Add variants for tk package (#11956)

TK can be built with support for libXft and X Screensaver. Both of these
are turned on in the Tk configure script. That means the system
libraries will get picked up if they are on the system and nothing is
specified in the package. Since the default for both of them is 'True' I
set the default value for the variants to 'True'.

1 files changed, 16 insertions, 3 deletions

diff --git a/var/spack/repos/builtin/packages/tk/package.py b/var/spack/repos/builtin/packages/tk/package.py
index c9bc2ce3e6..2a09333740 100644
--- a/var/spack/repos/builtin/packages/tk/package.py
+++ b/var/spack/repos/builtin/packages/tk/package.py
@@ -23,10 +23,17 @@ class Tk(AutotoolsPackage):
     version('8.6.3', '85ca4dbf4dcc19777fd456f6ee5d0221')
     version('8.5.19', 'e89df710447cce0fc0bde65667c12f85')
 
+    variant('xft', default=True,
+            description='Enable X FreeType')
+    variant('xss', default=True,
+            description='Enable X Screen Saver')
+
     extends('tcl')
 
     depends_on('tcl@8.6:', when='@8.6:')
     depends_on('libx11')
+    depends_on('libxft', when='+xft')
+    depends_on('libxscrnsaver', when='+xss')
 
     configure_directory = 'unix'
 
@@ -65,9 +72,15 @@ class Tk(AutotoolsPackage):
 
     def configure_args(self):
         spec = self.spec
-        return ['--with-tcl={0}'.format(spec['tcl'].prefix.lib),
-                '--x-includes={0}'.format(spec['libx11'].prefix.include),
-                '--x-libraries={0}'.format(spec['libx11'].prefix.lib)]
+        config_args = [
+            '--with-tcl={0}'.format(spec['tcl'].prefix.lib),
+            '--x-includes={0}'.format(spec['libx11'].prefix.include),
+            '--x-libraries={0}'.format(spec['libx11'].prefix.lib)
+        ]
+        config_args += self.enable_or_disable('xft')
+        config_args += self.enable_or_disable('xss')
+
+        return config_args
 
     @run_after('install')
     def symlink_wish(self):