Conan: Provide info of the dep graph when a recipe is missing

[Minimonium]

The problem:
When a deep dependency throws an error on info/install/create step it's not as obvious in which nested reference an error occurred. Printing whole information (on error only?) would be very useful.

Current behaviour:

$ conan info . --only=None
DeepDep/1.0.0@user/stable: Not found in local cache, looking in remotes...
DeepDep/1.0.0@user/stable: Trying with 'bincrafters'...
DeepDep/1.0.0@user/stable: Trying with 'conan-center'...
ERROR: Unable to find 'DeepDep/1.0.0@user/stable' in remotes

Possible Solution?:

$ conan info . --only=None
ProjectA/1.0.0@user/stable:
- ProjectB/1.0.0@user/stable:
- ProjectC/1.0.0@user/stable:
- - DeepDep/1.0.0@user/stable: Not found in local cache, looking in remotes...
- - DeepDep/1.0.0@user/stable: Trying with 'bincrafters'...
- - DeepDep/1.0.0@user/stable: Trying with 'conan-center'...
ERROR: Unable to find 'DeepDep/1.0.0@user/stable' in remotes

[lasote]

in which nested reference an error occurred.

Why is it relevant?

At first sight, it doesn't look like an obvious thing because a graph is not a tree. For knowing the relationships between the nodes you can use later the conan info command.

[Minimonium]

@lasote as you can see in the example I attached in a situation when one of the dependencies is broken - conan info doesn't work and doesn't give you information about where such broken dep is located.
I ask about providing deep log trace on error, so the user can track broken deps.

[lasote]

Now I see. It is not a build error but a missing recipe error.

[ericLemanissier]

This kind of information would be useful too in case of conflict between requirements:

ERROR: Conflict in pcre/8.41@bincrafters/stable
    Requirement bzip2/1.0.8@conan/stable conflicts with already defined bzip2/1.0.6@conan/stable
    To change it, override it in your base requirements

We have the information that pcre is requiring bzip2/1.0.8, but conan does not show which package is requiring bzip2/1.0.6, so it is very hard to find out the package that needs to have its requirements updated.

[Minimonium]

I suggest making an additional flag for the conan info to force the indented output like that (names are welcomed).
@lasote I can look into it if such a solution would be okay.

[ytimenkov]

:+1: In this case "fail fast" seems to be a wrong choice. Would be better to just mark packages as absent / conflicting / etc. Maybe with different command.

[ericLemanissier]

Another option could be to show, in error cases, the dependency chain from the package user asked to create/install/info to the offending package (the one which has no recipe, or the conflicting packages), something like ProjectA/1.0.0@user/stable -> ProjectB/1.0.0@user/stable -> ProjectC/1.0.0@user/stable -> DeepDep/1.0.0@user/stable
There can be several chain from ProjectA to DeepDep, showing any of them is a useful information, showing all of them would be even better.

[jgsogo]

About conflicts, we are working on this PR https://github.com/conan-io/conan/pull/5684 (issue https://github.com/conan-io/conan/issues/5617). Please comment there if you feel like the output already proposed is not good enough (or it is). Conan v1.19 should be ready shortly 🙄