[patch+7.9] compile: Filter out -fpreprocessed

[Doug Evans]

On Fri, Jan 16, 2015 at 2:42 PM, Jan Kratochvil
<jan.kratochvil@redhat.com> wrote:
> [...]
> It is wrong that gcc puts -fpreprocessed into DW_AT_producer - I may post a gcc
> patch for it.

Hi.
I wasn't aware there are now rules for what can and cannot go in DW_AT_producer.
DW_AT_producer has gone from being informational to having a formal
spec (in the sense that something will break if, for example, a
particular option is mentioned).
Is this spec written down somewhere? [At least guidelines for what
things may lead to breakage?]