[PATCH v2 5/5] doc/Makefile: turn warnings into errors

[Heinrich Schuchardt]

Several patches delivered incorrect restructured text as documentation. We
should be able to discover this in Travis CI, Gitlab CI, or Azure CI.

So let us turn all build warnings into errors.

Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
v2:
	change commit message
---
 doc/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/Makefile b/doc/Makefile
index 5135a96e88..0e0da5666f 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -56,6 +56,7 @@ quiet_cmd_sphinx = SPHINX  $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
 	PYTHONDONTWRITEBYTECODE=1 \
 	BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(srctree)/$(src)/$5/$(SPHINX_CONF)) \
 	$(SPHINXBUILD) \
+	-W \
 	-b $2 \
 	-c $(abspath $(srctree)/$(src)) \
 	-d $(abspath $(BUILDDIR)/.doctrees/$3) \
--
2.25.0