Signature-help should trigger on unfinished let ... in bindings

CHANGES.md

@@ -10,6 +10,8 @@ unreleased
     - Add a test to ensure the behavior showed in issue #1517 is no longer relevant (#1995)
     - Add a test to ensure the code fragment exhibited in issue #1118 no longer makes Merlin crash (#1996)
     - Add a test reproducing issue #1983 where `document` command which sometime concatenates consecutive variants and labels (#2005)
+    - Signature-help should trigger on unfinished `let ... in` bindings (#2009)
+
 
 merlin 5.6
 ==========

tests/test-dirs/signature-help/issue_let_in_binding.t

@@ -0,0 +1,20 @@
+  $ cat > test1.ml <<'EOF'
+  > let _ =
+  > let f = List.map   in
+  > let _ = 5 in
+  > 7
+  > EOF
+
+  $ $MERLIN single signature-help -position 2:17 -filename test1 < test1.ml | jq '.value.signatures[0].label'
+  "List.map : ('a -> 'b) -> 'a list -> 'b list"
+
+FIXME: Signature-help does not trigger on unfinished let ... in bindings.
+  $ cat > test2.ml <<'EOF'
+  > let _ =
+  > let f = List.map  
+  > let _ = 5 in
+  > 7
+  > EOF
+
+  $ $MERLIN single signature-help -position 2:17 -filename test2 < test2.ml | jq '.value.signatures[0].label'
+  null