Automatically update cargo when necessary

1 files changed, 8 insertions, 1 deletions

diff --git a/python/servo/command_base.py b/python/servo/command_base.py
index 45c1b230eb2..d78c0e13a1c 100644
--- a/python/servo/command_base.py
+++ b/python/servo/command_base.py
@@ -74,7 +74,7 @@ class CommandBase(object):
                 context.sharedir, "rust", *self.rust_snapshot_path().split("/"))
         if not self.config["tools"]["system-cargo"]:
             self.config["tools"]["cargo-root"] = path.join(
-                context.sharedir, "cargo")
+                context.sharedir, "cargo", self.cargo_build_id())
 
         self.config.setdefault("build", {})
         self.config["build"].setdefault("android", False)
@@ -85,6 +85,7 @@ class CommandBase(object):
         self.config["android"].setdefault("toolchain", "")
 
     _rust_snapshot_path = None
+    _cargo_build_id = None
 
     def rust_snapshot_path(self):
         if self._rust_snapshot_path is None:
@@ -93,6 +94,12 @@ class CommandBase(object):
             self._rust_snapshot_path = "%s-%s" % (snapshot_hash, host_triple())
         return self._rust_snapshot_path
 
+    def cargo_build_id(self):
+        if self._cargo_build_id is None:
+            filename = path.join(self.context.topdir, "cargo-nightly-build")
+            self._cargo_build_id = open(filename).read().strip()
+        return self._cargo_build_id
+
     def build_env(self):
         """Return an extended environment dictionary."""
         env = os.environ.copy()