build-details.json should be installed to different locations for nondebug/debug builds and have distinct base_interpreter values

[befeleme]

Bug report

Bug description:

In Fedora, we build Python in 4 variants: debug, optimized, freethreading-debug and freethreading. For all of them builds the base_interpreter value stored in the file build-details.json is the same:

  "base_interpreter": "/usr/bin/python3.14",

I suspect it should reflect the build type and contain the applicable suffix(es): d, t, td.
Because of this line, when we run Python's test suite on an installed python3-debug, the test fails, as you can see e.g. here: https://artifacts.dev.testing-farm.io/0ac8ab69-ed5f-4602-9c01-8c13293aa9b6/

test_base_interpreter (test.test_build_details.CPythonBuildDetailsTests.test_base_interpreter) ... FAIL

======================================================================
FAIL: test_base_interpreter (test.test_build_details.CPythonBuildDetailsTests.test_base_interpreter)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib64/python3.14/test/test_build_details.py", line 124, in test_base_interpreter
    self.assertEqual(os.path.realpath(value), os.path.realpath(sys.executable))
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: '/usr/bin/python3.14' != '/usr/bin/python3.14d'
- /usr/bin/python3.14
+ /usr/bin/python3.14d
?                    +

Another issue is that in both cases, the debug and non-debug files are installed to the same location, resulting in a single rewritten file. In case of our sequential build of 4 Pythons, we end up with just two files. Should they be stored in distinct locations for each build instead?

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs

• gh-131372: Include LDVERSION and EXE in base_interpreter value #142256
• GH-131372: only install build-details.json in the main install #142269
• gh-131372: Configurable build-details.json name #150098
• gh-131372: Fix a typo #150414

[hugovk]

cc @FFY00

[FFY00]

Another issue is that in both cases, the debug and non-debug files are installed to the same location, resulting in a single rewritten file. In case of our sequential build of 4 Pythons, we end up with just two files. Should they be stored in distinct locations for each build instead?

Just ship the file for the main/default interpreter, I guess? We probably shouldn't install the file in altinstall, and better document expectations for scenarios like yours.

[vstinner]

Another issue is that in both cases, the debug and non-debug files are installed to the same location, resulting in a single rewritten file. In case of our sequential build of 4 Pythons, we end up with just two files. Should they be stored in distinct locations for each build instead?

We may do something similar to sysconfigdata filename like including ABI tags. Example:

• build-details.json: default Python
• build-details_d.json: debug build
• etc.

[stefanor]

FWIW, there is a draft PEP PR to resolve the design: python/peps#4889