Hi,
On Mon, 5 Mar 2007, Bill Lear wrote:
> On Monday, March 5, 2007 at 14:37:15 (-0800) Linus Torvalds writes:
> >On Mon, 5 Mar 2007, Bill Lear wrote:
> >> I edit sourcefile.c, compile it, then commit it with
> >> N=timestamp(sourcefile.c) on master. N is <
> >> timestamp(.master/sourcefile.o). I then switch to branchX. N is
> >> stored by git for master:sourcefile.c. No stored timestamp are on
> >> this branch, so the file gets the timestamp it gets on checkout
> >> M=timestamp(sourcefile.c). I compile the file again, all is well. I
> >> move back to master branch. Git stores M as branchX:sourcefile.c Git
> >> checks out the file, and stamps it with N. I do a make. No
> >> recompilation happens.
> >
> >WHICH IS WRONG! You need to recompile, since the compile you did on the
> >other branch DOES NOT MATCH in "sourcefile.c" any more.
>
> Well, I'll let it drop after this, but I think you're wrong. I do NOT
> need it to recompile when I do the third make above.
Bill, maybe you don't want to hear it, but for all those following this
thread, here is why you are wrong:
"make" does _not_ match the time stamps of xyz.c and xyz.o. After you
"make", the only thing which is guaranteed is that if xyz.c is _newer_
than xyz.o, the compiler is started.
Example:
00:05 you pull upstream into your master branch, which has a newer xzy.c
00:07 you type make. xyz.o is built, because make sees that xyz.c is
newer than xyz.o
00:12 you checkout your side branch, xyz.c is updated.
00:13 you type make, and again xzy.o is built, because xyz.c is newer than
xyz.o
00:25 you switch back to your master branch.
Now, if your wish would be granted, and xyz.c has the same timestamp as
before, then it _still_ is older than xyz.o. So make will not rebuild it.
BUT xyz.o is actually compiled from the side branch's version of xyz.c!
Hth,
Dscho
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