Use question_mark feature in librustc.

src/librustc/hir/print.rs

@@ -1756,9 +1756,9 @@ pub fn print_pat(&mut self, pat: &hir::Pat) -> io::Result<()> {
                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p))?;
                     }
                 } else {
-                    try!(self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p)));
+                    self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p))?;
                 }
-                try!(self.pclose());
+                self.pclose()?;
             }
             PatKind::Path(None, ref path) => {
                 self.print_path(path, true, 0)?;

src/librustc/infer/higher_ranked/mod.rs

@@ -130,7 +130,7 @@ pub fn higher_ranked_match<T, U>(&mut self,
             debug!("higher_ranked_match: skol_map={:?}", skol_map);
 
             // Equate types now that bound regions have been replaced.
-            try!(self.equate(a_is_expected).relate(&a_match, &b_match));
+            self.equate(a_is_expected).relate(&a_match, &b_match)?;
 
             // Map each skolemized region to a vector of other regions that it
             // must be equated with. (Note that this vector may include other

src/librustc/util/fs.rs

@@ -68,7 +68,7 @@ pub fn link_or_copy<P: AsRef<Path>, Q: AsRef<Path>>(p: P, q: Q) -> io::Result<Li
     let p = p.as_ref();
     let q = q.as_ref();
     if q.exists() {
-        try!(fs::remove_file(&q));
+        fs::remove_file(&q)?;
     }
 
     match fs::hard_link(p, q) {