hgmain: fix undefined python symbol at runtime.

[ghost]

Commit dc45ccb introduced pygitcompat to talk to git from python.

extension-module is enabled:

https://github.com/facebook/sapling/blob/dc45ccbbc2bafb850e4535159d6c96793f27738e/eden/scm/saplingnative/bindings/modules/pygitcompat/Cargo.toml#L10

which ultimately enables python3-sys/extension-module.

According to the python3-sys documentation, extension-module prevents the final artifact from being linked against the shared Python library:

 # Use this feature when building an extension module.
 # It tells the linker to keep the python symbols unresolved,
 # so that the module can also be used with statically linked python interpreters.
extension-module = [ "python3-sys/extension-module" ]

It leads to a bug where the final binary sl is not linked against Python:

$ otool -L /tmp/sl_dc45ccb
/tmp/sl_dc45ccb:
        /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 1700.255.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1345.100.2)
        /System/Library/Frameworks/Cocoa.framework/Versions/A/Cocoa (compatibility version 1.0.0, current version 24.0.0)
        /System/Library/Frameworks/WebKit.framework/Versions/A/WebKit (compatibility version 1.0.0, current version 618.1.15)
        /usr/lib/libiconv.2.dylib (compatibility version 7.0.0, current version 7.0.0)
        /System/Library/Frameworks/Security.framework/Versions/A/Security (compatibility version 1.0.0, current version 61123.100.169)
        /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 2420.0.0)
        /opt/homebrew/opt/openssl@3/lib/libssl.3.dylib (compatibility version 3.0.0, current version 3.0.0)
        /opt/homebrew/opt/openssl@3/lib/libcrypto.3.dylib (compatibility version 3.0.0, current version 3.0.0)
        /System/Library/Frameworks/CoreServices.framework/Versions/A/CoreServices (compatibility version 1.0.0, current version 1226.0.0)
        /System/Library/Frameworks/SystemConfiguration.framework/Versions/A/SystemConfiguration (compatibility version 1.0.0, current version 1300.100.9)
        /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.12)
        /usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)
$ /tmp/sl_dc45ccb
dyld[8926]: symbol not found in flat namespace '_PyBool_Type'
Abort trap: 6

This commit removes the extension-module feature flag to link again against libpython:

$ otool -L /tmp/sl_fix
/tmp/sl_fix:
        /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 1700.255.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1345.100.2)
        /System/Library/Frameworks/Cocoa.framework/Versions/A/Cocoa (compatibility version 1.0.0, current version 24.0.0)
        /System/Library/Frameworks/WebKit.framework/Versions/A/WebKit (compatibility version 1.0.0, current version 618.1.15)
        /usr/lib/libiconv.2.dylib (compatibility version 7.0.0, current version 7.0.0)
        /System/Library/Frameworks/Security.framework/Versions/A/Security (compatibility version 1.0.0, current version 61123.100.169)
        /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 2420.0.0)
        /opt/homebrew/opt/openssl@3/lib/libssl.3.dylib (compatibility version 3.0.0, current version 3.0.0)
        /opt/homebrew/opt/openssl@3/lib/libcrypto.3.dylib (compatibility version 3.0.0, current version 3.0.0)
        /System/Library/Frameworks/CoreServices.framework/Versions/A/CoreServices (compatibility version 1.0.0, current version 1226.0.0)
        /System/Library/Frameworks/SystemConfiguration.framework/Versions/A/SystemConfiguration (compatibility version 1.0.0, current version 1300.100.9)
        /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.12)
>>>>>   /opt/homebrew/opt/python@3.11/Frameworks/Python.framework/Versions/3.11/Python (compatibility version 3.11.0, current version 3.11.0)
        /usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)

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[ghost]

Hi sapling team! 👋 I've seen that the file I've modified is generated by some internal tool you have (I guess autocargo?), but I couldn't find the original files used by that generator.

https://github.com/facebook/sapling/blob/6c49fe382c91bc1a28be0a6c3d348b159a96c957/eden/scm/saplingnative/bindings/modules/pygitcompat/Cargo.toml#L1

If you can provide me with some hints I could make it right!

[muirdm]

I've imported your PR and turned the features off in the underlying build file. Thanks!

[facebook-github-bot]

@muirdm merged this pull request in facebook/sapling@01313b573e830619dfbc76c729b5c2b91f8c4569.