On Thu, Nov 08, 2018 at 06:28:29AM +0900, Mike Hommey wrote: > On Wed, Nov 07, 2018 at 01:21:44PM -0800, Josh Triplett wrote: > > > I have worked with the Rust upstream sources > > > well enough to know these issues. You have a regression in Rust 1.25 and > > > you will have a very hard time trying to bisect the issues simply because > > > you cannot even build 1.25 using a 1.19 compiler because the language > > > has changed too much in the mean time. > > > > Why do you need to build 1.25 with a 1.19 compiler in order to bisect? > > Presumably because none of versions 1.20 to 1.24 work.
Then you wouldn't need to start bisection at version 1.25, if version 1.20 broke. But that aside, this is one of *many* reasons why such efforts can't have a cadence of occurring six versions apart.