[Qemu-devel] Re: [PATCH 00/37] Generate a proper LIBS variable

[Paolo Bonzini]

> --extra-cflags: remove it, we can use:
>
> CFLAGS="foo bar" ./configure
> (it is not there yet, but we can do it)

Agreed.

> And we can use in each place that we modify CFLAGS:
>
> CFLAGS="more stuff $CFLAGS"
>
> Notice that the stuff that we invoked ./configure with comes last, as
> we wanted for EXTRA_CFLAGS.
>
> As an added bonus, we can compile all the tests in ./configure with that
> variable set.

Which is good (e.g. if you have incompatible include files that cannot 
be included together).

> As for compiling a file with different options, we want something like
> that for Makefile, i.e.
>
> make all
> rm foo.o
> make CFLAGS=-O0 foo.o
>
> compile with -O0 as last option, that way we can "overwrite" the -O2
> that came from the config-hosts.mak

Yes, that would work even though it's not the way Autoconf/Automake 
packages usually support CFLAGS (the idea there is that the user can put 
all crazy -f/-m options on configure's CFLAGS and disable them with 
"make CFLAGS=-g"; each way has opposite advantages and disadvantages).

Paolo