Do not trigger warning if there is whitespace after ;;

OCaml toplevel ignores trailing whitespace so it would make sense to
just ignore it in MDX as well.

Unfortunately Astring does not have `rtrim` so both prefix and suffix
are removed, but except for additional useless computation load it
doesn't make a difference since we only check for the suffix.

Author: Leonidas-from-XIV

lib/deprecated.ml

@@ -27,12 +27,15 @@ let warn ?replacement s ~since =
 module Missing_double_semicolon = struct
   let missing_semicolon = ref false
 
-  let check_toplevel : Toplevel.t -> unit = function
-    | toplevel -> (
-        match List.rev toplevel.command with
-        | cmd :: _ when not @@ Astring.String.is_suffix ~affix:";;" cmd ->
-            missing_semicolon := true
-        | _ -> ())
+  let check_toplevel : Toplevel.t -> unit =
+   fun toplevel ->
+    match List.rev toplevel.command with
+    | cmd :: _ ->
+        let ends_with_semi =
+          cmd |> Astring.String.trim |> Astring.String.is_suffix ~affix:";;"
+        in
+        if not ends_with_semi then missing_semicolon := true
+    | [] -> ()
 
   let check_block block = List.iter check_toplevel block
 

test/bin/mdx-test/expect/trailing-whitespaces/test-case.md

@@ -9,3 +9,13 @@ val x : int = 13
 $ echo "bob  "
 bob  
 ```
+
+Also, it should be valid to terminate phrases that end with `;;` but have
+trailing whitespace:
+
+```ocaml
+# let terminated_with_space = 42;; 
+val terminated_with_space : int = 42
+# let terminated_with_tab = 42;;	
+val terminated_with_tab : int = 42
+```

test/bin/mdx-test/expect/trailing-whitespaces/test-case.md.expected

@@ -9,3 +9,13 @@ val x : int = 13
 $ echo "bob  "
 bob
 ```
+
+Also, it should be valid to terminate phrases that end with `;;` but have
+trailing whitespace:
+
+```ocaml
+# let terminated_with_space = 42;; 
+val terminated_with_space : int = 42
+# let terminated_with_tab = 42;;	
+val terminated_with_tab : int = 42
+```