unikernel/duniverse/dune_/test/blackbox-tests/test-cases/env/env-unused.t

@@ -0,0 +1,41 @@
+  $ cat > dune-project << EOF
+  > (lang dune 3.3)
+  > EOF
+
+(env) is evaluated sequentially:
+
+  $ cat > dune << 'EOF'
+  > (rule
+  >  (alias runtest)
+  >  (action (system "echo $VAR")))
+  > 
+  > (env
+  >  (_   (env-vars (VAR default )))
+  >  (dev (env-vars (VAR specific))))
+  > EOF
+
+A warning is displayed when there are unreachable cases.
+
+  $ dune runtest
+  File "dune", lines 5-7, characters 0-71:
+  5 | (env
+  6 |  (_   (env-vars (VAR default )))
+  7 |  (dev (env-vars (VAR specific))))
+  Warning: This env stanza contains rules after a wildcard rule. These are
+  going to be ignored.
+  default
+
+In 3.4, this warning becomes fatal.
+
+  $ cat > dune-project << EOF
+  > (lang dune 3.4)
+  > EOF
+
+  $ dune runtest
+  File "dune", lines 5-7, characters 0-71:
+  5 | (env
+  6 |  (_   (env-vars (VAR default )))
+  7 |  (dev (env-vars (VAR specific))))
+  Error: This env stanza contains rules after a wildcard rule. These are going
+  to be ignored.
+  [1]