Auto merge of #25006 - alexcrichton:unstable-indexing, r=aturon

These implementations were intended to be unstable, but currently the stability
attributes cannot handle a stable trait with an unstable `impl` block. This
commit also audits the rest of the standard library for explicitly-`#[unstable]`
impl blocks. No others were removed but some annotations were changed to
`#[stable]` as they're defacto stable anyway.

One particularly interesting `impl` marked `#[stable]` as part of this commit
is the `Add<&[T]>` impl for `Vec<T>`, which uses `push_all` and implicitly
clones all elements of the vector provided.

Closes #24791

[breaking-change]

3 files changed, 5 insertions, 6 deletions

diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index 9ba90c470f8..ec130e8233a 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -1605,8 +1605,7 @@ impl HashState for RandomState {
     }
 }
 
-#[unstable(feature = "std_misc",
-           reason = "hashing an hash maps may be altered")]
+#[stable(feature = "rust1", since = "1.0.0")]
 impl Default for RandomState {
     #[inline]
     fn default() -> RandomState {
diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index 897ac673182..6f3649c8320 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -119,7 +119,7 @@ impl<R> fmt::Debug for BufReader<R> where R: fmt::Debug {
     }
 }
 
-#[unstable(feature = "buf_seek", reason = "recently added")]
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<R: Seek> Seek for BufReader<R> {
     /// Seek to an offset, in bytes, in the underlying reader.
     ///
@@ -283,8 +283,8 @@ impl<W: Write> fmt::Debug for BufWriter<W> where W: fmt::Debug {
     }
 }
 
-#[unstable(feature = "buf_seek", reason = "recently added")]
-impl<W: Write+Seek> Seek for BufWriter<W> {
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<W: Write + Seek> Seek for BufWriter<W> {
     /// Seek to the offset, in bytes, in the underlying writer.
     ///
     /// Seeking always writes out the internal buffer before seeking.
diff --git a/src/libstd/net/parser.rs b/src/libstd/net/parser.rs
index 7c1667a603f..88cfc5a7b2d 100644
--- a/src/libstd/net/parser.rs
+++ b/src/libstd/net/parser.rs
@@ -291,7 +291,7 @@ impl<'a> Parser<'a> {
     }
 }
 
-#[unstable(feature = "ip_addr", reason = "recent addition")]
+#[stable(feature = "rust1", since = "1.0.0")]
 impl FromStr for IpAddr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<IpAddr, AddrParseError> {