[Bug libstdc++/88999] [9 Regression] testcases using in_avail() fail on nios2-elf

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88999

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to sandra from comment #0)
> I see that these tests are xfailed for bare-metal ARM targets with a note
> that ARM semihosting doesn't support the underlying fstat call, but that is
> not true of nios2.  These tests all passed on nios2-elf with GCC 8.

I see no relevant changes on trunk compared to gcc-8-branch.

> I realize it is hard for other people to test this target, but I'd be happy
> to test a patch or do some debugging to try to track it down given some
> clues about where to look.  (Maybe this failure rings a bell with someone
> already familiar with the code?)

This should cover all the relevant code (and a few more bits) and doesn't show
anything that looks relevant:

  git diff gcc-8-branch master  -- config/io/  src/c++??/*stream* \
    include/{bits,std}/*stream*  include/ext/stdio*filebuf.h