[RFC] Change PCH "checksum"

[Nathan Sidwell]

On 2/26/19 11:18 AM, Michael Matz wrote:
> Hi,
> 
> On Tue, 26 Feb 2019, Richard Biener wrote:
> 
>> get_build_id_1 (struct dl_phdr_info *info, size_t, void *data)
>> {
> 
> Isn't this all a bit silly?  We could simply encode the svn revision, or
> maybe even just some random bytes generated once in stage1 at build time
> as "checksum" and be done with.  In the latter case PCHs will then not
> work across different compiler builds, but so what?

FWIW, here's what I do on the modules branch, which has similar 
versioning concerns.

1) in experimental mode, I stamp with the local timestamp modification 
of the cp directory.  I allow mixing versions with in the same day (with 
a warning).

2) in non-experimental mode, I plan to lock to the GCC major.minor tuple.

PCH would need to look at more than the cp directory, but that's good 
enough for me.  I'm pondering an 'ignore version' developer option, but 
as it's only me right now, that's not been a need.

nathan

-- 
Nathan Sidwell