registerPackage fails with multiple command line --package-conf= flags
in registerPackage the database to operate on is filtered, whereas the databases to validate are *truncated*. The trucation can be seen in the code:
let truncated_stack = dropWhile ((/= to_modify).location) db_stack -- truncate the stack for validation, because we don't allow -- packages lower in the stack to refer to those higher up. validatePackageConfig pkg truncated_stack auto_ghci_libs update force
notice the use of dropWhile instead of filter. The problem is that if I want to update a package with a command with multiple --package-conf= parameters, then these parameters get ignored during validation and if the package being installed depends on the packages in these databases, the installation will fail (unless --force is used). For example if you run the command
ghc-pkg --package-conf=myPkg1 --package-conf=myPkg2 --package-conf=myPkg3 --global --user update newPkg.conf
then the command will fail with the error ""something" doesn't exist (use --force to override)" if newPkg.conf depends on something in on of myPkgs.
In fact, with the above command, the truncated_stack consists of only two packages: [the-user-pkg,the-global-pkg].
I think the fix is to use a filter instead of dropWhile, but maybe there is some purpose behind using dropWhile. In any case a bug does exist because the above ghc-pkg command should succeed.