From d9a840ff11d680e3b8801228e359b3a6d7e06182 Mon Sep 17 00:00:00 2001
From: Andre Noll <maan@tuebingen.mpg.de>
Date: Sat, 16 May 2020 13:23:03 +0200
Subject: [PATCH] build: Create dependencies on the fly.

This is faster since we run the compiler only once. It is more robust,
too, because the build does not break if a random .h file is added to
the working directory. Using $(wildcard) is almost always a mistake..
---
 .gitignore |  2 +-
 Makefile   | 15 +++++++--------
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/.gitignore b/.gitignore
index 907447f..8a57428 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
-*.[oa]
+*.[oad]
 foo
 bar*
 *lsg.[ch]
diff --git a/Makefile b/Makefile
index 7ce4493..c52eaea 100644
--- a/Makefile
+++ b/Makefile
@@ -7,6 +7,7 @@ mandir := $(PREFIX)/man/man1
 
 objects := osl.o util.o rbtree.o sha1.o
 fsck_objects := fsck.o osl.o util.o rbtree.o sha1.o oslfsck.lsg.o
+deps := $(sort $(objects:.o=.d) $(fsck_objects:.o=.d))
 headers := osl.h
 executables := oslfsck
 man_pages := oslfsck.1
@@ -115,15 +116,13 @@ endif
 all: $(realname) $(executables) $(man_pages)
 shared: $(realname)
 
-Makefile.deps: $(wildcard *.c *.h)
-	$(CC) -MM -MG *.c > $@
-osl.c fsck.c:
-
--include Makefile.deps
-
+ifeq ($(findstring clean, $(MAKECMDGOALS)),)
+-include $(deps)
+endif
 %.o: %.c Makefile errtab.h
-	$(CC) -c $(CPPFLAGS) $(CFLAGS) $(LIBCFLAGS) $<
+	$(CC) $(CPPFLAGS) -c -MMD -MF $(*F).d -MT $@ $(CFLAGS) $(LIBCFLAGS) $<
 
+fsck.o: oslfsck.lsg.h
 oslfsck: $(fsck_objects)
 	$(CC) -o $@ $(fsck_objects) -llopsub
 
@@ -164,7 +163,7 @@ osl.h: osl.h.in osl_errors.h Makefile
 	echo '#endif /* _OSL_H */' >> $@
 clean:
 	rm -f *.o $(realname) osl.h osl_errors.h errtab.h \
-		oslfsck *.a *.ga *.sym *.lsg.*
+		oslfsck *.a *.ga *.sym *.lsg.* *.d
 
 distclean: clean
 	rm -f web/index.html web/oslfsck.1.html web/osl.png
-- 
2.39.5