From 9170804ca467cf624b87737752aedb0866d7fc49 Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Fri, 9 Sep 2022 04:38:14 +0000
Subject: [PATCH] Assert that all defined features are in the known features
 set

Now that the features contexts track the full set of all known
features, rather than the set of supported features, all defined
features should be listed in the context definition macro.

This adds a compile-time assertion to check that all bits for known
features are set in the context known set.
---
 lightning/src/ln/features.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs
index 4425a78e..b372e6af 100644
--- a/lightning/src/ln/features.rs
+++ b/lightning/src/ln/features.rs
@@ -203,6 +203,12 @@ mod sealed {
 				/// [`ODD_BIT`]: #associatedconstant.ODD_BIT
 				const ASSERT_ODD_BIT_PARITY: usize;
 
+				/// Assertion that the bits are set in the context's [`KNOWN_FEATURE_MASK`].
+				///
+				/// [`KNOWN_FEATURE_MASK`]: Context::KNOWN_FEATURE_MASK
+				#[cfg(not(test))] // We violate this constraint with `UnknownFeature`
+				const ASSERT_BITS_IN_MASK: u8;
+
 				/// The byte where the feature is set.
 				const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
 
@@ -289,6 +295,12 @@ mod sealed {
 
 					// ODD_BIT % 2 == 1
 					const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
+
+					// (byte & (REQUIRED_MASK | OPTIONAL_MASK)) >> (EVEN_BIT % 8) == 3
+					#[cfg(not(test))] // We violate this constraint with `UnknownFeature`
+					const ASSERT_BITS_IN_MASK: u8 =
+						((<$context>::KNOWN_FEATURE_MASK[<Self as $feature>::BYTE_OFFSET] & (<Self as $feature>::REQUIRED_MASK | <Self as $feature>::OPTIONAL_MASK))
+						 >> (<Self as $feature>::EVEN_BIT % 8)) - 3;
 				}
 			)*
 		};
-- 
2.30.2