Using registires

[johne53]

I'm running the latest version of vcpkg (downloaded this morning). I'm eventually hoping to build the glibmm port but with some of the ports (glib and glibmm) building earlier versions. But for testing purposes at the moment I'm attempting this with just glibmm.

The impression I've got from other threads here is that the way to do this is in Manifext mode and with the use of something called registries (i.e. vcpkg-configuration.json files). I created my own build folder and added a vcpkg.json file which looks like this:-

{
  "$comment": "baseline value is the latest commit in vcpkg repo as of 14.03.2026",
  "builtin-baseline": "4b77da7fed37817f124936239197833469f1b9a8",
  "dependencies": [
    "glibmm"
  ],
  "overrides": [
    {
      "name": "glibmm",
      "version": "2.80.1"
    },
    {
      "$comment": "glibmm 2.76.0 depends on a package that has been renamed, so need to specify that too",
      "name": "libsigcpp-3",
      "version": "3.0.3#1"
    }
  ]
}

I then tried to override it by adding a file called vcpkg-configuration.json which looks like this:-

{
  "default-registry": {
    "kind": "git",
    "repository": "https://github.com/Microsoft/vcpkg",
    "baseline": "4b77da7fed37817f124936239197833469f1b9a8"
  },
  "registries": [
    {
      "kind": "git",
      "repository": "https://github.com/Microsoft/vcpkg",
      "baseline": "934a99dc13cabb330824ae1a5ab4a53a9acc5a49",
      "packages": [ "glibmm*", "giomm*" ]
    }
  ]
}

My understanding is that the baseline beginning with 934a99d is the one for specifying an earlier glibmm version (2.74.0). And sure enough when I try a dry run, it starts off by showing me this message::-

warning: attempting to set builtin-baseline in vcpkg.json while overriding the default-registry in vcpkg-configuration.json.
the default-registry from vcpkg-configuration.json will be used.

So it looks live my vcpkg-configuration.json file will get used - but using the default baseline and not use the entry I'd added for building version 2.74.0. And in fact later, the dry run confirms that glibmm will get built at version 2.80.1

What have I done wrong??

[johne53]

I think I figured it out... in my vcpkg.joson file there's a section like this:-

  "overrides": [
    {
      "name": "glibmm",
      "version": "2.80.1" // <--- THIS LINE !!!
    },

Previously I'd thought that vcpkg-configuration.json would override vcpkg.json (i.e. vcpkg.json would be ignored). But AFAICT that doesn't seem to be the case.

But it begs the question ,will I need to edit vcpkg.json whan I come to need glib to build an earlier version too? My understanding is that vcpkg.json can either contain the baseline for glibmm OR for gflib (i.e. not both) so I'm a bit confused.

[johne53]

Or can someone please tell me how to obtain the builtin-baseline for a port (sometimes called the default baseline)? I f found this example:-

https://learn.microsoft.com/en-us/vcpkg/commands/hash

which shows how to obtain a hash (builtin-baseline / default baseline?) for the port called boost_1_83_0. It relies on the user being able to find a file called boost_1_83_0.tar.bz2. Unfortunately it doesn't explain how (or where) the .bz2 files can be found. Maybe at one time they were provided when cloning vcpkg but AFAICT that doesn't seem to be the case any more.

[Osyotr]

https://stackoverflow.com/a/78150426/5802715

[johne53]

If anyone could suggest a way to download the .bz2 archive file for a given port, I'd be happy to try that tutorial I linked to (assuming the .bz2 files still exist somewhere?)