Auto merge of #47544 - U007D:master, r=nikomatsakis

Relax termination_trait's error bound

As per [this conversation](https://github.com/withoutboats/failure/issues/130#issuecomment-358572413) with @withoutboats and @bkchr

Author: bors

src/libstd/termination.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use error::Error;
+use fmt::Debug;
 #[cfg(target_arch = "wasm32")]
 mod exit {
     pub const SUCCESS: i32 = 0;
@@ -45,27 +45,18 @@ impl Termination for () {
 }
 
 #[unstable(feature = "termination_trait", issue = "43301")]
-impl<T: Termination, E: Error> Termination for Result<T, E> {
+impl<T: Termination, E: Debug> Termination for Result<T, E> {
     fn report(self) -> i32 {
         match self {
             Ok(val) => val.report(),
             Err(err) => {
-                print_error(err);
+                eprintln!("Error: {:?}", err);
                 exit::FAILURE
             }
         }
     }
 }
 
-#[unstable(feature = "termination_trait", issue = "43301")]
-fn print_error<E: Error>(err: E) {
-    eprintln!("Error: {}", err.description());
-
-    if let Some(ref err) = err.cause() {
-        eprintln!("Caused by: {}", err.description());
-    }
-}
-
 #[unstable(feature = "termination_trait", issue = "43301")]
 impl Termination for ! {
     fn report(self) -> i32 { unreachable!(); }

src/test/compile-fail/main-wrong-type-2.rs renamed to src/test/compile-fail/rfc-1937-termination-trait/termination-trait-main-wrong-type.rs

@@ -0,0 +1,20 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// must-compile-successfully
+// failure-status: 1
+
+#![feature(termination_trait)]
+
+use std::io::{Error, ErrorKind};
+
+fn main() -> Result<(), Box<Error>> {
+    Err(Box::new(Error::new(ErrorKind::Other, "returned Box<Error> from main()")))
+}

src/test/compile-fail/termination-trait-not-satisfied.rs renamed to src/test/compile-fail/rfc-1937-termination-trait/termination-trait-not-satisfied.rs

@@ -0,0 +1,17 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(termination_trait)]
+
+use std::io::Error;
+
+fn main() -> Result<(), Box<Error>> {
+    Ok(())
+}

src/test/run-fail/rfc-1937-termination-trait/termination-trait-for-result-box-error_err.rs

@@ -0,0 +1,17 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(termination_trait)]
+
+use std::io::Error;
+
+fn main() -> Result<(), Box<Error>> {
+    Ok(())
+}

src/test/run-pass/termination-trait-for-empty.rs renamed to src/test/run-pass/rfc-1937-termination-trait/termination-trait-for-empty.rs

@@ -232,6 +232,7 @@ pub struct TestProps {
     // customized normalization rules
     pub normalize_stdout: Vec<(String, String)>,
     pub normalize_stderr: Vec<(String, String)>,
+    pub failure_status: i32,
 }
 
 impl TestProps {
@@ -260,6 +261,7 @@ impl TestProps {
             run_pass: false,
             normalize_stdout: vec![],
             normalize_stderr: vec![],
+            failure_status: 101,
         }
     }
 
@@ -383,6 +385,10 @@ impl TestProps {
             if let Some(rule) = config.parse_custom_normalization(ln, "normalize-stderr") {
                 self.normalize_stderr.push(rule);
             }
+
+            if let Some(code) = config.parse_failure_status(ln) {
+                self.failure_status = code;
+            }
         });
 
         for key in &["RUST_TEST_NOCAPTURE", "RUST_TEST_THREADS"] {
@@ -488,6 +494,13 @@ impl Config {
         self.parse_name_directive(line, "pretty-compare-only")
     }
 
+    fn parse_failure_status(&self, line: &str) -> Option<i32> {
+        match self.parse_name_value_directive(line, "failure-status") {
+            Some(code) => code.trim().parse::<i32>().ok(),
+            _ => None,
+        }
+    }
+
     fn parse_must_compile_successfully(&self, line: &str) -> bool {
         self.parse_name_directive(line, "must-compile-successfully")
     }