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

4 files changed, 10 insertions, 10 deletions

diff --git a/src/librustc_trans/back/link.rs b/src/librustc_trans/back/link.rs
index dacf620cbd1..a46dc7b33f7 100644
--- a/src/librustc_trans/back/link.rs
+++ b/src/librustc_trans/back/link.rs
@@ -779,14 +779,14 @@ fn link_natively(sess: &Session, trans: &CrateTranslation, dylib: bool,
     }
 
     if sess.opts.debugging_opts.print_link_args {
-        println!("{}", &cmd);
+        println!("{:?}", &cmd);
     }
 
     // May have not found libraries in the right formats.
     sess.abort_if_errors();
 
     // Invoke the system linker
-    debug!("{}", &cmd);
+    debug!("{:?}", &cmd);
     let prog = time(sess.time_passes(), "running linker", (), |()| cmd.output());
     match prog {
         Ok(prog) => {
@@ -794,7 +794,7 @@ fn link_natively(sess: &Session, trans: &CrateTranslation, dylib: bool,
                 sess.err(&format!("linking with `{}` failed: {}",
                                  pname,
                                  prog.status)[]);
-                sess.note(&format!("{}", &cmd)[]);
+                sess.note(&format!("{:?}", &cmd)[]);
                 let mut output = prog.error.clone();
                 output.push_all(&prog.output[]);
                 sess.note(str::from_utf8(&output[]).unwrap());
diff --git a/src/librustc_trans/back/write.rs b/src/librustc_trans/back/write.rs
index aa51b0c5ee2..0ade5aaab3d 100644
--- a/src/librustc_trans/back/write.rs
+++ b/src/librustc_trans/back/write.rs
@@ -716,7 +716,7 @@ pub fn run_passes(sess: &Session,
         cmd.args(&sess.target.target.options.post_link_args[]);
 
         if sess.opts.debugging_opts.print_link_args {
-            println!("{}", &cmd);
+            println!("{:?}", &cmd);
         }
 
         cmd.stdin(::std::io::process::Ignored)
@@ -725,7 +725,7 @@ pub fn run_passes(sess: &Session,
         match cmd.status() {
             Ok(status) => {
                 if !status.success() {
-                    sess.err(&format!("linking of {} with `{}` failed",
+                    sess.err(&format!("linking of {} with `{:?}` failed",
                                      output_path.display(), cmd)[]);
                     sess.abort_if_errors();
                 }
@@ -953,7 +953,7 @@ pub fn run_assembler(sess: &Session, outputs: &OutputFilenames) {
 
     cmd.arg("-c").arg("-o").arg(outputs.path(config::OutputTypeObject))
                            .arg(outputs.temp_path(config::OutputTypeAssembly));
-    debug!("{}", &cmd);
+    debug!("{:?}", &cmd);
 
     match cmd.output() {
         Ok(prog) => {
@@ -961,7 +961,7 @@ pub fn run_assembler(sess: &Session, outputs: &OutputFilenames) {
                 sess.err(&format!("linking with `{}` failed: {}",
                                  pname,
                                  prog.status)[]);
-                sess.note(&format!("{}", &cmd)[]);
+                sess.note(&format!("{:?}", &cmd)[]);
                 let mut note = prog.error.clone();
                 note.push_all(&prog.output[]);
                 sess.note(str::from_utf8(&note[]).unwrap());
diff --git a/src/librustc_trans/trans/cleanup.rs b/src/librustc_trans/trans/cleanup.rs
index 5658889aaf3..de2a69226bd 100644
--- a/src/librustc_trans/trans/cleanup.rs
+++ b/src/librustc_trans/trans/cleanup.rs
@@ -65,7 +65,7 @@ pub enum CleanupScopeKind<'blk, 'tcx: 'blk> {
     LoopScopeKind(ast::NodeId, [Block<'blk, 'tcx>; EXIT_MAX])
 }
 
-impl<'blk, 'tcx: 'blk> fmt::Show for CleanupScopeKind<'blk, 'tcx> {
+impl<'blk, 'tcx: 'blk> fmt::Debug for CleanupScopeKind<'blk, 'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             CustomScopeKind => write!(f, "CustomScopeKind"),
diff --git a/src/librustc_trans/trans/datum.rs b/src/librustc_trans/trans/datum.rs
index 8b52732f4ee..cba12babb9b 100644
--- a/src/librustc_trans/trans/datum.rs
+++ b/src/librustc_trans/trans/datum.rs
@@ -481,7 +481,7 @@ impl<'tcx> Datum<'tcx, Lvalue> {
 }
 
 /// Generic methods applicable to any sort of datum.
-impl<'tcx, K: KindOps + fmt::Show> Datum<'tcx, K> {
+impl<'tcx, K: KindOps + fmt::Debug> Datum<'tcx, K> {
     pub fn new(val: ValueRef, ty: Ty<'tcx>, kind: K) -> Datum<'tcx, K> {
         Datum { val: val, ty: ty, kind: kind }
     }
@@ -591,7 +591,7 @@ impl<'blk, 'tcx, K> DatumBlock<'blk, 'tcx, K> {
     }
 }
 
-impl<'blk, 'tcx, K: KindOps + fmt::Show> DatumBlock<'blk, 'tcx, K> {
+impl<'blk, 'tcx, K: KindOps + fmt::Debug> DatumBlock<'blk, 'tcx, K> {
     pub fn to_expr_datumblock(self) -> DatumBlock<'blk, 'tcx, Expr> {
         DatumBlock::new(self.bcx, self.datum.to_expr_datum())
     }