Use the symlink-resolved location of Python in getpath on 3.14+

[geofft]

Mostly fixes #380, and also fixes #713 because we prefer the actual
binary path to argv[0].

[jjhelmus]

Passing the path the the executable via the library variable in getpath.py has a smell as the variable is described as being the path to the dylib/DLL/so. When static linking there is no shared library so I see the logic in passing the path to the binary (as it is a DSO) itself.

[jjhelmus]

With this patch the directory pointed to by home in the pyvenv.cfg is still searched if the library search fails (but it should not fail).

The change from python/cpython#106045 (comment) (below) would update this path to the directory of the base_executable when it exists. I'm somewhat partial to that solution in addition to this change.

@@ -411,6 +412,9 @@ def search_up(prefix, *landmarks, test=isfile):
                             if isfile(candidate):
                                 base_executable = candidate
                                 break
+                if base_executable and isfile(base_executable):
+                    # Update the executable directory to be based on the resolved base executable
+                    executable_dir = real_executable_dir = dirname(base_executable)
             # home key found; stop iterating over lines
             break

[jjhelmus]

I've found following helpful check/reproduce/debug this issue:

./configure --prefix=/example
make -j
make DESTDIR=<some_real_path> install
cd <some_real_path>
./example/bin/python3.14 # can be used to create symlinks/venv/etc 

[zanieb]

Did you mean to close this?

[jjhelmus]

Did you mean to close this?

Nope, oops

[geofft]

I think adding both this patch and the one in #903 is a good idea, though even with both patches I would consider it not quite a complete fix.

I've added some test cases based on #380 and #713. The patch in #903 by itself passes the tests for #380 but not the one in #713. (On the other hand the patch in #903 works on 3.11+.)

Getting this patch to work for 3.11-3.13 isn't hard, but I'm not sure if I will get to that today.

[zanieb]

Can this be a part of the skipif?

[geofft]

I don't think you can skipIf a single subTest. You can call self.skipTest("doesn't yet work on arm64"). I probably could have structured this one as a separate test case, though....

[zanieb]

Includes #903?

[jjhelmus]

Includes #903?

Yes, this supersedes #903

[geofft]

Yes, to fix the aarch64 failures.