From a9d7525dd6d7fd93875e1c36c50f43d6dec54c3e Mon Sep 17 00:00:00 2001
From: Spencer Brower <6729162+sbrow@users.noreply.github.com>
Date: Mon, 10 Aug 2026 17:36:32 -0400
Subject: [PATCH] fix: Empty tags now report diagnostics.

---
 DIAGNOSTIC_TESTS.yaml                    | 15 ++++++++++++++-
 mustache/diagnostic_test_cases_test.odin |  5 +++++
 mustache/mustache.odin                   | 16 ++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/DIAGNOSTIC_TESTS.yaml b/DIAGNOSTIC_TESTS.yaml
index 6a94fc0..2e87721 100644
--- a/DIAGNOSTIC_TESTS.yaml
+++ b/DIAGNOSTIC_TESTS.yaml
@@ -130,7 +130,7 @@ input: |
   </footer>
 expected: |
   Empty tag
-   --> <test>:11:28
+    --> <test>:11:28
      |
    9 |       href="https://edwardtufte.github.io/tufte-css/">Tufte CSS</a>
   10 |   </p>
@@ -139,6 +139,19 @@ expected: |
   12 | </footer>
      |
 ---
+name: empty raw tag
+enable: true
+should: error
+input: |
+  Hello, {{&}}
+expected: |
+  Empty tag
+   --> <test>:1:8
+    |
+  1 | Hello, {{&}}
+    |        ^^^^^ tag must contain a key
+    |
+---
 name: Missing pipe arguement
 enable: true
 should: error
diff --git a/mustache/diagnostic_test_cases_test.odin b/mustache/diagnostic_test_cases_test.odin
index ad83795..fb39626 100644
--- a/mustache/diagnostic_test_cases_test.odin
+++ b/mustache/diagnostic_test_cases_test.odin
@@ -28,6 +28,11 @@ test_diag_empty_tag :: proc(t: ^testing.T) {
 	run_diag_case(t, "empty tag")
 }
 
+@(test)
+test_diag_empty_raw_tag :: proc(t: ^testing.T) {
+	run_diag_case(t, "empty raw tag")
+}
+
 @(test)
 test_diag_missing_pipe_arguement :: proc(t: ^testing.T) {
 	run_diag_case(t, "Missing pipe arguement")
diff --git a/mustache/mustache.odin b/mustache/mustache.odin
index 86b0482..ce18864 100644
--- a/mustache/mustache.odin
+++ b/mustache/mustache.odin
@@ -271,6 +271,14 @@ parse_section :: proc(
 			pos^ += 1
 
 		case .Variable:
+			if len(strings.trim_space(tok.value)) == 0 {
+				return Error_Body {
+					msg = "Empty tag",
+					pos = tok.pos,
+					kind = .Syntax,
+					hint = "tag must contain a key",
+				}
+			}
 			idx := len(nodes)
 			append(nodes, Node{kind = .Variable})
 			pipe_key, perr := parse_pipeline(
@@ -290,6 +298,14 @@ parse_section :: proc(
 			pos^ += 1
 
 		case .Unescaped:
+			if len(strings.trim_space(tok.value)) == 0 {
+				return Error_Body {
+					msg = "Empty tag",
+					pos = tok.pos,
+					kind = .Syntax,
+					hint = "tag must contain a key",
+				}
+			}
 			idx := len(nodes)
 			append(nodes, Node{kind = .Unescaped})
 			pipe_key, perr := parse_pipeline(