Improve span when temporary receiver is dropped in edition 2024

Author: compiler-errors

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -17,6 +17,7 @@ use rustc_middle::mir::{
 };
 use rustc_middle::ty::adjustment::PointerCoercion;
 use rustc_middle::ty::{self,RegionVid,Ty,TyCtxt};
+use rustc_middle::util::CallKind;
 use rustc_span::{DesugaringKind,Span,Symbol, kw, sym};
 use rustc_trait_selection::error_reporting::traits::FindExprBySpan;
 use tracing::{debug, instrument};
@@ -635,6 +636,39 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
 // Used in a closure.
 (LaterUseKind::ClosureCapture, capture_kind_span,Some(path_span))
 }
+// In the case that the borrowed value (probably a temporary)
+// overlaps with the method's receiver, then point at the method.
+UseSpans::FnSelfUse{
+var_span: span,
+kind:CallKind::Normal{desugaring:None, .. },
+ ..
+}if span
+.overlaps(self.body.local_decls[borrow.assigned_place.local].source_info.span) =>
+{
+ifletTerminatorKind::Call{ func,call_source:CallSource::Normal, .. } =
+&self.body.basic_blocks[location.block].terminator().kind
+{
+// Just point to the function, to reduce the chance of overlapping spans.
+let function_span = match func {
+Operand::Constant(c) => c.span,
+Operand::Copy(place) | Operand::Move(place) => {
+ifletSome(l) = place.as_local(){
+let local_decl = &self.body.local_decls[l];
+ifself.local_names[l].is_none(){
+ local_decl.source_info.span
+}else{
+ span
+}
+}else{
+ span
+}
+}
+};
+(LaterUseKind::Call, function_span,None)
+}else{
+(LaterUseKind::Other, span,None)
+}
+}
 UseSpans::PatUse(span)
  | UseSpans::OtherUse(span)
  | UseSpans::FnSelfUse{var_span: span, .. } => {

tests/ui/lifetimes/tail-expr-in-nested-expr.stderr

@@ -2,11 +2,10 @@ error[E0716]: temporary value dropped while borrowed
  --> $DIR/tail-expr-in-nested-expr.rs:4:15
  |
 LL | let _ = { String::new().as_str() }.len();
- | ^^^^^^^^^^^^^---------
+ | ^^^^^^^^^^^^^ - --- borrow later used by call
  | | |
  | | temporary value is freed at the end of this statement
  | creates a temporary value which is freed while still in use
- | borrow later used here
  |
  = note: consider using a `let` binding to create a longer lived value