Synopsis:

avr-gcc-5.4.0_2 fails to build on 11.1-STABLE amd64 r331989 (on Clang 6.0.0)

Clang version info:

clang --version
FreeBSD clang version 6.0.0 (tags/RELEASE_600/final 326565) (based on LLVM 6.0.0)
Target: x86_64-unknown-freebsd11.1
Thread model: posix
InstalledDir: /usr/bin

Workaround: 

Setting "CXXFLAGS+= -std=gnu++03" for clang compiler in the Makefile prevents halting compilation due to the C++11 errors. A small patch here for devel/avr-gcc/Makefile:

Index: Makefile
===================================================================
--- Makefile    (revision 467805)
+++ Makefile    (working copy)
@@ -37,6 +37,8 @@

 CONFLICTS=     avr-gcc-devel*

+CXXFLAGS+=     -std=gnu++03
+
 CONFIGURE_ARGS=        --target=avr --disable-libssp --with-gmp=${LOCALBASE} --enable-languages="c c++"

 WITHOUT_CPU_CFLAGS=This is a cross-compiler.

Error log:

c++ -c   -O2 -pipe -fno-omit-frame-pointer -fno-strict-aliasing  -DIN_GCC  -DCROSS_DIRECTORY_STRUCTURE  -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings   -DHAVE_CONFIG_H -DGENERATOR_FILE -I. -Ibuild -I../.././gcc -I../.././gcc/build -I../.././gcc/../include  -I../.././gcc/../libcpp/include -I/usr/local/include \
        -o build/genopinit.o ../.././gcc/genopinit.c
In file included from ../.././gcc/gencheck.c:25:
../.././gcc/coretypes.h:62:1: warning: class 'rtx_def' was previously declared
      as a struct [-Wmismatched-tags]
class rtx_def;
^
../.././gcc/coretypes.h:55:8: note: previous use is here
struct rtx_def;
       ^
In file included from ../.././gcc/gencheck.c:26:
In file included from ./tm.h:18:
../.././gcc/config/elfos.h:102:25: error: invalid suffix on literal; C++11
      requires a space between literal and identifier
      [-Wreserved-user-defined-literal]
   fprintf ((FILE), "%s"HOST_WIDE_INT_PRINT_UNSIGNED"\n",\
                        ^

../.././gcc/config/elfos.h:170:27: error: invalid suffix on literal; C++11
      requires a space between literal and identifier
      [-Wreserved-user-defined-literal]
      fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n",          \
                          ^

1 warning and 2 errors generated.
gmake[4]: *** [Makefile:2428: build/gencheck.o] Error 1
gmake[4]: *** Waiting for unfinished jobs....
c++: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
In file included from ../.././gcc/genopinit.c:23:
../.././gcc/coretypes.h:62:1: warning: class 'rtx_def' was previously declared
      as a struct [-Wmismatched-tags]
class rtx_def;
^
../.././gcc/coretypes.h:55:8: note: previous use is here
struct rtx_def;
       ^
In file included from ../.././gcc/genopinit.c:24:
In file included from ./tm.h:18:
../.././gcc/config/elfos.h:102:25: error: invalid suffix on literal; C++11
      requires a space between literal and identifier
      [-Wreserved-user-defined-literal]
   fprintf ((FILE), "%s"HOST_WIDE_INT_PRINT_UNSIGNED"\n",\
                        ^

../.././gcc/config/elfos.h:170:27: error: invalid suffix on literal; C++11
      requires a space between literal and identifier
      [-Wreserved-user-defined-literal]
      fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n",          \
                          ^

In file included from ../.././gcc/genopinit.c:25:
In file included from ../.././gcc/rtl.h:26:
In file included from ../.././gcc/real.h:25:
../.././gcc/wide-int.h:1116:1: warning: 'fixed_wide_int_storage' defined as a
      class template here but previously declared as a struct template
      [-Wmismatched-tags]
class GTY(()) fixed_wide_int_storage
^
../.././gcc/wide-int.h:284:18: note: did you mean class here?
template <int N> struct fixed_wide_int_storage;
                 ^~~~~~
                 class
In file included from ../.././gcc/genopinit.c:25:
../.././gcc/rtl.h:282:1: warning: 'rtx_def' defined as a struct here but
      previously declared as a class [-Wmismatched-tags]
struct GTY((desc("0"), tag("0"),
^
../.././gcc/coretypes.h:62:1: note: did you mean struct here?
class rtx_def;
^~~~~
struct
3 warnings and 2 errors generated.
gmake[4]: *** [Makefile:2428: build/genopinit.o] Error 1
rm gcc.pod
gmake[4]: Leaving directory '/usr/ports/devel/avr-gcc/work/gcc-5.4.0/host-x86_64-portbld-freebsd11.1/gcc'
gmake[3]: *** [Makefile:4095: all-gcc] Error 2