From b44b7acce631485e0938c2c873e0d9196f41e1a0 Mon Sep 17 00:00:00 2001
From: Tomas Bjerre <tomas.bjerre85@gmail.com>
Date: Tue, 15 Sep 2026 16:20:43 +0200
Subject: [PATCH] fix: pass params and hash to helpers invoked via standalone
 inverse tags

visitUnless() (handling standalone {{^helper args}}...{{/helper}}
tags) always built its Block with Collections.emptyList()/emptyMap()
for params/hash, discarding whatever the parser had actually parsed
from ctx.sexpr(). The sibling visitBlock() (handling {{#helper
args}}...{{/helper}}), which shares the same sexpr grammar rule,
correctly does params(sexpr.param()) / hash(sexpr.hash()) - visitUnless
just never got the same treatment.

For a helper without a body context binding, this is mostly invisible.
But for a custom helper that relies on its own hash arguments (e.g.
{{^ifSomething . scope="x"}}...{{/ifSomething}}), Options.hash("scope")
silently comes back null. Depending on what the helper does with the
missing value, this can surface as a confusing NullPointerException
deep inside the helper rather than any indication that the arguments
were dropped.

Fix mirrors visitBlock() exactly: params(sexpr.param()) and
hash(sexpr.hash()) instead of the hardcoded empty collections.

Added UnlessBlockHelperArgsTest covering both the context (first
positional param) and hash argument pass-through on a standalone
inverse tag. Ran the full handlebars module test suite
(1030 tests, 0 failures/errors) to confirm no regressions.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4LemHUKaqfXULRkmxfxwx
---
 .../handlebars/internal/TemplateBuilder.java  |  4 +-
 .../handlebars/UnlessBlockHelperArgsTest.java | 45 +++++++++++++++++++
 2 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 handlebars/src/test/java/com/github/jknack/handlebars/UnlessBlockHelperArgsTest.java

diff --git a/handlebars/src/main/java/com/github/jknack/handlebars/internal/TemplateBuilder.java b/handlebars/src/main/java/com/github/jknack/handlebars/internal/TemplateBuilder.java
index ea196c12..7aca78ce 100644
--- a/handlebars/src/main/java/com/github/jknack/handlebars/internal/TemplateBuilder.java
+++ b/handlebars/src/main/java/com/github/jknack/handlebars/internal/TemplateBuilder.java
@@ -333,8 +333,8 @@ public Template visitUnless(final UnlessContext ctx) {
             name,
             true,
             "^",
-            Collections.emptyList(),
-            Collections.emptyMap(),
+            params(sexpr.param()),
+            hash(sexpr.hash()),
             blockParams(ctx.blockParams()),
             source(ctx));
     block.filename(source.filename());
diff --git a/handlebars/src/test/java/com/github/jknack/handlebars/UnlessBlockHelperArgsTest.java b/handlebars/src/test/java/com/github/jknack/handlebars/UnlessBlockHelperArgsTest.java
new file mode 100644
index 00000000..b61e52b3
--- /dev/null
+++ b/handlebars/src/test/java/com/github/jknack/handlebars/UnlessBlockHelperArgsTest.java
@@ -0,0 +1,45 @@
+/*
+ * Handlebars.java: https://github.com/jknack/handlebars.java
+ * Apache License Version 2.0 http://www.apache.org/licenses/LICENSE-2.0
+ * Copyright (c) 2012 Edgar Espina
+ */
+package com.github.jknack.handlebars;
+
+import java.io.IOException;
+
+import org.junit.jupiter.api.Test;
+
+public class UnlessBlockHelperArgsTest extends AbstractTest {
+
+  /**
+   * A standalone inverted section ({@code {{^helper args}}...{{/helper}}}) invoking a custom block
+   * helper must pass through the helper's context (first param) and hash arguments the same way the
+   * matching positive section ({@code {{#helper args}}...{{/helper}}}) does.
+   */
+  @Test
+  public void unlessPassesContextAndHashArgumentsToHelper() throws IOException {
+    Helper<Object> helper =
+        (context, options) -> "context=" + context + ",scope=" + options.hash("scope");
+
+    shouldCompileTo(
+        "{{^myHelper foo scope=\"deps\"}}{{/myHelper}}",
+        $("foo", "bar"),
+        $("myHelper", helper),
+        "context=bar,scope=deps");
+  }
+
+  /**
+   * A second positional param (beyond the first, which becomes the context) must also flow through.
+   */
+  @Test
+  public void unlessPassesExtraParamsToHelper() throws IOException {
+    Helper<Object> helper =
+        (context, options) -> "context=" + context + ",param0=" + options.param(0);
+
+    shouldCompileTo(
+        "{{^myHelper foo bar}}{{/myHelper}}",
+        $("foo", "a", "bar", "b"),
+        $("myHelper", helper),
+        "context=a,param0=b");
+  }
+}