pq-inc != pkg-config --cflags libpq
pq-lib != pkg-config --libs libpq

cc-flags = -std=c2x $(pq-inc)
ld-flags = $(pq-lib)

B = build

# link rule 
.PHONY: wgsync
$B/wgsync: $B/wgsync.o $B/wireguard.o | $B/
	$(CC) $(ld-flags) $^ -o $@

# build rules 
$B/%.o: src/%.c | $B/
	$(CC) $(cc-flags) -c $< -o $@

$B/wireguard.o: ext/wglib/wireguard.c ext/wglib/wireguard.h | $B/
	$(CC) -std=c11 -c $< -o $@

# dep listings
$B/wgsync.o: ext/wglib/wireguard.h

# fetch rules
%/:
	mkdir -p $@

wg-lib-uri = https://git.zx2c4.com/wireguard-tools/plain/contrib/embeddable-wg-library
ext/wglib/%: | ext/wglib/
	curl $(wg-lib-uri)/$* >$@
