std: Remove `rand` crate and module

This commit removes the `rand` crate from the standard library facade as
well as the `__rand` module in the standard library. Neither of these
were used in any meaningful way in the standard library itself. The only
need for randomness in libstd is to initialize the thread-local keys of
a `HashMap`, and that unconditionally used `OsRng` defined in the
standard library anyway.

The cruft of the `rand` crate and the extra `rand` support in the
standard library makes libstd slightly more difficult to port to new
platforms, namely WebAssembly which doesn't have any randomness at all
(without interfacing with JS). The purpose of this commit is to clarify
and streamline randomness in libstd, focusing on how it's only required
in one location, hashmap seeds.

Note that the `rand` crate out of tree has almost always been a drop-in
replacement for the `rand` crate in-tree, so any usage (accidental or
purposeful) of the crate in-tree should switch to the `rand` crate on
crates.io. This then also has the further benefit of avoiding
duplication (mostly) between the two crates!

1 files changed, 2 insertions, 46 deletions

diff --git a/src/libstd/sys/redox/rand.rs b/src/libstd/sys/redox/rand.rs
index eb28eca38bc..3b378f53429 100644
--- a/src/libstd/sys/redox/rand.rs
+++ b/src/libstd/sys/redox/rand.rs
@@ -8,50 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use io;
-use rand::Rng;
-
-// FIXME: Use rand:
-pub struct OsRng {
-    state: [u64; 2]
-}
-
-impl OsRng {
-    /// Create a new `OsRng`.
-    pub fn new() -> io::Result<OsRng> {
-        Ok(OsRng {
-            state: [0xBADF00D1, 0xDEADBEEF]
-        })
-    }
-}
-
-impl Rng for OsRng {
-    fn next_u32(&mut self) -> u32 {
-        self.next_u64() as u32
-    }
-    fn next_u64(&mut self) -> u64 {
-        // Store the first and second part.
-        let mut x = self.state[0];
-        let y = self.state[1];
-
-        // Put the second part into the first slot.
-        self.state[0] = y;
-        // Twist the first slot.
-        x ^= x << 23;
-        // Update the second slot.
-        self.state[1] = x ^ y ^ (x >> 17) ^ (y >> 26);
-
-        // Generate the final integer.
-        self.state[1].wrapping_add(y)
-
-    }
-    fn fill_bytes(&mut self, buf: &mut [u8]) {
-        for chunk in buf.chunks_mut(8) {
-            let mut rand: u64 = self.next_u64();
-            for b in chunk.iter_mut() {
-                *b = rand as u8;
-                rand = rand >> 8;
-            }
-        }
-    }
+pub fn hashmap_random_keys() -> (u64, u64) {
+    (0, 0)
 }