Re: [PATCH 1/2] doc: add an option to have Asciidoctor build man pages directly

[Jeff King <peff@peff.net>]

On Wed, May 12, 2021 at 02:11:37AM +0000, brian m. carlson wrote:

> @@ -367,9 +370,16 @@ $(OBSOLETE_HTML): %.html : %.txto asciidoc.conf asciidoctor-extensions.rb GIT-AS
>  manpage-base-url.xsl: manpage-base-url.xsl.in
>  	$(QUIET_GEN)sed "s|@@MAN_BASE_URL@@|$(MAN_BASE_URL)|" $< > $@
>  
> +ifdef TXT_TO_MAN
> +%.1 %.5 %.7 : %.txt asciidoc.conf asciidoctor-extensions.rb GIT-ASCIIDOCFLAGS
> +	$(QUIET_ASCIIDOC)$(RM) $@+ $@ && \
> +	$(TXT_TO_MAN) -o $@+ $< && \
> +	mv $@+ $@
> +else

This depends on GIT-ASCIIDOCFLAGS, which is good. But I think we'd also
want to tell that file whether we are using the direct backend or not.
Otherwise, doing:

  make USE_ASCIIDOCTOR=1 git.1
  make USE_ASCIIDOCTOR=1 USE_ASCIIDOCTOR_MANPAGE=1 git.1

gets confused. Because git.1 is more recent than git.txt, it things
there is nothing to build in the second case. I think you want:

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 536d9a5f3d..4b66a61f51 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -337,7 +337,7 @@ mergetools-list.made: ../git-mergetool--lib.sh $(wildcard ../mergetools/*)
 		show_tool_names can_merge "* " || :' >mergetools-merge.txt && \
 	date >$@
 
-TRACK_ASCIIDOCFLAGS = $(subst ','\'',$(ASCIIDOC_COMMON):$(ASCIIDOC_HTML):$(ASCIIDOC_DOCBOOK))
+TRACK_ASCIIDOCFLAGS = $(subst ','\'',$(ASCIIDOC_COMMON):$(ASCIIDOC_HTML):$(ASCIIDOC_DOCBOOK):$(USE_ASCIIDOCTOR_MANPAGE))
 
 GIT-ASCIIDOCFLAGS: FORCE
 	@FLAGS='$(TRACK_ASCIIDOCFLAGS)'; \

With that change, plus a patch I'll send in a minute, it's easy to run
doc-diff on the result.

> diff --git a/Documentation/asciidoctor-extensions.rb b/Documentation/asciidoctor-extensions.rb
> index d906a00803..40fa87b121 100644
> --- a/Documentation/asciidoctor-extensions.rb
> +++ b/Documentation/asciidoctor-extensions.rb
> @@ -15,6 +15,8 @@ module Git
>            "#{target}(#{attrs[1]})</ulink>"
>          elsif parent.document.basebackend? 'html'
>            %(<a href="#{prefix}#{target}.html">#{target}(#{attrs[1]})</a>)
> +        elsif parent.document.basebackend? 'manpage'
> +          %(\\fB#{target}\\fP\\fR(#{attrs[1]})\\fP)

Unfortunately, this doesn't seem to work. Diffing the rendered docs
between regular asciidoctor-then-xmlto and direct-to-manpage shows a lot
of hunks like:

              For more details about the <pathspec> syntax, see the pathspec
  -           entry in gitglossary(7).
  +           entry in \fBgitglossary\fP\fR(7)\fP.

-Peff