Re: zlib detection in Meson on Windows broken?

Hi Dave,

On Tue, May 21, 2024 at 3:12 PM Dave Page <dpage(at)pgadmin(dot)org> wrote:

> Hi Sandeep, Nazir,
>
> On Tue, 21 May 2024 at 10:14, Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>
> wrote:
>
>> Hi,
>>
>> On Tue, 21 May 2024 at 10:20, Sandeep Thakkar
>> <sandeep(dot)thakkar(at)enterprisedb(dot)com> wrote:
>> >
>> > Hi Dave,
>> >
>> > Is the .pc file generated after the successful build of zlib? If yes,
>> then meson should be able to detect the installation ideally
>>
>> If meson is not able to find the .pc file automatically, using 'meson
>> setup ... --pkg-config-path $ZLIB_PC_PATH' might help.
>>
>
> The problem is that on Windows there are no standard locations for a
> Unix-style development library installation such as this, so the chances
> are that the .pc file will point to entirely the wrong location.
>
> For example, please see
> https://github.com/dpage/winpgbuild/actions/runs/9172187335 which is a
> Github action that builds a completely vanilla zlib using VC++. If you look
> at the uploaded artefact containing the build output and example the .pc
> file, you'll see it references /zlib as the location, which is simply where
> I built it in that action. On a developer's machine that's almost certainly
> not going to be where it actually ends up. For example, on the pgAdmin
> build farm, the dependencies all end up in C:\build64\[whatever]. On the
> similar Github action I'm building for PostgreSQL, that artefact will be
> unpacked into /build/zlib.
>
>
The above link returned 404. But I found a successful build at
https://github.com/dpage/winpgbuild/actions/runs/9175426807. I downloaded
the artifact but didn't find .pc file as I wanted to look into the content
of that file.

I had a word with Murali who mentioned he encountered a similar issue while
building PG17 on windows. He worked-around is by using a template .pc file
that includes these lines:
--
prefix=${pcfiledir}/../..
exec_prefix=${prefix}
libdir=${prefix}/lib
sharedlibdir=${prefix}/lib
includedir=${prefix}/include
--

But in general I agree with you on the issue of Meson's dependency on
pkgconfig files to detect the third party libraries.

Of course, for my own builds I can easily make everything use consistent
> directories, however most people who are likely to want to build PostgreSQL
> may not want to also build all the dependencies themselves as well, as some
> are a lot more difficult than zlib. So what tends to happen is people find
> third party builds or upstream official builds.
>
> I would therefore argue that if the .pc file that's found doesn't provide
> correct paths for us, then Meson should fall back to searching in the paths
> specified on its command line for the appropriate libraries/headers (which
> is what it does for OpenSSL for example, as that doesn't include a .pc
> file). This is also what happens with PG16 and earlier.
>
> One other thing I will note is that PG16 and earlier try to use the wrong
> filename for the import library. For years, it's been a requirement to do
> something like this: "copy \zlib\lib\zlib.lib \zlib\lib\zdll.lib" to make a
> build succeed against a "vanilla" zlib build. I haven't got as far as
> figuring out if the same is true with Meson yet.
>
> --
> Dave Page
> pgAdmin: https://www.pgadmin.org
> PostgreSQL: https://www.postgresql.org
> EDB: https://www.enterprisedb.com
>
>

--
Sandeep Thakkar