Trying to understand why manifest mode rebuild packages already built in classic mode, bypassing the cache

[nbmaltais]

I am trying to understand why when using manifest mode, packages are rebuilt event thought they have been built in classic mode.

I undesrtand that the manifest mode may use a different baseline than classic mode, but I did my test usign a freshly clone vcpkg repository.

Here is the test:
in classic mode:

vcpkg install fmt --debug

In manifest mode:

vcpkg new --application
vcpkg add port fmt
vcpkg install --debug

When I look at the various debug message, I see that the abientries varies for vcpkg-cmake and vcpkg-cmake-config

ABI for classic:
[DEBUG]
[DEBUG] cmake|3.31.1
[DEBUG] features|core
[DEBUG] portfile.cmake|4a1a39b9362c963ad53915f8e9326887aa70b20709b6805fcbc9aaeb086f1b35
[DEBUG] ports.cmake|f4cc0e4d312b743fcb1e9b680c66d17bb556996dc267dc1301eac9037608a378
[DEBUG] post_build_checks|2
[DEBUG] powershell|7.5.3
[DEBUG] triplet|x64-windows
[DEBUG] triplet_abi|4556164a2cd3dd6f4742101eabb46def7e71b6e5856faa88e5d005aac12a803c-1d3d767ab10b488977977b83f6c2da7e06afd80b1e375a2a41c60c343e7b3f94-69f3fcb4287a82aeae53eb50206a3b209714d0ac
[DEBUG] usage|ece096518c58df58cfc60f5ad8120d248a86383482455f539d91b8ca6eac14a7
[DEBUG] vcpkg-cmake|708aabf8f500fd8398cef29811cc76fc50cd5aec6a31397edbfbd415a74c1572
[DEBUG] vcpkg-cmake-config|ad8ccb4e17e096b1f3af0b4869eb1fa6c9728511b888ea2bec2ce04132dca47b
[DEBUG] vcpkg.json|56643eba77a1084e3b9a6dea7a13449a4b94c2760c9da46aa8b33aef5ccf2aad
[DEBUG] vcpkg_copy_pdbs|d15c2f2822d93ecb9023af44803328e491c5374136e0813600289582a72d196d
[DEBUG] vcpkg_fixup_pkgconfig|1a15f6c6d8e2b244d83a7514a0412d339127d2217d1df60ad1388b546c85f777
[DEBUG] vcpkg_from_git|96ed81968f76354c00096dd8cd4e63c6a235fa969334a11ab18d11c0c512ff58
[DEBUG] vcpkg_from_github|1284881728e98a182fc63e841be04e39b8c94753fdc361603c72a63c1adcf846
[DEBUG] vcpkg_install_copyright|ba6c169ab4e59fa05682e530cdeb883767de22c8391f023d4e6844a7ec5dd3d2
[DEBUG]

ABI for manifest:

[DEBUG]
[DEBUG] cmake|3.31.1
[DEBUG] features|core
[DEBUG] portfile.cmake|4a1a39b9362c963ad53915f8e9326887aa70b20709b6805fcbc9aaeb086f1b35
[DEBUG] ports.cmake|f4cc0e4d312b743fcb1e9b680c66d17bb556996dc267dc1301eac9037608a378
[DEBUG] post_build_checks|2
[DEBUG] powershell|7.5.3
[DEBUG] triplet|x64-windows
[DEBUG] triplet_abi|4556164a2cd3dd6f4742101eabb46def7e71b6e5856faa88e5d005aac12a803c-1d3d767ab10b488977977b83f6c2da7e06afd80b1e375a2a41c60c343e7b3f94-69f3fcb4287a82aeae53eb50206a3b209714d0ac
[DEBUG] usage|ece096518c58df58cfc60f5ad8120d248a86383482455f539d91b8ca6eac14a7
[DEBUG] vcpkg-cmake|7d6b37af7ab0e35ed2d873445b58289a84d07db856a678d755b4092a330e8d7a
[DEBUG] vcpkg-cmake-config|273b92322240fc452aec671908073d4e9b7deff906e05024edc81e1acedafdb9
[DEBUG] vcpkg.json|56643eba77a1084e3b9a6dea7a13449a4b94c2760c9da46aa8b33aef5ccf2aad
[DEBUG] vcpkg_copy_pdbs|d15c2f2822d93ecb9023af44803328e491c5374136e0813600289582a72d196d
[DEBUG] vcpkg_fixup_pkgconfig|1a15f6c6d8e2b244d83a7514a0412d339127d2217d1df60ad1388b546c85f777
[DEBUG] vcpkg_from_git|96ed81968f76354c00096dd8cd4e63c6a235fa969334a11ab18d11c0c512ff58
[DEBUG] vcpkg_from_github|1284881728e98a182fc63e841be04e39b8c94753fdc361603c72a63c1adcf846
[DEBUG] vcpkg_install_copyright|ba6c169ab4e59fa05682e530cdeb883767de22c8391f023d4e6844a7ec5dd3d2
[DEBUG]

I can't understand why the two modes won't result in the same ABI since they use exactly the same tripplet, compiler, etc.
For small library, this is not a problem, but for large libraries like Qt, rebuilding is very long.

Is it a bug? Am I missing something?

Regards,

Nicolas

[Osyotr]

Probably outdated vcpkg-cmake in classic mode. Try removing installed/.

[nbmaltais]

Ok, this works, but is it overkill?

Why didn't the vcpkg-cmake package get updated when we pull the latest version of the repo and run the upgrade command?

[Osyotr]

This was designed before manifest mode was a thing. Ironically, to reduce the number of excessive rebuilds.

[nbmaltais]

Is there any way for force update those file, appart from deleting installed ?

[Osyotr]

There is vcpkg upgrade.
I recommend sticking to manifest mode though.

[dg0yt]

Note that classic mode doesn't use versioning and will use what is currently checked out in the vcpkg clone, in combination with what is already installed.
Manifest mode will select versions starting from the user-defined "baseline" instead, independent of what is already installed.

(I see now that one part of my initial comment is mentioned in the initial post.)