Auto merge of #41588 - cengizIO:master, r=nikomatsakis

use diff crate for compile-fail test diagnostics #41474

Hello!

This fixes #41474

We were using a custom implementation to dump the differences between expected and actual outputs of compile-fail tests.

I removed this internal implementation and added `diff` crate as a new dependency to `compile-fail`.

Again, huge thanks to @nikomatsakis for guiding.

Author: bors

src/Cargo.lock

@@ -8,3 +8,4 @@ log = "0.3"
 env_logger = { version = "0.4", default-features = false }
 rustc-serialize = "0.3"
 filetime = "0.1"
+diff = "0.1.10"

src/tools/compiletest/Cargo.toml

@@ -25,6 +25,7 @@ extern crate rustc_serialize;
 extern crate log;
 extern crate env_logger;
 extern crate filetime;
+extern crate diff;
 
 use std::env;
 use std::ffi::OsString;
@@ -49,7 +50,6 @@ pub mod runtest;
 pub mod common;
 pub mod errors;
 mod raise_fd_limit;
-mod uidiff;
 
 fn main() {
     env_logger::init().unwrap();

src/tools/compiletest/src/main.rs

@@ -12,13 +12,13 @@ use common::Config;
 use common::{CompileFail, ParseFail, Pretty, RunFail, RunPass, RunPassValgrind};
 use common::{Codegen, DebugInfoLldb, DebugInfoGdb, Rustdoc, CodegenUnits};
 use common::{Incremental, RunMake, Ui, MirOpt};
+use diff;
 use errors::{self, ErrorKind, Error};
 use filetime::FileTime;
 use json;
 use header::TestProps;
 use procsrv;
 use test::TestPaths;
-use uidiff;
 use util::logv;
 
 use std::collections::HashSet;
@@ -2411,8 +2411,13 @@ actual:\n\
         println!("normalized {}:\n{}\n", kind, actual);
         println!("expected {}:\n{}\n", kind, expected);
         println!("diff of {}:\n", kind);
-        for line in uidiff::diff_lines(actual, expected) {
-            println!("{}", line);
+
+        for diff in diff::lines(actual, expected) {
+            match diff {
+                diff::Result::Left(l)    => println!("+{}", l),
+                diff::Result::Both(l, _) => println!(" {}", l),
+                diff::Result::Right(r)   => println!("-{}", r),
+            }
         }
 
         let output_file = self.output_base_name().with_extension(kind);