Auto merge of #58051 - SimonSapin:str_escape, r=alexcrichton

Stabilize str::escape_* methods with new return types…

… that implement `Display` and `Iterator<Item=char>`, as proposed in FCP: https://github.com/rust-lang/rust/issues/27791#issuecomment-376864727

4 files changed, 34 insertions, 73 deletions

diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 189ba84eeed..d4ee428a3b5 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -68,7 +68,6 @@
 #![warn(intra_doc_link_resolution_failure)]
 #![warn(missing_debug_implementations)]
 
-#![cfg_attr(not(test), feature(fn_traits))]
 #![cfg_attr(not(test), feature(generator_trait))]
 #![cfg_attr(test, feature(test))]
 
@@ -86,6 +85,7 @@
 #![feature(dropck_eyepatch)]
 #![feature(exact_size_is_empty)]
 #![feature(fmt_internals)]
+#![feature(fn_traits)]
 #![feature(fundamental)]
 #![feature(futures_api)]
 #![feature(lang_items)]
@@ -100,6 +100,7 @@
 #![feature(receiver_trait)]
 #![feature(specialization)]
 #![feature(staged_api)]
+#![feature(std_internals)]
 #![feature(str_internals)]
 #![feature(trusted_len)]
 #![feature(try_reserve)]
diff --git a/src/liballoc/str.rs b/src/liballoc/str.rs
index 1fd4c9978a6..a36804bddff 100644
--- a/src/liballoc/str.rs
+++ b/src/liballoc/str.rs
@@ -29,8 +29,6 @@
 #![allow(unused_imports)]
 
 use core::borrow::Borrow;
-use core::fmt;
-use core::str as core_str;
 use core::str::pattern::{Pattern, Searcher, ReverseSearcher, DoubleEndedSearcher};
 use core::mem;
 use core::ptr;
@@ -443,45 +441,6 @@ impl str {
         return s;
     }
 
-    /// Escapes each char in `s` with [`char::escape_debug`].
-    ///
-    /// Note: only extended grapheme codepoints that begin the string will be
-    /// 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")]
-    pub fn escape_debug(&self) -> String {
-        let mut string = String::with_capacity(self.len());
-        let mut chars = self.chars();
-        if let Some(first) = chars.next() {
-            string.extend(first.escape_debug_ext(true))
-        }
-        string.extend(chars.flat_map(|c| c.escape_debug_ext(false)));
-        string
-    }
-
-    /// 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")]
-    pub fn escape_default(&self) -> String {
-        self.chars().flat_map(|c| c.escape_default()).collect()
-    }
-
-    /// 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")]
-    pub fn escape_unicode(&self) -> String {
-        self.chars().flat_map(|c| c.escape_unicode()).collect()
-    }
-
     /// Converts a [`Box<str>`] into a [`String`] without copying or allocating.
     ///
     /// [`String`]: string/struct.String.html
@@ -612,3 +571,4 @@ impl str {
 pub unsafe fn from_boxed_utf8_unchecked(v: Box<[u8]>) -> Box<str> {
     Box::from_raw(Box::into_raw(v) as *mut str)
 }
+
diff --git a/src/liballoc/tests/lib.rs b/src/liballoc/tests/lib.rs
index a76fd87a1a9..2b63ac5c7d2 100644
--- a/src/liballoc/tests/lib.rs
+++ b/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)]
diff --git a/src/liballoc/tests/str.rs b/src/liballoc/tests/str.rs
index f4e6bc9ea31..a1dc763f6d8 100644
--- a/src/liballoc/tests/str.rs
+++ b/src/liballoc/tests/str.rs
@@ -990,15 +990,15 @@ fn test_split_at_boundscheck() {
 
 #[test]
 fn test_escape_unicode() {
-    assert_eq!("abc".escape_unicode(), "\\u{61}\\u{62}\\u{63}");
-    assert_eq!("a c".escape_unicode(), "\\u{61}\\u{20}\\u{63}");
-    assert_eq!("\r\n\t".escape_unicode(), "\\u{d}\\u{a}\\u{9}");
-    assert_eq!("'\"\\".escape_unicode(), "\\u{27}\\u{22}\\u{5c}");
-    assert_eq!("\x00\x01\u{fe}\u{ff}".escape_unicode(), "\\u{0}\\u{1}\\u{fe}\\u{ff}");
-    assert_eq!("\u{100}\u{ffff}".escape_unicode(), "\\u{100}\\u{ffff}");
-    assert_eq!("\u{10000}\u{10ffff}".escape_unicode(), "\\u{10000}\\u{10ffff}");
-    assert_eq!("ab\u{fb00}".escape_unicode(), "\\u{61}\\u{62}\\u{fb00}");
-    assert_eq!("\u{1d4ea}\r".escape_unicode(), "\\u{1d4ea}\\u{d}");
+    assert_eq!("abc".escape_unicode().to_string(), "\\u{61}\\u{62}\\u{63}");
+    assert_eq!("a c".escape_unicode().to_string(), "\\u{61}\\u{20}\\u{63}");
+    assert_eq!("\r\n\t".escape_unicode().to_string(), "\\u{d}\\u{a}\\u{9}");
+    assert_eq!("'\"\\".escape_unicode().to_string(), "\\u{27}\\u{22}\\u{5c}");
+    assert_eq!("\x00\x01\u{fe}\u{ff}".escape_unicode().to_string(), "\\u{0}\\u{1}\\u{fe}\\u{ff}");
+    assert_eq!("\u{100}\u{ffff}".escape_unicode().to_string(), "\\u{100}\\u{ffff}");
+    assert_eq!("\u{10000}\u{10ffff}".escape_unicode().to_string(), "\\u{10000}\\u{10ffff}");
+    assert_eq!("ab\u{fb00}".escape_unicode().to_string(), "\\u{61}\\u{62}\\u{fb00}");
+    assert_eq!("\u{1d4ea}\r".escape_unicode().to_string(), "\\u{1d4ea}\\u{d}");
 }
 
 #[test]
@@ -1009,31 +1009,32 @@ fn test_escape_debug() {
     // they are escaped. However, when the character is unescaped (e.g., for
     // printable characters), only a single backslash appears (as the character
     // itself appears in the debug string).
-    assert_eq!("abc".escape_debug(), "abc");
-    assert_eq!("a c".escape_debug(), "a c");
-    assert_eq!("éèê".escape_debug(), "éèê");
-    assert_eq!("\r\n\t".escape_debug(), "\\r\\n\\t");
-    assert_eq!("'\"\\".escape_debug(), "\\'\\\"\\\\");
-    assert_eq!("\u{7f}\u{ff}".escape_debug(), "\\u{7f}\u{ff}");
-    assert_eq!("\u{100}\u{ffff}".escape_debug(), "\u{100}\\u{ffff}");
-    assert_eq!("\u{10000}\u{10ffff}".escape_debug(), "\u{10000}\\u{10ffff}");
-    assert_eq!("ab\u{200b}".escape_debug(), "ab\\u{200b}");
-    assert_eq!("\u{10d4ea}\r".escape_debug(), "\\u{10d4ea}\\r");
-    assert_eq!("\u{301}a\u{301}bé\u{e000}".escape_debug(), "\\u{301}a\u{301}bé\\u{e000}");
+    assert_eq!("abc".escape_debug().to_string(), "abc");
+    assert_eq!("a c".escape_debug().to_string(), "a c");
+    assert_eq!("éèê".escape_debug().to_string(), "éèê");
+    assert_eq!("\r\n\t".escape_debug().to_string(), "\\r\\n\\t");
+    assert_eq!("'\"\\".escape_debug().to_string(), "\\'\\\"\\\\");
+    assert_eq!("\u{7f}\u{ff}".escape_debug().to_string(), "\\u{7f}\u{ff}");
+    assert_eq!("\u{100}\u{ffff}".escape_debug().to_string(), "\u{100}\\u{ffff}");
+    assert_eq!("\u{10000}\u{10ffff}".escape_debug().to_string(), "\u{10000}\\u{10ffff}");
+    assert_eq!("ab\u{200b}".escape_debug().to_string(), "ab\\u{200b}");
+    assert_eq!("\u{10d4ea}\r".escape_debug().to_string(), "\\u{10d4ea}\\r");
+    assert_eq!("\u{301}a\u{301}bé\u{e000}".escape_debug().to_string(),
+               "\\u{301}a\u{301}bé\\u{e000}");
 }
 
 #[test]
 fn test_escape_default() {
-    assert_eq!("abc".escape_default(), "abc");
-    assert_eq!("a c".escape_default(), "a c");
-    assert_eq!("éèê".escape_default(), "\\u{e9}\\u{e8}\\u{ea}");
-    assert_eq!("\r\n\t".escape_default(), "\\r\\n\\t");
-    assert_eq!("'\"\\".escape_default(), "\\'\\\"\\\\");
-    assert_eq!("\u{7f}\u{ff}".escape_default(), "\\u{7f}\\u{ff}");
-    assert_eq!("\u{100}\u{ffff}".escape_default(), "\\u{100}\\u{ffff}");
-    assert_eq!("\u{10000}\u{10ffff}".escape_default(), "\\u{10000}\\u{10ffff}");
-    assert_eq!("ab\u{200b}".escape_default(), "ab\\u{200b}");
-    assert_eq!("\u{10d4ea}\r".escape_default(), "\\u{10d4ea}\\r");
+    assert_eq!("abc".escape_default().to_string(), "abc");
+    assert_eq!("a c".escape_default().to_string(), "a c");
+    assert_eq!("éèê".escape_default().to_string(), "\\u{e9}\\u{e8}\\u{ea}");
+    assert_eq!("\r\n\t".escape_default().to_string(), "\\r\\n\\t");
+    assert_eq!("'\"\\".escape_default().to_string(), "\\'\\\"\\\\");
+    assert_eq!("\u{7f}\u{ff}".escape_default().to_string(), "\\u{7f}\\u{ff}");
+    assert_eq!("\u{100}\u{ffff}".escape_default().to_string(), "\\u{100}\\u{ffff}");
+    assert_eq!("\u{10000}\u{10ffff}".escape_default().to_string(), "\\u{10000}\\u{10ffff}");
+    assert_eq!("ab\u{200b}".escape_default().to_string(), "ab\\u{200b}");
+    assert_eq!("\u{10d4ea}\r".escape_default().to_string(), "\\u{10d4ea}\\r");
 }
 
 #[test]