cos7 CDTs and new compilers

As part of our effort to add support for cos7 to linux-64, we’d like to do some refactoring of the structure of our CDTs. We (@isuruf and myself) are looking for community help in this work.

To do:

1. make sure old CDTs are mutually exclusive with the new ones

• patch the repo data to make all current CDTs conflict with the sysroot packages (https://github.com/conda-forge/conda-forge-repodata-patches-feedstock/pull/60)
• patch the CDT repo data on defaults so they conflict with the sysroot package (https://github.com/AnacondaRecipes/repodata-hotfixes/pull/94)
• patch repodata so that new sysroots don’t interact with old compilers (https://github.com/conda-forge/conda-forge-repodata-patches-feedstock/pull/66, https://github.com/conda-forge/conda-forge-repodata-patches-feedstock/pull/65)

1. build CDTS

• setup one-off CDT builds on conda-forge (https://github.com/conda-forge/cdt-builds/pull/2)
• build all of the old-style CDTs
• build all of the new-style ones too
• make all CDTs use no_hoist: true in the source sections
• new-style CDTs should use the new conda sysroot (i.e., {{ arch }}-conda-linux-gnu) sysroot
• new-style CDTs should depend on the correct version of the sysroot package (i.e., cos6 depends on 2.12 and cos7 depends on 2.17)
• old-style CDTs need to have the proper run_constrained
• see https://hackmd.io/T5q0GPa1QfKfQ6irNWAe5Q?edit for notes from the CDT discussion

1. move to only conda-forge CDTs

• enable strict channel priority in the ci setup scripts (to make sure we always use our CDTs, https://github.com/conda-forge/conda-forge-ci-setup-feedstock/pull/110)

1. turn on new compilers

• finally remove the symlinks and CDT-location variants in the new compilers (https://github.com/conda-forge/linux-sysroot-feedstock/pull/26, https://github.com/conda-forge/linux-sysroot-feedstock/pull/27)
• make sure to add a sysroot run dep to gcc_impl, gxx_impl and gfortran_impl so that the repo data patches above don’t break the new compilers (https://github.com/conda-forge/ctng-compilers-feedstock/pull/32)

cc @isuruf @jakirkham @kkraus14 @nehaljwani @mingwandroid @jjhelmus

xref: https://github.com/conda-forge/conda-forge.github.io/issues/900 closes https://github.com/conda-forge/ctng-compilers-feedstock/issues/28

[beckermr]

I planned to do this at the core meeting

[beckermr]

I will push the script later. There are ~250 cdts in defaults. Idk which ones we use