libmodbus Add version 3.1.12 and stop publishing revs for older versions

[ottmar-zittlau]

Summary

Add libmodbus/3.1.12

Motivation

Added libmodbus v3.1.12 because they fixed some issues on their side (stephane/libmodbus#829 & stephane/libmodbus#830) that complicate the current recipe.

Details

Added the new version and stopped publishing revs for older versions.

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• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• If this is a bug fix, please link related issue or provide bug details
• Tested locally with at least one configuration using a recent version of Conan

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[ottmar-zittlau]

@uilianries I looked into the failing MacOs test and I think the build is already failing (log), because there are some errors of the type:
ld: warning: ignoring file '.libs/modbus.o': found architecture 'arm64', required architecture 'x86_64'
If I understand this correctly the linker just ignores all the interesting parts.

I tried the cross-compilation on my (ubuntu 24.04) machine with gcc14 by running

conan create . --version 3.1.12 -s:h arch=x86_64 -s:b arch=armv8 --build missing
This works and compared the output that is generated to the pipeline job output. I noticed that the ldflags in the pipeline job contain an explicit -arch x86_64:
ldflags: -m64 -isysroot /Applications/conan/xcode/26.0.1/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX26.0.sdk -arch x86_64
On my machine it's only
ldflags: -m64
but I don't understand what the apple linker requires.

Do I need to handle the cross-compilation case explicitly in my recipe, e.g. by using apple_arch_flag (cf. https://docs.conan.io/2/reference/tools/gnu/autotoolstoolchain.html#customization)?

[uilianries]

@ottmar-zittlau Thank you for investigating the case!

The problem was related to cflags not being respected: on OSX we pass -arch x86_64 when generating for Mac Intel cpus, but it's injected via CFGLAS. Fortunately, the upstream has a proper fix merged on its master branch.

I just updated your PR to use that patch, so we will not need to care about it in the future.

I also removed version 1.3.11 from conandata.yml, as no other recipe in the Conan Center Index consumes libmodbus. No version will be removed from Conan Center; all packages will remain there. The only change is that CI will stop producing new revisions for those older versions.

Regards!

[uilianries]

The build https://github.com/conan-io/conan-center-index/pull/30083/checks?check_run_id=74180454570 failed due MSVC trying to consume GCC warning flags.

This error was mitigated previously by applying a non-official patch to remove warning flags.

I reported this case to the upstream, so we may have a proper fix in the future: stephane/libmodbus#846

As an alternative, I simplified the previous patch to only use those warning flags in case of using a supported compiler: 0627c3d

[uilianries]

@ottmar-zittlau Thank you for your PR! It looks good to me now! 😄

Reviewer Notes

• Latest version is 3.1.12: https://github.com/stephane/libmodbus/releases
• No other recipe is consuming libmodbus in Conan Center, so removing old versions from conandata.yml is fine; No package will be removed from Conan Center, all old version will remain available for download as before.

Maintainer Changes

• Dropped version 3.1.11 from conandata.yml as version 3.1.12 cover the same version, plus, more fixes.
• Using official patch 0001-repect-cflags.patch from the upstream to deal with cflags. So far, we have had a custom implementation in this recipe.
• Reported the upstream about MSVC error with warning flags: stephane/libmodbus#846
• Using a proposed patch, similar to the previous one, to avoid consuming Warning flags for non GCC compatible compilers
• Proposed a fix for ssize_t redefinition on Windows: stephane/libmodbus#847 - The same is now listed as 0003-fix-typedef-int.patch

[ottmar-zittlau]

@uilianries Thanks a lot for finishing this and explaining your changes!