Fix accuracy of T: Clone check in suggestion

Author: estebank

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -988,6 +988,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
     }
 
     pub(crate) fn suggest_cloning(&self, err: &mut Diag<'_>, ty: Ty<'tcx>, expr: &hir::Expr<'_>) {
+        let ty = ty.peel_refs();
         if let Some(clone_trait_def) = self.infcx.tcx.lang_items().clone_trait()
             && self
                 .infcx

tests/ui/associated-types/associated-types-outlives.stderr

@@ -10,12 +10,6 @@ LL |         drop(x);
    |              ^ move out of `x` occurs here
 LL |         return f(y);
    |                  - borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -         's: loop { y = denormalise(&x); break }
-LL +         's: loop { y = denormalise(x.clone()); break }
-   |
 
 error: aborting due to 1 previous error
 

tests/ui/binop/binop-move-semantics.stderr

@@ -51,12 +51,6 @@ LL |     x
 ...
 LL |     use_mut(n); use_imm(m);
    |                         - borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -     let m = &x;
-LL +     let m = x.clone();
-   |
 
 error[E0505]: cannot move out of `y` because it is borrowed
   --> $DIR/binop-move-semantics.rs:23:5

tests/ui/borrowck/borrowck-issue-48962.stderr

@@ -17,6 +17,11 @@ LL |     {src};
    |      --- value moved here
 LL |     src.0 = 66;
    |     ^^^^^^^^^^ value used here after move
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |     {src.clone()};
+   |         ++++++++
 
 error: aborting due to 2 previous errors
 

tests/ui/borrowck/borrowck-move-subcomponent.stderr

@@ -9,12 +9,6 @@ LL |   let S { x: ax } = a;
    |              ^^ move out of `a.x` occurs here
 LL |   f(pb);
    |     -- borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -   let pb = &a;
-LL +   let pb = a.clone();
-   |
 
 error: aborting due to 1 previous error
 

tests/ui/borrowck/borrowck-overloaded-index-move-index.stderr

@@ -11,6 +11,12 @@ LL |     println!("{}", f[s]);
 ...
 LL |     use_mut(rs);
    |             -- borrow later used here
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL -     let rs = &mut s;
+LL +     let rs = s.clone();
+   |
 
 error[E0505]: cannot move out of `s` because it is borrowed
   --> $DIR/borrowck-overloaded-index-move-index.rs:53:7
@@ -25,6 +31,12 @@ LL |     f[s] = 10;
 ...
 LL |     use_mut(rs);
    |             -- borrow later used here
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL -     let rs = &mut s;
+LL +     let rs = s.clone();
+   |
 
 error[E0382]: use of moved value: `s`
   --> $DIR/borrowck-overloaded-index-move-index.rs:53:7

tests/ui/borrowck/clone-on-ref.fixed

@@ -9,7 +9,7 @@ fn foo<T: Default + Clone>(list: &mut Vec<T>) {
     drop(cloned_items);
 }
 fn bar<T: std::fmt::Display + Clone>(x: T) {
-    let a = x.clone();
+    let a = &x;
     let b = a.clone();
     drop(x);
     //~^ ERROR cannot move out of `x` because it is borrowed
@@ -19,7 +19,7 @@ fn bar<T: std::fmt::Display + Clone>(x: T) {
 #[derive(Clone)]
 struct A;
 fn qux(x: A) {
-    let a = x.clone();
+    let a = &x;
     let b = a.clone();
     drop(x);
     //~^ ERROR cannot move out of `x` because it is borrowed

tests/ui/borrowck/clone-on-ref.stderr

@@ -36,11 +36,6 @@ help: consider further restricting this bound
    |
 LL | fn bar<T: std::fmt::Display + Clone>(x: T) {
    |                             +++++++
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -     let a = &x;
-LL +     let a = x.clone();
-   |
 
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/clone-on-ref.rs:23:10
@@ -62,11 +57,6 @@ help: consider annotating `A` with `#[derive(Clone)]`
 LL + #[derive(Clone)]
 LL | struct A;
    |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -     let a = &x;
-LL +     let a = x.clone();
-   |
 
 error: aborting due to 3 previous errors
 

tests/ui/error-codes/E0504.stderr

@@ -13,12 +13,6 @@ LL |         println!("child function: {}", fancy_num.num);
 ...
 LL |     println!("main function: {}", fancy_ref.num);
    |                                   ------------- borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -     let fancy_ref = &fancy_num;
-LL +     let fancy_ref = fancy_num.clone();
-   |
 
 error: aborting due to 1 previous error
 

tests/ui/error-codes/E0505.stderr

@@ -10,12 +10,6 @@ LL |         eat(x);
    |             ^ move out of `x` occurs here
 LL |         _ref_to_val.use_ref();
    |         ----------- borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -         let _ref_to_val: &Value = &x;
-LL +         let _ref_to_val: &Value = x.clone();
-   |
 
 error: aborting due to 1 previous error
 

tests/ui/nll/closure-access-spans.stderr

@@ -109,6 +109,11 @@ LL |     || *x = String::new();
    |     ^^ -- borrow occurs due to use in closure
    |     |
    |     value borrowed here after move
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |     let r = x.clone();
+   |              ++++++++
 
 error[E0382]: use of moved value: `x`
   --> $DIR/closure-access-spans.rs:50:5
@@ -121,6 +126,11 @@ LL |     || x;
    |     ^^ - use occurs due to use in closure
    |     |
    |     value used here after move
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |     let r = x.clone();
+   |              ++++++++
 
 error: aborting due to 9 previous errors
 

tests/ui/nll/issue-52059-report-when-borrow-and-drop-conflict.stderr

@@ -41,6 +41,10 @@ help: consider borrowing here
    |
 LL |     let p = &s.url; p
    |             +
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |     let p = s.url.clone(); p
+   |                  ++++++++
 
 error: aborting due to 4 previous errors
 

tests/ui/nll/polonius/polonius-smoke-test.stderr

@@ -27,6 +27,12 @@ LL |     let z = x;
    |             ^ move out of `x` occurs here
 LL |     y
    |     - returning this value requires that `*x` is borrowed for `'1`
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL -     let y = &mut *x;
+LL +     let y = x.clone();
+   |
 
 error[E0505]: cannot move out of `s` because it is borrowed
   --> $DIR/polonius-smoke-test.rs:42:5
@@ -40,6 +46,12 @@ LL |     s;
    |     ^ move out of `s` occurs here
 LL |     tmp;
    |     --- borrow later used here
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL -     let r = &mut *s;
+LL +     let r = s.clone();
+   |
 
 error: aborting due to 4 previous errors
 

tests/ui/pattern/move-ref-patterns/borrowck-move-ref-pattern.stderr

@@ -10,12 +10,6 @@ LL |     let [ref _x0_hold, _x1, ref xs_hold @ ..] = arr;
 LL |     _x1 = U;
 LL |     drop(hold_all);
    |          -------- borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -     let hold_all = &arr;
-LL +     let hold_all = arr.clone();
-   |
 
 error[E0384]: cannot assign twice to immutable variable `_x1`
   --> $DIR/borrowck-move-ref-pattern.rs:9:5

tests/ui/try-block/try-block-bad-lifetime.stderr

@@ -34,6 +34,11 @@ LL |             Err(k) ?;
 ...
 LL |         ::std::mem::drop(k);
    |                          ^ value used here after move
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |             Err(k.clone()) ?;
+   |                  ++++++++
 
 error[E0506]: cannot assign to `i` because it is borrowed
   --> $DIR/try-block-bad-lifetime.rs:32:9

tests/ui/unop-move-semantics.stderr

@@ -33,12 +33,6 @@ LL |     !x;
 ...
 LL |     use_mut(n); use_imm(m);
    |                         - borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -     let m = &x;
-LL +     let m = x.clone();
-   |
 
 error[E0505]: cannot move out of `y` because it is borrowed
   --> $DIR/unop-move-semantics.rs:17:6

tests/ui/variance/variance-issue-20533.stderr

@@ -9,12 +9,6 @@ LL |         drop(a);
    |              ^ move out of `a` occurs here
 LL |         drop(x);
    |              - borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -         let x = foo(&a);
-LL +         let x = foo(a.clone());
-   |
 
 error[E0505]: cannot move out of `a` because it is borrowed
   --> $DIR/variance-issue-20533.rs:34:14
@@ -27,12 +21,6 @@ LL |         drop(a);
    |              ^ move out of `a` occurs here
 LL |         drop(x);
    |              - borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -         let x = bar(&a);
-LL +         let x = bar(a.clone());
-   |
 
 error[E0505]: cannot move out of `a` because it is borrowed
   --> $DIR/variance-issue-20533.rs:40:14
@@ -45,12 +33,6 @@ LL |         drop(a);
    |              ^ move out of `a` occurs here
 LL |         drop(x);
    |              - borrow later used here
-   |
-help: consider cloning the value if the performance cost is acceptable
-   |
-LL -         let x = baz(&a);
-LL +         let x = baz(a.clone());
-   |
 
 error: aborting due to 3 previous errors