getopts: format failure messages with `Show`.

This obsoletes the old `to_err_msg` method. Replace

    println!("Error: {}", failure.to_err_msg())

    let string = failure.to_err_msg();

with

    println!("Error: {}", failure)

    let string = failure.to_str();

[breaking-change]

1 files changed, 1 insertions, 1 deletions

diff --git a/src/compiletest/compiletest.rs b/src/compiletest/compiletest.rs
index 977b7dc32c5..1d7f36d0fe0 100644
--- a/src/compiletest/compiletest.rs
+++ b/src/compiletest/compiletest.rs
@@ -110,7 +110,7 @@ pub fn parse_config(args: Vec<String> ) -> Config {
     let matches =
         &match getopts::getopts(args_.as_slice(), groups.as_slice()) {
           Ok(m) => m,
-          Err(f) => fail!("{}", f.to_err_msg())
+          Err(f) => fail!("{}", f)
         };
 
     if matches.opt_present("h") || matches.opt_present("help") {