gcc being built with fno-exceptions - exception

Question

I am trying to build gcc5.4.0. My configure command looks something like this:
../"$GCC_SRCDIR"/configure --prefix="$PREFIX" --with-sysroot="$PREFIX" --with-gxx-include-dir="$PREFIX/lib64/gcc/$TARGET/$GCC_VER/include" --enable-languages=c,c++ --disable-checking --disable-werror --disable-libmudflap --disable-libssp --disable-nls --disable-multilib --disable-libsanitizer --disable-libgomp --disable-libcilkrts --disable-libquadmath --enable-__cxa_atexit --enable-clocale=gnu --disable-bootstrap --with-system-zlib --with-pic --enable-poison-system-directories --with-plugin-ld=ld.gold
But somehow it seems that it is addind -fno-exceptions while building due to which when it goes ahead and tries to build libstdc++.so, the configure script fails saying
checking for exception model to use... configure: error: unable to detect exception model
I see that this is being printed while configuring gcc:
checking whether gcc supports -fno-exceptions... yes`
checking whether gcc supports -fno-rtti... yes
checking whether gcc supports -fasynchronous-unwind-tables... yes
g++ -c -g -O2 -DIN_GCC -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wwrite-strings -Wcast-qual -Wmissing-format-attribute -Woverloaded-virtual -DHAVE_CONFIG_H -DGENERATOR_FILE -I. -Ibuild -I../../gcc-5.4.0/gcc -I../../gcc-5.4.0/gcc/build -I../../gcc-5.4.0/gcc/../include -I../../gcc-5.4.0/gcc/../libcpp/include \
-DBASEVER="\"5.4.0\"" -DDATESTAMP="\"\"" \
-DREVISION="\"\"" \
-DDEVPHASE="\"\"" -DPKGVERSION="\"(GCC) \"" \
-DBUGURL="\"<http://gcc.gnu.org/bugs.html>\"" -o build/version.o ../../gcc-5.4.0/gcc/version.c
But I am not sure why -fno-exceptions is being taken when I did not specify this option
UPDATE
I tried to compile conftest.cpp
struct S { ~S(); };
void bar();
void foo()
{
S s;
bar();
}
using gcc5.4.0 and gcc4.9.2 that I had built
gcc4.9.2 one had these two elements which were missing in gcc5.4.0:
_Unwind_Resume
.cfi_personality

Answer 1

Turns out “--disable-bootstrap --with-system-zlib” seemed to be disabling exceptions. Removed them and now conftest.cpp has _Unwind_Resume in the assembly generated using the new gcc. Thanks Ulrich Eckhardt.