Re: [PATCH v4 for-5.0] configure: warn if not using a separate build directory

[Eric Blake]

On 4/3/20 9:02 AM, Eric Blake wrote:
> On 4/3/20 8:53 AM, Daniel P. Berrangé wrote:
> > Running configure directly from the source directory is a build
> > configuration that will go away in future. It is also not currently
> > covered by any automated testing. Display a deprecation warning if
> > the user attempts to use an in-srcdir build setup, so that they are
> > aware that they're building QEMU in an undesirable manner.
> >
> > Reviewed-by: Eric Blake <address@hidden>
> > Reviewed-by: Markus Armbruster <address@hidden>
> > Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
> > Tested-by: Philippe Mathieu-Daudé <address@hidden>
> > Signed-off-by: Daniel P. Berrangé <address@hidden>
> > ---
> >
> > Changed in v4:
> >    - Adopted Eric's suggested wording
>
> > +if test "$in_srcdir" = "yes"; then
> > +    echo
> > +    echo "WARNING: SUPPORT FOR BUILDING IN THE SOURCE DIR IS DEPRECATED"
> > +    echo
> > +    echo "Support for running the 'configure' script directly from the"
> > +    echo "source directory is deprecated. In-tree builds are not 
> > covered"
> > +    echo "by automated testing and thus may not correctly build QEMU."
> > +    echo "Users are recommended to use a separate build directory:"
> > +    echo
> > +    echo "  $ mkdir build"
> > +    echo "  $ cd build"
> > +    echo "  $ ../configure"
> > +    echo "  $ make"
>
> Late question, but:
>
> Since this is just a warning, we still manage to complete the 
> ./configure run, including whatever generated files it leaves in-tree. 
> Is there any additional step we need to recommend prior to 'mkdir build' 
> that will clean up the in-tree artifacts, so that the user then 
> attempting the VPATH build won't still have a broken build due to the 
> leftovers from the in-tree attempt?  'make distclean', perhaps?
>
> /me starts testing; I'll reply back once it finishes...

tl;dr: 'make distclean' isn't perfect (it still leaves 2 directories 
behind), but does clean up a lot of directories and .mak files, and IS 
necessary before you can build in the subdirectory; but at least make 
warns you.  Still, I'd prefer adding that step in the warning, rather 
than getting an error several steps later.

On a fresh git checkout:

$ ./configure
...
$ git clean -dfxn
Would remove aarch64-linux-user/
Would remove aarch64-softmmu/
Would remove aarch64_be-linux-user/
Would remove alpha-linux-user/
Would remove alpha-softmmu/
Would remove arm-linux-user/
Would remove arm-softmmu/
Would remove armeb-linux-user/
Would remove config-all-disas.mak
Would remove config-host.mak
Would remove config.log
Would remove config.status
Would remove cris-linux-user/
Would remove cris-softmmu/
Would remove docs/sphinx/__pycache__/
Would remove hppa-linux-user/
Would remove hppa-softmmu/
Would remove i386-linux-user/
Would remove i386-softmmu/
Would remove linux-headers/asm
Would remove lm32-softmmu/
Would remove m68k-linux-user/
Would remove m68k-softmmu/
Would remove microblaze-linux-user/
Would remove microblaze-softmmu/
Would remove microblazeel-linux-user/
Would remove microblazeel-softmmu/
Would remove mips-linux-user/
Would remove mips-softmmu/
Would remove mips64-linux-user/
Would remove mips64-softmmu/
Would remove mips64el-linux-user/
Would remove mips64el-softmmu/
Would remove mipsel-linux-user/
Would remove mipsel-softmmu/
Would remove mipsn32-linux-user/
Would remove mipsn32el-linux-user/
Would remove moxie-softmmu/
Would remove nios2-linux-user/
Would remove nios2-softmmu/
Would remove or1k-linux-user/
Would remove or1k-softmmu/
Would remove ppc-linux-user/
Would remove ppc-softmmu/
Would remove ppc64-linux-user/
Would remove ppc64-softmmu/
Would remove ppc64abi32-linux-user/
Would remove ppc64le-linux-user/
Would remove riscv32-linux-user/
Would remove riscv32-softmmu/
Would remove riscv64-linux-user/
Would remove riscv64-softmmu/
Would remove rx-softmmu/
Would remove s390x-linux-user/
Would remove s390x-softmmu/
Would remove sh4-linux-user/
Would remove sh4-softmmu/
Would remove sh4eb-linux-user/
Would remove sh4eb-softmmu/
Would remove sparc-linux-user/
Would remove sparc-softmmu/
Would remove sparc32plus-linux-user/
Would remove sparc64-linux-user/
Would remove sparc64-softmmu/
Would remove tests/qemu-iotests/common.env
Would remove tests/qgraph/
Would remove tests/tcg/config-aarch64-linux-user.mak
Would remove tests/tcg/config-aarch64-softmmu.mak
Would remove tests/tcg/config-aarch64_be-linux-user.mak
Would remove tests/tcg/config-alpha-linux-user.mak
Would remove tests/tcg/config-alpha-softmmu.mak
Would remove tests/tcg/config-arm-linux-user.mak
Would remove tests/tcg/config-arm-softmmu.mak
Would remove tests/tcg/config-armeb-linux-user.mak
Would remove tests/tcg/config-cris-linux-user.mak
Would remove tests/tcg/config-cris-softmmu.mak
Would remove tests/tcg/config-hppa-linux-user.mak
Would remove tests/tcg/config-hppa-softmmu.mak
Would remove tests/tcg/config-i386-linux-user.mak
Would remove tests/tcg/config-i386-softmmu.mak
Would remove tests/tcg/config-lm32-softmmu.mak
Would remove tests/tcg/config-m68k-linux-user.mak
Would remove tests/tcg/config-m68k-softmmu.mak
Would remove tests/tcg/config-mips-linux-user.mak
Would remove tests/tcg/config-mips-softmmu.mak
Would remove tests/tcg/config-mips64-linux-user.mak
Would remove tests/tcg/config-mips64-softmmu.mak
Would remove tests/tcg/config-mips64el-linux-user.mak
Would remove tests/tcg/config-mips64el-softmmu.mak
Would remove tests/tcg/config-mipsel-linux-user.mak
Would remove tests/tcg/config-mipsel-softmmu.mak
Would remove tests/tcg/config-mipsn32-linux-user.mak
Would remove tests/tcg/config-mipsn32el-linux-user.mak
Would remove tests/tcg/config-ppc-linux-user.mak
Would remove tests/tcg/config-ppc-softmmu.mak
Would remove tests/tcg/config-ppc64-linux-user.mak
Would remove tests/tcg/config-ppc64-softmmu.mak
Would remove tests/tcg/config-ppc64abi32-linux-user.mak
Would remove tests/tcg/config-ppc64le-linux-user.mak
Would remove tests/tcg/config-riscv64-linux-user.mak
Would remove tests/tcg/config-riscv64-softmmu.mak
Would remove tests/tcg/config-s390x-linux-user.mak
Would remove tests/tcg/config-s390x-softmmu.mak
Would remove tests/tcg/config-sh4-linux-user.mak
Would remove tests/tcg/config-sh4-softmmu.mak
Would remove tests/tcg/config-sh4eb-linux-user.mak
Would remove tests/tcg/config-sh4eb-softmmu.mak
Would remove tests/tcg/config-sparc64-linux-user.mak
Would remove tests/tcg/config-sparc64-softmmu.mak
Would remove tests/tcg/config-x86_64-linux-user.mak
Would remove tests/tcg/config-x86_64-softmmu.mak
Would remove tests/tcg/config-xtensa-linux-user.mak
Would remove tests/tcg/config-xtensa-softmmu.mak
Would remove tests/tcg/config-xtensaeb-linux-user.mak
Would remove tests/tcg/config-xtensaeb-softmmu.mak
Would remove tilegx-linux-user/
Would remove tricore-softmmu/
Would remove unicore32-softmmu/
Would remove x86_64-linux-user/
Would remove x86_64-softmmu/
Would remove xtensa-linux-user/
Would remove xtensa-softmmu/
Would remove xtensaeb-linux-user/
Would remove xtensaeb-softmmu/
$ make distclean
...
$ git clean -dfxn
Would remove docs/sphinx/__pycache__/
Would remove tests/qgraph/
$ ./configure
...
$ mkdir build
$ cd build
$ ../configure
$ make
Makefile:58: *** This is an out of tree build but your source tree 
(/home/eblake/qemu-tmp) seems to have been used for an in-tree build. 
You can fix this by running "make distclean && rm -rf *-linux-user 
*-softmmu" in your source tree.  Stop.
$ cd ..
$ make distclean && rm -rf *-linux-user *-softmmu
$ cd build
$ make
...


--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org