@item @anchor{GDC-prerequisite}GDC
In order to build GDC, the D compiler, you need a working GDC
-compiler (GCC version 9.1 or later), as the D front end is written in D.
+compiler (GCC version 9.1 or later) and D runtime library,
+@samp{libphobos}, as the D front end is written in D.
Versions of GDC prior to 12 can be built with an ISO C++11 compiler, which can
then be installed and used to bootstrap newer versions of the D front end.
of the D language, if too old a GDC version is installed and
@option{--enable-languages=d} is used, the build will fail.
+On some targets, @samp{libphobos} isn't enabled by default, but compiles
+and works if @option{--enable-libphobos} is used. Specifics are
+documented for affected targets.
+
@item A ``working'' POSIX compatible shell, or GNU bash
Necessary when running @command{configure} because some
appropriate version is found. Solaris @command{c++filt} from the Solaris
Studio compilers does @emph{not} work.
+In order to build the GNU D compiler, GDC, a working @samp{libphobos} is
+needed. That library wasn't built by default in GCC 9--11 on SPARC, or
+on x86 when the Solaris assembler is used, but can be enabled by
+configuring with @option{--enable-libphobos}. Also, GDC 9.4.0 is
+required on x86, while GDC 9.3.0 is known to work on SPARC.
+
The versions of the GNU Multiple Precision Library (GMP), the MPFR
library and the MPC library bundled with Solaris 11.3 and later are
usually recent enough to match GCC's requirements. There are two
@item
The version of the MPFR libary included in Solaris 11.3 is too old; you
need to provide a more recent one.
+
@end itemize
@html