Reenable hardening options with Rust on Travis

Previously the sanitizers are forcibly disabled as they were found to be
incompatible with Rust code. The nightly channel of Rust, however, now
has some fixes which should make this disabling no longer necessary.

.travis.yml

@@ -33,12 +33,8 @@ env:
     ## We don't list default variable values, because we set the defaults
     ## in global (or the default is unset)
     -
-    ## We turn off hardening for Rust builds, because they are incompatible,
-    ## and it's going to take a while for them to be fixed. See:
-    ##   https:/trac.torproject.org/projects/tor/ticket/25386
-    ##   https:/trac.torproject.org/projects/tor/ticket/26398
     ## TOR_RUST_DEPENDENCIES is spelt RUST_DEPENDENCIES in 0.3.2
-    - RUST_OPTIONS="--enable-rust" TOR_RUST_DEPENDENCIES=true HARDENING_OPTIONS=""
+    - RUST_OPTIONS="--enable-rust" TOR_RUST_DEPENDENCIES=true
 
 matrix:
   ## include creates builds with gcc, linux, sudo: false
@@ -52,10 +48,9 @@ matrix:
     ## We check asciidoc with distcheck, to make sure we remove doc products
     - env: DISTCHECK="yes" ASCIIDOC_OPTIONS=""
     ## Check rust online with distcheck, to make sure we remove rust products
-    ## But without hardening (see above)
-    - env: DISTCHECK="yes" RUST_OPTIONS="--enable-rust --enable-cargo-online-mode" HARDENING_OPTIONS=""
+    - env: DISTCHECK="yes" RUST_OPTIONS="--enable-rust --enable-cargo-online-mode"
     ## Check disable module dirauth with and without rust
-    - env: MODULES_OPTIONS="--disable-module-dirauth" RUST_OPTIONS="--enable-rust" TOR_RUST_DEPENDENCIES=true HARDENING_OPTIONS=""
+    - env: MODULES_OPTIONS="--disable-module-dirauth" RUST_OPTIONS="--enable-rust" TOR_RUST_DEPENDENCIES=true
     - env: MODULES_OPTIONS="--disable-module-dirauth"
 
   ## Uncomment to allow the build to report success (with non-required
@@ -167,8 +162,8 @@ install:
   - if [[ "$ASCIIDOC_OPTIONS" == "" ]] && [[ "$TRAVIS_OS_NAME" == "osx" ]]; then export XML_CATALOG_FILES="/usr/local/etc/xml/catalog"; fi
   ## If we're using Rust, download rustup
   - if [[ "$RUST_OPTIONS" != "" ]]; then curl -Ssf -o rustup.sh https://sh.rustup.rs; fi
-  ## Install the stable channels of rustc and cargo and setup our toolchain environment
-  - if [[ "$RUST_OPTIONS" != "" ]]; then sh rustup.sh -y --default-toolchain stable; fi
+  ## Install the nightly channels of rustc and cargo and setup our toolchain environment
+  - if [[ "$RUST_OPTIONS" != "" ]]; then sh rustup.sh -y --default-toolchain nightly; fi
   - if [[ "$RUST_OPTIONS" != "" ]]; then source $HOME/.cargo/env; fi
   ## If we're testing rust builds in offline-mode, then set up our vendored dependencies
   - if [[ "$TOR_RUST_DEPENDENCIES" == "true" ]]; then export TOR_RUST_DEPENDENCIES=$PWD/src/ext/rust/crates; fi