From 26478c81fd3152eb0d272209dc02cdacfcb22aba Mon Sep 17 00:00:00 2001
From: Henry Boisdequin <65845077+henryboisdequin@users.noreply.github.com>
Date: Tue, 9 Mar 2021 20:12:47 +0530
Subject: [PATCH] Don't show note if `span` is `DUMMY_SP`

---
 .../diagnostics/conflict_errors.rs            | 13 ++++++-----
 src/test/ui/loops/issue-82916.rs              | 10 ++++++++
 src/test/ui/loops/issue-82916.stderr          | 23 +++++++++++++++++++
 3 files changed, 40 insertions(+), 6 deletions(-)
 create mode 100644 src/test/ui/loops/issue-82916.rs
 create mode 100644 src/test/ui/loops/issue-82916.stderr

diff --git a/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs b/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs
index 24b9408ffb6..eb942b195b2 100644
--- a/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs
+++ b/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 --git a/src/test/ui/loops/issue-82916.rs b/src/test/ui/loops/issue-82916.rs
new file mode 100644
index 00000000000..8633ea1e8cb
--- /dev/null
+++ b/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 --git a/src/test/ui/loops/issue-82916.stderr b/src/test/ui/loops/issue-82916.stderr
new file mode 100644
index 00000000000..ad42cce71f6
--- /dev/null
+++ b/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`.