Python 3.13 alpha breaks explain()

[mwichmann]

A change in Python 3.13 on Windows has causes unexpected output from --debug=explain. This doesn't come up often, of course, but the test suite does try to tickle the explainer behavior, and now we're seeing:

C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe test\explain\basic.py
STDOUT =========================================================================
6c6,9
< scons: rebuilding `file1' because `file1.in' changed
---
> scons: rebuilding `file1' because:
>            `\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is no longer a dependency
>            `file1.in' changed
>            `C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is a new dependency
8c11,14
< scons: rebuilding `file2' because `yyy' changed
---
> scons: rebuilding `file2' because:
>            `\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is no longer a dependency
>            `yyy' changed
>            `C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is a new dependency
10a17
>            `\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is no longer a dependency
12a20
>            `C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is a new dependency
14c22,28
< scons: rebuilding `file5' because `C:\Users\mats\AppData\Local\Temp\scons\testcmd.8680.tzpsvwcy\inc\bbb.k' changed
---
> scons: rebuilding `file5' because:
>            `\Users\mats\AppData\Local\Temp\scons\testcmd.8680.tzpsvwcy\inc\aaa' is no longer a dependency
>            `\Users\mats\AppData\Local\Temp\scons\testcmd.8680.tzpsvwcy\inc\bbb.k' is no longer a dependency
>            `\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is no longer a dependency
>            `C:\Users\mats\AppData\Local\Temp\scons\testcmd.8680.tzpsvwcy\inc\aaa' is a new dependency
>            `C:\Users\mats\AppData\Local\Temp\scons\testcmd.8680.tzpsvwcy\inc\bbb.k' is a new dependency
>            `C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is a new dependency
19a34
>            `\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is no longer a dependency
20a36
>            `C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is a new dependency

FAILED test of C:\Users\mats\Documents\github\scons\scripts\scons.py
        at line 680 of C:\Users\mats\Documents\github\scons\testing\framework\TestCommon.py (_complete)
        from line 775 of C:\Users\mats\Documents\github\scons\testing\framework\TestCommon.py (run)
        from line 458 of C:\Users\mats\Documents\github\scons\testing\framework\TestSCons.py (run)
        from line 262 of C:\Users\mats\Documents\github\scons\test\explain\basic.py

and

C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe test\explain\save-info.py
STDOUT =========================================================================
4c4,7
< scons: rebuilding `file1' because `file1.in' changed
---
> scons: rebuilding `file1' because:
>            `\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is no longer a dependency
>            `file1.in' changed
>            `C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is a new dependency
6c9,12
< scons: rebuilding `file2' because `yyy' changed
---
> scons: rebuilding `file2' because:
>            `\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is no longer a dependency
>            `yyy' changed
>            `C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is a new dependency
8a15
>            `\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is no longer a dependency
10a18
>            `C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is a new dependency
14c22,28
< scons: rebuilding `file5' because `C:\Users\mats\AppData\Local\Temp\scons\testcmd.19048.0_f116ml\inc\bbb.k' changed
---
> scons: rebuilding `file5' because:
>            `\Users\mats\AppData\Local\Temp\scons\testcmd.19048.0_f116ml\inc\aaa' is no longer a dependency
>            `\Users\mats\AppData\Local\Temp\scons\testcmd.19048.0_f116ml\inc\bbb.k' is no longer a dependency
>            `\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is no longer a dependency
>            `C:\Users\mats\AppData\Local\Temp\scons\testcmd.19048.0_f116ml\inc\aaa' is a new dependency
>            `C:\Users\mats\AppData\Local\Temp\scons\testcmd.19048.0_f116ml\inc\bbb.k' is a new dependency
>            `C:\Users\mats\AppData\Local\Programs\Python\Python313\python.exe' is a new dependency

FAILED test of C:\Users\mats\Documents\github\scons\scripts\scons.py
        at line 680 of C:\Users\mats\Documents\github\scons\testing\framework\TestCommon.py (_complete)
        from line 775 of C:\Users\mats\Documents\github\scons\testing\framework\TestCommon.py (run)
        from line 458 of C:\Users\mats\Documents\github\scons\testing\framework\TestSCons.py (run)
        from line 187 of C:\Users\mats\Documents\github\scons\test\explain\save-info.py

Initial suspicion is that this is caused by python/cpython#113829 which changes the behavior of isabs, and is the result (in part) of an ancient Python bug from 2007 (2.5 days)!.

It seems like it's only the debugging routine (SCons.Node.Node.explain) that's confused by this, which would make it relatively low priority. The only other open issue against 3.13 is #4502 which does not at first glance seem like it's likely related to this.

[mwichmann]

As an FYI:

C:\Users\mats\Documents\github\scons>py -3.12
Python 3.12.2 (tags/v3.12.2:6abddd9, Feb  6 2024, 21:26:36) [MSC v.1937 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> s = r'\users\mats'
>>> os.path.isabs(s)
True
>>> ^Z

C:\Users\mats\Documents\github\scons>py -3.13
Python 3.13.0a5 (tags/v3.13.0a5:076d169, Mar 12 2024, 21:29:03) [MSC v.1938 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> s = r'\users\mats'
>>> os.path.isabs(s)
False
>>> ^Z

[mwichmann]

Seems like this and #4502 are the same issue after all, rooted in the str_to_node methods in FileNodeInfo and DirNodeInfo.

[mwichmann]

Completed by #4505