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!

Author: alexcrichton

src/Cargo.lock

@@ -107,8 +107,8 @@ impl Step for Std {
         let mut cargo = builder.cargo(compiler, Mode::Libstd, target, "build");
         std_cargo(build, &compiler, target, &mut cargo);
         run_cargo(build,
-                &mut cargo,
-                &libstd_stamp(build, compiler, target));
+                  &mut cargo,
+                  &libstd_stamp(build, compiler, target));
 
         builder.ensure(StdLink {
             compiler: builder.compiler(compiler.stage, build.build),
@@ -359,8 +359,8 @@ impl Step for Test {
         let mut cargo = builder.cargo(compiler, Mode::Libtest, target, "build");
         test_cargo(build, &compiler, target, &mut cargo);
         run_cargo(build,
-                &mut cargo,
-                &libtest_stamp(build, compiler, target));
+                  &mut cargo,
+                  &libtest_stamp(build, compiler, target));
 
         builder.ensure(TestLink {
             compiler: builder.compiler(compiler.stage, build.build),
@@ -866,12 +866,13 @@ fn run_cargo(build: &Build, cargo: &mut Command, stamp: &Path) {
             // `std-<hash>.dll.lib` on Windows. The aforementioned methods only
             // split the file name by the last extension (`.lib`) while we need
             // to split by all extensions (`.dll.lib`).
+            let expected_len = t!(filename.metadata()).len();
             let filename = filename.file_name().unwrap().to_str().unwrap();
             let mut parts = filename.splitn(2, '.');
             let file_stem = parts.next().unwrap().to_owned();
             let extension = parts.next().unwrap().to_owned();
 
-            toplevel.push((file_stem, extension));
+            toplevel.push((file_stem, extension, expected_len));
         }
     }
 
@@ -891,11 +892,12 @@ fn run_cargo(build: &Build, cargo: &mut Command, stamp: &Path) {
         .map(|e| t!(e))
         .map(|e| (e.path(), e.file_name().into_string().unwrap(), t!(e.metadata())))
         .collect::<Vec<_>>();
-    for (prefix, extension) in toplevel {
-        let candidates = contents.iter().filter(|&&(_, ref filename, _)| {
+    for (prefix, extension, expected_len) in toplevel {
+        let candidates = contents.iter().filter(|&&(_, ref filename, ref meta)| {
             filename.starts_with(&prefix[..]) &&
                 filename[prefix.len()..].starts_with("-") &&
-                filename.ends_with(&extension[..])
+                filename.ends_with(&extension[..]) &&
+                meta.len() == expected_len
         });
         let max = candidates.max_by_key(|&&(_, _, ref metadata)| {
             FileTime::from_last_modification_time(metadata)

src/bootstrap/compile.rs

@@ -743,7 +743,6 @@ impl Step for Src {
             "src/liblibc",
             "src/libpanic_abort",
             "src/libpanic_unwind",
-            "src/librand",
             "src/librustc_asan",
             "src/librustc_lsan",
             "src/librustc_msan",

src/bootstrap/dist.rs

@@ -11,6 +11,9 @@ path = "lib.rs"
 core = { path = "../libcore" }
 std_unicode = { path = "../libstd_unicode" }
 
+[dev-dependencies]
+rand = "0.3"
+
 [[test]]
 name = "collectionstests"
 path = "../liballoc/tests/lib.rs"

src/doc/unstable-book/src/library-features/rand.md

@@ -135,6 +135,8 @@
 extern crate std;
 #[cfg(test)]
 extern crate test;
+#[cfg(test)]
+extern crate rand;
 
 extern crate std_unicode;
 

src/liballoc/Cargo.toml

@@ -1269,10 +1269,11 @@ unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
 
 #[cfg(test)]
 mod tests {
-    use std::__rand::{thread_rng, Rng};
     use std::thread;
     use std::vec::Vec;
 
+    use rand::{thread_rng, Rng};
+
     use super::{LinkedList, Node};
 
     #[cfg(test)]

src/liballoc/lib.rs

@@ -30,6 +30,7 @@
 #![feature(unicode)]
 
 extern crate std_unicode;
+extern crate rand;
 
 use std::hash::{Hash, Hasher};
 use std::collections::hash_map::DefaultHasher;

src/liballoc/linked_list.rs

@@ -10,9 +10,10 @@
 
 use std::cmp::Ordering::{Equal, Greater, Less};
 use std::mem;
-use std::__rand::{Rng, thread_rng};
 use std::rc::Rc;
 
+use rand::{Rng, thread_rng};
+
 fn square(n: usize) -> usize {
     n * n
 }

src/liballoc/tests/lib.rs

@@ -10,7 +10,7 @@ test = false
 bench = false
 
 [dev-dependencies]
-rand = { path = "../librand" }
+rand = "0.3"
 
 [[test]]
 name = "coretests"