Re: 回复： Implicit rule for linking multiple object files

[Martin Dorey]

> I want to compile objects in order of the writting

Just because, today, make happens to pick nearly what you want it to do without being told about your ordering constraint, doesn't mean that you should rely on it continuing to do so.  You should teach make about that order.  You could contrive a function to $(eval) your y.o z.o x.o list into a chain of pairwise dependencies:

z.o: y.o

x.o: z.o

Like this:

martind@sirius:~/tmp/ljh-2022-08-11$ cat Makefile

objs = y.o z.o x.o

space = $(subst :,,: :)

makeDependency = $(eval $(lastword $(1)): $(firstword $(1)))

$(foreach pair,$(filter-out guard@@% %@@guard,$(join guard $(objs),$(addprefix @@,$(objs) guard))),$(call makeDependency,$(subst @@,$(space),$(pair))))

martind@sirius:~/tmp/ljh-2022-08-11$ make -p | grep '[xyz]\.o: [xyz].o'

make: *** No rule to make target 'y.o', needed by 'z.o'.  Stop.

z.o: y.o

x.o: z.o

martind@sirius:~/tmp/ljh-2022-08-11$

---

From: Bug-make <bug-make-bounces+martin.dorey=hds.com@gnu.org> on behalf of ljh <ljhm@qq.com>
Sent: Thursday, August 11, 2022 01:56
To: Philip Guenther <guenther@gmail.com>
Cc: psmith <psmith@gnu.org>; bug-make <bug-make@gnu.org>
Subject: 回复： Implicit rule for linking multiple object files

 

***** EXTERNAL EMAIL *****

Thanks Philip,

I want to compile objects in order of the writting: y.o z.o x.o .

The order of compiling x.o are different in below three cases.

I don't understand the difference. 

x : y.o z.o x.o  # compiles x.o last

        $(CC) $^ -o $@  # with recipe

x : y.o z.o      # compiles x.o last

x : y.o z.o x.o  # compiles x.o first

My purpose is to keep my Makefile simple. With the patsubst function in 

Makefile, I just put Makefile with my source files and need to do nothing.

It just compiles. But this is gone if the order of compiling matters.

x : $(patsubst %.c,%.o,$(wildcard *.c))

Thanks

---

# My Minimal Makefile for C, C++

# build shared library with -fPIC, -shared

CFLAGS   = -Wall -Wextra -g # -O3 -fPIC  # CXXFLAGS for .cpp

LDFLAGS  = # -L../hello # -shared

LDLIBS   = # -lhello

CPPFLAGS = -MMD -MP # -I../hello

#CC      = $(CXX)  # link with CXX for .cpp

# target name is basename of one of the source files

main : $(patsubst %.c,%.o,$(wildcard *.c))  # .cpp

-include *.d

clean : ; -rm -fr *.o *.d

.PHONY : clean