Re-displaying diagnostics

Hello,

This page:

https://clang.llvm.org/docs/ClangTools.html#clang-check

contains the text:

"It can also accept flags to re-display the diagnostics in different
formats with different flags"

What does this mean?

I am looking for a tool which issues the diagnostics from a yaml file
created by clang-tidy. Does such a tool exist? It is what I expect from
clang-check given the description above, but on reading the source of clang-
check, I don't think it has that feature.

This may be an XY problem. In reality, I have a large number of files which
I am running clang-tidy on using run_clang_tidy.py. Because my (custom)
clang-tidy feature changes headers, I get flooded with diagnostics from the
same lines in the same headers and can't really see what is happening.

So, I thought I would send the actual output from clang-tidy to /dev/null
and read the yaml file of fixes instead, filtering out entries for
diagnostics which have already been issued and emitting the diagnostics for
the rest. This filtering would require some changes to run_clang_tidy which
I'm happy to make locally. I think it would make sense as a no-op -n option
to clang-apply-replacements, which is common in other tools.

Does a tool for doing that re-issuing of diagnostics exist, or am I missing
some other way of filtering such messages?

Thanks,

Stephen.