1 files changed, 48 insertions, 0 deletions
diff --git a/src/test/ui/suggestions/mut-borrow-needed-by-trait.stderr b/src/test/ui/suggestions/mut-borrow-needed-by-trait.stderr
new file mode 100644
index 000000000..d121932c8
--- /dev/null
+++ b/src/test/ui/suggestions/mut-borrow-needed-by-trait.stderr
@@ -0,0 +1,48 @@
+error[E0277]: the trait bound `&dyn std::io::Write: std::io::Write` is not satisfied
+  --> $DIR/mut-borrow-needed-by-trait.rs:17:29
+   |
+LL |     let fp = BufWriter::new(fp);
+   |              -------------- ^^ the trait `std::io::Write` is not implemented for `&dyn std::io::Write`
+   |              |
+   |              required by a bound introduced by this call
+   |
+   = note: `std::io::Write` is implemented for `&mut dyn std::io::Write`, but not for `&dyn std::io::Write`
+note: required by a bound in `BufWriter::<W>::new`
+  --> $SRC_DIR/std/src/io/buffered/bufwriter.rs:LL:COL
+   |
+LL | impl<W: Write> BufWriter<W> {
+   |         ^^^^^ required by this bound in `BufWriter::<W>::new`
+
+error[E0277]: the trait bound `&dyn std::io::Write: std::io::Write` is not satisfied
+  --> $DIR/mut-borrow-needed-by-trait.rs:17:14
+   |
+LL |     let fp = BufWriter::new(fp);
+   |              ^^^^^^^^^^^^^^^^^^ the trait `std::io::Write` is not implemented for `&dyn std::io::Write`
+   |
+   = note: `std::io::Write` is implemented for `&mut dyn std::io::Write`, but not for `&dyn std::io::Write`
+note: required by a bound in `BufWriter`
+  --> $SRC_DIR/std/src/io/buffered/bufwriter.rs:LL:COL
+   |
+LL | pub struct BufWriter<W: Write> {
+   |                         ^^^^^ required by this bound in `BufWriter`
+
+error[E0599]: the method `write_fmt` exists for struct `BufWriter<&dyn std::io::Write>`, but its trait bounds were not satisfied
+  --> $DIR/mut-borrow-needed-by-trait.rs:21:5
+   |
+LL |     writeln!(fp, "hello world").unwrap();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ method cannot be called on `BufWriter<&dyn std::io::Write>` due to unsatisfied trait bounds
+   |
+  ::: $SRC_DIR/std/src/io/buffered/bufwriter.rs:LL:COL
+   |
+LL | pub struct BufWriter<W: Write> {
+   | ------------------------------ doesn't satisfy `BufWriter<&dyn std::io::Write>: std::io::Write`
+   |
+   = note: the following trait bounds were not satisfied:
+           `&dyn std::io::Write: std::io::Write`
+           which is required by `BufWriter<&dyn std::io::Write>: std::io::Write`
+   = note: this error originates in the macro `writeln` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0277, E0599.
+For more information about an error, try `rustc --explain E0277`.