[2831] allow skipping build sh-mem support. set -Wno-error if necessary.

configure.ac

@@ -884,6 +884,17 @@ if test "$BOOST_NUMERIC_CAST_WOULDFAIL" = "yes" -a X"$werror_ok" = X1 -a $CLANGP
     AC_MSG_ERROR([Failed to compile a required header file.  If you are using FreeBSD and Boost installed via ports, retry with specifying --without-werror.  See the ChangeLog entry for Trac no. 1991 for more details.])
 fi
 
+use_shared_memory=yes
+AC_ARG_WITH(shared-memory,
+    AC_HELP_STRING([--with-shared-memory],
+    [Build with Boost shared memory support; for large scale authoritative DNS servers]),
+    [use_shared_memory=$withval])
+if test X$use_shared_memory = Xyes -a "$BOOST_MAPPED_FILE_WOULDFAIL" = "yes"; then
+    AC_MSG_ERROR([Boost shared memory does not compile on this system.  If you don't need it (most normal users won't) build without it; using a different compiler or a different version of Boost may also help.])
+fi
+AM_CONDITIONAL([USE_SHARED_MEMORY], [test x$use_shared_memory = xyes])
+AC_SUBST(BOOST_MAPPED_FILE_CXXFLAG)
+
 # Add some default CPP flags needed for Boost, identified by the AX macro.
 CPPFLAGS="$CPPFLAGS $CPPFLAGS_BOOST_THREADCONF"
 

src/lib/util/Makefile.am

@@ -18,7 +18,9 @@ libb10_util_la_SOURCES += interprocess_sync_file.h interprocess_sync_file.cc
 libb10_util_la_SOURCES += interprocess_sync_null.h interprocess_sync_null.cc
 libb10_util_la_SOURCES += memory_segment.h
 libb10_util_la_SOURCES += memory_segment_local.h memory_segment_local.cc
+if USE_SHARED_MEMORY
 libb10_util_la_SOURCES += memory_segment_mapped.h memory_segment_mapped.cc
+endif
 libb10_util_la_SOURCES += range_utilities.h
 libb10_util_la_SOURCES += hash/sha1.h hash/sha1.cc
 libb10_util_la_SOURCES += encode/base16_from_binary.h

src/lib/util/tests/Makefile.am

@@ -8,6 +8,18 @@ AM_CPPFLAGS += -DTEST_DATA_BUILDDIR=\"$(abs_builddir)\"
 # the limit of file name path size.
 AM_CPPFLAGS += -DTEST_DATA_TOPBUILDDIR=\"$(abs_top_builddir)\"
 AM_CXXFLAGS = $(B10_CXXFLAGS)
+# If we use the shared-memory support, corresponding Boost library may
+# cause build failures especially if it's strict about warnings.  We've
+# detected it in ./configure and set BOOST_MAPPED_FILE_CXXFLAG to be more
+# lenient as necessary (specifically, when set it'd usually supporess -Werror).
+# This is a module wide setting, and has a possible bad side effect of hiding
+# issues in other files, but making it per-file seems to be too costly.
+# So we begin with the wider setting. If the side effect turns out to be too
+# harmful, we'll consider other measure, e.g, moving the related files into
+# a subdirectory.
+if USE_SHARED_MEMORY
+AM_CXXFLAGS += $(BOOST_MAPPED_FILE_CXXFLAG)
+endif
 
 if USE_STATIC_LINK
 AM_LDFLAGS = -static
@@ -34,7 +46,9 @@ run_unittests_SOURCES += lru_list_unittest.cc
 run_unittests_SOURCES += interprocess_sync_file_unittest.cc
 run_unittests_SOURCES += interprocess_sync_null_unittest.cc
 run_unittests_SOURCES += memory_segment_local_unittest.cc
+if USE_SHARED_MEMORY
 run_unittests_SOURCES += memory_segment_mapped_unittest.cc
+endif
 run_unittests_SOURCES += memory_segment_common_unittest.h
 run_unittests_SOURCES += memory_segment_common_unittest.cc
 run_unittests_SOURCES += qid_gen_unittest.cc