From b075f7a35d25ec0a4414b011142744f8f1821b47 Mon Sep 17 00:00:00 2001
From: Ilya Kiselev <kis-ilya-a@yandex.ru>
Date: Mon, 23 Mar 2026 18:20:54 +0300
Subject: [PATCH] feat(engine): add mustToToml template function

Add `mustToToml` that panics on marshal error, consistent with
`mustToYaml` and `mustToJson`. This makes it possible for chart authors
to get a hard failure when TOML serialization fails, rather than having
to inspect the output manually.

`toToml` behavior is unchanged in this commit.

Closes #31430

Signed-off-by: Ilya Kiselev <kis-ilya-a@yandex.ru>
---
 pkg/engine/funcs.go      | 16 ++++++++++++++++
 pkg/engine/funcs_test.go |  7 +++++++
 2 files changed, 23 insertions(+)

diff --git a/pkg/engine/funcs.go b/pkg/engine/funcs.go
index ba842a51a..97db47dfd 100644
--- a/pkg/engine/funcs.go
+++ b/pkg/engine/funcs.go
@@ -50,6 +50,7 @@ func funcMap() template.FuncMap {
 	// Add some extra functionality
 	extra := template.FuncMap{
 		"toToml":        toTOML,
+		"mustToToml":    mustToTOML,
 		"fromToml":      fromTOML,
 		"toYaml":        toYAML,
 		"mustToYaml":    mustToYAML,
@@ -162,6 +163,21 @@ func toTOML(v any) string {
 	return b.String()
 }
 
+// mustToTOML takes an interface, marshals it to toml, and returns a string.
+// It will panic if there is an error.
+//
+// This is designed to be called from a template when you need to ensure that the
+// output TOML is valid.
+func mustToTOML(v any) string {
+	b := bytes.NewBuffer(nil)
+	e := toml.NewEncoder(b)
+	err := e.Encode(v)
+	if err != nil {
+		panic(err)
+	}
+	return b.String()
+}
+
 // fromTOML converts a TOML document into a map[string]interface{}.
 //
 // This is not a general-purpose TOML parser, and will not parse all valid
diff --git a/pkg/engine/funcs_test.go b/pkg/engine/funcs_test.go
index 48202454e..be9d0153f 100644
--- a/pkg/engine/funcs_test.go
+++ b/pkg/engine/funcs_test.go
@@ -159,6 +159,13 @@ keyInElement1 = "valueInElement1"`,
 		tpl:    `{{ toJson . }}`,
 		expect: "", // should return empty string and swallow error
 		vars:   loopMap,
+	}, {
+		tpl:  `{{ mustToToml . }}`,
+		vars: map[int]string{1: "one"}, // non-string key is invalid in TOML
+	}, {
+		tpl:    `{{ mustToToml . }}`,
+		expect: "foo = \"bar\"\n", // should succeed and return TOML string
+		vars:   map[string]string{"foo": "bar"},
 	},
 	}