Make as_ref suggestion a note

Author: compiler-errors

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -1086,14 +1086,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             ),
                         );
                     }
-                    if is_option_or_result && maybe_reinitialized_locations_is_empty {
-                        err.span_suggestion_verbose(
-                            fn_call_span.shrink_to_lo(),
-                            "consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents",
-                            "as_ref().",
-                            Applicability::MachineApplicable,
-                        );
-                    }
                     // Avoid pointing to the same function in multiple different
                     // error messages.
                     if span != DUMMY_SP && self.fn_self_span_reported.insert(self_arg.span) {
@@ -1102,6 +1094,12 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             &format!("this function takes ownership of the receiver `self`, which moves {}", place_name)
                         );
                     }
+                    if is_option_or_result && maybe_reinitialized_locations_is_empty {
+                        err.span_label(
+                            var_span,
+                            "help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents",
+                        );
+                    }
                 }
                 // Other desugarings takes &self, which cannot cause a move
                 _ => {}

src/test/ui/borrowck/suggest-as-ref-on-mut-closure.stderr

@@ -5,17 +5,14 @@ LL |     cb.map(|cb| cb());
    |     ^^^--------------
    |     |  |
    |     |  `*cb` moved due to this method call
+   |     help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents
    |     move occurs because `*cb` has type `Option<&mut dyn FnMut()>`, which does not implement the `Copy` trait
    |
 note: this function takes ownership of the receiver `self`, which moves `*cb`
   --> $SRC_DIR/core/src/option.rs:LL:COL
    |
 LL |     pub const fn map<U, F>(self, f: F) -> Option<U>
    |                            ^^^^
-help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents
-   |
-LL |     cb.as_ref().map(|cb| cb());
-   |        +++++++++
 
 error[E0596]: cannot borrow `*cb` as mutable, as it is behind a `&` reference
   --> $DIR/suggest-as-ref-on-mut-closure.rs:12:26

src/test/ui/suggestions/as-ref-2.fixed

@@ -1,5 +1,3 @@
-// run-rustfix
-
 struct Struct;
 
 fn bar(_: &Struct) -> Struct {

src/test/ui/suggestions/as-ref-2.rs

@@ -1,10 +1,12 @@
 error[E0382]: use of moved value: `foo`
-  --> $DIR/as-ref-2.rs:12:14
+  --> $DIR/as-ref-2.rs:10:14
    |
 LL |     let foo = Some(Struct);
    |         --- move occurs because `foo` has type `Option<Struct>`, which does not implement the `Copy` trait
 LL |     let _x: Option<Struct> = foo.map(|s| bar(&s));
-   |                                  ---------------- `foo` moved due to this method call
+   |                              --- ---------------- `foo` moved due to this method call
+   |                              |
+   |                              help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents
 LL |     let _y = foo;
    |              ^^^ value used here after move
    |
@@ -13,10 +15,6 @@ note: this function takes ownership of the receiver `self`, which moves `foo`
    |
 LL |     pub const fn map<U, F>(self, f: F) -> Option<U>
    |                            ^^^^
-help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents
-   |
-LL |     let _x: Option<Struct> = foo.as_ref().map(|s| bar(&s));
-   |                                  +++++++++
 
 error: aborting due to previous error
 

src/test/ui/suggestions/as-ref-2.stderr

@@ -1,5 +1,3 @@
-//run-rustfix
-
 pub struct LipogramCorpora {
     selections: Vec<(char, Option<String>)>,
 }

src/test/ui/suggestions/option-content-move.fixed

@@ -1,38 +1,32 @@
 error[E0507]: cannot move out of `selection.1` which is behind a shared reference
-  --> $DIR/option-content-move.rs:11:20
+  --> $DIR/option-content-move.rs:9:20
    |
 LL |                 if selection.1.unwrap().contains(selection.0) {
    |                    ^^^^^^^^^^^ -------- `selection.1` moved due to this method call
    |                    |
+   |                    help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents
    |                    move occurs because `selection.1` has type `Option<String>`, which does not implement the `Copy` trait
    |
 note: this function takes ownership of the receiver `self`, which moves `selection.1`
   --> $SRC_DIR/core/src/option.rs:LL:COL
    |
 LL |     pub const fn unwrap(self) -> T {
    |                         ^^^^
-help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents
-   |
-LL |                 if selection.1.as_ref().unwrap().contains(selection.0) {
-   |                                +++++++++
 
 error[E0507]: cannot move out of `selection.1` which is behind a shared reference
-  --> $DIR/option-content-move.rs:29:20
+  --> $DIR/option-content-move.rs:27:20
    |
 LL |                 if selection.1.unwrap().contains(selection.0) {
    |                    ^^^^^^^^^^^ -------- `selection.1` moved due to this method call
    |                    |
+   |                    help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents
    |                    move occurs because `selection.1` has type `Result<String, String>`, which does not implement the `Copy` trait
    |
 note: this function takes ownership of the receiver `self`, which moves `selection.1`
   --> $SRC_DIR/core/src/result.rs:LL:COL
    |
 LL |     pub fn unwrap(self) -> T
    |                   ^^^^
-help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents
-   |
-LL |                 if selection.1.as_ref().unwrap().contains(selection.0) {
-   |                                +++++++++
 
 error: aborting due to 2 previous errors