show deprecated instance warnings

.gitlab-ci.yml

@@ -31,7 +31,6 @@ build-coq.8.14.1:
   <<: *template
   variables:
     OPAM_PINS: "coq version 8.14.1"
-    DENY_WARNINGS: "1"
     MANGLE_NAMES: "1"
 
 build-coq.8.13.2:

_CoqProject

@@ -4,8 +4,6 @@
 # Cannot use non-canonical projections as it causes massive unification failures
 # (https://github.com/coq/coq/issues/6294).
 -arg -w -arg -redundant-canonical-projection
-# There is currently no good way to fix all those instance warnings.
--arg -w -arg -deprecated-instance-without-locality
 
 theories/logic/satisfiable.v
 theories/simulation/language.v