When suggesting to borrow, remove useless clones

Author: estebank

src/librustc_typeck/check/demand.rs

@@ -425,6 +425,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                 }
                             }
                         }
+                        // If this expression had a clone call, when suggesting borrowing, we
+                        // want to suggest removing it
+                        let sugg_expr = sugg_expr.trim_end_matches(".clone()");
                         return Some(match mutability {
                             hir::Mutability::MutMutable => (
                                 sp,

src/test/ui/issues/issue-61106.rs

@@ -0,0 +1,6 @@
+fn main() {
+    let x = String::new();
+    foo(x.clone()); //~ ERROR mismatched types
+}
+
+fn foo(_: &str) {}

src/test/ui/issues/issue-61106.stderr

@@ -0,0 +1,15 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-61106.rs:3:9
+   |
+LL |     foo(x.clone());
+   |         ^^^^^^^^^
+   |         |
+   |         expected &str, found struct `std::string::String`
+   |         help: consider borrowing here: `&x`
+   |
+   = note: expected type `&str`
+              found type `std::string::String`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.