[Bug other/59365] New: Configure script does not pass CFLAGS/CXXFLAGS down to subtargets @ stage1

["djfd at mail dot ru" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59365

            Bug ID: 59365
           Summary: Configure script does not pass CFLAGS/CXXFLAGS down to
                    subtargets @ stage1
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: djfd at mail dot ru

Hi,

If I confgure gcc build with CFLAGS/CXXFLAGS set to custom values, these are
not propagate down to subtargets (to gcc @ stage1, particularly).

how to reproduce
----------------
mkdir -p ~/tmp-gcc/bld
cd ~/tmp-gcc

#companion libraries
wget ftp://ftp.gnu.org/gnu/gmp/gmp-5.1.3.tar.bz2
tar -xf gmp-5.1.3.tar.bz2

wget ftp://ftp.gnu.org/gnu/mpfr/mpfr-3.1.2.tar.bz2
tar -xf mpfr-3.1.2.tar.bz2

wget ftp://ftp.gnu.org/gnu/mpc/mpc-1.0.1.tar.gz
tar -xf mpc-1.0.1.tar.gz

# gcc itself
wget ftp://ftp.gnu.org/gnu/gcc/gcc-4.8.2/gcc-4.8.2.tar.bz2
tar -xf gcc-4.8.2.tar.bz2

PFX=$HOME/fresh-gcc

mkdir bld/gmp ; cd bld/gmp
../../gmp-5.1.3/configure --prefix=$PFX && make && make install
cd ../..

mkdir bld/mpfr ; cd bld/mpfr
../../mpfr-3.1.2/configure --prefix=$PFX --with-gmp=$PFX && make && make
install
cd ../..

mkdir bld/mpc ; cd bld/mpc
../../mpc-1.0.1/configure --prefix=$PFX --with-gmp=$PFX --with-mpfr=$PFX &&
make && make install
cd ../..

mkdir bld/gcc ; cd bld/gcc
CFLAGS="--sysroot=/"   \
CXXFLAGS="--sysroot=/" \
../../gcc-4.8.2/configure \
    --prefix=$PFX      \
    --with-gmp=$PFX    \
    --with-mpfr=$PFX   \
    --with-mpc=$PFX    \
 && make

then sit back, relax until ~/tmp-gcc/bld/gcc/gcc/config.cache is created. After
that stop the process by ^C and check the flags passed:

find ~/tmp-gc/bld/gcc -name config.status -print0 | xargs -0 egrep
'"C(XX)?FLAGS"'

which gives:
bld/gcc/config.status:S["CXXFLAGS"]="--sysroot=/"
bld/gcc/config.status:S["CFLAGS"]="--sysroot=/"
bld/gcc/libiberty/config.status:S["CFLAGS"]="-g"
bld/gcc/lto-plugin/config.status:S["CFLAGS"]="-g"
bld/gcc/gcc/config.status:S["CXXFLAGS"]="-g "
bld/gcc/gcc/config.status:S["CFLAGS"]="-g "
bld/gcc/intl/config.status:S["CFLAGS"]="-g"

ie. main config.cache (two first lines) has correct values set and lower ones
are wrong (or at least unexpected).

a possible way to fix
---------------------
there is a line in main configure script:

# Stage specific cflags for build.
stage1_cflags="-g"

this causes such behaviour, as it will be later expanded (in
~/tmp-gcc/bld/gcc/Makefile) as
STAGE1_CFLAGS = -g
...
# Override the above if we're bootstrapping C++.
STAGE1_CXXFLAGS = $(STAGE1_CFLAGS)
...
BASE_FLAGS_TO_PASS = ... "STAGE1_CFLAGS=$(STAGE1_CFLAGS)"
"STAGE1_CXXFLAGS=$(STAGE1_CXXFLAGS)"...
...
RECURSE_FLAGS_TO_PASS = $(BASE_FLAGS_TO_PASS)

which in turn will be passed to other subtargets via $(MAKE)
$(RECURSE_FLAGS_TO_PASS)... calls

So maybe make it more sophisticated instead of just assigning "-g" flag? Say,
`stage1_cflags="-g" $CFLAGS` (or, if we want to have that -g flag, reverse the
order, ie. stage1_cflags=$CFLAGS "-g"

Or maybe am I wrong and it is intentionally, by design?

Regards