lint-man.mk: lint-man-groff-eqn: Fail if eqn(1) writes to stderr

eqn(1) still exits with 0 after reporting errors.  Let's grep stderr,
and if there's anything, fail.

Signed-off-by: Alejandro Colomar <alx@kernel.org>

diff --git a/lib/lint-man.mk b/lib/lint-man.mk
index 5d4c3ae9bd540ac8031abb5422e39f8891b604b6..0583964b4c009ab6bf6f8494b5a7e0d1f156a9aa 100644 (file)
--- a/lib/lint-man.mk
+++ b/lib/lint-man.mk
@@ -95,7 +95,8 @@ $(_LINT_man_groff_eqn): %.eqn: %.tbl | $$(@D)/.
 
 $(_LINT_man_groff_troff): %.troff: %.eqn | $$(@D)/.
        $(info LINT (eqn)       $@)
-       $(EQN) $(EQNFLAGS) <$< >$@
+       $(EQN) $(EQNFLAGS) <$< 2>&1 >$@ \
+       | ( ! $(GREP) . )
 
 $(_LINT_man_groff_grotty): %.grotty: %.troff | $$(@D)/.
        $(info LINT (troff)     $@)