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git/Documentation/doc-diff
Jeff King beb188e22a add a script to diff rendered documentation
After making a change to the documentation, it's easy to
forget to check the rendered version to make sure it was
formatted as you intended. And simply doing a diff between
the two built versions is less trivial than you might hope:

  - diffing the roff or html output isn't particularly
    readable; what we really care about is what the end user
    will see

  - you have to tweak a few build variables to avoid
    spurious differences (e.g., version numbers, build
    times)

Let's provide a script that builds and installs the manpages
for two commits, renders the results using "man", and diffs
the result. Since this is time-consuming, we'll also do our
best to avoid repeated work, keeping intermediate results
between runs.

Some of this could probably be made a little less ugly if we
built support into Documentation/Makefile. But by relying
only on "make install-man" working, this script should work
for generating a diff between any two versions, whether they
include this script or not.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-06 12:30:23 -07:00

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#!/bin/sh
OPTIONS_SPEC="\
doc-diff [options] <from> <to> [-- <diff-options>]
--
j=n parallel argument to pass to make
f force rebuild; do not rely on cached results
"
SUBDIRECTORY_OK=1
. "$(git --exec-path)/git-sh-setup"
parallel=
force=
while test $# -gt 0
do
case "$1" in
-j)
parallel=$2; shift ;;
-f)
force=t ;;
--)
shift; break ;;
*)
usage ;;
esac
shift
done
if test -z "$parallel"
then
parallel=$(getconf _NPROCESSORS_ONLN 2>/dev/null)
if test $? != 0 || test -z "$parallel"
then
parallel=1
fi
fi
test $# -gt 1 || usage
from=$1; shift
to=$1; shift
from_oid=$(git rev-parse --verify "$from") || exit 1
to_oid=$(git rev-parse --verify "$to") || exit 1
cd_to_toplevel
tmp=Documentation/tmp-doc-diff
if test -n "$force"
then
rm -rf "$tmp"
fi
# We'll do both builds in a single worktree, which lets "make" reuse
# results that don't differ between the two trees.
if ! test -d "$tmp/worktree"
then
git worktree add --detach "$tmp/worktree" "$from" &&
dots=$(echo "$tmp/worktree" | sed 's#[^/]*#..#g') &&
ln -s "$dots/config.mak" "$tmp/worktree/config.mak"
fi
# generate_render_makefile <srcdir> <dstdir>
generate_render_makefile () {
find "$1" -type f |
while read src
do
dst=$2/${src#$1/}
printf 'all:: %s\n' "$dst"
printf '%s: %s\n' "$dst" "$src"
printf '\t@echo >&2 " RENDER $(notdir $@)" && \\\n'
printf '\tmkdir -p $(dir $@) && \\\n'
printf '\tMANWIDTH=80 man -l $< >$@+ && \\\n'
printf '\tmv $@+ $@\n'
done
}
# render_tree <dirname> <committish>
render_tree () {
# Skip install-man entirely if we already have an installed directory.
# We can't rely on make here, since "install-man" unconditionally
# copies the files (spending effort, but also updating timestamps that
# we then can't rely on during the render step). We use "mv" to make
# sure we don't get confused by a previous run that failed partway
# through.
if ! test -d "$tmp/installed/$1"
then
git -C "$tmp/worktree" checkout "$2" &&
make -j$parallel -C "$tmp/worktree" \
GIT_VERSION=omitted \
SOURCE_DATE_EPOCH=0 \
DESTDIR="$PWD/$tmp/installed/$1+" \
install-man &&
mv "$tmp/installed/$1+" "$tmp/installed/$1"
fi &&
# As with "installed" above, we skip the render if it's already been
# done. So using make here is primarily just about running in
# parallel.
if ! test -d "$tmp/rendered/$1"
then
generate_render_makefile "$tmp/installed/$1" "$tmp/rendered/$1+" |
make -j$parallel -f - &&
mv "$tmp/rendered/$1+" "$tmp/rendered/$1"
fi
}
render_tree $from_oid "$from" &&
render_tree $to_oid "$to" &&
git -C $tmp/rendered diff --no-index "$@" $from_oid $to_oid