Don't show note if span is DUMMY_SP

Author: henryboisdequin

Diff for: compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs

@@ -13,7 +13,7 @@ use rustc_middle::mir::{
 use rustc_middle::ty::{self, suggest_constraining_type_param, Ty, TypeFoldable};
 use rustc_span::source_map::DesugaringKind;
 use rustc_span::symbol::sym;
-use rustc_span::Span;
+use rustc_span::{Span, DUMMY_SP};
 
 use crate::dataflow::drop_flag_effects;
 use crate::dataflow::indexes::{MoveOutIndex, MovePathIndex};
@@ -216,12 +216,13 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                 );
                             }
                             // Avoid pointing to the same function in multiple different
-                            // error messages
-                            if self.fn_self_span_reported.insert(self_arg.span) {
+                            // error messages.
+                            if span != DUMMY_SP && self.fn_self_span_reported.insert(self_arg.span)
+                            {
                                 err.span_note(
-                                    self_arg.span,
-                                    &format!("this function takes ownership of the receiver `self`, which moves {}", place_name)
-                                );
+                                        self_arg.span,
+                                        &format!("this function takes ownership of the receiver `self`, which moves {}", place_name)
+                                    );
                             }
                         }
                         // Deref::deref takes &self, which cannot cause a move

Diff for: src/test/ui/loops/issue-82916.rs

@@ -0,0 +1,10 @@
+struct S(i32);
+
+fn foo(x: Vec<S>) {
+    for y in x {
+
+    }
+    let z = x; //~ ERROR use of moved value: `x`
+}
+
+fn main() {}

Diff for: src/test/ui/loops/issue-82916.stderr

@@ -0,0 +1,23 @@
+error[E0382]: use of moved value: `x`
+  --> $DIR/issue-82916.rs:7:13
+   |
+LL | fn foo(x: Vec<S>) {
+   |        - move occurs because `x` has type `Vec<S>`, which does not implement the `Copy` trait
+LL |     for y in x {
+   |              -
+   |              |
+   |              `x` moved due to this implicit call to `.into_iter()`
+   |              help: consider borrowing to avoid moving into the for loop: `&x`
+...
+LL |     let z = x;
+   |             ^ value used here after move
+   |
+note: this function takes ownership of the receiver `self`, which moves `x`
+  --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
+   |
+LL |     fn into_iter(self) -> Self::IntoIter;
+   |                  ^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0382`.