Set library version on future releases

[jin-eld]

Adding this issue as discussed with @iphydf on IRC as a reminder for future versions:

make sure to correctly set the library version which describes ABI compatibility.

For the autotools build this can be done by setting the LIBTOXCORE_LT_VERSION variable in configure.ac, its value is then passed to libtool. There probably is something similar for the cmake build as well.

More details about library versioning can be found here:
https://www.gnu.org/software/libtool/manual/libtool.html#Versioning

[iphydf]

@cebe #394 solves this for cmake, right? @jin-eld can we automate this for autotools somehow?

[jin-eld]

@iphydf well, I am not familiar with the cmake versioning, but from what I saw in the #394 diff you basically use the c-toxcore project version as the .so version?

That would not work for autotools, have a look at:
https://www.gnu.org/software/libtool/manual/libtool.html#Versioning

libtool has a clearly defined versioning scheme for libraries that has nothing to do with the project version, I am not sure if this can be automated, because you actually have to know what you changed in the library in order to set the version, i.e. you need to know if you did or did not break the ABI on the new release then set the .so version accordingly...

[cebe]

@iphydf I thought it should, but reading these docs seems it is not 100% correct. Need to verify that in more detail.

[jin-eld]

@cebe we discussed the so versioning with @iphydf on IRC yesterday and came up with an idea that it would make sense if both build systems use the same .so versioning scheme, basically it should not matter if you build using autotools or cmake - the resulting library should always be exactly the same (provided that you used the same optional parameters).

I read the cmake links you posted regarding the version and it seemed to me that there are no hard requirements there, you can just set major.minor, at the same time it was not clear if setting x.y.z (3 numbers) would cause any problems for the cmake build?

Since libtool has strict requirements regarding the .so version while cmake does not seem to care that much, I suggest that both builds use the libtool versioning.

Ideally both build systems should take the version numbers from the same file, the file can/will be processed by the sync-version script that is being used during the release process (but that's another topic).

And here's where I need your help, because I am not familiar with cmake at all.

Can you easily import configurations (I would just include some soversion.config in Makefile.am) and what format would be usable in cmake?

For autotools I'd either put LIBTOXCORE_LT_VERSION=x:y:z there or it could also be split
into something like:

CURRENT=x
REVISIOON=y
AGE=y
SO_VERSION=$CURRENT:$REVISION:$AGE

Maybe /msg me on IRC so we can talk (please really use /msg otherwise I might not notice, because I am not constantly reading the channel), thank you.

[cebe]

basically it should not matter if you build using autotools or cmake - the resulting library should always be exactly the same

fully agree

Ideally both build systems should take the version numbers from the same file, the file can/will be processed by the sync-version script that is being used during the release process (but that's another topic).

👍

I have never read something from a file in cmake but there seems to be a command that does that:
https://cmake.org/cmake/help/v3.0/command/file.html

[cebe]

The following will work in cmake:

# .so library version / following libtool scheme
#
#            current:revision:age
#
# current:  increment if interfaces have been added, removed or changed
# revision: increment if source code has changed, set to zero if current is
#           incremented
# age:      increment if interfaces have been added, set to zero if
#           interfaces have been removed or changed

CURRENT=0
REVISION=0
AGE=0 

file(STRINGS ${toxcore_SOURCE_DIR}/soversion SOVERSION_CURRENT REGEX "^CURRENT=[0-9]+$")
string(SUBSTRING "${SOVERSION_CURRENT}" 8 -1 SOVERSION_CURRENT)
file(STRINGS ${toxcore_SOURCE_DIR}/soversion SOVERSION_REVISION REGEX "^REVISION=[0-9]+$")
string(SUBSTRING "${SOVERSION_REVISION}" 9 -1 SOVERSION_REVISION)
file(STRINGS ${toxcore_SOURCE_DIR}/soversion SOVERSION_AGE REGEX "^AGE=[0-9]+$")
string(SUBSTRING "${SOVERSION_AGE}" 4 -1 SOVERSION_AGE)
message("SOVERSION: ${SOVERSION_CURRENT}:${SOVERSION_REVISION}:${SOVERSION_AGE}")

[jin-eld]

Not sure why, but it did not work, I fixed the file name (I am using so.version) and I tried replacing : with . because cmake expects x.y.z unlike libtool that expect x:y:z and I also tried setting VERSION instead of SOVERSION but I did not get anywhere.

I'd be happy if you could follow up on the cmake part, the autotools PR is here:
#420