Merge remote-tracking branch 'origin/master' into frewsxcv-san

1 files changed, 21 insertions, 10 deletions

diff --git a/src/bootstrap/bootstrap.py b/src/bootstrap/bootstrap.py
index a819e1b6e2f..b8bae69d063 100644
--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -192,8 +192,10 @@ def default_build_triple(verbose):
     # If the user already has a host build triple with an existing `rustc`
     # install, use their preference. This fixes most issues with Windows builds
     # being detected as GNU instead of MSVC.
+    default_encoding = sys.getdefaultencoding()
     try:
         version = subprocess.check_output(["rustc", "--version", "--verbose"])
+        version = version.decode(default_encoding)
         host = next(x for x in version.split('\n') if x.startswith("host: "))
         triple = host.split("host: ")[1]
         if verbose:
@@ -204,7 +206,6 @@ def default_build_triple(verbose):
             print("rustup not detected: {}".format(e))
             print("falling back to auto-detect")
 
-    default_encoding = sys.getdefaultencoding()
     required = sys.platform != 'win32'
     ostype = require(["uname", "-s"], exit=required)
     cputype = require(['uname', '-m'], exit=required)
@@ -350,11 +351,13 @@ def output(filepath):
     with open(tmp, 'w') as f:
         yield f
     try:
-        os.remove(filepath)  # PermissionError/OSError on Win32 if in use
-        os.rename(tmp, filepath)
+        if os.path.exists(filepath):
+            os.remove(filepath)  # PermissionError/OSError on Win32 if in use
     except OSError:
         shutil.copy2(tmp, filepath)
         os.remove(tmp)
+        return
+    os.rename(tmp, filepath)
 
 
 class RustBuild(object):
@@ -794,7 +797,7 @@ class RustBuild(object):
         env.setdefault("RUSTFLAGS", "")
         env["RUSTFLAGS"] += " -Cdebuginfo=2"
 
-        build_section = "target.{}".format(self.build_triple())
+        build_section = "target.{}".format(self.build)
         target_features = []
         if self.get_toml("crt-static", build_section) == "true":
             target_features += ["+crt-static"]
@@ -825,7 +828,11 @@ class RustBuild(object):
         run(args, env=env, verbose=self.verbose)
 
     def build_triple(self):
-        """Build triple as in LLVM"""
+        """Build triple as in LLVM
+
+        Note that `default_build_triple` is moderately expensive,
+        so use `self.build` where possible.
+        """
         config = self.get_toml('build')
         if config:
             return config
@@ -892,13 +899,17 @@ class RustBuild(object):
         filtered_submodules = []
         submodules_names = []
         llvm_checked_out = os.path.exists(os.path.join(self.rust_root, "src/llvm-project/.git"))
+        external_llvm_provided = self.get_toml('llvm-config') or self.downloading_llvm()
+        llvm_needed = not self.get_toml('codegen-backends', 'rust') \
+            or "llvm" in self.get_toml('codegen-backends', 'rust')
         for module in submodules:
             if module.endswith("llvm-project"):
-                # Don't sync the llvm-project submodule either if an external LLVM
-                # was provided, or if we are downloading LLVM. Also, if the
-                # submodule has been initialized already, sync it anyways so that
-                # it doesn't mess up contributor pull requests.
-                if self.get_toml('llvm-config') or self.downloading_llvm():
+                # Don't sync the llvm-project submodule if an external LLVM was
+                # provided, if we are downloading LLVM or if the LLVM backend is
+                # not being built. Also, if the submodule has been initialized
+                # already, sync it anyways so that it doesn't mess up contributor
+                # pull requests.
+                if external_llvm_provided or not llvm_needed:
                     if self.get_toml('lld') != 'true' and not llvm_checked_out:
                         continue
             check = self.check_submodule(module, slow_submodules)