Re: [PATCH v2] configure: add support for pseudo-"in source tree" builds

[Eric Blake]

On 8/20/20 12:31 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

s/the the/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>
> ---

> In v2:
>
>   - Use a marker file so we don't blow away a build/ dir
>     we didn't create
>   - Silence the distclean rule
>   - Fix broken use of error_exit that's not defined yet
>   - Add comment to GNUmakefile
>
>   .gitignore |  2 ++
>   configure  | 48 +++++++++++++++++++++++++++++++++++++++++++++---
>   2 files changed, 47 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..cdffe221c7 100755
> --- a/configure
> +++ b/configure
> @@ -11,6 +11,51 @@ 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)

Our mails crossed; my 1 comment about CDPATH impacting this is still valid.

> +
> +if test "$PWD" == "$source_path"

and s/==/=/ for non-bash

> +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

TAB damage.

> +       fi
> +    fi
> +
> +    mkdir build
> +    touch $MARKER
> +
> +    cat > GNUmakefile <<EOF
> +# This file is auto-generated by configure to support in-source tree
> +# 'make' command invokation

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

Quote the first EOF to avoid having to quote all $ in the heredoc

> +    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 +342,6 @@ 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"

With corrections, this is looking good; I'm okay if v3 includes:
Reviewed-by: Eric Blake <eblake@redhat.com>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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