Re: Make: Unexpected Behavior with Dependencies and include Statement

[John Westing]

I made a typo in my previous email: The following make file duplicates the problem, the one in the previous email does not:

    a.d:
        gcc -m32 -MM -o $@ a.c
        sed 's!a.o!$@ a.o!' --in-place $@
    
    a.o:
        gcc -c -m32 -o $@ a.c
    
    all: a.d a.o
    
    -include a.d

Any ideas?

On Wed, Sep 23, 2015 at 11:14 AM, John Westing <address@hidden> wrote:

I originally posted this problem here:

http://stackoverflow.com/questions/32742321/make-unexpected-behavior-with-dependencies-and-include-statement

Here's my problem:

I have the following Makefile:

    a.d:
        gcc -m32 -MM -o $@ a.c
        sed 's!a.o!$@ a.o!' --in-place $@
   
    a.o:
        gcc -c -m32 -o $@ a.c
   
    all: a.d a.o
   
    a.d a.o: a.c a.h

The contents of a.d are:

    a.d a.o: a.c a.h

I'm having 2 problems. 1, after running "make all" if I run:

    touch a.h
    make a.d

I see this:

    gcc -m32 -MM -o a.d a.c
    sed 's!a.o!a.d a.o!' --in-place a.d
    make: 'a.d' is up to date.

The a.d rule clearly ran, why do I see "make: 'a.d' is up to date."?

2, after running "make all" when I run this:

    touch a.h
    make a.o

I see this:

    gcc -m32 -MM -o a.d a.c
    sed 's!a.o!a.d a.o!' --in-place a.d
    gcc -c -m32 -o a.o a.c

Why did it also run the a.d rule? There are no dependencies on it.

What I really don't understand is when I replace "-include a.d" with the contents of a.d in the make file, for example:

    #-include a.d
    a.d a.o: a.c a.h

I don't see either problem. Shouldn't the include statement make it as if the include file were included directly in the same make file?

This is what my a.h looks like:

    #define FOO 0

And this is a.c:

    #include <stdio.h>
    #include "a.h"
   
    void foo(void)
    {
        printf("foo %d", FOO);
    }

I'm using Cygwin 64-bit. Here's my output from make -v:

    $ make -v
    GNU Make 4.1
    Built for x86_64-unknown-cygwin
    Copyright (C) 1988-2014 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
    This is free software: you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law.

Any ideas?