win32: mach and build command fixes

- Add SERVO_USE_NIGHTLY_RUST env var to use the latest rust/cargo nightly snapshot
- Fix up looking for cargo binary (in cargo/bin/cargo, not bin/cargo)
- Fix up win32 executable checking (use .exe suffix)
- fix up win32 PATH handling (subprocess must use shell=True for PATH change to be honored)

python/servo/command_base.py

@@ -16,6 +16,10 @@ import toml
 
 from mach.registrar import Registrar
 
+BIN_SUFFIX = ""
+if sys.platform == "win32":
+    BIN_SUFFIX = ".exe"
+
 
 @contextlib.contextmanager
 def cd(new_path):
@@ -36,6 +40,8 @@ def host_triple():
         os_type = "apple-darwin"
     elif os_type == "android":
         os_type = "linux-androideabi"
+    elif os_type.startswith("mingw64_nt-"):
+        os_type = "pc-windows-gnu"
     else:
         os_type = "unknown"
 
@@ -52,6 +58,37 @@ def host_triple():
     return "%s-%s" % (cpu_type, os_type)
 
 
+def use_nightly_rust():
+    envvar = os.environ.get("SERVO_USE_NIGHTLY_RUST")
+    if envvar:
+        return envvar != "0"
+    return False
+
+
+def call(*args, **kwargs):
+    """Wrap `subprocess.call`, printing the command if verbose=True."""
+    verbose = kwargs.pop('verbose', False)
+    if verbose:
+        print(' '.join(args[0]))
+    if sys.platform == "win32":
+        # we have to use shell=True in order to get PATH handling
+        # when looking for the binary on Windows
+        return subprocess.call(*args, shell=True, **kwargs)
+    return subprocess.call(*args, **kwargs)
+
+
+def check_call(*args, **kwargs):
+    """Wrap `subprocess.check_call`, printing the command if verbose=True."""
+    verbose = kwargs.pop('verbose', False)
+    if verbose:
+        print(' '.join(args[0]))
+    if sys.platform == "win32":
+        # we have to use shell=True in order to get PATH handling
+        # when looking for the binary on Windows
+        return subprocess.check_call(*args, shell=True, **kwargs)
+    return subprocess.check_call(*args, **kwargs)
+
+
 class CommandBase(object):
     """Base class for mach command providers.
 
@@ -333,13 +370,13 @@ class CommandBase(object):
 
         if not self.config["tools"]["system-rust"] and \
            not path.exists(path.join(
-                self.config["tools"]["rust-root"], "rustc", "bin", "rustc")):
+                self.config["tools"]["rust-root"], "rustc", "bin", "rustc" + BIN_SUFFIX)):
             print("looking for rustc at %s" % path.join(
-                self.config["tools"]["rust-root"], "rustc", "bin", "rustc"))
+                self.config["tools"]["rust-root"], "rustc", "bin", "rustc" + BIN_SUFFIX))
             Registrar.dispatch("bootstrap-rust", context=self.context)
         if not self.config["tools"]["system-cargo"] and \
            not path.exists(path.join(
-                self.config["tools"]["cargo-root"], "cargo", "bin", "cargo")):
+                self.config["tools"]["cargo-root"], "cargo", "bin", "cargo" + BIN_SUFFIX)):
             Registrar.dispatch("bootstrap-cargo", context=self.context)
 
         self.context.bootstrapped = True