Suggest function borrow ignoring needs_note

`needs_note` is false if we've already suggested why the type is Copy...
but that has nothing to do with the diagnostic.

9 files changed, 53 insertions, 4 deletions

diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index fcbefc74895..883f711b201 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -284,10 +284,14 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 None => "value".to_owned(),
             };
             if self.suggest_borrow_fn_like(&mut err, ty, &move_site_vec, &note_msg) {
-                // Suppress the next note, since we don't want to put more `Fn`-like bounds onto something that already has them
-            } else if needs_note {
+                // Suppress the next suggestion since we don't want to put more bounds onto
+                // something that already has `Fn`-like bounds (or is a closure), so we can't
+                // restrict anyways.
+            } else {
                 self.suggest_adding_copy_bounds(&mut err, ty, span);
+            }
 
+            if needs_note {
                 let span = if let Some(local) = place.as_local() {
                     Some(self.body.local_decls[local].source_info.span)
                 } else {
diff --git a/src/test/ui/chalkify/closure.stderr b/src/test/ui/chalkify/closure.stderr
index d5a48a7dc6f..515e0cf0142 100644
--- a/src/test/ui/chalkify/closure.stderr
+++ b/src/test/ui/chalkify/closure.stderr
@@ -12,6 +12,10 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
    |
 LL |         a = 1;
    |         ^
+help: consider mutably borrowing `b`
+   |
+LL |     let mut c = &mut b;
+   |                 ++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-multi-variant-diagnostics.stderr b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-multi-variant-diagnostics.stderr
index 066c000c832..83d282aadb9 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-multi-variant-diagnostics.stderr
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-multi-variant-diagnostics.stderr
@@ -11,6 +11,10 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
    |
 LL |         if let MultiVariant::Point(ref mut x, _) = point {
    |                                                    ^^^^^
+help: consider mutably borrowing `c`
+   |
+LL |     let a = &mut c;
+   |             ++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-single-variant-diagnostics.stderr b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-single-variant-diagnostics.stderr
index 2a6e00850fa..46323b75210 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-single-variant-diagnostics.stderr
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-single-variant-diagnostics.stderr
@@ -11,6 +11,10 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
    |
 LL |         let SingleVariant::Point(ref mut x, _) = point;
    |                                                  ^^^^^
+help: consider mutably borrowing `c`
+   |
+LL |     let b = &mut c;
+   |             ++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-struct-diagnostics.stderr b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-struct-diagnostics.stderr
index d7fc51c55ea..25029cc7bd8 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-struct-diagnostics.stderr
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-struct-diagnostics.stderr
@@ -11,6 +11,10 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
    |
 LL |         x.y.a += 1;
    |         ^^^^^
+help: consider mutably borrowing `hello`
+   |
+LL |     let b = &mut hello;
+   |             ++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-tuple-diagnostics-1.stderr b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-tuple-diagnostics-1.stderr
index 63e2d300eb0..06ef7baf9c0 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-tuple-diagnostics-1.stderr
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-tuple-diagnostics-1.stderr
@@ -11,6 +11,10 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
    |
 LL |         x.0 += 1;
    |         ^^^
+help: consider mutably borrowing `hello`
+   |
+LL |     let b = &mut hello;
+   |             ++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/moves/borrow-closures-instead-of-move.rs b/src/test/ui/moves/borrow-closures-instead-of-move.rs
index adbbf4ee1a8..51771ced7f2 100644
--- a/src/test/ui/moves/borrow-closures-instead-of-move.rs
+++ b/src/test/ui/moves/borrow-closures-instead-of-move.rs
@@ -17,11 +17,13 @@ fn takes_fn_mut(m: impl FnMut()) {
 
 fn has_closure() {
     let mut x = 0;
-    let closure = || {
+    let mut closure = || {
         x += 1;
     };
     takes_fnonce(closure);
+    //~^ HELP consider mutably borrowing
     closure();
+    //~^ ERROR borrow of moved value
 }
 
 fn maybe() -> bool {
diff --git a/src/test/ui/moves/borrow-closures-instead-of-move.stderr b/src/test/ui/moves/borrow-closures-instead-of-move.stderr
index ff10d3c6006..3146b695900 100644
--- a/src/test/ui/moves/borrow-closures-instead-of-move.stderr
+++ b/src/test/ui/moves/borrow-closures-instead-of-move.stderr
@@ -29,6 +29,25 @@ help: consider mutably borrowing `m`
 LL |         takes_fnonce(&mut m);
    |                      ++++
 
-error: aborting due to 2 previous errors
+error[E0382]: borrow of moved value: `closure`
+  --> $DIR/borrow-closures-instead-of-move.rs:25:5
+   |
+LL |     takes_fnonce(closure);
+   |                  ------- value moved here
+LL |
+LL |     closure();
+   |     ^^^^^^^ value borrowed here after move
+   |
+note: closure cannot be moved more than once as it is not `Copy` due to moving the variable `x` out of its environment
+  --> $DIR/borrow-closures-instead-of-move.rs:21:9
+   |
+LL |         x += 1;
+   |         ^
+help: consider mutably borrowing `closure`
+   |
+LL |     takes_fnonce(&mut closure);
+   |                  ++++
+
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0382`.
diff --git a/src/test/ui/not-copy-closure.stderr b/src/test/ui/not-copy-closure.stderr
index 10bf570727f..93e011ccec4 100644
--- a/src/test/ui/not-copy-closure.stderr
+++ b/src/test/ui/not-copy-closure.stderr
@@ -11,6 +11,10 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
    |
 LL |         a += 1;
    |         ^
+help: consider mutably borrowing `hello`
+   |
+LL |     let b = &mut hello;
+   |             ++++
 
 error: aborting due to previous error