ghc-pkg and ghc do not agree about package with internal libraries
Initially I reported this to Cabal (https://github.com/haskell/cabal/issues/5857), but I think this is actually a GHC bug.
Repro here: https://github.com/michaelpj/cabal-bug-package-db
In particular, you can run the following.
$ cabal build
$ ghc-pkg field test exposed -f dist/package.conf.inplace
exposed: True
$ ghc-pkg find-module Test -f dist/package.conf.inplace
dist/package.conf.inplace
test-0.1.0.0
$ ghc -package-db dist/package.conf.inplace Use.hs
[1 of 1] Compiling Use ( Use.hs, Use.o )
Use.hs:3:1: error:
Could not load module ‘Test’
It is a member of the hidden package ‘test-0.1.0.0’.
You can run ‘:set -package test’ to expose it.
(Note: this unloads all the modules in the current scope.)
Use -v to see a list of the files searched for.
|
3 | import Test
| ^^^^^^^^^^^
$ ghc -package-db dist/package.conf.inplace -package test Use.hs
[1 of 1] Compiling Use ( Use.hs, Use.o )That is:
-
ghc-pkgthinks the package is present, exposed, and contains the module in question. -
ghcthinks the package is hidden, and will accept it when specified with-package.
If you comment out the internal library this does not happen, but regardless it seems bad that there's a disagreement between ghc-pkg and ghc.
I've also observed (although I don't have a small reproduction for this) a similar case where ghc does not even think the module is hidden, but again will accept it with -package.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 8.6.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | ghc-pkg |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |