Test coq.9.0.0 in CI.

.gitlab-ci.yml

@@ -45,10 +45,10 @@ variables:
 ## Build jobs
 
 # The newest version runs with timing.
-build-coq.8.20.1:
+build-coq.9.0.0:
   <<: *template
   variables:
-    OPAM_PINS: "coq version 8.20.1"
+    OPAM_PINS: "coq version 9.0.0"
     DENY_WARNINGS: "1"
     MANGLE_NAMES: "1"
     CI_COQCHK: "1"
@@ -59,21 +59,27 @@ build-coq.8.20.1:
   interruptible: false
 
 # The newest version also runs in MRs, without timing.
-build-coq.8.20.1-mr:
+build-coq.9.0.0-mr:
   <<: *template
   <<: *only_mr
   variables:
-    OPAM_PINS: "coq version 8.20.1"
+    OPAM_PINS: "coq version 9.0.0"
     DENY_WARNINGS: "1"
     MANGLE_NAMES: "1"
 
-# Also ensure Dune works.
+# Also ensure Dune works (currently broken on 9.0.0).
 build-coq.8.20.1-dune:
   <<: *template
   variables:
-    OPAM_PINS: "coq version 8.20.1   dune version 3.15.2"
+    OPAM_PINS: "coq version 8.20.1   dune version 3.18.1"
     MAKE_TARGET: "dune"
 
+build-coq.8.20.1:
+  <<: *template
+  variables:
+    OPAM_PINS: "coq version 8.20.1"
+    DENY_WARNINGS: "1"
+
 build-coq.8.19.1:
   <<: *template
   variables:

README.md

@@ -43,7 +43,7 @@ Notably:
 
 This version is known to compile with:
 
- - Coq version 8.18.0 / 8.19.1 / 8.20.1
+ - Coq version 8.18.0 / 8.19.1 / 8.20.1 / 9.0.0
 
 Generally we always aim to support the last two stable Coq releases. Support for
 older versions will be dropped when it is convenient.