01/01: gnu: ghc-7: Fix build with ncurses 6.1.

[Ricardo Wurmus]

rekado pushed a commit to branch core-updates
in repository guix.

commit 74733195244f645158a89c0aa74d6fc6ae525060
Author: Ricardo Wurmus <address@hidden>
Date:   Wed Mar 14 19:58:32 2018 +0100

    gnu: ghc-7: Fix build with ncurses 6.1.
    
    * gnu/packages/haskell.scm (ghc-7)[arguments]: Make ncurses major+minor
    version detection more robust.
---
 gnu/packages/haskell.scm | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/gnu/packages/haskell.scm b/gnu/packages/haskell.scm
index c5408f8..4b1e3f2 100644
--- a/gnu/packages/haskell.scm
+++ b/gnu/packages/haskell.scm
@@ -282,9 +282,11 @@ top of CLISP.")
                   (mkdir-p libtinfo-dir)
                   (symlink
                    (string-append ncurses-lib "/libncursesw.so."
-                                  ;; Extract "6.0" from "6.0-20170930".
+                                  ;; Extract "6.0" from "6.0-20170930" if a
+                                  ;; dash-separated version tag exists.
                                   ,(let* ((v (package-version ncurses))
-                                          (d (string-index v #\-)))
+                                          (d (or (string-index v #\-)
+                                                 (string-length v))))
                                      (version-major+minor (string-take v d))))
                    (string-append libtinfo-dir "/libtinfo.so.5"))