backpack breaks --enable-coverage

[vmchale]

Describe the bug

Running cabal build --enable-coverage does not work when depending on backpack-ified packages; cabal build --enable-profiling does work

To Reproduce

In my archive-backpack repo:

rm -rf dist-newstyle
cabal v2-build all -w ghc-8.6.5 --enable-coverage
...
Configuring hstar-0.1.0.0...
Error:
    The following packages are broken because other packages they depend on are missing. These broken packages must be rebuilt before they can be used.
planned package hstar-0.1.0.0 is broken due to missing package archive-sig-0.2.0.2-inplace+5LcY8JHokyDHyTjA8czqM

cabal: Failed to build hstar-0.1.0.0. The failure occurred during the
configure step.
...

Expected behavior

Build would not fail

System information

• Linux, x86_64

cabal-install version 3.0.0.0
compiled using version 3.0.0.0 of the Cabal library 

• GHC 8.6.5

Thanks :)

[alt-romes]

#9464 will make it so that backpack no longer breaks --enable-coverage, so that it will now work and emit coverage reports. However, the indefinite modules will not be included in the reports -- as far as I know, HPC does not support backpack in the sense that it's unclear what it means to cover an indefinite module with multiple instantiations...

So, as I see it, #9464 should close this?

[gbaz]

I think its fine to close this issue with that -- but might be worth opening an issue for HPC just to note the conceptual problem to be solved.