Error installing muscle: it needs a version of libcxx which I cannot install

[lauraamaral]

I'm trying to use muscle on a mac (Sonoma, M2) and I keep having the same error regardless of how I install it (even using conda):

Could not solve for environment specs
The following packages are incompatible
└─ muscle is not installable because there are no viable options
  ├─ muscle [3.8.1551|5.3] would require
  │ └─ libcxx >=18 , which does not exist (perhaps a missing channel);
  └─ muscle [5.1.0|5.2|5.3] would require
   └─ libcxx >=16 , which does not exist (perhaps a missing channel).

When I print the list of packages in the env, it says that I actually have libcxx:

conda list libcxx
# packages in environment at /Users/jakeklemm/anaconda3:
#
# Name          Version          Build Channel
libcxx          20.0.0.dev5     h2d01d05_0  conda-forge/label/l

I tried to instal libcxx and libxc to fix the error but I still have the same issue. I troubleshoot in so many ways that I have lost hope, please help me!! haha Thank you!

[rcedgar]

This particular error looks like a bug in the Conda package. I have no idea how the packages are built, presumably there is a way to open an issue with the package rather than with muscle as such.

I'm not very familiar with Mac OSX. Muscle is self-contained C/C++ software with no dependencies on third-party code. Under Linux, this means that a binary is self-contained and that's all you need. Unfortunately, OSX does not allow static binaries, so there are dependencies on standard compiler libraries such as libcxx.

If your CPU is x86 or ARM, there is a pre-built OSX binary in the release here:

https://github.com/rcedgar/muscle/releases/tag/v5.3

If using the pre-built binary gives an error, googling the error message may give you a solution. Most likely, there are one or two standard dynamic libraries that are needed which should be straightforward to install.

Otherwise, you could try re-compiling from source. You can using the GitHub Actions for compiling on OSX as a starting point for which commands to use:

https://github.com/rcedgar/muscle/tree/main/.github/workflows