node: basic support for *expr.Closure

fixtures/0013-closures.php

@@ -0,0 +1,9 @@
+<?php
+
+const FOO = 'X';
+
+$x = function(string $param): string {
+	return $param . FOO;
+};
+
+echo $x("x");

node.go

@@ -1036,6 +1036,24 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 
 		return className + constName, nil
 
+	case *expr.Closure:
+		// Need to decide what to do with `this` binding
+		// TODO figure out what it means to use `this` in all types of nested closures
+
+		if n.Static {
+			return "", parseErr{n, fmt.Errorf("use of `static` in closure implies `this`-insensitive, but we can't make that true")}
+		}
+
+		// TODO n.PhpDocComment
+		// TODO n.ClosureUse
+
+		body, err := this.convertFunctionCommon(n.Params, n.ReturnType, n.ReturnsRef, n.Stmts)
+		if err != nil {
+			return "", parseErr{n, err}
+		}
+
+		return "(func" + strings.TrimRight(body, " \n") + ")", nil
+
 	case *expr.Exit:
 		// die(0) - set process exit code and exit
 		// die("message") - print to stdout and exit 0