false "Undefined" message from type checker for variable introduced in concrete syntax pattern in comprehension.

[jurgenvinju]

Describe the bug

rel[str from, str to] edges = {<"<from>", "<to>"> | /(Edge) `<Node from> -- <Node to>` := g}

This gets an Undefined from and Undefined to from the type-checker.

[jurgenvinju]

module Syntax

start syntax Graph = "graph" Node+ top "{" Edge* edges "}";

syntax Edge = Node from "--" Node to;

layout Whitespace = [\ \t\n\r]*;

lexical Node = [$A-Za-z0-9\-]+;

[PaulKlint]

Thanks for reporting. Apart from the fact that the variable g is undefined in the given code snippets, the undefined messages are gone now.