Re: [PATCH 1/5] Makefile: drop builtins from MSVC pdb list

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Aug 14, 2020, 14:18 UTC
Message-ID: <nycvar.QRO.7.76.6.2008141611490.54@tvgsbejvaqbjf.bet>
In-Reply-To: <20200813150828.GA891963@coredump.intra.peff.net>

Hi Peff,

On Thu, 13 Aug 2020, Jeff King wrote:

Show 28 quoted lines

> On Thu, Aug 13, 2020 at 11:04:28AM -0400, Taylor Blau wrote:
>
> > On Thu, Aug 13, 2020 at 10:57:19AM -0400, Jeff King wrote:
> > > Over the years some more programs have become builtins, but nobody
> > > updated this MSVC-specific section of the file (which specifically says
> > > that it should not include builtins). Let's bring it up to date.
> > >
> > > Signed-off-by: Jeff King <peff@peff.net>
> > > ---
> > > Given that nobody has mentioned this, it makes me wonder if anybody is
> > > even using this part of the Makefile at all these days. Or maybe having
> > > extra lines here isn't a problem (though it's also missing some entries,
> > > like one for git-bugreport).
> >
> > If having extra entries didn't cause a problem, I would suspect that it
> > was just that. But that missing entries *also* doesn't cause a problem,
> > I'd suspect that this section of the Makefile just isn't being used.
> >
> > Of course, I'm not using it since I'm not on Windows, but maybe dscho or
> > Stolee would know if there are legitimate uses. Of course, if there
> > aren't, I'm favor of getting rid of this section entirely.
>
> I cc'd Jeff Hostetler, who added it. :)
>
> I'm also pretty not-knowledgeable about Windows, but I think that
> anybody using MSVC would do so through Visual Studio these days. And
> that's being covered with recent cmake stuff. Or maybe I'm just
> clueless. We'll see.

We have a couple ways to build Git on Windows:

- the standard way, in a Git for Windows SDK (which is a slightly modified
  subset of MSYS2). This uses GCC and GNU make and all the things that you
  might suspect given Git's origins on Linux.

- the Visual Studio way, after running `make vcxproj` in Git for Windows'
  SDK. As part of the `vcxproj` target, the non-C parts of Git are
  generated and committed.

- the "new" Visual Studio way, after running CMake. The non-C parts are
  generated through CMake, which is nice because no Git for Windows SDK is
  required to build this from start to finish.

- the Visual C way, as championed by Jeff (and which was a prerequisite to
  working on the `vcxproj` target): in a Git for Windows SDK, use GNU make
  but replace GCC by MSVC (via the command-line): `make MSVC=1`.

While all four methods work, the only one that is regularly used with the `make install` command is the first one.

The location you modified is in the `MSVC` part of `compat.mak.uname`, i.e. in the Visual C part.

We originally had a tentative plan to eventually, maybe, build Git for Windows using Visual C by default. However, it turned out that the standard malloc in Visual C's runtime was tuned for other workloads than Gits, and that nedmalloc performed better, and we originally could not get nedmalloc to compile with a modern Visual C, so we stopped that effort.

That's why you still have support for `make MSVC=1 install`.

Since it seems not to be too much trouble, I would prefer to keep it working for now, even if it is rarely exercised and regressions might creep in (like the ones you fixed).

Thanks, Dscho