bootstrap comparison failure with bootstrap-lto

[Matt <matt at use dot net>]

I am getting this on Ubuntu 11.10/amd64. If I remove the 
--with-build-config=bootstrap-lto, the build succeeds just fine. Is this a 
known problem, or should I file a bug? (A search of bugzilla didn't bring 
up this specific symptom.)

matt@matt-desktop:~/src/gcc-trunk/obj$ ../configure --enable-bootstrap 
--prefix=/home/matt --enable-clocale=gnu --with-system-zlib 
--enable-shared --with-demangler-in-ld --enable-lto 
--with-build-config=bootstrap-lto --with-fpmath=sse 
--enable-languages=c,c++,lto

matt@matt-desktop:~/src/gcc-trunk/obj$ make -j7

make "DESTDIR=" "RPATH_ENVVAR=LD_LIBRARY_PATH" 
"TARGET_SUBDIR=x86_64-unknown-linux-gnu" "bindir=/home/matt/bin" 
"datadir=/home/matt/share" "exec_prefix=/home/matt" 
"includedir=/home/matt/include" "datarootdir=/home/matt/share" 
"docdir=/home/matt/share/doc/" "infodir=/home/matt/share/info" 
"pdfdir=/home/matt/share/doc/" "htmldir=/home/matt/share/doc/" 
"libdir=/home/matt/lib" "libexecdir=/home/matt/libexec" "lispdir=" 
"localstatedir=/home/matt/var" "mandir=/home/matt/share/man" 
"oldincludedir=/usr/include" "prefix=/home/matt" "sbindir=/home/matt/sbin" 
"sharedstatedir=/home/matt/com" "sysconfdir=/home/matt/etc" 
"tooldir=/home/matt/x86_64-unknown-linux-gnu" 
"build_tooldir=/home/matt/x86_64-unknown-linux-gnu" 
"target_alias=x86_64-unknown-linux-gnu" "AWK=gawk" "BISON=bison" 
"CC_FOR_BUILD=gcc" "CFLAGS_FOR_BUILD=-g -O2" "CXX_FOR_BUILD=g++" 
"EXPECT=expect" "FLEX=flex" "INSTALL=/usr/bin/install -c" 
"INSTALL_DATA=/usr/bin/install -c -m 644" 
"INSTALL_PROGRAM=/usr/bin/install -c" "INSTALL_SCRIPT=/usr/bin/install -c" 
"LDFLAGS_FOR_BUILD=" "LEX=flex" "M4=m4" "MAKE=make" "RUNTEST=runtest" 
"RUNTESTFLAGS=" "SED=/bin/sed" "SHELL=/bin/bash" "YACC=bison -y" "`echo 
'ADAFLAGS=' | sed -e s'/[^=][^=]*=$/XFOO=/'`" "ADA_CFLAGS=" "AR_FLAGS=rc" 
"`echo 'BOOT_ADAFLAGS=-gnatpg -gnata' | sed -e s'/[^=][^=]*=$/XFOO=/'`" 
"BOOT_CFLAGS=-g -O2" "BOOT_LDFLAGS=" "CFLAGS=-g -O2" "CXXFLAGS=-g -O2" 
"LDFLAGS=" "LIBCFLAGS=-g -O2" "LIBCXXFLAGS=-g -O2 -fno-implicit-templates" 
"STAGE1_CHECKING=--enable-checking=yes,types" "STAGE1_LANGUAGES=c,c++,lto" 
"GNATBIND=gnatbind" "GNATMAKE=gnatmake" "AR_FOR_TARGET=ar" 
"AS_FOR_TARGET=as" "CC_FOR_TARGET=/home/matt/src/gcc-trunk/obj/./gcc/xgcc 
-B/home/matt/src/gcc-trunk/obj/./gcc/" "CFLAGS_FOR_TARGET=-g -O2" 
"CPPFLAGS_FOR_TARGET=" "CXXFLAGS_FOR_TARGET=-g -O2 -D_GNU_SOURCE" 
"DLLTOOL_FOR_TARGET=dlltool" 
"FLAGS_FOR_TARGET=-B/home/matt/x86_64-unknown-linux-gnu/bin/ 
-B/home/matt/x86_64-unknown-linux-gnu/lib/ -isystem 
/home/matt/x86_64-unknown-linux-gnu/include -isystem 
/home/matt/x86_64-unknown-linux-gnu/sys-include" "GCJ_FOR_TARGET=" 
"GFORTRAN_FOR_TARGET=" "GOC_FOR_TARGET=" "GOCFLAGS_FOR_TARGET=-O2 -g" 
"LD_FOR_TARGET=ld" "LIPO_FOR_TARGET=lipo" "LDFLAGS_FOR_TARGET=" 
"LIBCFLAGS_FOR_TARGET=-g -O2" "LIBCXXFLAGS_FOR_TARGET=-g -O2 -D_GNU_SOURCE 
-fno-implicit-templates" "NM_FOR_TARGET=nm" "OBJDUMP_FOR_TARGET=objdump" 
"RANLIB_FOR_TARGET=ranlib" "READELF_FOR_TARGET=readelf" 
"STRIP_FOR_TARGET=strip" "WINDRES_FOR_TARGET=windres" 
"WINDMC_FOR_TARGET=windmc" "BUILD_CONFIG=bootstrap-lto" "`echo 
'LANGUAGES=' | sed -e s'/[^=][^=]*=$/XFOO=/'`" "LEAN=false" 
"STAGE1_CFLAGS=-g -fkeep-inline-functions" "STAGE1_CXXFLAGS=-g 
-fkeep-inline-functions" "STAGE1_TFLAGS=" "STAGE2_CFLAGS=-g -O2 
-flto=jobserver -frandom-seed=1" "STAGE2_CXXFLAGS=-g -O2 -flto=jobserver 
-frandom-seed=1" "STAGE2_TFLAGS=" "STAGE3_CFLAGS=-g -O2 -flto=jobserver 
-frandom-seed=1" "STAGE3_CXXFLAGS=-g -O2 -flto=jobserver -frandom-seed=1" 
"STAGE3_TFLAGS=" "STAGE4_CFLAGS=-g -O2" "STAGE4_CXXFLAGS=-g -O2" 
"STAGE4_TFLAGS=" "STAGEprofile_CFLAGS=-g -O2 -flto=jobserver 
-frandom-seed=1 -fprofile-generate -fno-lto" "STAGEprofile_CXXFLAGS=-g -O2 
-flto=jobserver -frandom-seed=1 -fprofile-generate -fno-lto" 
"STAGEprofile_TFLAGS=" "STAGEfeedback_CFLAGS=-g -O2 -flto=jobserver 
-frandom-seed=1 -fprofile-use" "STAGEfeedback_CXXFLAGS=-g -O2 
-flto=jobserver -frandom-seed=1 -fprofile-use" "STAGEfeedback_TFLAGS=" 
"CXX_FOR_TARGET= $r/./gcc/g++ -B$r/./gcc/ -nostdinc++ `if test -f 
$r/x86_64-unknown-linux-gnu/libstdc++-v3/scripts/testsuite_flags; then 
/bin/bash $r/x86_64-unknown-linux-gnu/libstdc++-v3/scripts/testsuite_flags 
--build-includes; else echo -funconfigured-libstdc++-v3 ; fi` 
-L$r/x86_64-unknown-linux-gnu/libstdc++-v3/src 
-L$r/x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs" "TFLAGS=" 
"CONFIG_SHELL=/bin/bash" "MAKEINFO=makeinfo --split-size=5000000 
--split-size=5000000"  compare
make[2]: Entering directory `/home/matt/src/gcc-trunk/obj'
make[3]: Entering directory `/home/matt/src/gcc-trunk/obj'
rm -f stage_current
make[3]: Leaving directory `/home/matt/src/gcc-trunk/obj'
Comparing stages 2 and 3
warning: gcc/cc1plus-checksum.o differs
warning: gcc/cc1-checksum.o differs
Bootstrap comparison failure!
libcpp/lex.o differs
make[2]: *** [compare] Error 1


--
tangled strands of DNA explain the way that I behave.
http://www.clock.org/~matt