1 files changed, 38 insertions, 0 deletions
diff --git a/contrib/bmake/unit-tests/use-inference.mk b/contrib/bmake/unit-tests/use-inference.mk
new file mode 100644
index 000000000000..cde3c772edaa
--- /dev/null
+++ b/contrib/bmake/unit-tests/use-inference.mk
@@ -0,0 +1,38 @@
+# $NetBSD: use-inference.mk,v 1.2 2020/11/05 00:41:04 rillig Exp $
+#
+# Demonstrate that .USE rules do not have an effect on inference rules.
+# At least not in the special case where the inference rule does not
+# have any associated commands.
+
+.SUFFIXES:
+.SUFFIXES: .from .to
+
+all: use-inference.to
+
+verbose: .USE
+	@echo 'Verbosely making $@ out of $>'
+
+.from.to: verbose
+# Since this inference rule does not have any associated commands, it
+# is ignored.
+#
+#	@echo 'Building $@ from $<'
+
+use-inference.from:		# assume it exists
+	@echo 'Building $@ from nothing'
+
+# Possible but unproven explanation:
+#
+# The main target is "all", which depends on "use-inference.to".
+# The inference connects the .from to the .to file, otherwise make
+# would not know that the .from file would need to be built.
+#
+# The .from file is then built.
+#
+# After this, make stops since it doesn't know how to make the .to file.
+# This is strange since make definitely knows about the .from.to suffix
+# inference rule.  But it seems to ignore it, maybe because it doesn't
+# have any associated commands.
+
+# XXX: Despite the error message "don't know how to make", the exit status
+# is 0.  This is inconsistent.