Add regression test

Author: estebank

src/test/ui/suggestions/import-trait-for-method-call.rs

@@ -0,0 +1,9 @@
+use std::hash::BuildHasher;
+
+fn next_u64() -> u64 {
+    let bh = std::collections::hash_map::RandomState::new();
+    let h = bh.build_hasher();
+    h.finish() //~ ERROR no method named `finish` found for struct `DefaultHasher`
+}
+
+fn main() {}

src/test/ui/suggestions/import-trait-for-method-call.stderr

@@ -0,0 +1,26 @@
+error[E0599]: no method named `finish` found for struct `DefaultHasher` in the current scope
+  --> $DIR/import-trait-for-method-call.rs:6:7
+   |
+LL |     h.finish()
+   |       ^^^^^^ method not found in `DefaultHasher`
+   | 
+  ::: $SRC_DIR/core/src/hash/mod.rs:LL:COL
+   |
+LL |     fn finish(&self) -> u64;
+   |        ------
+   |        |
+   |        the method is available for `Box<DefaultHasher>` here
+   |        the method is available for `Box<&mut DefaultHasher>` here
+   |
+help: consider wrapping the receiver expression with the appropriate type
+   |
+LL |     Box::new(h).finish()
+   |     ^^^^^^^^^ ^
+help: consider wrapping the receiver expression with the appropriate type
+   |
+LL |     Box::new(&mut h).finish()
+   |     ^^^^^^^^^^^^^  ^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.