Rollup of 10 pull requests

compiler/rustc_borrowck/src/type_check/opaque_types.rs

@@ -25,8 +25,8 @@ pub(super) fn take_opaques_and_register_member_constraints<'tcx>(
     let opaque_types = infcx
         .take_opaque_types()
         .into_iter()
-        .map(|(opaque_type_key, decl)| {
-            let hidden_type = infcx.resolve_vars_if_possible(decl.hidden_type);
+        .map(|(opaque_type_key, hidden_type)| {
+            let hidden_type = infcx.resolve_vars_if_possible(hidden_type);
             register_member_constraints(
                 typeck,
                 &mut member_constraints,

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2451,10 +2451,10 @@ fn add_order_independent_options(
     }
 
     if sess.target.os == "emscripten" {
-        cmd.cc_arg(if sess.panic_strategy() == PanicStrategy::Abort {
-            "-sDISABLE_EXCEPTION_CATCHING=1"
-        } else if sess.opts.unstable_opts.emscripten_wasm_eh {
+        cmd.cc_arg(if sess.opts.unstable_opts.emscripten_wasm_eh {
             "-fwasm-exceptions"
+        } else if sess.panic_strategy() == PanicStrategy::Abort {
+            "-sDISABLE_EXCEPTION_CATCHING=1"
         } else {
             "-sDISABLE_EXCEPTION_CATCHING=0"
         });

compiler/rustc_hir_analysis/src/check/check.rs

@@ -436,9 +436,9 @@ fn check_opaque_meets_bounds<'tcx>(
     } else {
         // Check that any hidden types found during wf checking match the hidden types that `type_of` sees.
         for (mut key, mut ty) in infcx.take_opaque_types() {
-            ty.hidden_type.ty = infcx.resolve_vars_if_possible(ty.hidden_type.ty);
+            ty.ty = infcx.resolve_vars_if_possible(ty.ty);
             key = infcx.resolve_vars_if_possible(key);
-            sanity_check_found_hidden_type(tcx, key, ty.hidden_type)?;
+            sanity_check_found_hidden_type(tcx, key, ty)?;
         }
         Ok(())
     }
@@ -1873,7 +1873,7 @@ pub(super) fn check_coroutine_obligations(
         // Check that any hidden types found when checking these stalled coroutine obligations
         // are valid.
         for (key, ty) in infcx.take_opaque_types() {
-            let hidden_type = infcx.resolve_vars_if_possible(ty.hidden_type);
+            let hidden_type = infcx.resolve_vars_if_possible(ty);
             let key = infcx.resolve_vars_if_possible(key);
             sanity_check_found_hidden_type(tcx, key, hidden_type)?;
         }

compiler/rustc_hir_typeck/src/demand.rs

@@ -85,6 +85,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         self.annotate_expected_due_to_let_ty(err, expr, error);
         self.annotate_loop_expected_due_to_inference(err, expr, error);
+        if self.annotate_mut_binding_to_immutable_binding(err, expr, error) {
+            return;
+        }
 
         // FIXME(#73154): For now, we do leak check when coercing function
         // pointers in typeck, instead of only during borrowck. This can lead
@@ -795,6 +798,98 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
+    /// Detect the following case
+    ///
+    /// ```text
+    /// fn change_object(mut a: &Ty) {
+    ///     let a = Ty::new();
+    ///     b = a;
+    /// }
+    /// ```
+    ///
+    /// where the user likely meant to modify the value behind there reference, use `a` as an out
+    /// parameter, instead of mutating the local binding. When encountering this we suggest:
+    ///
+    /// ```text
+    /// fn change_object(a: &'_ mut Ty) {
+    ///     let a = Ty::new();
+    ///     *b = a;
+    /// }
+    /// ```
+    fn annotate_mut_binding_to_immutable_binding(
+        &self,
+        err: &mut Diag<'_>,
+        expr: &hir::Expr<'_>,
+        error: Option<TypeError<'tcx>>,
+    ) -> bool {
+        if let Some(TypeError::Sorts(ExpectedFound { expected, found })) = error
+            && let ty::Ref(_, inner, hir::Mutability::Not) = expected.kind()
+
+            // The difference between the expected and found values is one level of borrowing.
+            && self.can_eq(self.param_env, *inner, found)
+
+            // We have an `ident = expr;` assignment.
+            && let hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Assign(lhs, rhs, _), .. }) =
+                self.tcx.parent_hir_node(expr.hir_id)
+            && rhs.hir_id == expr.hir_id
+
+            // We are assigning to some binding.
+            && let hir::ExprKind::Path(hir::QPath::Resolved(
+                None,
+                hir::Path { res: hir::def::Res::Local(hir_id), .. },
+            )) = lhs.kind
+            && let hir::Node::Pat(pat) = self.tcx.hir_node(*hir_id)
+
+            // The pattern we have is an fn argument.
+            && let hir::Node::Param(hir::Param { ty_span, .. }) =
+                self.tcx.parent_hir_node(pat.hir_id)
+            && let item = self.tcx.hir().get_parent_item(pat.hir_id)
+            && let item = self.tcx.hir_owner_node(item)
+            && let Some(fn_decl) = item.fn_decl()
+
+            // We have a mutable binding in the argument.
+            && let hir::PatKind::Binding(hir::BindingMode::MUT, _hir_id, ident, _) = pat.kind
+
+            // Look for the type corresponding to the argument pattern we have in the argument list.
+            && let Some(ty_sugg) = fn_decl
+                .inputs
+                .iter()
+                .filter_map(|ty| {
+                    if ty.span == *ty_span
+                        && let hir::TyKind::Ref(lt, x) = ty.kind
+                    {
+                        // `&'name Ty` -> `&'name mut Ty` or `&Ty` -> `&mut Ty`
+                        Some((
+                            x.ty.span.shrink_to_lo(),
+                            format!(
+                                "{}mut ",
+                                if lt.ident.span.lo() == lt.ident.span.hi() { "" } else { " " }
+                            ),
+                        ))
+                    } else {
+                        None
+                    }
+                })
+                .next()
+        {
+            let sugg = vec![
+                ty_sugg,
+                (pat.span.until(ident.span), String::new()),
+                (lhs.span.shrink_to_lo(), "*".to_string()),
+            ];
+            // We suggest changing the argument from `mut ident: &Ty` to `ident: &'_ mut Ty` and the
+            // assignment from `ident = val;` to `*ident = val;`.
+            err.multipart_suggestion_verbose(
+                "you might have meant to mutate the pointed at value being passed in, instead of \
+                changing the reference in the local binding",
+                sugg,
+                Applicability::MaybeIncorrect,
+            );
+            return true;
+        }
+        false
+    }
+
     fn annotate_alternative_method_deref(
         &self,
         err: &mut Diag<'_>,

compiler/rustc_hir_typeck/src/writeback.rs

@@ -562,9 +562,9 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         // types or by using this function at the end of writeback and running it as a
         // fixpoint.
         let opaque_types = self.fcx.infcx.clone_opaque_types();
-        for (opaque_type_key, decl) in opaque_types {
-            let hidden_type = self.resolve(decl.hidden_type, &decl.hidden_type.span);
-            let opaque_type_key = self.resolve(opaque_type_key, &decl.hidden_type.span);
+        for (opaque_type_key, hidden_type) in opaque_types {
+            let hidden_type = self.resolve(hidden_type, &hidden_type.span);
+            let opaque_type_key = self.resolve(opaque_type_key, &hidden_type.span);
 
             if !self.fcx.next_trait_solver() {
                 if let ty::Alias(ty::Opaque, alias_ty) = hidden_type.ty.kind()

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -155,12 +155,12 @@ impl<'tcx> InferCtxt<'tcx> {
             .opaque_type_storage
             .opaque_types
             .iter()
-            .map(|(k, v)| (*k, v.hidden_type.ty))
+            .map(|(k, v)| (*k, v.ty))
             .collect()
     }
 
     fn take_opaque_types_for_query_response(&self) -> Vec<(ty::OpaqueTypeKey<'tcx>, Ty<'tcx>)> {
-        self.take_opaque_types().into_iter().map(|(k, v)| (k, v.hidden_type.ty)).collect()
+        self.take_opaque_types().into_iter().map(|(k, v)| (k, v.ty)).collect()
     }
 
     /// Given the (canonicalized) result to a canonical query,

compiler/rustc_infer/src/infer/mod.rs

@@ -234,7 +234,7 @@ impl<'tcx> InferCtxtInner<'tcx> {
     pub fn iter_opaque_types(
         &self,
     ) -> impl Iterator<Item = (ty::OpaqueTypeKey<'tcx>, ty::OpaqueHiddenType<'tcx>)> + '_ {
-        self.opaque_type_storage.opaque_types.iter().map(|(&k, v)| (k, v.hidden_type))
+        self.opaque_type_storage.opaque_types.iter().map(|(&k, &v)| (k, v))
     }
 }
 

compiler/rustc_infer/src/infer/opaque_types/mod.rs

@@ -19,20 +19,9 @@ use crate::traits::{self, Obligation, PredicateObligations};
 
 mod table;
 
-pub(crate) type OpaqueTypeMap<'tcx> = FxIndexMap<OpaqueTypeKey<'tcx>, OpaqueTypeDecl<'tcx>>;
+pub(crate) type OpaqueTypeMap<'tcx> = FxIndexMap<OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>>;
 pub(crate) use table::{OpaqueTypeStorage, OpaqueTypeTable};
 
-/// Information about the opaque types whose values we
-/// are inferring in this function (these are the `impl Trait` that
-/// appear in the return type).
-#[derive(Clone, Debug)]
-pub struct OpaqueTypeDecl<'tcx> {
-    /// The hidden types that have been inferred for this opaque type.
-    /// There can be multiple, but they are all `lub`ed together at the end
-    /// to obtain the canonical hidden type.
-    pub hidden_type: OpaqueHiddenType<'tcx>,
-}
-
 impl<'tcx> InferCtxt<'tcx> {
     /// This is a backwards compatibility hack to prevent breaking changes from
     /// lazy TAIT around RPIT handling.

compiler/rustc_infer/src/infer/opaque_types/table.rs

@@ -3,23 +3,27 @@ use rustc_middle::bug;
 use rustc_middle::ty::{self, OpaqueHiddenType, OpaqueTypeKey, Ty};
 use tracing::instrument;
 
-use super::{OpaqueTypeDecl, OpaqueTypeMap};
+use super::OpaqueTypeMap;
 use crate::infer::snapshot::undo_log::{InferCtxtUndoLogs, UndoLog};
 
 #[derive(Default, Debug, Clone)]
 pub(crate) struct OpaqueTypeStorage<'tcx> {
     /// Opaque types found in explicit return types and their
     /// associated fresh inference variable. Writeback resolves these
     /// variables to get the concrete type, which can be used to
-    /// 'de-opaque' OpaqueTypeDecl, after typeck is done with all functions.
+    /// 'de-opaque' OpaqueHiddenType, after typeck is done with all functions.
     pub opaque_types: OpaqueTypeMap<'tcx>,
 }
 
 impl<'tcx> OpaqueTypeStorage<'tcx> {
     #[instrument(level = "debug")]
-    pub(crate) fn remove(&mut self, key: OpaqueTypeKey<'tcx>, idx: Option<OpaqueHiddenType<'tcx>>) {
-        if let Some(idx) = idx {
-            self.opaque_types.get_mut(&key).unwrap().hidden_type = idx;
+    pub(crate) fn remove(
+        &mut self,
+        key: OpaqueTypeKey<'tcx>,
+        prev: Option<OpaqueHiddenType<'tcx>>,
+    ) {
+        if let Some(prev) = prev {
+            *self.opaque_types.get_mut(&key).unwrap() = prev;
         } else {
             // FIXME(#120456) - is `swap_remove` correct?
             match self.opaque_types.swap_remove(&key) {
@@ -59,13 +63,12 @@ impl<'a, 'tcx> OpaqueTypeTable<'a, 'tcx> {
         key: OpaqueTypeKey<'tcx>,
         hidden_type: OpaqueHiddenType<'tcx>,
     ) -> Option<Ty<'tcx>> {
-        if let Some(decl) = self.storage.opaque_types.get_mut(&key) {
-            let prev = std::mem::replace(&mut decl.hidden_type, hidden_type);
+        if let Some(entry) = self.storage.opaque_types.get_mut(&key) {
+            let prev = std::mem::replace(entry, hidden_type);
             self.undo_log.push(UndoLog::OpaqueTypes(key, Some(prev)));
             return Some(prev.ty);
         }
-        let decl = OpaqueTypeDecl { hidden_type };
-        self.storage.opaque_types.insert(key, decl);
+        self.storage.opaque_types.insert(key, hidden_type);
         self.undo_log.push(UndoLog::OpaqueTypes(key, None));
         None
     }

compiler/rustc_lint/src/impl_trait_overcaptures.rs

@@ -99,7 +99,7 @@ declare_lint! {
     /// To fix this, remove the `use<'a>`, since the lifetime is already captured
     /// since it is in scope.
     pub IMPL_TRAIT_REDUNDANT_CAPTURES,
-    Warn,
+    Allow,
     "redundant precise-capturing `use<...>` syntax on an `impl Trait`",
 }
 

compiler/rustc_middle/src/mir/pretty.rs

@@ -1555,16 +1555,22 @@ pub fn write_allocations<'tcx>(
                 write!(w, " (vtable: impl {dyn_ty} for {ty})")?
             }
             Some(GlobalAlloc::Static(did)) if !tcx.is_foreign_item(did) => {
-                match tcx.eval_static_initializer(did) {
-                    Ok(alloc) => {
-                        write!(w, " (static: {}, ", tcx.def_path_str(did))?;
-                        write_allocation_track_relocs(w, alloc)?;
+                write!(w, " (static: {}", tcx.def_path_str(did))?;
+                if body.phase <= MirPhase::Runtime(RuntimePhase::PostCleanup)
+                    && tcx.hir().body_const_context(body.source.def_id()).is_some()
+                {
+                    // Statics may be cyclic and evaluating them too early
+                    // in the MIR pipeline may cause cycle errors even though
+                    // normal compilation is fine.
+                    write!(w, ")")?;
+                } else {
+                    match tcx.eval_static_initializer(did) {
+                        Ok(alloc) => {
+                            write!(w, ", ")?;
+                            write_allocation_track_relocs(w, alloc)?;
+                        }
+                        Err(_) => write!(w, ", error during initializer evaluation)")?,
                     }
-                    Err(_) => write!(
-                        w,
-                        " (static: {}, error during initializer evaluation)",
-                        tcx.def_path_str(did)
-                    )?,
                 }
             }
             Some(GlobalAlloc::Static(did)) => {

compiler/rustc_passes/messages.ftl

@@ -799,6 +799,9 @@ passes_unused_assign = value assigned to `{$name}` is never read
 passes_unused_assign_passed = value passed to `{$name}` is never read
     .help = maybe it is overwritten before being read?
 
+passes_unused_assign_suggestion =
+    you might have meant to mutate the pointed at value being passed in, instead of changing the reference in the local binding
+
 passes_unused_capture_maybe_capture_ref = value captured by `{$name}` is never read
     .help = did you mean to capture by reference instead?
 

compiler/rustc_passes/src/errors.rs

@@ -1787,9 +1787,26 @@ pub(crate) struct IneffectiveUnstableImpl;
 
 #[derive(LintDiagnostic)]
 #[diag(passes_unused_assign)]
-#[help]
 pub(crate) struct UnusedAssign {
     pub name: String,
+    #[subdiagnostic]
+    pub suggestion: Option<UnusedAssignSuggestion>,
+    #[help]
+    pub help: bool,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(passes_unused_assign_suggestion, applicability = "maybe-incorrect")]
+pub(crate) struct UnusedAssignSuggestion {
+    pub pre: &'static str,
+    #[suggestion_part(code = "{pre}mut ")]
+    pub ty_span: Span,
+    #[suggestion_part(code = "")]
+    pub ty_ref_span: Span,
+    #[suggestion_part(code = "*")]
+    pub ident_span: Span,
+    #[suggestion_part(code = "")]
+    pub expr_ref_span: Span,
 }
 
 #[derive(LintDiagnostic)]