: def_bm, top_info: ti, .. } = pat_info;
+        let PatInfo { binding_mode: BindingAnnotation(def_br, _), top_info: ti, .. } = pat_info;
 
         // Determine the binding mode...
         let bm = match ba {
-            BindingAnnotation(ByRef::No, Mutability::Not) => def_bm,
-            _ => ba,
+            BindingAnnotation(ByRef::No, Mutability::Mut)
+                if !(pat.span.at_least_rust_2024()
+                    && self.tcx.features().mut_preserve_binding_mode_2024)
+                    && matches!(def_br, ByRef::Yes(_)) =>
+            {
+                // `mut x` resets the binding mode in edition <= 2021.
+                self.tcx.emit_node_span_lint(
+                    lint::builtin::DEREFERENCING_MUT_BINDING,
+                    pat.hir_id,
+                    pat.span,
+                    errors::DereferencingMutBinding { span: pat.span },
+                );
+                BindingAnnotation(ByRef::No, Mutability::Mut)
+            }
+            BindingAnnotation(ByRef::No, mutbl) => BindingAnnotation(def_br, mutbl),
+            BindingAnnotation(ByRef::Yes(_), _) => ba,
         };
         // ...and store it in a side table:
         self.typeck_results.borrow_mut().pat_binding_modes_mut().insert(pat.hir_id, bm);
@@ -743,7 +758,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
-    // Precondition: pat is a Ref(_) pattern
+    /// Precondition: pat is a `Ref(_)` pattern
     fn borrow_pat_suggestion(&self, err: &mut Diag<'_>, pat: &Pat<'_>) {
         let tcx = self.tcx;
         if let PatKind::Ref(inner, mutbl) = pat.kind

compiler/rustc_infer/src/infer/at.rs

@@ -282,7 +282,7 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
     {
         let Trace { at, trace } = self;
         debug_assert!(at.infcx.next_trait_solver());
-        let mut fields = at.infcx.combine_fields(trace, at.param_env, DefineOpaqueTypes::No);
+        let mut fields = at.infcx.combine_fields(trace, at.param_env, DefineOpaqueTypes::Yes);
         fields
             .equate(StructurallyRelateAliases::Yes)
             .relate(a, b)

compiler/rustc_lint/src/context/diagnostics/check_cfg.rs

@@ -168,7 +168,7 @@ pub(super) fn unexpected_cfg_name(
         diag.note("see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration");
     } else {
         diag.help(format!("to expect this configuration use `--check-cfg={inst}`"));
-        diag.note("see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration");
+        diag.note("see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration");
     }
 }
 
@@ -272,6 +272,6 @@ pub(super) fn unexpected_cfg_value(
         if !is_cfg_a_well_know_name {
             diag.help(format!("to expect this configuration use `--check-cfg={inst}`"));
         }
-        diag.note("see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration");
+        diag.note("see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration");
     }
 }

compiler/rustc_lint_defs/src/builtin.rs

@@ -38,6 +38,7 @@ declare_lint_pass! {
         DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
         DEPRECATED_IN_FUTURE,
         DEPRECATED_WHERE_CLAUSE_LOCATION,
+        DEREFERENCING_MUT_BINDING,
         DUPLICATE_MACRO_ATTRIBUTES,
         ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
         ELIDED_LIFETIMES_IN_PATHS,
@@ -1627,6 +1628,42 @@ declare_lint! {
     "detect mut variables which don't need to be mutable"
 }
 
+declare_lint! {
+    /// The `dereferencing_mut_binding` lint detects a `mut x` pattern that resets the binding mode,
+    /// as this behavior will change in rust 2024.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// # #![warn(dereferencing_mut_binding)]
+    /// let x = Some(123u32);
+    /// let _y = match &x {
+    ///     Some(mut x) => {
+    ///         x += 1;
+    ///         x
+    ///     }
+    ///     None => 0,
+    /// };
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Without the `mut`, `x` would have type `&u32`. Pre-2024, adding `mut` makes `x` have type
+    /// `u32`, which was deemed surprising. After edition 2024, adding `mut` will not change the
+    /// type of `x`. This lint warns users of editions before 2024 to update their code.
+    pub DEREFERENCING_MUT_BINDING,
+    Allow,
+    "detects `mut x` bindings that change the type of `x`",
+    @feature_gate = sym::mut_preserve_binding_mode_2024;
+    // FIXME uncomment below upon stabilization
+    /*@future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::EditionSemanticsChange(Edition::Edition2024),
+        reference: "123076",
+    };*/
+}
+
 declare_lint! {
     /// The `unconditional_recursion` lint detects functions that cannot
     /// return without calling themselves.

compiler/rustc_session/src/config.rs

@@ -1373,7 +1373,7 @@ pub fn rustc_short_optgroups() -> Vec<RustcOptGroup> {
         opt::flag_s("h", "help", "Display this message"),
         opt::multi_s("", "cfg", "Configure the compilation environment.
                              SPEC supports the syntax `NAME[=\"VALUE\"]`.", "SPEC"),
-        opt::multi("", "check-cfg", "Provide list of valid cfg options for checking", "SPEC"),
+        opt::multi_s("", "check-cfg", "Provide list of expected cfgs for checking", "SPEC"),
         opt::multi_s(
             "L",
             "",

compiler/rustc_session/src/config/cfg.rs

@@ -257,7 +257,7 @@ impl CheckCfg {
         // `tests/ui/check-cfg/well-known-values.rs` (in order to test the
         // expected values of the new config) and bless the all directory.
         //
-        // Don't forget to update `src/doc/unstable-book/src/compiler-flags/check-cfg.md`
+        // Don't forget to update `src/doc/rustc/src/check-cfg.md`
         // in the unstable book as well!
 
         ins!(sym::debug_assertions, no_values);

compiler/rustc_span/src/symbol.rs

@@ -1194,6 +1194,7 @@ symbols! {
         multiple_supertrait_upcastable,
         must_not_suspend,
         must_use,
+        mut_preserve_binding_mode_2024,
         mut_ref,
         naked,
         naked_functions,

src/bootstrap/src/bin/main.rs

@@ -131,10 +131,6 @@ fn main() {
 fn check_version(config: &Config) -> Option<String> {
     let mut msg = String::new();
 
-    if config.changelog_seen.is_some() {
-        msg.push_str("WARNING: The use of `changelog-seen` is deprecated. Please refer to `change-id` option in `config.example.toml` instead.\n");
-    }
-
     let latest_change_id = CONFIG_CHANGE_HISTORY.last().unwrap().change_id;
     let warned_id_path = config.out.join("bootstrap").join(".last-warned-change-id");