[Bug bootstrap/51388] New: Configure failure to detect unsupported warning options for non-bootstrap builds (including cross builds)

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51388

             Bug #: 51388
           Summary: Configure failure to detect unsupported warning
                    options for non-bootstrap builds (including cross
                    builds)
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: steven@gcc.gnu.org


GCC current trunk (r181908) fails to do a non-bootstrap build (i.e.
--disable-bootstrap, or a cross-compiler build). The build compiler I used was
GCC 4.3. 

...
make[2]: Entering directory `/home/stevenb/devel/build/zlib'
true "AR_FLAGS=rc" "CC_FOR_BUILD=gcc" "CFLAGS=-g -O2" "CXXFLAGS=-g -O2"
"CFLAGS_FOR_BUILD=-g -O2" "CFLAGS_FOR_TARGET=-g -O2" "INSTALL=/usr/b
in/install -c" "INSTALL_DATA=/usr/bin/install -c -m 644"
"INSTALL_PROGRAM=/usr/bin/install -c" "INSTALL_SCRIPT=/usr/bin/install -c"
"LDFLAGS
=" "LIBCFLAGS=-g -O2" "LIBCFLAGS_FOR_TARGET=-g -O2" "MAKE=make"
"MAKEINFO=makeinfo --split-size=5000000 --split-size=5000000 " "PICFLAG=" "P
ICFLAG_FOR_TARGET=" "SHELL=/bin/sh" "EXPECT=expect" "RUNTEST=runtest"
"RUNTESTFLAGS=" "exec_prefix=/usr/local" "infodir=/usr/local/share/inf
o" "libdir=/usr/local/lib" "prefix=/usr/local"
"tooldir=/usr/local/x86_64-unknown-linux-gnu" "AR=ar" "AS=as" "CC=gcc"
"CXX=g++" "LD=ld" "LIB
CFLAGS=-g -O2" "NM=nm" "PICFLAG=" "RANLIB=ranlib" "DESTDIR=" DO=all multi-do #
make
make[2]: Leaving directory `/home/stevenb/devel/build/zlib'
make[2]: Entering directory `/home/stevenb/devel/build/libcpp'
gcc  -I../../trunk/libcpp -I. -I../../trunk/libcpp/../include
-I../../trunk/libcpp/include  -g -O2 -W -Wall -Wno-narrowing -Wwrite-strings -
Wmissing-format-attribute -Wstrict-prototypes -Wmissing-prototypes
-Wold-style-definition -Wc++-compat -pedantic -Wno-long-long  -I../../tru
nk/libcpp -I. -I../../trunk/libcpp/../include -I../../trunk/libcpp/include  -c
-o macro.o -MT macro.o -MMD -MP -MF .deps/macro.Tpo ../../tru
nk/libcpp/macro.c
../../trunk/libcpp/macro.c:146: warning: â?~tokens_buff_remove_last_tokenâ?T
declared inline after being called
../../trunk/libcpp/macro.c:146: warning: previous declaration of
â?~tokens_buff_remove_last_tokenâ?T was here
cc1: error: unrecognized command line option "-Wno-narrowing"
make[2]: *** [macro.o] Error 1
make[2]: Target `all' not remade because of errors.
make[2]: Leaving directory `/home/stevenb/devel/build/libcpp'
make[1]: *** [all-libcpp] Error 2
make[2]: Entering directory `/home/stevenb/devel/build/libdecnumber'
make[2]: Nothing to be done for `all'.
make[2]: Leaving directory `/home/stevenb/devel/build/libdecnumber'
make[1]: Target `all-host' not remade because of errors.
make[1]: Target `all-target' not remade because of errors.
make[1]: Leaving directory `/home/stevenb/devel/build'
make: *** [all] Error 2
$

Note the cc1 error. Problem seems to be that ACX_PROG_CC_WARNING_OPTS checks
for -Wno-narrowing in isolation, and that check passes, but the actual options
passed to GCC do not:

$ cat t.c
#ifdef HAVE_ARG
void foo (int t) { return; }
#else
void foo (void) { return; }
#endif

$ # This is how the build process calls GCC, note -W -Wall
$ gcc -c -W -Wall -Wno-narrowing t.c -DHAVE_ARG
t.c:2: warning: unused parameter â?~tâ?T
cc1: error: unrecognized command line option "-Wno-narrowing"
$ # This is how the configure check calls the compiler
$ gcc -c -Wno-narrowing t.c -DHAVE_ARG
$ 
$ # Even more confusing: Make foo a void function, and the warning
$ # does not trigger anymore at all!
$ gcc -c -W -Wall -Wno-narrowing t.c
$ gcc -c -Wno-narrowing t.c
$