[dune] Build refman with fatal warnings by default like in the Makefile build.

The way to override this default is not exactly the same as in the legacy Makefile
but it has been documented as well.

1 files changed, 4 insertions, 2 deletions

diff --git a/doc/dune b/doc/dune
index 54ffa87205..6372fe4a91 100644
--- a/doc/dune
+++ b/doc/dune
@@ -10,8 +10,10 @@
   ;   + tools/coqdoc/coqdoc.css
   (package coq)
   (source_tree sphinx)
-  (source_tree tools))
- (action (run sphinx-build -j4 -b html -d sphinx_build/doctrees sphinx sphinx_build/html)))
+  (source_tree tools)
+  (env_var SPHINXWARNOPT))
+ (action
+  (run sphinx-build -j4 %{env:SPHINXWARNOPT=-W} -b html -d sphinx_build/doctrees sphinx sphinx_build/html)))
 
 (alias
  (name refman-html)