add test case

Author: nikomatsakis

src/test/ui/rust-2018/try-macro.fixed

@@ -0,0 +1,16 @@
+// Test that `try!` macros are rewritten.
+
+// run-rustfix
+// compile-pass
+
+#![warn(rust_2018_compatibility)]
+#![allow(unused_variables)]
+#![allow(dead_code)]
+
+fn foo() -> Result<usize, ()> {
+    let x: Result<usize, ()> = Ok(22);
+    r#try!(x);
+    Ok(44)
+}
+
+fn main() { }

src/test/ui/rust-2018/try-macro.rs

@@ -0,0 +1,16 @@
+// Test that `try!` macros are rewritten.
+
+// run-rustfix
+// compile-pass
+
+#![warn(rust_2018_compatibility)]
+#![allow(unused_variables)]
+#![allow(dead_code)]
+
+fn foo() -> Result<usize, ()> {
+    let x: Result<usize, ()> = Ok(22);
+    try!(x);
+    Ok(44)
+}
+
+fn main() { }

src/test/ui/rust-2018/try-macro.stderr

@@ -0,0 +1,15 @@
+warning: `try` is a keyword in the 2018 edition
+  --> $DIR/try-macro.rs:12:5
+   |
+LL |     try!(x);
+   |     ^^^ help: you can use a raw identifier to stay compatible: `r#try`
+   |
+note: lint level defined here
+  --> $DIR/try-macro.rs:6:9
+   |
+LL | #![warn(rust_2018_compatibility)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^
+   = note: #[warn(keyword_idents)] implied by #[warn(rust_2018_compatibility)]
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+