std: Rename Show/String to Debug/Display

This commit is an implementation of [RFC 565][rfc] which is a stabilization of
the `std::fmt` module and the implementations of various formatting traits.
Specifically, the following changes were performed:

[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0565-show-string-guidelines.md

* The `Show` trait is now deprecated, it was renamed to `Debug`
* The `String` trait is now deprecated, it was renamed to `Display`
* Many `Debug` and `Display` implementations were audited in accordance with the
  RFC and audited implementations now have the `#[stable]` attribute
  * Integers and floats no longer print a suffix
  * Smart pointers no longer print details that they are a smart pointer
  * Paths with `Debug` are now quoted and escape characters
* The `unwrap` methods on `Result` now require `Display` instead of `Debug`
* The `Error` trait no longer has a `detail` method and now requires that
  `Display` must be implemented. With the loss of `String`, this has moved into
  libcore.
* `impl<E: Error> FromError<E> for Box<Error>` now exists
* `derive(Show)` has been renamed to `derive(Debug)`. This is not currently
  warned about due to warnings being emitted on stage1+

While backwards compatibility is attempted to be maintained with a blanket
implementation of `Display` for the old `String` trait (and the same for
`Show`/`Debug`) this is still a breaking change due to primitives no longer
implementing `String` as well as modifications such as `unwrap` and the `Error`
trait. Most code is fairly straightforward to update with a rename or tweaks of
method calls.

[breaking-change]
Closes #21436

2 files changed, 6 insertions, 12 deletions

diff --git a/src/compiletest/common.rs b/src/compiletest/common.rs
index c29f74d7418..8de8d9ce741 100644
--- a/src/compiletest/common.rs
+++ b/src/compiletest/common.rs
@@ -13,7 +13,7 @@ use std::fmt;
 use std::str::FromStr;
 use regex::Regex;
 
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, Debug)]
 pub enum Mode {
     CompileFail,
     RunFail,
@@ -43,9 +43,9 @@ impl FromStr for Mode {
     }
 }
 
-impl fmt::String for Mode {
+impl fmt::Display for Mode {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(match *self {
+        fmt::Display::fmt(match *self {
             CompileFail => "compile-fail",
             RunFail => "run-fail",
             RunPass => "run-pass",
@@ -58,12 +58,6 @@ impl fmt::String for Mode {
     }
 }
 
-impl fmt::Show for Mode {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(self, f)
-    }
-}
-
 #[derive(Clone)]
 pub struct Config {
     // The library paths required for running the compiler
diff --git a/src/compiletest/runtest.rs b/src/compiletest/runtest.rs
index 5579479c5e5..d9debb88a5c 100644
--- a/src/compiletest/runtest.rs
+++ b/src/compiletest/runtest.rs
@@ -547,7 +547,7 @@ fn run_debuginfo_gdb_test(config: &Config, props: &TestProps, testfile: &Path) {
 
             // Add line breakpoints
             for line in breakpoint_lines.iter() {
-                script_str.push_str(&format!("break '{:?}':{}\n",
+                script_str.push_str(&format!("break '{}':{}\n",
                                              testfile.filename_display(),
                                              *line)[]);
             }
@@ -750,7 +750,7 @@ fn run_debuginfo_lldb_test(config: &Config, props: &TestProps, testfile: &Path)
             status: status,
             stdout: out,
             stderr: err,
-            cmdline: format!("{}", cmd)
+            cmdline: format!("{:?}", cmd)
         };
     }
 }
@@ -953,7 +953,7 @@ fn check_expected_errors(expected_errors: Vec<errors::ExpectedError> ,
     }
 
     let prefixes = expected_errors.iter().map(|ee| {
-        format!("{:?}:{}:", testfile.display(), ee.line)
+        format!("{}:{}:", testfile.display(), ee.line)
     }).collect::<Vec<String> >();
 
     #[cfg(windows)]