dnl -------------------------------------------------------------
dnl Triangle Delaunay triangulation library by J.R. Shewchuk
dnl -------------------------------------------------------------
AC_DEFUN([CONFIGURE_TRIANGLE],
[
  AC_ARG_ENABLE(triangle,
                AS_HELP_STRING([--disable-triangle],
                               [build without Triangle Delaunay triangulation library support]),
                [AS_CASE("${enableval}",
                         [yes], [enabletriangle=yes],
                         [no],  [enabletriangle=no],
                         [AC_MSG_ERROR(bad value ${enableval} for --enable-triangle)])],
                [enabletriangle=$enableoptional])

  dnl The TRIANGLE API is distributed with libmesh, so we don't have to guess
  dnl where it might be installed...
  AS_IF([test "x$enabletriangle" = "xyes"],
        [
          TRIANGLE_INCLUDE="-I\$(top_srcdir)/contrib/triangle"
          TRIANGLE_LIBRARY="\$(EXTERNAL_LIBDIR)/libtriangle\$(libext)"
          AC_DEFINE(HAVE_TRIANGLE, 1, [Flag indicating whether the library will be compiled with Triangle support])
          AC_MSG_RESULT(<<< Configuring library with Triangle support >>>)
        ],
        [
          TRIANGLE_INCLUDE=""
          TRIANGLE_LIBRARY=""
          enabletriangle=no
        ])

  AC_SUBST(TRIANGLE_INCLUDE)
  AC_SUBST(TRIANGLE_LIBRARY)
])

dnl -------------------------------------------------------------
dnl Triangle Delaunay triangulation library by J.R. Shewchuk
dnl -------------------------------------------------------------
AC_DEFUN([CONFIGURE_TRIANGLE],
[
  AC_ARG_ENABLE(triangle,
                AS_HELP_STRING([--disable-triangle],
                               [build without Triangle Delaunay triangulation library support]),
                [AS_CASE("${enableval}",
                         [yes], [enabletriangle=yes],
                         [no],  [enabletriangle=no],
                         [AC_MSG_ERROR(bad value ${enableval} for --enable-triangle)])],
                [enabletriangle=$enableoptional])

  AS_IF([test "x$enabletriangle" = "xyes" &&
         test "x$enablequadrupleprecision" != "xno"],
        [enabletriangle=no
         AC_MSG_RESULT(<<< Disabling Triangle support due to quadruple precision >>>)
        ], [])

  dnl The TRIANGLE API is distributed with libmesh, so we don't have to guess
  dnl where it might be installed...
  AS_IF([test "x$enabletriangle" = "xyes"],
        [
          TRIANGLE_INCLUDE="-I\$(top_srcdir)/contrib/triangle"
          TRIANGLE_LIBRARY="\$(EXTERNAL_LIBDIR)/libtriangle\$(libext)"
          AC_DEFINE(HAVE_TRIANGLE, 1, [Flag indicating whether the library will be compiled with Triangle support])
          AC_MSG_RESULT(<<< Configuring library with Triangle support >>>)
        ],
        [
          TRIANGLE_INCLUDE=""
          TRIANGLE_LIBRARY=""
          enabletriangle=no
        ])

  AC_SUBST(TRIANGLE_INCLUDE)
  AC_SUBST(TRIANGLE_LIBRARY)
])

Disable Triangle in quad precision
Disable Triangle in quad precision

It turns out that Boost C++ headers do not play nicely in C files.
