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I just found this old PR #485 when creating a new PR for a similar topic: #931 .

Just a comment on this PR #485 here (I know it is quite old, but maybe someone reads it):
The change here solves only half of the issue, e.g., whitespaces in the parameter for the @-file itself are allowed.
However, this ignores any other parameter with whitespaces, like filenames for sourcefiles, and (from a user's perspective) it is unexpected that the quotes appear only after the @-symbol, like @"some file", and not around the complete parameter, like "@some file" or "some other param".