Any nice way to inspect build configuration from binaries?

[EliahKagan]

Git has git version --build-options, which gives some information about the build, though not which libraries it is linked against:

ek@Glub:~$ git version --build-options
git version 2.34.1
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh

Libraries Git uses that are shared libraries can be inspected with ldd:

ek@Glub:~$ ldd "$(command -v git)"
        linux-vdso.so.1 (0x00007ffe61462000)
        libpcre2-8.so.0 => /lib/x86_64-linux-gnu/libpcre2-8.so.0 (0x00007fe87a15f000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fe87a143000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fe879f1a000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fe87a5ad000)

(I don't know if git provides any convenient way to list which features that require library support are available when the library is statically linked.)

Does gix or ein have any way to obtain this kind of information about itself? It would be useful to know details corresponding to the output of git version --build-options where applicable, but even more so to know which feature flags gix and ein are compiled with.

Even if gitoxide does not have corresponding functionality, is there an easy way to check this by running or inspecting the binaries? (I've opened this as a question rather than a feature request because I'm not sure I wish to request a change. Maybe this information is already readily available.)

[NobodyXu]

There's verge which enables encoding the build environment and git sha in the binary.

cargo-binstall print these info on -vV.

There's also cargo-auditable, which encodes the dependencies in the binary for auditing, we were able to use it with cargo-zigbuild by setting export CARGO=cargo-zigbuild

[Byron]

Thanks for clarifying this. So it does seem that GitHub releases could definitely incorporate this knowledge, with env_opt! maybe, I'd definitely appreciate it, and it seems like a simple and portable first step. BoM could be a second one but is riskier due to an additional tool being involved.

[Byron]

Cargo already sets a bunch of variables at build time, but it doesn't look like top-level feature flags are among them.

To at least get some feature information you could have something like a static storing whether the feature is enabled i.e.

static HAS_FEATURE_BAR: bool = cfg!(feature="bar");

I thought about this but rejected it for myself as it needs maintenance, and I know I will forget it, for sure 😅. Using specific environment variables that are known to exist in GitHub releases seems like the way to go.

[Skgland]

Cargo already sets a bunch of variables at build time, but it doesn't look like top-level feature flags are among them.

For build script cargo sets CARGO_FEATURE_<name> for each activated feature, so a build script could collect all available environment variables starting with CARGO_FEATURE_ to get a list of enabled features, but given that you currently don't appear to be using build scripts this is probably not useful.

CARGO_FEATURE_<name> — For each activated feature of the package being built, this environment variable will be present where <name> is the name of the feature uppercased and having - translated to _.

[NobodyXu]

but given that you currently don't appear to be using build scripts this is probably not useful.

I think build-script is required if we want gitoxide to work on 32-bit windows cargo-bins/cargo-quickinstall#254

Windows requires you to embed a manifest in the binary for it to work.

Cargo-binstall uses build-script to generate a windows manifest and record build environment.

https://github.com/cargo-bins/cargo-binstall/blob/main/crates/bin/build.rs

[Byron]

There is indeed a build script for the binaries already, which could then aggregate cargo features and make them available in another environment variable, thanks @Skgland for the suggestion.

This makes me think a general embedding of features to present when running gix -v or gix -vv would be quite easy to accomplish.