Change of libcxx linkage

[jjerphan]

#70 changed the linkage of libcxx which is now linked dynamically by default.

This has been observed for mamba with mamba-org/mamba#3434 (see those logs).

[h-vetinari]

If it's "just" the default, then prioritizing the shared library is actually in the interest of conda-forge's general preference for shared libraries. In that case micromamba should still be able to specify that it wants to link to libc++.a specifically?

If static linkage is not possible anymore then that would obviously be a bigger problem

[jjerphan]

OK, probably this should be advertised. What do you think?

[h-vetinari]

Most packages should be completely fine with shared linkage, as we ship libcxx basically in every environment. Cases like micromamba (everything statically linked) are very rare to my knowledge, so I doubt a conda-forge-wide announce is useful. But I don't mind in principle... 🤷‍♂️

[jjerphan]

OK let's close it then.

[isuruf]

#70 changed the linkage of libcxx which is now linked dynamically by default.

Why do you think #70 is the culprit?

[jjerphan]

The build logs on micromamba passed with the previous build but do not with the new one, here is the environment change in between the two:

@@ -424,10 +425,10 @@ List of packages in environment: "/Users/runner/micromamba/envs/mambabuild"
   bzip2                      1.0.8         h99b78c6_7          conda-forge
   c-ares                     1.33.1        hd74edd7_0          conda-forge
   ca-certificates            2024.8.30     hf0a4a13_0          conda-forge
-  cctools                    986           h4c9edd9_3          conda-forge
-  cctools_osx-arm64          986           hf2da8af_3          conda-forge
+  cctools                    1009.2        h4c9edd9_0          conda-forge
+  cctools_osx-arm64          1009.2        hfaac078_0          conda-forge
   certifi                    2024.8.30     pyhd8ed1ab_0        conda-forge
-  cffi                       1.17.0        py312h0fad829_1     conda-forge
+  cffi                       1.17.1        py312h0fad829_0     conda-forge
   chardet                    5.2.0         py312h81bd7bf_2     conda-forge
   charset-normalizer         3.3.2         pyhd8ed1ab_0        conda-forge
   click                      8.1.7         unix_pyh707e725_0   conda-forge
@@ -457,14 +458,14 @@ List of packages in environment: "/Users/runner/micromamba/envs/mambabuild"
   jsonschema                 4.23.0        pyhd8ed1ab_0        conda-forge
   jsonschema-specifications  2023.12.1     pyhd8ed1ab_0        conda-forge
   krb5                       1.21.3        h237132a_0          conda-forge
-  ld64                       711           h4c6efb1_3          conda-forge
-  ld64_osx-arm64             711           h5ecc89c_3          conda-forge
+  ld64                       907           h4c6efb1_0          conda-forge
+  ld64_osx-arm64             907           hdd277f2_0          conda-forge
   libarchive                 3.7.4         h83d404f_0          conda-forge
   libcurl                    8.9.1         hfd8ffcc_0          conda-forge
   libcxx                     18.1.8        h3ed4263_7          conda-forge
   libedit                    3.1.20191231  hc8eb9b7_2          conda-forge
   libev                      4.33          h93a5062_2          conda-forge
-  libexpat                   2.6.2         hebf3989_0          conda-forge
+  libexpat                   2.6.3         hf9b8971_0          conda-forge
   libffi                     3.4.2         h3422bc3_5          conda-forge
   libiconv                   1.17          h0d3ecfb_2          conda-forge
   liblief                    0.14.1        h3f3aa29_1          conda-forge
@@ -477,13 +478,15 @@ List of packages in environment: "/Users/runner/micromamba/envs/mambabuild"
   libssh2                    1.11.0        h7a5bd25_0          conda-forge
   libxml2                    2.12.7        h01dff8b_4          conda-forge
   libzlib                    1.3.1         hfb2fe0b_1          conda-forge
+  llvm-tools                 18.1.8        h5090b49_2          conda-forge
+  llvm-tools-18              18.1.8        h5090b49_2          conda-forge

[isuruf]

I would need to see the full compiler and linker commands to help with debugging.

[jjerphan]

I am not using a machine on macOS so I cannot really tell the different commands used. I recommend that you can browse those logs. Note that this was fixed for micromamba with mamba-org/mamba#3436.

[isuruf]

-static-libstdc++ was a deprecated option and I guess they removed it.