Assertion failure in D.C.Install

[23Skidoo]

With current master, when I do:

$ cabal get log
$ cd log-0.5.3
$ cabal sandbox init
$ cabal install --only-dep

I get the following assertion failure:

$ cabal install --only-dep
Warning: the --global flag is deprecated -- it is generally considered a bad
idea to install packages into the global store
Resolving dependencies...
Notice: installing into a sandbox located at
/home/refold/code/haskell/log-0.5.3/.cabal-sandbox
Configuring base64-bytestring-1.0.0.1...
Configuring base-orphans-0.5.4...
[...]
Building nats-1.1.1...
Installed nats-1.1.1
Configuring network-2.6.3.1...
Configuring old-locale-1.0.0.7...
Assertion failed
CallStack (from HasCallStack):
assert, called at ./Distribution/Client/Install.hs:1427:34 in
main:Distribution.Client.Install

This does not seem to happen with 1.24 (I checked that I compiled with assertions on).

[23Skidoo]

/cc @ezyang - The assertion was introduced by you in 3601819.

[ezyang]

Can you post a -v3 log with -j1 (no parallelism).

[23Skidoo]

Uploaded the -j1 -v3 log here: https://gist.github.com/23Skidoo/70445e3c9d4de15165f2c21a789ecca9

[ezyang]

Ah, that makes this very clear. hsc2hs indeed, does not have a library. But why are we building it in the legacy codepath? I thought I fixed this in 9e99b3f but if you are on the newest master, clearly not!

[ezyang]

Confirmed reproduction: when I do your test case with HEAD hsc2hs gets built.