Hi,
I uploaded a fix for this bug to DELAYED/10. debdiff attached.
Willi
diff -Nru mrtrix-0.2.12/debian/changelog mrtrix-0.2.12/debian/changelog
--- mrtrix-0.2.12/debian/changelog 2015-12-29 18:21:14.000000000 +0100
+++ mrtrix-0.2.12/debian/changelog 2017-10-21 16:22:07.000000000 +0200
@@ -1,3 +1,10 @@
+mrtrix (0.2.12-2.1) unstable; urgency=medium
+
+ * Non-maintainer upload.
+ * Fix build error with ambigous call to round (closes: #816570)
+
+ -- Willi Mann <wi...@debian.org> Sat, 21 Oct 2017 16:22:07 +0200
+
mrtrix (0.2.12-2) unstable; urgency=medium
* Add patch to include <cstddef> to fix FTBFS due to missing size_t.
diff -Nru mrtrix-0.2.12/debian/patches/fix-build-error-round mrtrix-0.2.12/debian/patches/fix-build-error-round
--- mrtrix-0.2.12/debian/patches/fix-build-error-round 1970-01-01 01:00:00.000000000 +0100
+++ mrtrix-0.2.12/debian/patches/fix-build-error-round 2017-10-21 16:22:03.000000000 +0200
@@ -0,0 +1,17 @@
+Index: mrtrix-0.2.12/cmd/tracks2prob.cpp
+===================================================================
+--- mrtrix-0.2.12.orig/cmd/tracks2prob.cpp
++++ mrtrix-0.2.12/cmd/tracks2prob.cpp
+@@ -127,9 +127,9 @@ class Voxel
+ z (_z_) { }
+
+ Voxel (const Point& p) :
+- x (round (p[0])),
+- y (round (p[1])),
+- z (round (p[2]))
++ x (MR::round (p[0])),
++ y (MR::round (p[1])),
++ z (MR::round (p[2]))
+ {
+ assert (gsl_finite (p[0]) && gsl_finite (p[1]) && gsl_finite (p[2]));
+ }
diff -Nru mrtrix-0.2.12/debian/patches/series mrtrix-0.2.12/debian/patches/series
--- mrtrix-0.2.12/debian/patches/series 2015-12-29 17:17:10.000000000 +0100
+++ mrtrix-0.2.12/debian/patches/series 2017-10-21 16:20:03.000000000 +0200
@@ -1,3 +1,4 @@
debian_build_cfg
glib-single-include.patch
size_t-ftbfs
+fix-build-error-round
