configure

#!/bin/sh

try_cflag(){
	flag="$1"
	target="$2"
	if test -z "$target"
	then target='CFLAGS_CONFIGURE'
	fi

	printf 'checking whether compiler accepts %s... ' "$flag"
	echo "typedef int abc;" >"$ctmp"

	if $CC "$flag" -c -o /dev/null "$ctmp" >/dev/null 2>&1
	then
		echo yes
		echo "$target += $flag" >> Makefile.cfg
		return 0
	else
		echo no
		return 1
	fi
}

if [ $# -ne 0 ]
then
	echo "Usage: $0" >&2
	echo "Pass CC, CFLAGS and LDFLAGS via the environment" >&2
	echo "e.g. CFLAGS=-O3 ./configure" >&2
	exit 1
fi

if [ -z "$TMPDIR" ]
then
	TMPDIR=tmp/
	mkdir -p "$TMPDIR" || exit $?
	trap "rm -r '$TMPDIR'" EXIT
fi

if [ -z "$CC" ]
then
	CC=cc
fi

irtmpdir="${TMPDIR}"/ir.$$
mkdir "$irtmpdir" || { echo "couldn't make temporary directory" >&2; exit 1; }
trap "rm -rf '$irtmpdir'" EXIT

ctmp="$irtmpdir/1.c"

echo > Makefile.cfg

echo "CC = $CC" >> Makefile.cfg
echo "CFLAGS_CONFIGURE = $CFLAGS" >> Makefile.cfg
echo "LDFLAGS_CONFIGURE = $LDFLAGS" >> Makefile.cfg

try_cflag -std=c89 || try_cflag -ansi
try_cflag -Wall
try_cflag -Wextra
try_cflag -Wmissing-prototypes
try_cflag -Wmissing-declarations

try_cflag -Werror=incompatible-pointer-types
try_cflag -Werror=int-conversion
try_cflag -Werror=implicit-function-declaration

try_cflag -Wno-missing-field-initializers
try_cflag -Wno-missing-braces
try_cflag -Wno-pointer-to-int-cast
try_cflag -Wno-sign-compare
try_cflag -Wno-implicit-fallthrough

try_cflag -g
try_cflag -g LDFLAGS_CONFIGURE