https://bugs.gentoo.org/917760
We can't build program without library, utils dependency is just in case
diff -ru a/Makefile b/Makefile
--- a/Makefile	2025-01-09 11:48:10.117085442 +0400
+++ b/Makefile	2025-01-09 11:48:27.041979565 +0400
@@ -19,10 +19,10 @@
 lib:
 	$(MAKE) -C libflake all
 
-progs:
+progs: lib
 	$(MAKE) -C flake all
 
-utils:
+utils: progs lib
 	$(MAKE) -C util all
 
 .PHONY: install
https://bugs.gentoo.org/912148
https://bugs.gentoo.org/880819
False dependency, if we put flake in build graph, make uses default build
rules, doesn't include library and failure to link occurs.
diff -ru a/flake/Makefile b/flake/Makefile
--- a/flake/Makefile	2025-01-09 11:57:17.279914146 +0400
+++ b/flake/Makefile	2025-01-09 11:59:25.559155784 +0400
@@ -21,6 +21,6 @@
 
-all: $(PROGS_G) $(PROGS)
+all: $(PROGS_G)
 
 flake_g$(EXESUF): flake.o wav.o $(DEP_LIBS)
 	$(CC) $(FLAKE_LIBDIRS) $(LDFLAGS) -o $@ flake.o wav.o $(FLAKE_LIBS) $(EXTRALIBS)
 	cp -p flake_g$(EXESUF) flake$(EXESUF)
Clean up implicit declaration in configure and prepare for C23
diff -ru a/configure b/configure
@@ -666,6 +667,7 @@
 # test for strnlen in string.h
 check_exec <<EOF && have_strnlen=yes || have_strnlen=no
 #define _ISOC9X_SOURCE  1
+#define _GNU_SOURCE  1
+#include <strings.h>
 #include <string.h>
 int main( void ) { return (strnlen("help", 6) == 4)?0:1; }
 EOF
diff -ru a/common.h b/common.h
--- a/common.h	2025-01-09 16:06:00.978525674 +0400
+++ b//common.h	2025-01-09 16:07:06.592168373 +0400
@@ -87,7 +87,8 @@
     return i;
 }
 #elif !defined(__USE_GNU)
-extern size_t strnlen(const char *s, size_t maxlen);
+#include <strings.h>
+//extern size_t strnlen(const char *s, size_t maxlen);
 #endif
 
 #endif /* COMMON_H */