?RCS: $Id: Checkcc.U 167 2013-05-08 17:58:00Z rmanfredi $
?RCS:
?RCS: Copyright (c) 1991-1997, 2004-2006, Raphael Manfredi
?RCS: 
?RCS: You may redistribute only under the terms of the Artistic License,
?RCS: as specified in the README file that comes with the distribution.
?RCS: You may reuse parts of this distribution only within the terms of
?RCS: that same Artistic License; a copy of which may be found at the root
?RCS: of the source tree for dist 4.0.
?RCS:
?RCS: Copyright (c) 2000, Jarkko Hietaniemi
?RCS: 
?X: 
?X: This unit produces a bit of shell code that must be dotted in order
?X: to make quick check on whether the current C compiler is working.
?X:	
?MAKE:Checkcc ccname ccversion: Myread Warn startsh cat contains test
?MAKE:	-pick add $@ %<
?S:ccname:
?S:	This can set either by hints files or by Configure.  If using
?S:	gcc, this is gcc, and if not, usually equal to cc, unimpressive, no?
?S:	Some platforms, however, make good use of this by storing the
?S:	flavor of the C compiler being used here.  For example if using
?S:	the Sun WorkShop suite, ccname will be 'workshop'.
?S:.
?S:ccversion:
?S:	This can set either by hints files or by Configure.  If using
?S:	a (non-gcc) vendor cc, this variable may contain a version for
?S:	the compiler.
?S:.
?F:./checkcc ./trygcc !checktmp
?V:despair
?T:trygcc
?LINT:extern cc rm ccflags ldflags
?LINT:change cc ccflags
?LINT:usefile checktmp
?INIT:ccname=''
?INIT:ccversion=''
: generate the trygcc script for later perusal
cat <<EOS >trygcc
$startsh
EOS
cat <<'EOSC' >>trygcc
case "$cc" in
'') ;;
*)  $rm -f try try.*
    $cat >try.c <<EOM
int main(int argc, char *argv[]) {
  (void) argc;
  (void) argv;
  return 0;
}
EOM
    if $cc -o try $ccflags $ldflags try.c; then
       :
    else
        echo "Uh-oh, the C compiler '$cc' doesn't seem to be working." >&4
        despair=yes
        trygcc=yes
        case "$cc" in
        *gcc*) trygcc=no ;;
        esac
        case "`$cc -v -c try.c 2>&1`" in
        *gcc*) trygcc=no ;;
        esac
        if $test X"$trygcc" = Xyes; then
            if gcc -o try -c try.c; then
                echo " "
                echo "You seem to have a working gcc, though." >&4
                rp="Would you like to use it?"
                dflt=y
                if $test -f myread; then
                    . ./myread
                else
                    if $test -f UU/myread; then
                        . ./UU/myread
                    else
                        echo "Cannot find myread, sorry.  Aborting." >&2
                        exit 1
                    fi
                fi  
                case "$ans" in
                [yY]*) cc=gcc; ccname=gcc; ccflags=''; despair=no;
?X: Look whether we have 'call-back units' generated by hints that would
?X: seemingly affect the compiling environment.
                       $cat *.cbu >checktmp 2>/dev/null
                       if $contains ccflags checktmp >/dev/null; then
                           ./warn 4>&4 <<EOM 
Any previous setting of the C compiler flags has been lost.
It may be necessary to pass -Dcc=gcc to Configure right away.
EOM
                       fi;;
                esac
            fi
        fi
    fi
    $rm -f try try.*
    ;;
esac
EOSC

: generate the checkcc script for later perusal
cat <<EOS >checkcc
$startsh
EOS
cat <<'EOSC' >>checkcc
case "$cc" in        
'') ;;
*)  $rm -f try try.*              
    $cat >try.c <<EOM
int main(int argc, char *argv[]) {
  (void) argc;
  (void) argv;
  return 0;
}
EOM
    if $cc -o try $ccflags $ldflags try.c; then
       :
    else
        if $test X"$despair" = Xyes; then
           echo "Uh-oh, the C compiler '$cc' doesn't seem to be working." >&4
        fi
        $cat >&4 <<EOM         
You need to find a working C compiler.
Either (purchase and) install the C compiler supplied by your OS vendor,
or for a free C compiler try http://gcc.gnu.org/
I cannot continue any further, aborting.
EOM
        exit 1
    fi
    $rm -f try try.*
    ;;
esac
EOSC