Override merge of dictionary: merge by dict keys?

[henryiii]

Description

I think I see a problem with override merging. I've set the following in TOML:

[tool.cibuildwheel.config-settings]
"cmake.define.RUN_CMAKE_TEST" = "ON"

[tool.cibuildwheel.linux.config-settings]
"cmake.define.OPENSSL_ROOT_DIR" = "/usr/local/ssl"
"cmake.define.CMAKE_JOB_POOL_COMPILE" = "compile"
"cmake.define.CMAKE_JOB_POOL_LINK" = "link"
"cmake.define.CMAKE_JOB_POOLS" = "compile=4;link=1"
"cmake.define.RUN_CMAKE_TEST" = "ON"

[[tool.cibuildwheel.overrides]]
select = ["*-musllinux_*",]
inherit.config-settings = "append"
config-settings."cmake.define.RUN_CMAKE_TEST_EXCLUDE" = "BootstrapTest|ExportImport|RunCMake.install|RunCMake.RuntimePath|RunCMake.file-GET_RUNTIME_DEPENDENCIES"

[[tool.cibuildwheel.overrides]]
select = ["*linux_aarch64", "*linux_ppc64le", "*linux_s390x"]
inherit.config-settings = "append"
config-settings."cmake.define.RUN_CMAKE_TEST" = "OFF"

And got:

 config_settings: 
    *: cmake.define.OPENSSL_ROOT_DIR=/usr/local/ssl cmake.define.CMAKE_JOB_POOL_COMPILE=compile cmake.define.CMAKE_JOB_POOL_LINK=link cmake.define.CMAKE_JOB_POOLS='compile=4;link=1' cmake.define.RUN_CMAKE_TEST=ON
    cp39-musllinux_s390x: cmake.define.OPENSSL_ROOT_DIR=/usr/local/ssl cmake.define.CMAKE_JOB_POOL_COMPILE=compile cmake.define.CMAKE_JOB_POOL_LINK=link cmake.define.CMAKE_JOB_POOLS='compile=4;link=1' cmake.define.RUN_CMAKE_TEST=ON cmake.define.RUN_CMAKE_TEST_EXCLUDE='BootstrapTest|ExportImport|RunCMake.install|RunCMake.RuntimePath|RunCMake.file-GET_RUNTIME_DEPENDENCIES' cmake.define.RUN_CMAKE_TEST=OFF

And it seems to be running the tests when building on these platforms. In theory, I would have expected it to merge config settings by key. Instead it seems to be appending strings.

python -m pip wheel /project --wheel-dir=/tmp/cibuildwheel/built_wheel --no-deps --config-settings=cmake.define.OPENSSL_ROOT_DIR=/usr/local/ssl --config-settings=cmake.define.CMAKE_JOB_POOL_COMPILE=compile --config-settings=cmake.define.CMAKE_JOB_POOL_LINK=link '--config-settings=cmake.define.CMAKE_JOB_POOLS=compile=4;link=1' --config-settings=cmake.define.RUN_CMAKE_TEST=ON '--config-settings=cmake.define.RUN_CMAKE_TEST_EXCLUDE=BootstrapTest|ExportImport|RunCMake.install|RunCMake.RuntimePath|RunCMake.file-GET_RUNTIME_DEPENDENCIES' --config-settings=cmake.define.RUN_CMAKE_TEST=OFF -v

Build (and now pip) will make a list if it gets the same value several times, that's how you make lists. So this produces {"cmake.define.RUN_CMAKE_TEST": ["ON", "OFF"]}, which seems to count for me as true.

I have a feeling that this was broken by #1730 (comment).

Build log

https://github.com/scikit-build/cmake-python-distributions/actions/runs/8609018236

CI config

No response