the mystery of math.h in lib/gcc/%triple-name%/%gcc-version%/include-fixed

[Marc Glisse]

On Wed, 24 Oct 2018, Jonathan Wakely wrote:

> On Wed, 24 Oct 2018 at 04:25, Dennis Clarke <dclarke@blastwave.org> wrote:
>> The question has to be where do these "include-fixed" headers come
>> from?
>
> The include-fixed headers are generated as part of the GCC build
> process. The contents of the fixincludes dir in the GCC sources apply
> a set of rules to fix known problems in the system headers (either
> conformance bugs, or incompatibilities with GCC). That means the
> include-fixed files are specific to the machine they were created for
> (and any machines with the same set of headers).
>
>> I am looking for an end point result that I know I can drop
>> on any similar machine and it will "just work"(tm).
>
> Generally "any similar machine" won't work, it needs to be exactly the
> same, because otherwise differences in the libc headers cause this
> kind of problem.

I have old memories of people copying the compiler then rerunning just 
fixincludes on the new machine. I see that we install fixincl and 
fixinc.sh, possibly so we can rerun it when we update the system headers, 
but it could also be used for the other machine.

-- 
Marc Glisse