Re: [PATCH v3] configure: add support for pseudo-"in source tree" builds

[Paolo Bonzini]

On 21/08/20 12:22, 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 results in the
> "build/" directory. This allows "./configure && make" to work as it
> did historically, albeit with the output binaries staying under build/.
> 
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
> 
> Changed in v3:
> 
>  - remove bashism  ==
>  - avoid need for quoting when generating GNUmakefile
>  - change line breaks in GNUmakefile for clarity
> 
>  .gitignore |  2 ++
>  configure  | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
>  2 files changed, 51 insertions(+), 3 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..4e5fe33211 100755
> --- a/configure
> +++ b/configure
> @@ -11,6 +11,55 @@ unset CLICOLOR_FORCE GREP_OPTIONS
>  # Don't allow CCACHE, if present, to use cached results of compile tests!
>  export CCACHE_RECACHE=yes
>  
> +# make source path absolute
> +source_path=$(cd "$(dirname -- "$0")"; pwd)
> +
> +if test "$PWD" = "$source_path"
> +then
> +    echo "Using './build' as the directory for build output"
> +
> +    MARKER=build/auto-created-by-configure
> +
> +    if test -e build
> +    then
> +        if test -f $MARKER
> +        then
> +           rm -rf build
> +        else
> +            echo "ERROR: ./build dir already exists and was not previously 
> created by configure"
> +            exit 1
> +        fi
> +    fi
> +
> +    mkdir build
> +    touch $MARKER
> +
> +    cat > GNUmakefile <<'EOF'
> +# This file is auto-generated by configure to support in-source tree
> +# 'make' command invocation
> +
> +ifeq ($(MAKECMDGOALS),)
> +recurse: all
> +endif
> +
> +.NOTPARALLEL: %
> +%: force
> +     @echo 'changing dir to build for $(MAKE) "$(MAKECMDGOALS)"...'
> +     @$(MAKE) -C build -f Makefile $(MAKECMDGOALS)
> +     @if test "$(MAKECMDGOALS)" = "distclean" && \
> +         test -e build/auto-created-by-configure ; \
> +     then \
> +         rm -rf build GNUmakefile ; \
> +     fi
> +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
> @@ -297,9 +346,6 @@ 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"
> 

v9, here I come :)

Paolo