[PATCH][RFC] Extend locations where to seach for Fortran pre-include.

[Joseph Myers]

On Fri, 23 Nov 2018, Martin Liška wrote:

> Looks the problematic is quite complex as I can understand. I prepared a patch
> that should hopefully follow advises provided.

I don't see how this version ensures that NATIVE_SYSTEM_HEADER_DIR is 
properly sysrooted.  Note there's add_sysrooted_prefix separate from 
add_prefix (but that's *not* the correct thing to use here because it uses 
target_sysroot_suffix whereas you need target_sysroot_hdrs_suffix).

The last argument to add_prefix, which you're setting to true, is 
os_multilib.  But using the OS multilib scheme seems wrong here, because 
the OS multilib names are names like "../lib64", which only make sense in 
directories called lib - you don't want to end up searching a directory 
<something>/include/finclude/../lib64.

In the multiarch case, do you want 
<something>/include/finclude/<multiarch> or 
<something>/include/<multiarch>/finclude?  (This is where I'd hope Debian 
/ Ubuntu GCC people would comment.)

-- 
Joseph S. Myers
joseph@codesourcery.com