As it turns out, ciolib isn't special.

We can't update a fat static library using ar on macOS. :(

src/encode/GNUmakefile

@@ -12,6 +12,9 @@ CFLAGS += -I$(ENCODE_SRC) $(XPDEV_CFLAGS)
 # ENCODE Library Link Rule
 $(ENCODE_BUILD): $(OBJODIR) $(OBJS)
 	@echo Creating $@ ...
+ifdef FAT
+	$(QUIET)$(DELETE) $@
+endif
 	$(QUIET)$(AR) rc $@ $(OBJS)
 	$(QUIET)$(RANLIB) $@
 

src/hash/GNUmakefile

@@ -12,6 +12,9 @@ CFLAGS += -I$(HASH_SRC) $(XPDEV_CFLAGS)
 # HASH Library Link Rule
 $(HASH_BUILD): $(OBJODIR) $(OBJS)
 	@echo Creating $@ ...
+ifdef FAT
+	$(QUIET)$(DELETE) $@
+endif
 	$(QUIET)$(AR) rc $@ $(OBJS)
 	$(QUIET)$(RANLIB) $@
 

src/sftp/GNUmakefile

@@ -17,5 +17,8 @@ CFLAGS += -I$(XPDEV_SRC) $(XPDEV-MT_CFLAGS)
 # MT-SFTP Library Link Rule
 $(SFTPLIB-MT_BUILD): $(MT_OBJS) | $(LIBODIR)
 	@echo Creating $@ ...
+ifdef FAT
+	$(QUIET)$(DELETE) $@
+endif
 	$(QUIET)$(AR) rc $@ $(MT_OBJS)
 	$(QUIET)$(RANLIB) $@

src/smblib/GNUmakefile

@@ -23,6 +23,9 @@ CFLAGS += -I$(XPDEV_SRC) $(ENCODE_CFLAGS) $(HASH_CFLAGS) $(XPDEV_CFLAGS)
 # SMBLIB Library Link Rule
 $(SMBLIB_BUILD): $(OBJS) | $(OBJODIR)
 	@echo Creating $@ ...
+ifdef FAT
+	$(QUIET)$(DELETE) $@
+endif
 	$(QUIET)$(AR) rc $@ $(OBJS)
 	$(QUIET)$(RANLIB) $@
 

src/uifc/GNUmakefile

@@ -22,6 +22,9 @@ CFLAGS += -I$(XPDEV_SRC) $(CIOLIB-MT_CFLAGS) $(XPDEV-MT_CFLAGS)
 # MT-UIFC Library Link Rule
 $(UIFCLIB-MT_BUILD): $(MT_OBJS) | $(MTOBJODIR) $(LIBODIR)
 	@echo Creating $@ ...
+ifdef FAT
+	$(QUIET)$(DELETE) $@
+endif
 	$(QUIET)$(AR) rc $@ $(MT_OBJS)
 	$(QUIET)$(RANLIB) $@
 

src/xpdev/GNUmakefile

@@ -39,6 +39,9 @@ $(XPTIME): $(OBJODIR)/xptime.o $(XPDEV_LIB_BUILD)
 
 $(XPDEV_LIB_BUILD): $(OBJS) | $(OBJODIR)
 	@echo Creating $@
+ifdef FAT
+	$(QUIET)$(DELETE) $@
+endif
 	$(QUIET)$(AR) rc $@ $(OBJS)
 	$(QUIET)$(RANLIB) $@
 
@@ -48,6 +51,9 @@ $(XPDEV_SHLIB_BUILD): $(OBJS) | $(OBJODIR)
 
 $(XPDEV-MT_LIB_BUILD): $(MTOBJS) | $(MTOBJODIR)
 	@echo Creating $@
+ifdef FAT
+	$(QUIET)$(DELETE) $@
+endif
 	$(QUIET)$(AR) rc $@ $(MTOBJS)
 	$(QUIET)$(RANLIB) $@