Stabilize str::escape_* methods

FCP: https://github.com/rust-lang/rust/issues/27791#issuecomment-376864727

src/liballoc/str.rs

@@ -452,9 +452,7 @@ impl str {
     /// escaped.
     ///
     /// [`char::escape_debug`]: primitive.char.html#method.escape_debug
-    #[unstable(feature = "str_escape",
-               reason = "return type may change to be an iterator",
-               issue = "27791")]
+    #[stable(feature = "str_escape", since = "1.34.0")]
     pub fn escape_debug(&self) -> EscapeDebug {
         let mut chars = self.chars();
         EscapeDebug {
@@ -469,9 +467,7 @@ impl str {
     /// Escapes each char in `s` with [`char::escape_default`].
     ///
     /// [`char::escape_default`]: primitive.char.html#method.escape_default
-    #[unstable(feature = "str_escape",
-               reason = "return type may change to be an iterator",
-               issue = "27791")]
+    #[stable(feature = "str_escape", since = "1.34.0")]
     pub fn escape_default(&self) -> EscapeDefault {
         EscapeDefault { inner: self.chars().flat_map(CharEscapeDefault) }
     }
@@ -479,9 +475,7 @@ impl str {
     /// Escapes each char in `s` with [`char::escape_unicode`].
     ///
     /// [`char::escape_unicode`]: primitive.char.html#method.escape_unicode
-    #[unstable(feature = "str_escape",
-               reason = "return type may change to be an iterator",
-               issue = "27791")]
+    #[stable(feature = "str_escape", since = "1.34.0")]
     pub fn escape_unicode(&self) -> EscapeUnicode {
         EscapeUnicode { inner: self.chars().flat_map(CharEscapeUnicode) }
     }
@@ -639,20 +633,20 @@ macro_rules! escape_types {
             inner: $Inner: ty,
         }
     )+) => {$(
-        #[unstable(feature = "str_escape", issue = "27791")]
+        #[stable(feature = "str_escape", since = "1.34.0")]
         #[derive(Clone, Debug)]
         pub struct $Name<'a> {
             inner: $Inner,
         }
 
-        #[unstable(feature = "str_escape", issue = "27791")]
+        #[stable(feature = "str_escape", since = "1.34.0")]
         impl<'a> fmt::Display for $Name<'a> {
             fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                 self.clone().try_for_each(|c| f.write_char(c))
             }
         }
 
-        #[unstable(feature = "str_escape", issue = "27791")]
+        #[stable(feature = "str_escape", since = "1.34.0")]
         impl<'a> Iterator for $Name<'a> {
             type Item = char;
 
@@ -677,7 +671,7 @@ macro_rules! escape_types {
             }
         }
 
-        #[unstable(feature = "str_escape", issue = "27791")]
+        #[stable(feature = "str_escape", since = "1.34.0")]
         impl<'a> FusedIterator for $Name<'a> {}
     )+}
 }

src/liballoc/tests/lib.rs

@@ -5,7 +5,6 @@
 #![feature(pattern)]
 #![feature(repeat_generic_slice)]
 #![feature(slice_sort_by_cached_key)]
-#![feature(str_escape)]
 #![feature(try_reserve)]
 #![feature(unboxed_closures)]
 #![feature(vecdeque_rotate)]

src/libgraphviz/lib.rs

@@ -277,7 +277,6 @@
 #![deny(rust_2018_idioms)]
 
 #![feature(nll)]
-#![feature(str_escape)]
 
 use LabelText::*;
 

src/libsyntax/lib.rs

@@ -15,7 +15,6 @@
 #![feature(rustc_attrs)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(slice_sort_by_cached_key)]
-#![feature(str_escape)]
 #![feature(step_trait)]
 #![feature(try_trait)]
 #![feature(unicode_internals)]

src/libsyntax_ext/lib.rs

@@ -10,7 +10,6 @@
 #![feature(proc_macro_span)]
 #![feature(decl_macro)]
 #![feature(nll)]
-#![feature(str_escape)]
 #![feature(rustc_diagnostic_macros)]
 
 #![recursion_limit="256"]

src/test/run-pass/threads-sendsync/sync-send-iterators-in-libcore.rs

@@ -2,9 +2,6 @@
 // pretty-expanded FIXME #23616
 
 #![allow(warnings)]
-#![feature(iter_empty)]
-#![feature(iter_once)]
-#![feature(str_escape)]
 
 use std::iter::{empty, once, repeat};