Re: ABI baseline update and build-many-glibcs.

[Joseph Myers <joseph at codesourcery dot com>]

On Mon, 26 Nov 2018, Carlos O'Donell wrote:

> Do we think that we should run 'make update-all-abi' during
> build-many-glibcs in order to look for errors or changes in
> the ABI baselines?

build-many-glibcs.py should never modify the glibc source tree.

Right now, it creates a copy of the source tree, but that's because the 
build might try to write into the source tree if file timestamps are in 
the wrong order.  I intend to make it touch more files at checkout time, 
and then remove the copying after doing further tests that all relevant 
files get touched (builds with a read-only source tree with all files 
having different timestamps in some arbitrary order except for the touched 
files, and then with the reverse of that order except for the touched 
files, to ensure no relevant dependencies causing source file rebuilds 
have been missed).

The copying is not a good thing; it can actually introduce transient build 
failures, if the checkout step results in an automatic "git gc", which is 
still running when the copying takes place, resulting in the copying 
failing because files in .git vanished during the copying.

-- 
Joseph S. Myers
joseph@codesourcery.com