added support for CI on gitlab

.gitlab-ci.yml

+include: 'https://gitlab.com/gasche/gitlab-ocaml-ci-example/-/raw/main/.gitlab-ci.yml'
+.build-matrix:
+  parallel:
+    matrix:
+    - OCAML_COMPILER: ["4.12.1", "4.13.1", "4.14.0", "5.0.0", "5.1.0", "5.2.0"]
+      DUNE_BUILD_TARGETS: "@all"
+      DUNE_TEST_TARGETS: "@runtest"
+      DUNE_DOC_TARGETS: "@doc"
+build:
+  stage: build
+  extends: .build-matrix # defines OCAML_COMPILER
+  image: ocaml/opam:debian-testing-ocaml-4.14
+  tags:
+  - ci.inria.fr
+  - small
+pages:
+  stage: deploy
+  tags:
+  - ci.inria.fr
+  - small
+variables:
+  CLEAN_OPAM_CACHE: "false"
+  CLEAN_DUNE_CACHE: "false"
\ No newline at end of file

Makefile

-.PHONY: all test clean fmt
-
+.PHONY: all clean fmt test doc doc-browse doc-commit-to-pages
 all:
-	dune build @all
-
-test:
-	dune test --auto-promote
+	dune build
 
 clean:
 	dune clean
 
 fmt:
-	dune fmt --auto-promote
+	dune build @fmt --auto-promote
+
+test:
+	dune runtest
+
+doc:
+	dune build @doc
+
+DOC_PATH := _build/default/_doc/_html
+
+doc-browse: doc
+	open ${DOC_PATH}/index.html
+
+doc-commit-to-pages: doc
+# compute the current commit hash and branch name
+	@git rev-parse --short HEAD > /tmp/commit
+	@git rev-parse --abbrev-ref HEAD > /tmp/branch
+	cp .gitlab-ci.yml /tmp
+
+# move to the 'pages' branch and commit the documentation there
+	git checkout pages
+	mkdir -p docs
+	@git rm --ignore-unmatch -r docs > /dev/null
+	rm -rf docs
+	cp -r ${DOC_PATH} docs
+	@git add docs
+# we also update the 'pages' CI script to follow original-branch changes
+	cp /tmp/.gitlab-ci.yml .
+	git add .gitlab-ci.yml
+	@git commit -m "documentation for $$(cat /tmp/branch) ($$(cat /tmp/commit))" \
+	&& git checkout $$(cat /tmp/branch) \
+	|| git checkout $$(cat /tmp/branch)
+
+	@echo
+	@echo "The documentation was committed to the 'pages' branch."
+	@echo "You can now push it with"
+	@echo "    git push origin pages"