tests failing with GNU Emacs 26.1

[dogsleg]

Hi,

I've ran make check-ert with repository's HEAD against GNU Emacs 26.1 and got some failures. Please, find the full log attached.

check-ert.log

For more information see Debian bug #916807

[thkoch2001]

This construct is used in tests/haskell-cabal-tests.el 4 times and causes the test failures:

(file-name-directory 
  (or (symbol-file 'haskell-cabal-get-field-1)
       (buffer-file-name)))

Apparently both symbol-file and buffer-file-name result in nil and cause file-name-directory to complain with "(wrong-type-argument stringp nil)".

Since I need to fix this quickly and only in the context of a debian build and don't know much elisp, I replaced those occurences with

let ((scriptDir (expand-file-name "tests" default-directory)))