string litteral with an extension node is wrongly marked as being unterminated

[EmileTrotignon]

The following code :

(* {%ext|babar|} *)

results in a syntax error displayed by lsp, even if the compiler is happy with it :

This was reproduced on emacs without lsp, so it is likely from the merlin parser.

[voodoos]

Thanks for the report @EmileTrotignon, I was able to reproduce the behavior you observe.

For reference, the manual says:

Furthermore, quoted strings {|...|} can be combined with extension nodes to embed foreign syntax fragments. Those fragments can be interpreted by a preprocessor and turned into OCaml code without requiring escaping quotes. A syntax shortcut is available for them:

{%%foo|...|}               === [%%foo{|...|}]
let x = {%foo|...|}        === let x = [%foo{|...|}]
let y = {%foo bar|...|bar} === let y = [%foo{bar|...|bar}]

For instance, you can use {%sql|...|} to represent arbitrary SQL statements – assuming you have a ppx-rewriter that recognizes the %sql extension.

It looks like Merlin lexer has diverged quite a bit from upstream for these cases.

[EmileTrotignon]

Hi @voodoos
This syntax is not illegal, it is an extension node.

{%ext|abc|}

is a shortcut for

[%ext {|abc|} ]

I guess it must be documented in "language extension" : https://v2.ocaml.org/manual/extensionnodes.html#ss%3Abuiltin-extension-nodes
It should be rejected by the type checker as an uninterpreted extension if you do not have a ppx that handles it, but any parser should accept it.

[voodoos]

Yes my bad, I was editing my comment but you were too fast :-)