Index: Portfile
===================================================================
--- Portfile	(revision 120690)
+++ Portfile	(working copy)
@@ -12,11 +12,11 @@
 # TODO: try to figure out if one could also build root6 on < 10.9
 
 # Essentially 6.00.00, but with some bug fixes to the build system
-github.setup        root-mirror root aaf9b65
+github.setup        root-mirror root bf20cb6
 #github.setup       root-mirror root 6-00-00 v
 version             6.00.00
-checksums           rmd160  e0b7080d897469f421dd5ee44ca570a4774dc5d4 \
-                    sha256  58692b7e2c970df5eac0dd298ab7d1ac5352e4ed549d61c29578d71915e831be
+checksums           rmd160  58ba2ac69df482ef8f86a75fdc2d803dc0e6a98e \
+                    sha256  6a19ac7df74a1be5d627c3bade450fddee8551efb239787064118e4d0fbabe61
 
 name                root6
 set version_major   6
@@ -37,6 +37,27 @@
 configure.dir       ${workpath}/build
 build.dir           ${configure.dir}
 
+platform darwin {
+    # Note that we are forcing this choice.  This means that anything linking
+    # against llvm-3.5 needs to also be using libc++.  This is possibly
+    # problematic, but luckily there is just a limited set of such dependents.
+
+    if {[info exists configure.cxx_stdlib]} {
+        configure.cxx_stdlib libc++
+    }
+
+    depends_lib-append port:libcxx
+}
+
+pre-fetch {
+    if {(${os.major} < 13 && ! [info exists configure.cxx_stdlib]) ||
+        (! [file exists /usr/lib/libc++.dylib])} {
+        ui_error "$name requires a C++11 runtime, which your configuration does not allow"
+        error "unsupported configuration"
+    }
+}
+
+
 post-extract {
     file mkdir ${configure.dir}
 }