doc/Makefile

rust: switch hg-core and hg-cpython to rust 2018 edition

Many interesting changes have happened in Rust since the Oxidation Plan was
introduced, like the 2018 edition and procedural macros:

    - Opting in to the 2018 edition is a clear benefit in terms of future
      proofing, new (nice to have) syntactical sugar notwithstanding. It
      also has a new non-lexical, non-AST based borrow checker that has
      fewer bugs(!) and allows us to write correct code that in some cases
      would have been rejected by the old one.
    - Procedural macros allow us to use the PyO3 crate which maintainers have
      expressed the clear goal of compiling on stable, which would help in
      code maintainability compared to rust-cpython.

In this patch are the following changes:
    - Removing most `extern crate` uses
    - Updating `use` clauses (`crate` keyword, nested `use`)
    - Removing `mod.rs` in favor of an aptly named module file

Like discussed in the mailing list (
https://www.mercurial-scm.org/pipermail/mercurial-devel/2019-July/132316.html
), until Rust integration in Mercurial is considered to be out of the
experimental phase, the maximum version of Rust allowed is whatever the latest
version Debian packages.

Differential Revision: https://phab.mercurial-scm.org/D6597

SOURCES=$(notdir $(wildcard ../mercurial/help/*.[0-9].txt))
MAN=$(SOURCES:%.txt=%)
HTML=$(SOURCES:%.txt=%.html)
GENDOC=gendoc.py ../mercurial/commands.py ../mercurial/help.py \
	../mercurial/help/*.txt ../hgext/*.py ../hgext/*/__init__.py
PREFIX=/usr/local
MANDIR=$(PREFIX)/share/man
INSTALL=install -c -m 644
PYTHON?=python
RSTARGS=

export HGENCODING=UTF-8

all: man html

man: $(MAN)

html: $(HTML)

# This logic is duplicated in setup.py:hgbuilddoc()
common.txt $(SOURCES) $(SOURCES:%.txt=%.gendoc.txt): $(GENDOC)
	${PYTHON} gendoc.py "$(basename $@)" > $@.tmp
	mv $@.tmp $@

%: %.txt %.gendoc.txt common.txt
	$(PYTHON) runrst hgmanpage $(RSTARGS) --halt warning \
	  --strip-elements-with-class htmlonly $*.txt $*

%.html: %.txt %.gendoc.txt common.txt
	$(PYTHON) runrst html $(RSTARGS) --halt warning \
	  --link-stylesheet --stylesheet-path style.css $*.txt $*.html

MANIFEST: man html
# tracked files are already in the main MANIFEST
	$(RM) $@
	for i in $(MAN) $(HTML); do \
	  echo "doc/$$i" >> $@ ; \
	done

install: man
	for i in $(MAN) ; do \
	  subdir=`echo $$i | sed -n 's/^.*\.\([0-9]\)$$/man\1/p'` ; \
	  mkdir -p "$(DESTDIR)$(MANDIR)"/$$subdir ; \
	  $(INSTALL) $$i "$(DESTDIR)$(MANDIR)"/$$subdir ; \
	done

clean:
	$(RM) $(MAN) $(HTML) common.txt $(SOURCES) $(SOURCES:%.txt=%.gendoc.txt) MANIFEST