Auto merge of #120136 - matthiaskrgr:rollup-3zzb0z9, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - #117561 (Stabilize `slice_first_last_chunk`)
 - #117662 ([rustdoc] Allows links in headings)
 - #119815 (Format sources into the error message when loading codegen backends)
 - #119835 (Exhaustiveness: simplify empty pattern logic)
 - #119984 (Change return type of unstable `Waker::noop()` from `Waker` to `&Waker`.)
 - #120009 (never_patterns: typecheck never patterns)
 - #120122 (Don't add needs-triage to A-diagnostics)
 - #120126 (Suggest `.swap()` when encountering conflicting borrows from `mem::swap` on a slice)
 - #120134 (Restrict access to the private field of newtype indexes)

Failed merges:

 - #119968 (Remove unused/unnecessary features)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

Cargo.lock

@@ -2187,16 +2187,6 @@ dependencies = [
  "cc",
 ]
 
-[[package]]
-name = "libloading"
-version = "0.7.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b67380fd3b2fbe7527a606e18729d21c6f3951633d0500574c4dc22d2d638b9f"
-dependencies = [
- "cfg-if",
- "winapi",
-]
-
 [[package]]
 name = "libloading"
 version = "0.8.1"
@@ -2479,7 +2469,7 @@ dependencies = [
  "lazy_static",
  "libc",
  "libffi",
- "libloading 0.8.1",
+ "libloading",
  "log",
  "measureme",
  "rand",
@@ -4005,7 +3995,7 @@ dependencies = [
 name = "rustc_interface"
 version = "0.0.0"
 dependencies = [
- "libloading 0.7.4",
+ "libloading",
  "rustc-rayon",
  "rustc-rayon-core",
  "rustc_ast",
@@ -4135,7 +4125,7 @@ name = "rustc_metadata"
 version = "0.0.0"
 dependencies = [
  "bitflags 2.4.1",
- "libloading 0.7.4",
+ "libloading",
  "odht",
  "rustc_ast",
  "rustc_attr",

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -26,6 +26,7 @@ use rustc_span::hygiene::DesugaringKind;
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{BytePos, Span, Symbol};
 use rustc_trait_selection::infer::InferCtxtExt;
+use rustc_trait_selection::traits::error_reporting::FindExprBySpan;
 use rustc_trait_selection::traits::ObligationCtxt;
 use std::iter;
 
@@ -1304,14 +1305,96 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         place: Place<'tcx>,
         borrowed_place: Place<'tcx>,
     ) {
-        if let ([ProjectionElem::Index(_)], [ProjectionElem::Index(_)]) =
-            (&place.projection[..], &borrowed_place.projection[..])
+        let tcx = self.infcx.tcx;
+        let hir = tcx.hir();
+
+        if let ([ProjectionElem::Index(index1)], [ProjectionElem::Index(index2)])
+        | (
+            [ProjectionElem::Deref, ProjectionElem::Index(index1)],
+            [ProjectionElem::Deref, ProjectionElem::Index(index2)],
+        ) = (&place.projection[..], &borrowed_place.projection[..])
         {
-            err.help(
-                "consider using `.split_at_mut(position)` or similar method to obtain \
-                     two mutable non-overlapping sub-slices",
-            )
-            .help("consider using `.swap(index_1, index_2)` to swap elements at the specified indices");
+            let mut note_default_suggestion = || {
+                err.help(
+                    "consider using `.split_at_mut(position)` or similar method to obtain \
+                         two mutable non-overlapping sub-slices",
+                )
+                .help("consider using `.swap(index_1, index_2)` to swap elements at the specified indices");
+            };
+
+            let Some(body_id) = tcx.hir_node(self.mir_hir_id()).body_id() else {
+                note_default_suggestion();
+                return;
+            };
+
+            let mut expr_finder =
+                FindExprBySpan::new(self.body.local_decls[*index1].source_info.span);
+            expr_finder.visit_expr(hir.body(body_id).value);
+            let Some(index1) = expr_finder.result else {
+                note_default_suggestion();
+                return;
+            };
+
+            expr_finder = FindExprBySpan::new(self.body.local_decls[*index2].source_info.span);
+            expr_finder.visit_expr(hir.body(body_id).value);
+            let Some(index2) = expr_finder.result else {
+                note_default_suggestion();
+                return;
+            };
+
+            let sm = tcx.sess.source_map();
+
+            let Ok(index1_str) = sm.span_to_snippet(index1.span) else {
+                note_default_suggestion();
+                return;
+            };
+
+            let Ok(index2_str) = sm.span_to_snippet(index2.span) else {
+                note_default_suggestion();
+                return;
+            };
+
+            let Some(object) = hir.parent_id_iter(index1.hir_id).find_map(|id| {
+                if let hir::Node::Expr(expr) = tcx.hir_node(id)
+                    && let hir::ExprKind::Index(obj, ..) = expr.kind
+                {
+                    Some(obj)
+                } else {
+                    None
+                }
+            }) else {
+                note_default_suggestion();
+                return;
+            };
+
+            let Ok(obj_str) = sm.span_to_snippet(object.span) else {
+                note_default_suggestion();
+                return;
+            };
+
+            let Some(swap_call) = hir.parent_id_iter(object.hir_id).find_map(|id| {
+                if let hir::Node::Expr(call) = tcx.hir_node(id)
+                    && let hir::ExprKind::Call(callee, ..) = call.kind
+                    && let hir::ExprKind::Path(qpath) = callee.kind
+                    && let hir::QPath::Resolved(None, res) = qpath
+                    && let hir::def::Res::Def(_, did) = res.res
+                    && tcx.is_diagnostic_item(sym::mem_swap, did)
+                {
+                    Some(call)
+                } else {
+                    None
+                }
+            }) else {
+                note_default_suggestion();
+                return;
+            };
+
+            err.span_suggestion(
+                swap_call.span,
+                "use `.swap()` to swap elements at the specified indices instead",
+                format!("{obj_str}.swap({index1_str}, {index2_str})"),
+                Applicability::MachineApplicable,
+            );
         }
     }