gh-148690: Build abi3t-compat\python3.dll on Windows

[encukou]

Per discussion in #146636 (comment), this adds abi3t-compat\python3.dll to Windows builds.

And to the WiX installer, though I haven't managed to test this.

• Issue: Free-threaded and GIL-enabled Windows builds should share an abi3 libpython dll #148690

[clin1234]

Looks congruent to me

[zooba]

Looks like a solid change, but probably simpler to just create a python3t.vcxproj and put the python3t.dll in the default location, which will remove a lot of the modifications (and can simplify things you didn't even add, since we'll just build it twice and python3.dll and python3t.dll are now both constants). We rearrange output files as part of building the installer, so that's where the directory should come into it.

It won't work so nicely for dev/in-tree builds, but I'm not so concerned about that. We probably need to choose an entirely new output directory for free-threaded builds, but that's going to break all sorts of stuff that assumes directory names in a build, so probably best to just say "ABI3 will get weird in dev builds if you don't clean before switching kind of build". I expect anyone trying to work on both simultaneously has separate clones anyway.

[chris-eibl]

I've tried to build the installer using your branch and get the same error as CI:

error CNDL0027: The File/@Name attribute's value, 'abi3t-compat\python3t.dll', is not a valid long name because it contains illegal characters.

Changing to

            <Component Id="python_abi3tcompat.dll" Directory="abi3t_compat" Guid="*">
                <File Id="python_abi3tcompat.dll" Name="python$(var.MajorVersionNumber)t.dll" KeyPath="yes" />
            </Component>

and adding the directory to Tools/msi/common.wxs:

    <Fragment>
        <DirectoryRef Id="InstallDirectory">
            <Directory Id="abi3t_compat" Name="abi3t-compat" />
        </DirectoryRef>
    </Fragment>

Note Id="abi3t_compat" is chosen, because - is not allowed in an identifier.

As Steve mentions

put the python3t.dll in the default location,

then the above did work for me (when manually copying the dll just to try it out).

Otherwise, you'd have to add a Source in

<File Id="python_abi3tcompat.dll" Name="python$(var.MajorVersionNumber)t.dll" KeyPath="yes" />

But this is all new to me as well ...

[chris-eibl]

Adding

        <LinkerBindInputPaths Include="$(BuildPath)">
            <BindName>build</BindName>
        </LinkerBindInputPaths>

to Tools\msi\msi.props and using

<File Id="python_abi3tcompat.dll" Name="python$(var.MajorVersionNumber)t.dll" Source="!(bindpath.build)\abi3t-compat\python$(var.MajorVersionNumber)t.dll" KeyPath="yes" />

did work for me using your current layout.

[chris-eibl]

And IMHO we should bundle python3t_d.dll in the installer as well.

[zooba]

Changing to

            <Component Id="python_abi3tcompat.dll" Directory="abi3t_compat" Guid="*">
                <File Id="python_abi3tcompat.dll" Name="python$(var.MajorVersionNumber)t.dll" KeyPath="yes" />
            </Component>

and adding the directory to Tools/msi/common.wxs:

    <Fragment>
        <DirectoryRef Id="InstallDirectory">
            <Directory Id="abi3t_compat" Name="abi3t-compat" />
        </DirectoryRef>
    </Fragment>

This is the way.

this is all new to me as well ...

In two more weeks we get to never touch this MSI again :)