Re: MSVC build broken (on cygwin)

From: Marius Storm-Olsen <mstormo@gmail.com>
Date: Oct 2, 2009, 08:07 UTC
Message-ID: <4AC5B4AE.5070307@gmail.com>
In-Reply-To: <4AC4E2C2.6030509@ramsay1.demon.co.uk>

Ramsay Jones said the following on 01.10.2009 19:11:

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> Hi Marius,
> 
> I know that I'm somewhat late to comment on your recent MSVC
> build patches, but I was busy at the time; better late than
> never... maybe ;-)
> 
> While the patches were traversing the list, I was feeling
> somewhat nervous about the effect of the patches on the
> cygwin build; in fact I remember thinking that they had
> *probably* broken the build. But I was busy...
> 
> Well I finally found time, yesterday, to take a closer look.
> I spent 10-15 minutes squinting at the code in order to
> convince myself that you had in fact *not* broken the cygwin
> build. :)

...

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> [Note: I was a little surprised that it got that far, since I didn't
> expect it to find the zlib header files. However, I have set the
> INCLUDE environment variable which msvc is respecting! yeah, a bit old
> fashioned!  Having also set the LIB environment variable, I was then
> a bit surprised that the linker didn't find the library; until I
> noticed that my library is called libz.lib *not* zlib.lib!]

... Clone the git://repo.or.cz/msvcgit.git, and run the setup_32bit_env.cmd script in there, and you should have everything you need to both compile and link Git with MSVC.

Show 7 quoted lines

> Note that the patch below includes some line-wrapping which you can
> ignore if you like, it just makes the Makefile easier to read.
> The only change that matters is inserting a space between -DWIN32 and
> -D_CONSOLE.
> 
> Anyway, the point is *not* to get the msvc build to work for me; rather
> it is to understand why the build *works* for you. ;-)

First of all, thanks for the thorough report! :) Second, I just recompiled, and it magically works for me. Why is a good question, since I also think it shouldn't at this point. The _WIN32 define is added by the compiler, and the WIN32 is added by windows.h, so our define guards *should* be testing for the _WIN32 define.

To how the guarded code reacts, I preprocessed the run-command.c with both version of the command line, and the result was the same:

( 9:54:49 - D:\msvc\git)
 > cl -E ... -DWIN32-D_CONSOLE ... run-command.c | grep run_thread
run-command.c
static unsigned __stdcall run_thread(void *data)
         async->tid = (HANDLE) _beginthreadex(((void *)0), 0, 
run_thread, async, 0, ((void *)0));

( 9:55:43 - D:\msvc\git)
 > cl -E ... -DWIN32 -D_CONSOLE ... run-command.c | grep run_thread
run-command.c
static unsigned __stdcall run_thread(void *data)
         async->tid = (HANDLE) _beginthreadex(((void *)0), 0, 
run_thread, async, 0, ((void *)0));

So, obviously, some magic in there is making it work for me. I have a hard time locating the magic in question though. :-/ That being said, does adding the space between the defines fix the MSVC compilation using Cygwin's GNU Make? It's none-the-less a correct patch, so you get an ack from me. Thanks!

Acked-by: Marius Storm-Olsen <mstormo@gmail.com>

-- .marius