Auto merge of #37439 - michaelwoerister:remove-sha256, r=alexcrichton

Replace all uses of SHA-256 with BLAKE2b.

Removes the SHA-256 implementation and replaces all uses of it with BLAKE2b, which we already use for debuginfo type guids and incremental compilation hashes. It doesn't make much sense to have two different cryptographic hash implementations in the compiler and Blake has a few advantages over SHA-2 (computationally less expensive, hashes of up to 512 bits).

mk/crates.mk

@@ -121,7 +121,7 @@ DEPS_rustc_driver := arena flate getopts graphviz libc rustc rustc_back rustc_bo
                      rustc_trans rustc_privacy rustc_lint rustc_plugin \
                      rustc_metadata syntax_ext proc_macro_plugin \
                      rustc_passes rustc_save_analysis rustc_const_eval \
-                     rustc_incremental syntax_pos rustc_errors proc_macro
+                     rustc_incremental syntax_pos rustc_errors proc_macro rustc_data_structures
 DEPS_rustc_errors := log libc serialize syntax_pos
 DEPS_rustc_lint := rustc log syntax syntax_pos rustc_const_eval
 DEPS_rustc_llvm := native:rustllvm libc std rustc_bitflags

src/librustc/lib.rs

@@ -111,8 +111,6 @@ pub mod traits;
 pub mod ty;
 
 pub mod util {
-    pub use rustc_back::sha2;
-
     pub mod common;
     pub mod ppaux;
     pub mod nodemap;

src/librustc/ty/util.rs

@@ -405,6 +405,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 ///
 /// The same goes for endianess: We always convert multi-byte integers to little
 /// endian before hashing.
+#[derive(Debug)]
 pub struct ArchIndependentHasher<H> {
     inner: H,
 }
@@ -413,6 +414,10 @@ impl<H> ArchIndependentHasher<H> {
     pub fn new(inner: H) -> ArchIndependentHasher<H> {
         ArchIndependentHasher { inner: inner }
     }
+
+    pub fn into_inner(self) -> H {
+        self.inner
+    }
 }
 
 impl<H: Hasher> Hasher for ArchIndependentHasher<H> {

src/librustc_back/lib.rs

@@ -36,9 +36,8 @@
 #![feature(rand)]
 #![feature(rustc_private)]
 #![feature(staged_api)]
-#![feature(step_by)]
 #![cfg_attr(stage0, feature(question_mark))]
-#![cfg_attr(test, feature(test, rand))]
+#![cfg_attr(test, feature(rand))]
 
 extern crate syntax;
 extern crate libc;
@@ -48,7 +47,6 @@ extern crate serialize;
 extern crate serialize as rustc_serialize; // used by deriving
 
 pub mod tempdir;
-pub mod sha2;
 pub mod target;
 pub mod slice;
 pub mod dynamic_lib;