Re: [PATCH] configure: add support for psuedo-"in source tree" builds

[Philippe Mathieu-Daudé]

Typo "pseudo" in subject.

On 8/20/20 6:55 PM, Daniel P. Berrangé wrote:
> Meson requires the build dir to be separate from the source tree. Many
> people are used to just running "./configure && make" though and the
> meson conversion breaks that.
> 
> This introduces some backcompat support to make it appear as if an
> "in source tree" build is being done, but with the the results in the
> "build/" directory. This allows "./configure && make" to work as it
> did historically, albeit with the output binaries staying under build/.
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
> 
> This is a simple integration of Eric's proposal from
> 
>   https://lists.gnu.org/archive/html/qemu-devel/2020-03/msg07290.html
> 
> with a bit of configure magic. It is enough to enable
> 
>    ./configure
>    make
>    make check

Lovely :)

> 
> I've not tested it beyond that. Note it blows away the "build/"
> dir each time ./configure is run so it is pristine each time.
> 
> We could optionally symlink binaries from build/ into $PWD
> if poeople think that is important, eg by changing GNUmakefile

Typo "people".

> to have:
> 
> recurse: all
>       for bin in `find build -maxdepth 1 -type f -executable | grep -v -E 
> '(ninjatool|config.status)'`; \
>       do \
>         ln -f -s $$bin . ; \
>       done
> 
> and some cleanup logic to purge the symlinks for "make clean"
> 
> This goes on top of Paolo's most recent meson port v175 posting,
> or whatever number it is upto now :-)
> 
>  .gitignore |  2 ++
>  configure  | 40 ++++++++++++++++++++++++++++++++--------
>  2 files changed, 34 insertions(+), 8 deletions(-)
> 
> diff --git a/.gitignore b/.gitignore
> index 92311284ef..4ccb9ed975 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -1,3 +1,5 @@
> +/GNUmakefile
> +/build/
>  /.doctrees
>  /config-devices.*
>  /config-all-devices.*
> diff --git a/configure b/configure
> index cc5f58f31a..a5c88ad1ac 100755
> --- a/configure
> +++ b/configure
> @@ -11,6 +11,38 @@ unset CLICOLOR_FORCE GREP_OPTIONS
>  # Don't allow CCACHE, if present, to use cached results of compile tests!
>  export CCACHE_RECACHE=yes
>  
> +source_path=$(cd "$(dirname -- "$0")"; pwd)
> +
> +if printf %s\\n "$source_path" "$PWD" | grep -q "[[:space:]:]";
> +then
> +  error_exit "main directory cannot contain spaces nor colons"
> +fi
> +
> +if test "$PWD" == "$source_path"
> +then
> +    echo "Using './build' as the directory for build output"
> +    rm -rf build
> +    mkdir -p build
> +    cat > GNUmakefile <<EOF
> +
> +ifeq (\$(MAKECMDGOALS),)
> +recurse: all
> +endif
> +
> +.NOTPARALLEL: %
> +%: force
> +     @echo 'changing dir to build for \$(MAKE) "\$(MAKECMDGOALS)"...'
> +     @\$(MAKE) -C build -f Makefile \$(MAKECMDGOALS)
> +     if test "\$(MAKECMDGOALS)" = "distclean" ; then rm -rf build ; fi

Can we use '@' to silent the last line too?

  make[1]: Leaving directory '/tmp/qemu/build'
  if test "help" = "distclean" ; then rm -rf build ; fi

Similarly to Peter, I also use the ./build/{conf1,conf2,...} each
subdir ./configured differently, so I wouldn't like to blow my
subdirs. Otherwise:

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> +force: ;
> +.PHONY: force
> +GNUmakefile: ;
> +
> +EOF
> +    cd build
> +    exec $source_path/configure "$@"
> +fi
> +
>  # Temporary directory used for files created while
>  # configure runs. Since it is in the build directory
>  # we can safely blow away any previous version of it
> @@ -297,14 +329,6 @@ ld_has() {
>      $ld --help 2>/dev/null | grep ".$1" >/dev/null 2>&1
>  }
>  
> -# make source path absolute
> -source_path=$(cd "$(dirname -- "$0")"; pwd)
> -
> -if printf %s\\n "$source_path" "$PWD" | grep -q "[[:space:]:]";
> -then
> -  error_exit "main directory cannot contain spaces nor colons"
> -fi
> -
>  # default parameters
>  cpu=""
>  iasl="iasl"
>