How to include header files in makefiles

[Chuck Robey]

Jonathon McKitrick wrote:
> Hi all,
> 
> I'm setting up a build system for a small project and I want to use included
> makefiles.  I have a base.mk that looks like this:

I will answer here, but be aware that you're getting all of my 
prejudices too, so take things with a grain of salt.

First item deals with the .path statements, and more specifically, your 
use of relative addressing.  It's my own experience that, if you use 
relative addressing, you make troubleshooting a broken build much more 
difficult, because

1) relative addressing means you have to be forever translating paths in 
listings, and very often the number of include paths gets to be rather long.
2) all the stuff like "../.." in listings is quite difficult to read
3) with the $(.CURDIR) variable, it's extremely easy to use absolute 
addressing.  You can also make use of $(.OBJDIR), and it's not so hard 
to make makefiles that work off of read-only sources like cdroms.


> 
> .PATH.h   : ../ ../include
> .INCLUDES : .h
> 
> CFLAGS   = -O -pipe -Wall -g
> CFLAGS  += $(.INCLUDES)
> 
> OBJS     = ${SRCS:R:S/$/.o/g}
> 
> and a bin.mk that looks like this:
> 
> include ../include/mk/base.mk
> 
> all: ${BIN}
> 
> ${BIN}: ${OBJS}
>         ${CC} ${LDFLAGS} -o ${.TARGET} ${.ALLSRC}
> 
> so that a makefile for a specific program looks like this:
> 
> BIN = app
> SRCS = app.c
> LDFLAGS += -pthread
> include ../include/mk/bin.mk

The Make(1) man page doesn't show "include", the advertised command is 
".include".  If you use .include, then you can modify your make, if you 
want, with the -m argument, and so get specific directories to be added 
to the search path for make include files.  I'm not sure, but I think 
that raw "include) is more a gmake item, and it's absolute addressing. 
Don't forget the "-" argument, so that you allow includes to fail if 
they need to, like for generating dependencies.

> 
> But I'm having a problem figuring out how to handle header files.  I have
> some that are local to this binary, but others are in the project include
> directory.
> 
> How can I include the .h files so the .c files are recompiled when the
> header files they require are changed?  GNU make has 'make depend' but I'd
> like a better, BSDmake-centric way, if possible.

Well, did you look at the files in /usr/share/mk, and specifically 
bsd.dep.mk?  You can even use the FreeBSD sources to figure out (to use 
as examples) how things should work.

Don't forget the use of -m, because you can use it to add to the include 
directory list, and so be able to add your own include files without 
corrupting the system files.

I honestly keep on switching back and forth, between thinking that the 
best make is bmake, or gmake.  They both have key items that make them 
uniquely better.

> 
> Thanks for your help,
> 
> jm