[cmake-developers] RfD: deprecate link_directories() and link_libraries()

[Rolf Eike Beer]

My dislike against these functions is probably known, and now I would like to
bring this to a new level: I would like to formally deprecate these functions.
I don't think they serve any useful purpose anymore, given that now even the
pkg-config module can (and does) return absolute paths to the libraries.

The plan is to introduce 2 new policies and whenever you set

cmake_minimum_required(VERSION 3.13)

and use these functions you will get a warning telling you to stop that
nonsense.

Thoughts?

Eike

[Brad King]

Post by Rolf Eike Beer
My dislike against these functions is probably known, and now I would like to
bring this to a new level: I would like to formally deprecate these functions.
I don't think they serve any useful purpose anymore, given that now even the
pkg-config module can (and does) return absolute paths to the libraries.

What harm does their presence cause?

Please ask on the user list to see if people are using them.

I suspect they may be used by some projects to link to special runtime
libraries when cross-compiling. We'd need to make sure there is a
better way for all such use cases before deprecating the commands.

-Brad
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[Rolf Eike Beer]

Post by Brad King

Post by Rolf Eike Beer
My dislike against these functions is probably known, and now I would like
to bring this to a new level: I would like to formally deprecate these
functions. I don't think they serve any useful purpose anymore, given
that now even the pkg-config module can (and does) return absolute paths
to the libraries.

What harm does their presence cause?
Please ask on the user list to see if people are using them.
I suspect they may be used by some projects to link to special runtime
libraries when cross-compiling. We'd need to make sure there is a
better way for all such use cases before deprecating the commands.

I have only seen this commands in failed attempts to convert Makefiles to
CMake without using the proper methods of calling find_library(). And then
showing up here or in #cmake and complaining that it breaks.

So, has anyone an example where these are still needed with CMake 3.12 for
anything that _can't_ be done properly?

Eike

[Gregor Jasny via cmake-developers]

Hello,

Post by Brad King

Post by Rolf Eike Beer
My dislike against these functions is probably known, and now I would like to
bring this to a new level: I would like to formally deprecate these functions.
I don't think they serve any useful purpose anymore, given that now even the
pkg-config module can (and does) return absolute paths to the libraries.

What harm does their presence cause?
Please ask on the user list to see if people are using them.
I suspect they may be used by some projects to link to special runtime
libraries when cross-compiling. We'd need to make sure there is a
better way for all such use cases before deprecating the commands.

We use link_directories() on Windows to give the windows linker the path
to the boost libraries. Those use '#pragma comment lib' to link required
libs.

How would one deal with '#pragma comment lib' w/o link_directories()?

Thanks,
Gregor
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[Ben Boeckel]

Post by Gregor Jasny via cmake-developers
How would one deal with '#pragma comment lib' w/o link_directories()?

I usually disable it with `-DBOOST_ALL_NO_LIB` (for Boost). In addition,
I find them to be not useful because Boost library names change between
static and shared (so they can live beside each other) and if you don't
set the preprocessor definitions right, they're not going to even use
the right filename anyways. Easier to just turn off autolinking and have
CMake do the right thing.

--Ben
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