Rework compilation of binaries; prepare for automatic dependencies

Don't involve user-adjustable variables like CFLAGS until the final
compilation steps, in part so it's clearer where they fit in.  Handle
all of bup's flags independently, and split them into separate
library (helpers) and executable (bin/bup, etc.)  groups via
bup_shared_cflags, helpers_cflags, embed_cflags, etc.

Change the build rules to specify -fPIE for the executables, and
include all dependencies ($^) and use OUTPUT_OPTION in preparation for
automatic C dependency generation.

Add -Wno-unused-command-line-argument for clang.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Tested-by: Rob Browning <rlb@defaultvalue.org>

diff --git a/Makefile b/Makefile
index 9510210c381990a7aac36e0332d23a28ef39ce90..b109a9cf29d05e6e8b877049a1966e2af370cdce 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -29,13 +29,20 @@ current_sampledata := test/sampledata/var/rev/v$(sampledata_rev)
 os := $(shell ($(pf); uname | sed 's/[-_].*//') $(isok))
 os := $(call shout,$(os),Unable to determine OS)
 
-CFLAGS := -O2 -Wall -Werror -Wformat=2 $(CFLAGS)
-CFLAGS := -Wno-unknown-pragmas -Wsign-compare $(CFLAGS)
-CFLAGS := -D_FILE_OFFSET_BITS=64 $(CFLAGS)
-SOEXT:=.so
-
+# Satisfy --warn-undefined-variables
+CFLAGS ?=
+CPPFLAGS ?=
+LDFLAGS ?=
+TARGET_ARCH ?=
+
+bup_shared_cflags := -O2 -Wall -Werror -Wformat=2
+bup_shared_cflags := -Wno-unused-command-line-argument $(bup_shared_cflags)
+bup_shared_cflags := -Wno-unknown-pragmas -Wsign-compare $(bup_shared_cflags)
+bup_shared_cflags := -D_FILE_OFFSET_BITS=64 $(bup_shared_cflags)
+
+soext := .so
 ifeq ($(os),CYGWIN)
-  SOEXT:=.dll
+  soext := .dll
 endif
 
 ifdef TMPDIR
@@ -57,25 +64,28 @@ config/config.vars: \
 # _XOPEN_SOURCE version, i.e. -Werror crashes on a mismatch, so for
 # now, we're just going to let Python's version win.
 
+helpers_cflags := $(bup_python_cflags) $(bup_shared_cflags)
+helpers_ldflags := $(bup_python_ldflags) $(bup_shared_ldflags)
+
 ifneq ($(strip $(bup_readline_cflags)),)
   readline_cflags += $(bup_readline_cflags)
   readline_xopen := $(filter -D_XOPEN_SOURCE=%,$(readline_cflags))
   readline_xopen := $(subst -D_XOPEN_SOURCE=,,$(readline_xopen))
   readline_cflags := $(filter-out -D_XOPEN_SOURCE=%,$(readline_cflags))
   readline_cflags += $(addprefix -DBUP_RL_EXPECTED_XOPEN_SOURCE=,$(readline_xopen))
-  CFLAGS += $(readline_cflags)
+  helpers_cflags += $(readline_cflags)
 endif
 
-LDFLAGS += $(bup_readline_ldflags)
+helpers_ldflags += $(bup_readline_ldflags)
 
 ifeq ($(bup_have_libacl),1)
-  CFLAGS += $(bup_libacl_cflags)
-  LDFLAGS += $(bup_libacl_ldflags)
+  helpers_cflags += $(bup_libacl_cflags)
+  helpers_ldflags += $(bup_libacl_ldflags)
 endif
 
 bup_ext_cmds := lib/cmd/bup-import-rdiff-backup lib/cmd/bup-import-rsnapshot
 
-bup_deps := lib/bup/_helpers$(SOEXT) lib/cmd/bup
+bup_deps := lib/bup/_helpers$(soext) lib/cmd/bup
 
 all: dev/bup-exec dev/bup-python dev/python $(bup_deps) Documentation/all \
   $(current_sampledata)
@@ -122,7 +132,7 @@ install: all
        $(INSTALL) -pm 0644 lib/bup/*.py $(dest_libdir)/bup/
        $(INSTALL) -pm 0644 lib/bup/cmd/*.py $(dest_libdir)/bup/cmd/
        $(INSTALL) -pm 0755 \
-               lib/bup/*$(SOEXT) \
+               lib/bup/*$(soext) \
                $(dest_libdir)/bup
        $(INSTALL) -pm 0644 \
                lib/web/static/* \
@@ -138,36 +148,43 @@ install: all
            $(INSTALL) -pm 0644 lib/bup/source_info.py $(dest_libdir)/bup/; \
        fi
 
+embed_cflags := $(bup_python_cflags_embed) $(bup_shared_cflags)
+embed_ldflags := $(bup_python_ldflags_embed) $(bup_shared_ldflags)
+
 config/config.h: config/config.vars
 clean_paths += config/config.h.tmp
 
-dev/python: dev/python.c config/config.h
-       $(CC) $(bup_python_cflags_embed) $< $(bup_python_ldflags_embed) -o $@-proposed
+cc_bin = $(CC) $(embed_cflags) $(CFLAGS) $^ $(embed_ldflags) $(LDFLAGS) -fPIE \
+  $(OUTPUT_OPTION)
+
+clean_paths += dev/python-proposed
+dev/python-proposed: dev/python.c config/config.h
+       rm -f dev/python
+       $(cc_bin)
+
+clean_paths += dev/python
+dev/python: dev/python-proposed
        dev/validate-python $@-proposed
-       mv $@-proposed $@
-clean_paths += dev/python dev/python-proposed
+       ln $@-proposed $@
 
-dev/bup-exec: lib/cmd/bup.c config/config.h
-       $(CC) $(bup_python_cflags_embed) $< $(bup_python_ldflags_embed) -fPIC \
-         -D BUP_DEV_BUP_EXEC=1 -o $@
 clean_paths += dev/bup-exec
+dev/bup-exec: CFLAGS += -D BUP_DEV_BUP_EXEC=1
+dev/bup-exec: lib/cmd/bup.c config/config.h
+       $(cc_bin)
 
-dev/bup-python: lib/cmd/bup.c config/config.h
-       $(CC) $(bup_python_cflags_embed) $< $(bup_python_ldflags_embed) -fPIC \
-         -D BUP_DEV_BUP_PYTHON=1 -o $@
 clean_paths += dev/bup-python
+dev/bup-python: CFLAGS += -D BUP_DEV_BUP_PYTHON=1
+dev/bup-python: lib/cmd/bup.c config/config.h
+       $(cc_bin)
 
-lib/cmd/bup: lib/cmd/bup.c config/config.h
-       $(CC) $(bup_python_cflags_embed) $< $(bup_python_ldflags_embed) -fPIC -o $@
 clean_paths += lib/cmd/bup
+lib/cmd/bup: lib/cmd/bup.c config/config.h
+       $(cc_bin)
 
-helper_src := config/config.h lib/bup/bupsplit.h lib/bup/bupsplit.c
-helper_src += lib/bup/_helpers.c
-
-lib/bup/_helpers$(SOEXT): dev/python $(helper_src)
-       $(CC) $(bup_python_cflags) $(CFLAGS) -shared -fPIC $(helper_src) \
-         $(bup_python_ldflags) $(LDFLAGS) -o $@
-clean_paths += lib/bup/_helpers$(SOEXT)
+clean_paths += lib/bup/_helpers$(soext)
+lib/bup/_helpers$(soext): lib/bup/_helpers.c lib/bup/bupsplit.c
+       $(CC) $(helpers_cflags) $(CFLAGS) -shared -fPIC $^ \
+         $(helpers_ldflags) $(LDFLAGS) $(OUTPUT_OPTION)
 
 test/tmp:
        mkdir test/tmp