[Software Issue] Unable to build with CMake 4.0

[tmiw]

Platform

Linux

Platform Version

GitHub ubuntu-24.04

FreeDV Version

2.0.0-dev2 (commit cfb4f04)

Steps to Reproduce

Configure FreeDV source code for build using CMake 4.0 (and force building of dependencies--most commonly done for Windows and macOS builds).

Expected Behavior

FreeDV is able to build.

Actual Behavior

Error during CMake execution:

-- Will attempt static build of samplerate.
CMake Warning (dev) at /usr/local/share/cmake-4.0/Modules/FetchContent.cmake:1953 (message):
  Calling FetchContent_Populate(samplerate) is deprecated, call
  FetchContent_MakeAvailable(samplerate) instead.  Policy CMP0169 can be set
  to OLD to allow FetchContent_Populate(samplerate) to be called directly for
  now, but the ability to call it with declared details will be removed
  completely in a future version.
Call Stack (most recent call first):
  cmake/BuildSamplerate.cmake:16 (FetchContent_Populate)
  CMakeLists.txt:500 (include)
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Error at build_windows/_deps/samplerate-src/CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 3.5 has been removed from CMake.

  Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
  to tell CMake that the project requires at least <min> but has been updated
  to work with policies introduced by <max> or earlier.

  Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.


-- Configuring incomplete, errors occurred!

Additional Comments

wxWidgets had a similar error during configuration but upgrading it to 3.2.7 fixed it for that project.

[tmiw]

Creating a GH issue for this to track. I'm not sure how common 4.0 is yet in the general community but it does mean that GH actions are no longer able to build.

@Tyrbiter, @barjac, I don't suppose Fedora's already using 4.0?

[Tyrbiter]

Fedora rawhide (which will become Fedora 43 in 6-7 months or so) has cmake-4.0.0~rc4 which means that it won't be in the mainstream distro for a while, although I can't say exactly when.

Fedora also has wxGTK-3.2.6 as the latest version currently, I don't see any rawhide wxGTK-3.2.7 builds yet.

[tmiw]

Fedora rawhide (which will become Fedora 43 in 6-7 months or so) has cmake-4.0.0~rc4 which means that it won't be in the mainstream distro for a while, although I can't say exactly when.

Fedora also has wxGTK-3.2.6 as the latest version currently, I don't see any rawhide wxGTK-3.2.7 builds yet.

Good to know. 👍

From what I can tell, this build failure only happens when CMake builds FreeDV dependencies (which typically only happens for Windows and macOS builds; Linux ones presumably use distro packages). Looking at the CMake code, it appears that it's mainly wxWidgets and libsamplerate that have problems.

Unfortunately, libsamplerate may have the same problem that sioclient did, namely that it doesn't seem to get many updates. Last update in their repo was almost a year ago, so I'm not sure if the PR someone created to fix this problem will be merged/a new release made any time soon. We could do one of the following:

1. Patch libsamplerate ourselves using the code in that PR. There's precedent for this with Hamlib.
2. Switch libsamplerate to being built with autoconf. Most other dependencies are built this way already, FWIW.
3. Include libsamplerate into our source tree and apply the PR code mentioned above. There aren't that many files in its src folder (I counted 8 .c and .h files), so this wouldn't be the most terrible idea.
4. Maybe revisit FreeDV resampling filters #777 and switch over to a different library?

Thoughts?

[tmiw]

This is now fixed in the latest v2.0-dev branch, so going ahead and closing.