From b21797682ea59d9c35eec77b4b03f74feb8aea06 Mon Sep 17 00:00:00 2001
From: Daniel Duan <daniel@duan.ca>
Date: Fri, 10 Jul 2026 10:39:01 -0700
Subject: [PATCH] Reject top-level single-value decoding

---
 Sources/TOMLDecoder/_TOMLDecoder.swift        | 11 ++++++++++-
 Tests/TOMLDecoderTests/TOMLDecoderTests.swift |  6 ++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/Sources/TOMLDecoder/_TOMLDecoder.swift b/Sources/TOMLDecoder/_TOMLDecoder.swift
index d46600d8..43b37220 100644
--- a/Sources/TOMLDecoder/_TOMLDecoder.swift
+++ b/Sources/TOMLDecoder/_TOMLDecoder.swift
@@ -51,7 +51,16 @@ final class _TOMLDecoder: Decoder {
     }
 
     func singleValueContainer() throws -> any SingleValueDecodingContainer {
-        self
+        guard token != .empty else {
+            throw DecodingError.typeMismatch(
+                (any SingleValueDecodingContainer).self,
+                DecodingError.Context(
+                    codingPath: codingPath,
+                    debugDescription: "Cannot decode a single value from a TOML table."
+                )
+            )
+        }
+        return self
     }
 
     init(referencing container: Container, at codingPath: [any CodingKey] = [], strategy: TOMLDecoder.Strategy, isLenient: Bool) {
diff --git a/Tests/TOMLDecoderTests/TOMLDecoderTests.swift b/Tests/TOMLDecoderTests/TOMLDecoderTests.swift
index 329d80e1..96f83ba8 100644
--- a/Tests/TOMLDecoderTests/TOMLDecoderTests.swift
+++ b/Tests/TOMLDecoderTests/TOMLDecoderTests.swift
@@ -501,6 +501,12 @@ struct TOMLDecoderTests {
         #expect(result == Team(languages: [.swift, .mojo, .zig], favorite: .swift))
     }
 
+    @Test func topLevelTableCannotDecodeAsSingleValue() {
+        #expect(throws: DecodingError.self) {
+            try TOMLDecoder().decode(Int.self, from: "-1 = true")
+        }
+    }
+
     @Test func twitter() throws {
         _ = try TOMLDecoder().decode(TwitterArchive.self, from: Resources.twitterTOMLString)
     }