On Wed, 25 Nov 2009 23:59:45 +0100 Ulrich Mueller wrote: > Real examples would be issues like bugs 83877 [1] or 263387 [2]. > Nothing that could be easily dismissed or worked around. Both issues > are fixed with Portage since a long time. Yes, those are examples of packages relying upon something that is undefined behaviour, and that behaves differently depending upon the Portage version you use. > I don't know of any example where non-preservation of nanosecond > timestamps would cause problems. Not non-preservation. Partial and inconsistent corruption. srcfile gets installed with its mtime preserved, because it is installed using rename. objfile, whose mtime should be a bit later than srctime's, gets installed with its mtime corrupted to be slightly less than it should be, and less than srctime's, because it is installed the slow way. A program checks that objfile's mtime is greater than or equal to srcfile's mtime. That check will fail, and reinstalls will randomly fix and break it depending upon which way the corruption goes. -- Ciaran McCreesh