mkComponentGraph is broken

[phadej]

-- | Create a 'Graph' of 'Component', or report a cycle if there is a
-- problem.
--
mkComponentsGraph :: ComponentRequestedSpec
                  -> PackageDescription
                  -> Either [ComponentName] ComponentsGraph
mkComponentsGraph enabled pkg_descr =
    let g = Graph.fromDistinctList
                           [ N c (componentName c) (componentDeps c)
                           | c <- pkgBuildableComponents pkg_descr
                           , componentEnabled enabled c ]
    in case Graph.cycles g of
          []     -> Right g
          ccycles -> Left  [ componentName c | N c _ _ <- concat ccycles ]
  where
    -- The dependencies for the given component
    componentDeps component =
      (CExeName <$> getAllInternalToolDependencies pkg_descr bi)

      ++ [ if pkgname == packageName pkg_descr
           then CLibName LMainLibName
           else CLibName (LSubLibName toolname)
         | Dependency pkgname _ _ <- targetBuildDepends bi
           -- ^ HERE, we ignore the library names all together
         , let toolname = packageNameToUnqualComponentName pkgname
         , toolname `elem` internalPkgDeps ]
      where

I think that because of this issue the foo:bar syntax is broken beyond repair in Cabal-3.0 and 3.2.

[phadej]

--- a/cabal-testsuite/PackageTests/InternalLibraries/p/p.cabal
+++ b/cabal-testsuite/PackageTests/InternalLibraries/p/p.cabal
@@ -1,10 +1,10 @@
+cabal-version:       3.0
 name:                p
 version:             0.1.0.0
-license:             BSD3
+license:             BSD-3-Clause
 author:              Edward Z. Yang
 maintainer:          ezyang@cs.stanford.edu
 build-type:          Simple
-cabal-version:       1.24
 
 library q
   build-depends:       base
@@ -13,7 +13,7 @@ library q
   default-language:    Haskell2010
 
 library
-  build-depends:       base, q
+  build-depends:       base, p:q
   exposed-modules:     P
   hs-source-dirs:      p
   default-language:    Haskell2010

is enough to reproduce this.

Run then make cabal-install-test TEST=PackageTests/InternalLibraries/setup.test.hs

[phadej]

Solver also errors

-----BEGIN CABAL OUTPUT-----
Error:
    Dependency cycle between the following components: library
    In the inplace package 'issue-6894'
-----END CABAL OUTPUT-----