Stop using "alternate" rustc builds.

With https://github.com/rust-lang/rust/pull/45810,
normal Nightly now has LLVM assertions disabled.

etc/ci/buildbot_steps.yml

@@ -31,10 +31,10 @@ mac-rel-wpt4:
 
 mac-dev-unit:
   - ./mach clean-nightlies --keep 3 --force
-  - env PKG_CONFIG_PATH=/usr/local/opt/zlib/lib/pkgconfig SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach build --dev
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach test-unit
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach package --dev
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach build-cef
+  - env PKG_CONFIG_PATH=/usr/local/opt/zlib/lib/pkgconfig ./mach build --dev
+  - env ./mach test-unit
+  - env ./mach package --dev
+  - env ./mach build-cef
   - ./mach build-geckolib
   - bash ./etc/ci/lockfile_changed.sh
   - bash ./etc/ci/manifest_changed.sh
@@ -78,12 +78,12 @@ linux-dev:
   - ./mach clean-nightlies --keep 3 --force
   - ./mach test-tidy --no-progress --all
   - ./mach test-tidy --no-progress --self-test
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach build --dev
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach test-compiletest
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach test-unit
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach package --dev
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach build-cef
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach build --dev --no-default-features --features default-except-unstable
+  - env ./mach build --dev
+  - env ./mach test-compiletest
+  - env ./mach test-unit
+  - env ./mach package --dev
+  - env ./mach build-cef
+  - env ./mach build --dev --no-default-features --features default-except-unstable
   - ./mach build-geckolib
   - ./mach test-stylo
   - bash ./etc/ci/lockfile_changed.sh
@@ -116,27 +116,27 @@ linux-nightly:
 
 android:
   - ./mach clean-nightlies --keep 3 --force
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ANDROID_SDK=/home/servo/android/sdk/r25.2.3 ./mach build --android --dev
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ANDROID_SDK=/home/servo/android/sdk/r25.2.3 ./mach package --android --dev
+  - env ANDROID_SDK=/home/servo/android/sdk/r25.2.3 ./mach build --android --dev
+  - env ANDROID_SDK=/home/servo/android/sdk/r25.2.3 ./mach package --android --dev
   - bash ./etc/ci/lockfile_changed.sh
   - bash ./etc/ci/manifest_changed.sh
   - python ./etc/ci/check_dynamic_symbols.py
 
 android-nightly:
   - ./mach clean-nightlies --keep 3 --force
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ANDROID_SDK=/home/servo/android/sdk/r25.2.3 ./mach build --android --release
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ANDROID_SDK=/home/servo/android/sdk/r25.2.3 ./mach package --android --release
+  - env ANDROID_SDK=/home/servo/android/sdk/r25.2.3 ./mach build --android --release
+  - env ANDROID_SDK=/home/servo/android/sdk/r25.2.3 ./mach package --android --release
   - ./mach upload-nightly android
 
 arm32:
   - ./mach clean-nightlies --keep 3 --force
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach build --rel --target=arm-unknown-linux-gnueabihf
+  - env ./mach build --rel --target=arm-unknown-linux-gnueabihf
   - bash ./etc/ci/lockfile_changed.sh
   - bash ./etc/ci/manifest_changed.sh
 
 arm64:
   - ./mach clean-nightlies --keep 3 --force
-  - env SERVO_RUSTC_LLVM_ASSERTIONS=1 ./mach build --rel --target=aarch64-unknown-linux-gnu
+  - env ./mach build --rel --target=aarch64-unknown-linux-gnu
   - bash ./etc/ci/lockfile_changed.sh
   - bash ./etc/ci/manifest_changed.sh
 

python/servo/bootstrap_commands.py

@@ -29,7 +29,7 @@ from mach.decorators import (
 import servo.bootstrap as bootstrap
 from servo.command_base import CommandBase, BIN_SUFFIX, cd
 from servo.util import delete, download_bytes, download_file, extract, host_triple
-from servo.util import STATIC_RUST_LANG_ORG_DIST, URLOPEN_KWARGS
+from servo.util import STATIC_RUST_LANG_ORG_DIST
 
 
 @CommandProvider
@@ -90,15 +90,8 @@ class MachCommands(CommandBase):
             # in that directory).
             if stable:
                 base_url = STATIC_RUST_LANG_ORG_DIST
-            elif self.config["build"]["llvm-assertions"]:
-                base_url = nightly_dist
             else:
-                import toml
-                channel = nightly_dist + "/channel-rust-nightly.toml"
-                manifest = toml.load(urllib2.urlopen(channel, **URLOPEN_KWARGS))
-                nightly_commit_hash = manifest["pkg"]["rustc"]["git_commit_hash"]
-
-                base_url = "https://s3.amazonaws.com/rust-lang-ci/rustc-builds-alt/" + nightly_commit_hash
+                base_url = nightly_dist
 
             rustc_url = base_url + "/rustc-%s-%s.tar.gz" % (version, host_triple())
             tgz_file = rust_dir + '-rustc.tar.gz'

python/servo/command_base.py

@@ -260,19 +260,9 @@ class CommandBase(object):
         self.config["tools"].setdefault("cargo-root", "")
         self.config["tools"].setdefault("rustc-with-gold", get_env_bool("SERVO_RUSTC_WITH_GOLD", True))
 
-        # https://github.com/rust-lang/rust/pull/39754
-        triples_with_rustc_alt_builds = [
-            "x86_64-unknown-linux-gnu",
-            "x86_64-apple-darwin",
-            "x86_64-pc-windows-msvc",
-        ]
-        llvm_assertions_default = ("SERVO_RUSTC_LLVM_ASSERTIONS" in os.environ
-                                   or host_triple() not in triples_with_rustc_alt_builds)
-
         self.config.setdefault("build", {})
         self.config["build"].setdefault("android", False)
         self.config["build"].setdefault("mode", "")
-        self.config["build"].setdefault("llvm-assertions", llvm_assertions_default)
         self.config["build"].setdefault("debug-mozjs", False)
         self.config["build"].setdefault("ccache", "")
         self.config["build"].setdefault("rustflags", "")
@@ -315,8 +305,6 @@ class CommandBase(object):
     def rust_install_dir(self):
         if self._use_stable_rust:
             return self.rust_stable_version()
-        elif not self.config["build"]["llvm-assertions"]:
-            return self.rust_nightly_date() + "-alt"
         else:
             return self.rust_nightly_date()
 

servobuild.example

@@ -39,9 +39,6 @@ rustc-with-gold = true
 # Defaults to prompting before building
 #mode = "dev"
 
-# Whether to enable LLVM assertions in rustc.
-#llvm-assertions = false
-
 # Set "android = true" or use `mach build --android` to build the Android app.
 android = false