PEP-739 build-details generation is broken when --relative-paths is specified

[itamaro]

Bug report

Bug description:

With a freshly python built from main (on MacOS in this repro, but also tested on Linux), trying to generating the PEP-739 build-details with the --relative-paths option fails.

$ ./python.exe -E Tools/build/generate-build-details.py /tmp/build-details.json --relative-paths

Traceback:

Traceback (most recent call last):
  File "/Users/itamaro/work/cpython/Tools/build/generate-build-details.py", line 194, in <module>
    main()
    ~~~~^^
  File "/Users/itamaro/work/cpython/Tools/build/generate-build-details.py", line 186, in main
    make_paths_relative(data, args.config_file_path)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/itamaro/work/cpython/Tools/build/generate-build-details.py", line 157, in make_paths_relative
    new_path = os.path.relpath(current_path, data['base_prefix'])
  File "/Users/itamaro/work/cpython/Lib/posixpath.py", line 519, in relpath
    path = os.fspath(path)
TypeError: expected str, bytes or os.PathLike object, not dict

CPython versions tested on:

CPython main branch, 3.15, 3.14

Operating systems tested on:

macOS, Linux

Linked PRs

• gh-136264: Fix PEP-739 build-details generation with relative-paths #136265
• gh-136264: Fix --relative-paths for PEP 739's build-details.json #138510
• [3.14] gh-136264: Fix --relative-paths for PEP 739's build-details.json (GH-138510) #138638

[StanFromIreland]

@itamaro The needs backport labels only work on prs.

[itamaro]

cc @FFY00

[itamaro]

cc @pfmoore maybe you can help out here (and on #136267), given your context with PEP-739? thanks!

[pfmoore]

Sorry, I don't have any useful insights to offer.