Allow disabling LLVM assertions in rustc (fixes #15548)

python/servo/bootstrap_commands.py

@@ -70,6 +70,8 @@ class MachCommands(CommandBase):
         rust_path = self.rust_path()
         rust_dir = path.join(self.context.sharedir, "rust", rust_path)
         install_dir = path.join(self.context.sharedir, "rust", version)
+        if not self.config["build"]["llvm-assertions"]:
+            install_dir += "-alt"
 
         if not force and path.exists(path.join(rust_dir, "rustc", "bin", "rustc" + BIN_SUFFIX)):
             print("Rust compiler already downloaded.", end=" ")
@@ -89,7 +91,10 @@ class MachCommands(CommandBase):
                 rustc_url = "https://static-rust-lang-org.s3.amazonaws.com/dist/" + tarball
             else:
                 tarball = "%s/rustc-nightly-%s.tar.gz" % (version, host_triple())
-                rustc_url = "https://s3.amazonaws.com/rust-lang-ci/rustc-builds/" + tarball
+                base_url = "https://s3.amazonaws.com/rust-lang-ci/rustc-builds"
+                if not self.config["build"]["llvm-assertions"]:
+                    base_url += "-alt"
+                rustc_url = base_url + "/" + tarball
             tgz_file = rust_dir + '-rustc.tar.gz'
 
             download_file("Rust compiler", rustc_url, tgz_file)

python/servo/command_base.py

@@ -258,7 +258,6 @@ class CommandBase(object):
         self.config["tools"].setdefault("system-cargo", False)
         self.config["tools"].setdefault("rust-root", "")
         self.config["tools"].setdefault("cargo-root", "")
-        self.set_use_stable_rust(False)
         if not self.config["tools"]["system-cargo"]:
             self.config["tools"]["cargo-root"] = path.join(
                 context.sharedir, "cargo", self.cargo_build_id())
@@ -267,6 +266,7 @@ class CommandBase(object):
         self.config.setdefault("build", {})
         self.config["build"].setdefault("android", False)
         self.config["build"].setdefault("mode", "")
+        self.config["build"].setdefault("llvm-assertions", True)
         self.config["build"].setdefault("debug-mozjs", False)
         self.config["build"].setdefault("ccache", "")
         self.config["build"].setdefault("rustflags", "")
@@ -279,6 +279,8 @@ class CommandBase(object):
         self.config["android"].setdefault("platform", "android-18")
         self.config["android"].setdefault("target", "arm-linux-androideabi")
 
+        self.set_use_stable_rust(False)
+
     _use_stable_rust = False
     _rust_version = None
     _rust_version_is_stable = False
@@ -297,8 +299,9 @@ class CommandBase(object):
         version = self.rust_version()
         if self._use_stable_rust:
             return os.path.join(version, "rustc-%s-%s" % (version, host_triple()))
-        else:
-            return os.path.join(version, "rustc-nightly-%s" % (host_triple()))
+        if not self.config["build"]["llvm-assertions"]:
+            version += "-alt"
+        return os.path.join(version, "rustc-nightly-%s" % (host_triple()))
 
     def rust_version(self):
         if self._rust_version is None or self._use_stable_rust != self._rust_version_is_stable:

servobuild.example

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