Re: Make 4.3 rebuilds .o files when unnecessary

[Kaz Kylheku (gmake)]

On 2020-11-22 10:25, Tommaso Fonda wrote: 

> Also, I've built make from source and I'm close to finding the commit that 
> introduced the issue. For now, I can say that setting the repo's HEAD to 
> commit: 
> b13dcfe Add more GCC warnings to the maintainer build. 
> produces a make binary that doesn't show the issue, but setting the HEAD to 
> commit: 
> 48c8a11 (HEAD -> test) * configure.ac [1]: Support GLIBC glob interface 
> version 2 
> produces a binary that shows it. 
> 
> I'll continue building make from source tomorrow, I hope to be able to find 
> the culprit soon. 
> Regards,

Once you're in the git workflow, "git bisect" is an efficient way to
find a commit where a change in behavior took place. 

$ git bisect start 
$ git checkout b13dcfe # known commit that doesn't show the issue 
$ git bisect good # inform git bisect 
$ git checkout 48c8a11 # known commit that shows issue 
$ git bisect bad # inform git bisect 

Now git bisect should find a midway commit for you to test and jump to
it. Build it and test, then respond with "git bisect good" or "git
bisect bad", and keep going. 

The commit that "git bisect" finally finds and reports as the bad one is
not necessarily the current one; you have to read the diagnostic. I.e.
if the last commit to be tested is a "git bisect good", it will stay
there and report the bad one. 

 

Links:
------
[1] http://configure.ac