Use the default install directory (installdir) if not specified.
This change updates the `cabal install` command to use the default install directory for executables if one was not specified in either Cabal's config file or on the command line with the --installdir flag. Previously this would error out, now it warns that it used the default and continues. PR #6624, resolves #5973.
Showing with 6 additions and 3 deletions