vendor/NetBSD/bmake/20200517

1 files changed, 23 insertions, 0 deletions

diff --git a/unit-tests/cond-late.mk b/unit-tests/cond-late.mk
new file mode 100644
index 000000000000..2eb02b42b920
--- /dev/null
+++ b/unit-tests/cond-late.mk
@@ -0,0 +1,23 @@
+# $NetBSD: cond-late.mk,v 1.1 2020/04/29 23:15:21 rillig Exp $
+#
+# Using the :? modifier, variable expressions can contain conditional
+# expressions that are evaluated late.  Any variables appearing in these
+# conditions are expanded before parsing the condition.  This is
+# different from many other places.
+#
+# Because of this, variables that are used in these lazy conditions
+# should not contain double-quotes, or the parser will probably fail.
+#
+# They should also not contain operators like == or <, since these are
+# actually interpreted as these operators. This is demonstrated below.
+#
+# If the order of evaluation were to change to first parse the condition
+# and then expand the variables, the output would change from the
+# current "yes no" to "yes yes", since both variables are non-empty.
+
+COND.true=	"yes" == "yes"
+COND.false=	"yes" != "yes"
+
+all:
+	@echo ${ ${COND.true} :?yes:no}
+	@echo ${ ${COND.false} :?yes:no}