Fix invalid AST due to empty binding list in ppx_regexp.

Author: paurkedal

CHANGES.md

@@ -1,3 +1,7 @@
+## v0.5.1 - 2022-06-09
+
+- Fix invalid AST due to empty binding list in `ppx_regexp`.
+
 ## v0.5.0 - 2022-06-06
 
 - Migrate `ppx_regexp` to ppxlib.

ppx_regexp/ppx_regexp.ml

@@ -224,6 +224,7 @@ end
 
 let impl str =
   let str, rev_bindings = transformation#structure str [] in
+  if rev_bindings = [] then str else
   let re_str =
     let loc = Location.none in
     [%str

tests/dune

@@ -9,16 +9,12 @@
 
 ; Tests for ppx_regexp
 
-(executable
-  (name test_ppx_regexp)
-  (modules test_ppx_regexp)
+(tests
+  (names test_ppx_regexp test_ppx_regexp_unused)
+  (modules test_ppx_regexp test_ppx_regexp_unused)
+  (package ppx_regexp)
   (libraries re re.perl)
   (preprocess (pps ppx_regexp)))
-(alias
-  (name runtest)
-  (package ppx_regexp)
-  (deps test_ppx_regexp.exe)
-  (action (run %{deps})))
 
 ; Tests for ppx_tyre
 

tests/test_ppx_regexp_unused.ml

@@ -0,0 +1 @@
+let () = ()