gnu: flex-2.6.1: Remove variable.

* gnu/packages/flex.scm (flex-2.6.1): Remove variable.
* gnu/packages/bootloaders.scm (grub, dtc): Use flex instead of flex-2.6.1.
* gnu/packages/embedded.scm (propeller-binutils, binutils-vc4): Likewise.
* gnu/packages/maths.scm (scotch): Likewise.
* gnu/packages/wine.scm (wine): Likewise.

gnu/packages/bootloaders.scm

@@ -114,10 +114,7 @@
     (native-inputs
      `(("unifont" ,unifont)
        ("bison" ,bison)
-       ;; Due to a bug in flex >= 2.6.2, GRUB must be built with an older flex:
-       ;; <http://lists.gnu.org/archive/html/grub-devel/2017-02/msg00133.html>
-       ;; TODO Try building with flex > 2.6.3.
-       ("flex" ,flex-2.6.1)
+       ("flex" ,flex)
        ("texinfo" ,texinfo)
        ("help2man" ,help2man)
 
@@ -240,7 +237,7 @@ menu to select one of the installed operating systems.")
     (build-system gnu-build-system)
     (native-inputs
      `(("bison" ,bison)
-       ("flex" ,flex-2.6.1))) ; A bug in flex prevents building with flex-2.6.3.
+       ("flex" ,flex)))
     (arguments
      `(#:make-flags
        (list "CC=gcc"

gnu/packages/embedded.scm

@@ -412,7 +412,7 @@ with a layered architecture of JTAG interface and TAP support.")
          ,@(package-arguments xbinutils)))
       (native-inputs
        `(("bison" ,bison)
-         ("flex" ,flex-2.6.1) ; needed because of yywrap error
+         ("flex" ,flex)
          ("texinfo" ,texinfo)
          ("dejagnu" ,dejagnu)
          ,@(package-native-inputs xbinutils))))))
@@ -764,7 +764,7 @@ simulator.")
                  (base32
                   "14b3h2ji740s8zq5vwm4qdcxs4aa4wxi6wb9di3bv1h39x14nyr9"))))
          ("texinfo" ,texinfo)
-         ("flex" ,flex-2.6.1) ; A bug in flex prevents building with flex-2.6.3.
+         ("flex" ,flex)
          ("bison" ,bison)
          ("guile-1.8" ,guile-1.8)
          ("which" ,base:which)))

gnu/packages/flex.scm

@@ -85,20 +85,3 @@ regular expressions for each rule.  Whenever it finds a match, it
 executes the corresponding C code.")
     (license (non-copyleft "file://COPYING"
                            "See COPYING in the distribution."))))
-
-;;; Many packages fail to build with flex > 2.6.1, due to this bug in flex:
-;;; <https://github.com/westes/flex/issues/162>
-;;; We must not use a flex before 2.6.1, due to CVE-2016-6354.
-;;; TODO Try using flex > 2.6.3.
-(define-public flex-2.6.1
-  (package
-    (inherit flex)
-    (version "2.6.1")
-    (source (origin
-              (method url-fetch)
-              (uri (string-append "https://github.com/westes/flex"
-                                  "/releases/download/v" version "/"
-                                  "flex-" version ".tar.xz"))
-             (sha256
-              (base32
-               "0gqhk4vkwy4gl9xbpgkljph8c0a5kpijz6wd0p5r9q202qn42yic"))))))

gnu/packages/maths.scm

@@ -1807,7 +1807,7 @@ implemented in ANSI C, and MPI for communications.")
     (build-system gnu-build-system)
     (inputs
      `(("zlib" ,zlib)
-       ("flex" ,flex-2.6.1) ; A bug in flex prevents building with flex-2.6.3.
+       ("flex" ,flex)
        ("bison" ,bison)))
     (arguments
      `(#:phases

gnu/packages/wine.scm

@@ -65,8 +65,7 @@
     (build-system gnu-build-system)
     (native-inputs `(("pkg-config" ,pkg-config)
                      ("gettext" ,gettext-minimal)
-                     ; A bug in flex prevents building with flex-2.6.3.
-                     ("flex" ,flex-2.6.1)
+                     ("flex" ,flex)
                      ("bison" ,bison)
                      ("perl" ,perl)))
     (inputs