feat(cli): --version, a CHANGELOG, and a release target

Groundwork for tagging. The project had no version anywhere: not in
dune-project, not in the binary, no CHANGELOG, no tags.

The version lives in two places -- dune-project, which generates
colitur.opam, and a constant in bin/main.ml, which is what --version
prints. Two rather than one because dune's watermarking only substitutes
in a release tarball, so a binary built the ordinary way from a checkout
would report a placeholder. The release target rewrites both and then
re-checks both, and finally requires the freshly built binary to report
the version it just wrote: a release that bumped one and not the other
would ship a binary disagreeing with its own package metadata.

--version is deliberately not embedded in the help text. cli.t pins
help's first line, and a version there would mean editing a test
expectation every release for no gain.

The release target mirrors lectio's, refusals included: no release from a
dirty tree, none without a CHANGELOG entry for that version, none whose
version bump silently failed to apply, and `make check` -- the full
1583-9999 sweep, not the sampling suite -- must pass before the tag is
created.

1 files changed, 25 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 75372ac..f90d32e 100644
--- a/Makefile
+++ b/Makefile
@@ -14,7 +14,7 @@ MANDIR   := $(PREFIX)/share/man/man1
 # over documenting the dune commands.
 DUNE := opam exec --
 
-.PHONY: help build test check install uninstall reinstall clean fmt man doc
+.PHONY: help build test check install uninstall reinstall clean fmt man doc release
 help: ## show this help
 	@grep -hE '^[a-z-]+:.*##' $(MAKEFILE_LIST) | sed -E 's/:.*## /\t/' | sort
 
@@ -53,3 +53,27 @@ fmt: ## format the OCaml sources
 
 clean: ## remove build artifacts
 	$(DUNE) dune clean
+
+# Mirrors lectio's own release target, including its refusals: no release from
+# a dirty tree, no release without a CHANGELOG line, and no release whose
+# version bump silently failed to apply. The version lives in TWO places
+# (dune-project, which feeds colitur.opam, and bin/main.ml's own constant,
+# which is what --version prints), so both are rewritten and both are
+# re-checked -- a release that bumped one and not the other would ship a
+# binary disagreeing with its own package metadata.
+release: ## cut a release: make release VERSION=0.1.0  (add its CHANGELOG line first)
+	@test -n "$(VERSION)" || { echo "set VERSION=X.Y.Z" >&2; exit 2; }
+	@echo "$(VERSION)" | grep -qE '^[0-9]+\.[0-9]+\.[0-9]+$$' || { echo "VERSION must be X.Y.Z" >&2; exit 2; }
+	@test -z "$$(git status --porcelain)" || { echo "working tree not clean; commit or stash first" >&2; exit 2; }
+	@grep -q '## \[$(VERSION)\]' CHANGELOG.md || { echo "add a one-line CHANGELOG.md entry under '## [$(VERSION)]' first" >&2; exit 2; }
+	@sed -i 's/^(version .*)$$/(version $(VERSION))/' dune-project
+	@sed -i 's/^let version = ".*"/let version = "$(VERSION)"/' bin/main.ml
+	@grep -q '^(version $(VERSION))$$' dune-project || { echo "dune-project version bump failed" >&2; exit 2; }
+	@grep -q '^let version = "$(VERSION)"' bin/main.ml || { echo "bin/main.ml version bump failed" >&2; exit 2; }
+	$(MAKE) check
+	@test "$$($(DUNE) dune exec --no-build colitur -- --version)" = "$(VERSION)" || \
+	  { echo "the built binary does not report $(VERSION)" >&2; exit 2; }
+	git add dune-project colitur.opam bin/main.ml CHANGELOG.md
+	git commit -m "release: v$(VERSION)"
+	git tag -a "v$(VERSION)" -m "colitur $(VERSION)"
+	@echo "tagged v$(VERSION). publish with: git push origin main v$(VERSION)"