SAT resolution failure

[AlejandroCabeza]

In the nim-libp2p repository, dependency resolution is failing when using the SAT dependency solver.

These are the scenarios:

1. nimble --solver:legacy install
   • Works
2. nimble --solver:sat install
   • Fails
3. nimble install_pinned (a custom mechanism that installs fixed versions from a .pinned file into a local nimbledeps directory, which is recreated each time it's run)
   • The outcome varies depending on how it's run:
     a) When run with legacy (nimble --solver:legacy install_pinned), it works.
     b) When run with SAT (nimble --solver:sat install_pinned), it fails.
     c) Interestingly, if you first run it with legacy and then run nimble --solver:sat check, the check passes.

At first I thought this was due to SAT not being able to resolve the dependencies in libp2p.nimble, but scenario 3c made me think that's not quite it.

I'm not sure anymore if this happens because our dependencies are actually unsolvable or there's a situation SAT just can't handle. Any ideas?

[2-towns]

I still have similar issue with 0.16.3.

In my .nimble file, I have a dependency to libp2p:

requires "libp2p >= 1.7.0"

When I run nimble install

I have this error:

.nimble/pkgcache/githubcom_ba0f3dnsclientnim_0.3.4/src/dnsclient.nim(1, 2) Error: cannot open file: ""
       Tip: 673 messages have been suppressed, use --verbose to show them.
nimble.nim(840)          install

    Error:  Aborting installation due to build failure.

But when i run nimble --solver:legacy install it works.

[jmgomez]

@2-towns fixed here: #1297
There is even a test case for libp2p in that PR

cc @arnetheduck