run panics if lldb is not installed and no output is produced.. Index: rust/src/bootstrap/src/core/build_steps/test.rs =================================================================== --- rust.orig/src/bootstrap/src/core/build_steps/test.rs +++ rust/src/bootstrap/src/core/build_steps/test.rs @@ -1779,7 +1779,11 @@ NOTE: if you're sure you want to do this .ok(); if let Some(ref vers) = lldb_version { cmd.arg("--lldb-version").arg(vers); - let lldb_python_dir = run(Command::new(lldb_exe).arg("-P")).ok(); + let lldb_python_dir = Command::new(lldb_exe) + .arg("-P") + .output() + .map(|output| String::from_utf8_lossy(&output.stdout).to_string()) + .ok(); if let Some(ref dir) = lldb_python_dir { cmd.arg("--lldb-python-dir").arg(dir); }