message: Use llvm rather than FileSystem::Unlink to delete a file.
diff: @@ -249,7 +249,7 @@ bool ExpressionSourceCode::SaveExpressionTextToTempFile(
  }
  }
  if (!success)
  - FileSystem::Unlink(FileSpec(expr_source_path, true));
  + llvm::sys::fs::remove(expr_source_path);
  }
  if (!success)
  expr_source_path.clear();
  