Re: [PATCH liburing 2/2] src/Makefile: Add header files as dependency

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

On 3/9/22 5:40 AM, Alviro Iskandar Setiawan wrote:
> When the header files are modified, the compiled object are not going
> to be recompiled because the header files are not marked as dependency
> for the objects. Add those header files as dependency so it is safe
> not to do "make clean" after changing those files.
> 
> Signed-off-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>
> ---
>   src/Makefile | 15 ++++++++++-----
>   1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/src/Makefile b/src/Makefile
> index f19d45e..b9428b7 100644
> --- a/src/Makefile
> +++ b/src/Makefile
> @@ -46,9 +46,16 @@ endif
>   liburing_objs := $(patsubst %.c,%.ol,$(liburing_srcs))
>   liburing_sobjs := $(patsubst %.c,%.os,$(liburing_srcs))
>   
> -$(liburing_srcs): syscall.h lib.h
> -
> -$(liburing_objs) $(liburing_sobjs): include/liburing/io_uring.h
> +$(liburing_objs) $(liburing_sobjs): \
> +	syscall.h \
> +	lib.h \
> +	arch/syscall-defs.h \
> +	arch/x86/syscall.h \
> +	arch/x86/lib.h \
> +	arch/aarch64/syscall.h \
> +	arch/generic/syscall.h \
> +	arch/generic/lib.h \
> +	include/liburing/io_uring.h

This is ugly, it blindly adds all of them to the dependency while
they're actually not dependencies for all the C files here. For
example, when compiling for x86, we don't touch aarch64 files.

It is not a problem for liburing at the moment, because we don't
have many files in the src directory now. But I think we better
provide a long term solution on this.

For the headers files, I think we should rely on the compilers to
generate the dependency list with something like:

    "-MT ... -MMD -MP -MF"

Then include the generated dependency list to the Makefile.

What do you think?

-- 
Ammar Faizi