If --verbose is passed, print a warning in `bootstrap.py` when download-rustc is ignored

1 files changed, 3 insertions, 0 deletions

diff --git a/src/bootstrap/bootstrap.py b/src/bootstrap/bootstrap.py
index 0cd0fabe9b1..5df3d0bde6d 100644
--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -726,6 +726,9 @@ class RustBuild(object):
         status = subprocess.call(["git", "diff-index", "--quiet", commit, "--", compiler, library])
         if status != 0:
             if download_rustc == "if-unchanged":
+                if self.verbose:
+                    print("warning: saw changes to compiler/ or library/ since {}; " \
+                          "ignoring `download-rustc`".format(commit))
                 return None
             print("warning: `download-rustc` is enabled, but there are changes to " \
                   "compiler/ or library/")