std: Changing the meaning of the count to splitn

This commit is an implementation of [RFC 979][rfc] which changes the meaning of
the count parameter to the `splitn` function on strings and slices. The
parameter now means the number of items that are returned from the iterator, not
the number of splits that are made.

[rfc]: https://github.com/rust-lang/rfcs/pull/979

Closes #23911
[breaking-change]

3 files changed, 3 insertions, 3 deletions

diff --git a/src/libstd/net/addr.rs b/src/libstd/net/addr.rs
index c45230e91ba..886f252fb19 100644
--- a/src/libstd/net/addr.rs
+++ b/src/libstd/net/addr.rs
@@ -441,7 +441,7 @@ impl ToSocketAddrs for str {
         }
 
         // split the string by ':' and convert the second part to u16
-        let mut parts_iter = self.rsplitn(1, ':');
+        let mut parts_iter = self.rsplitn(2, ':');
         let port_str = try_opt!(parts_iter.next(), "invalid socket address");
         let host = try_opt!(parts_iter.next(), "invalid socket address");
         let port: u16 = try_opt!(port_str.parse().ok(), "invalid port value");
diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index 9006ed33654..ee4b572335b 100644
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -406,7 +406,7 @@ fn split_file_at_dot(file: &OsStr) -> (Option<&OsStr>, Option<&OsStr>) {
         // contents of the encoding and (2) new &OsStr values are produced
         // only from ASCII-bounded slices of existing &OsStr values.
 
-        let mut iter = os_str_as_u8_slice(file).rsplitn(1, |b| *b == b'.');
+        let mut iter = os_str_as_u8_slice(file).rsplitn(2, |b| *b == b'.');
         let after = iter.next();
         let before = iter.next();
         if before == Some(b"") {
diff --git a/src/libstd/sys/unix/os.rs b/src/libstd/sys/unix/os.rs
index 7b13e951b9b..d2220bdec32 100644
--- a/src/libstd/sys/unix/os.rs
+++ b/src/libstd/sys/unix/os.rs
@@ -409,7 +409,7 @@ pub fn env() -> Env {
     };
 
     fn parse(input: &[u8]) -> (OsString, OsString) {
-        let mut it = input.splitn(1, |b| *b == b'=');
+        let mut it = input.splitn(2, |b| *b == b'=');
         let key = it.next().unwrap().to_vec();
         let default: &[u8] = &[];
         let val = it.next().unwrap_or(default).to_vec();