unikernel/duniverse/dune_/test/blackbox-tests/test-cases/ppx/ppx-flags-plus.t

@@ -0,0 +1,49 @@
+Create ppx1 and exe:
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.7)
+  > EOF
+  $ cat > dune <<EOF
+  > (library
+  >  (name ppx)
+  >  (kind ppx_rewriter)
+  >  (modules ppx)
+  >  (ppx.driver (main Ppx.main)))
+  > (executable
+  >  (name the_exe)
+  >  (modules the_exe)
+  >  (preprocess (pps ppx --alert ++foo)))
+  > EOF
+  $ cat > ppx.ml <<EOF
+  > let main () =
+  >   let out = ref "" in
+  >   let args =
+  >     [ ("-o", Arg.Set_string out, "")
+  >     ; ("--impl", Arg.Set_string (ref ""), "")
+  >     ; ("--as-ppx", Arg.Set (ref false), "")
+  >     ; ("--cookie", Arg.Set (ref false), "")
+  >     ; ("--alert", Arg.Set_string (ref ""), "")
+  >     ]
+  >   in
+  >   let anon _ = () in
+  >   Arg.parse (Arg.align args) anon "";
+  >   let out = open_out !out in
+  >   close_out out;
+  > EOF
+  $ touch the_exe.ml
+
+  $ dune build ./the_exe.exe
+  File "dune", line 9, characters 30-35:
+  9 |  (preprocess (pps ppx --alert ++foo)))
+                                    ^^^^^
+  Error: PPX args starting with `+' cannot be used before version 3.18 of the
+  dune language
+  Hint: Upgrade your dune-project to `(lang dune 3.18)'
+  [1]
+
+Works since Dune 3.18
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.18)
+  > EOF
+  $ dune build ./the_exe.exe