Stop tracking feature bits as known or required in features.rs

Now that the `*Features::known` constructor has been removed, there
is no reason to define feature bits as either optional required in
`features.rs` - that logic now belongs in the modules that are
responsible for the given features.

Instead, we only list all features in each context.

diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs
index 0566a80b3daf5b8c0b613fc3a486629deaf88c83..4425a78e03f9ad406fe885e9f65d91a00d866115 100644 (file)
--- a/lightning/src/ln/features.rs
+++ b/lightning/src/ln/features.rs
@@ -71,15 +71,11 @@ mod sealed {
        use prelude::*;
        use ln::features::Features;
 
-       /// The context in which [`Features`] are applicable. Defines which features are required and
-       /// which are optional for the context.
+       /// The context in which [`Features`] are applicable. Defines which features are known to the
+       /// implementation, though specification of them as required or optional is up to the code
+       /// constructing a features object.
        pub trait Context {
-               /// Features that are known to the implementation, where a required feature is indicated by
-               /// its even bit and an optional feature is indicated by its odd bit.
-               const KNOWN_FEATURE_FLAGS: &'static [u8];
-
-               /// Bitmask for selecting features that are known to the implementation, regardless of
-               /// whether each feature is required or optional.
+               /// Bitmask for selecting features that are known to the implementation.
                const KNOWN_FEATURE_MASK: &'static [u8];
        }
 
@@ -87,41 +83,16 @@ mod sealed {
        /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
        /// feature identifiers.
        macro_rules! define_context {
-               ($context: ident {
-                       required_features: [$( $( $required_feature: ident )|*, )*],
-                       optional_features: [$( $( $optional_feature: ident )|*, )*],
-               }) => {
+               ($context: ident, [$( $( $known_feature: ident )|*, )*]) => {
                        #[derive(Eq, PartialEq)]
                        pub struct $context {}
 
                        impl Context for $context {
-                               const KNOWN_FEATURE_FLAGS: &'static [u8] = &[
-                                       // For each byte, use bitwise-OR to compute the applicable flags for known
-                                       // required features `r_i` and optional features `o_j` for all `i` and `j` such
-                                       // that the following slice is formed:
-                                       //
-                                       // [
-                                       //  `r_0` | `r_1` | ... | `o_0` | `o_1` | ...,
-                                       //  ...,
-                                       // ]
-                                       $(
-                                               0b00_00_00_00 $(|
-                                                       <Self as $required_feature>::REQUIRED_MASK)*
-                                               $(|
-                                                       <Self as $optional_feature>::OPTIONAL_MASK)*,
-                                       )*
-                               ];
-
                                const KNOWN_FEATURE_MASK: &'static [u8] = &[
-                                       // Similar as above, but set both flags for each feature regardless of whether
-                                       // the feature is required or optional.
                                        $(
                                                0b00_00_00_00 $(|
-                                                       <Self as $required_feature>::REQUIRED_MASK |
-                                                       <Self as $required_feature>::OPTIONAL_MASK)*
-                                               $(|
-                                                       <Self as $optional_feature>::REQUIRED_MASK |
-                                                       <Self as $optional_feature>::OPTIONAL_MASK)*,
+                                                       <Self as $known_feature>::REQUIRED_MASK |
+                                                       <Self as $known_feature>::OPTIONAL_MASK)*,
                                        )*
                                ];
                        }
@@ -130,17 +101,12 @@ mod sealed {
                                fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
                                        $(
                                                $(
-                                                       fmt.write_fmt(format_args!("{}: {}, ", stringify!($required_feature),
-                                                               if <$context as $required_feature>::requires_feature(&self.flags) { "required" }
-                                                               else if <$context as $required_feature>::supports_feature(&self.flags) { "supported" }
-                                                               else { "not supported" }))?;
-                                               )*
-                                               $(
-                                                       fmt.write_fmt(format_args!("{}: {}, ", stringify!($optional_feature),
-                                                               if <$context as $optional_feature>::requires_feature(&self.flags) { "required" }
-                                                               else if <$context as $optional_feature>::supports_feature(&self.flags) { "supported" }
+                                                       fmt.write_fmt(format_args!("{}: {}, ", stringify!($known_feature),
+                                                               if <$context as $known_feature>::requires_feature(&self.flags) { "required" }
+                                                               else if <$context as $known_feature>::supports_feature(&self.flags) { "supported" }
                                                                else { "not supported" }))?;
                                                )*
+                                               {} // Rust gets mad if we only have a $()* block here, so add a dummy {}
                                        )*
                                        fmt.write_fmt(format_args!("unknown flags: {}",
                                                if self.requires_unknown_bits() { "required" }
@@ -150,132 +116,65 @@ mod sealed {
                };
        }
 
-       define_context!(InitContext {
-               required_features: [
-                       // Byte 0
-                       ,
-                       // Byte 1
-                       VariableLengthOnion | StaticRemoteKey | PaymentSecret,
-                       // Byte 2
-                       ,
-                       // Byte 3
-                       ,
-                       // Byte 4
-                       ,
-                       // Byte 5
-                       ,
-                       // Byte 6
-                       ,
-               ],
-               optional_features: [
-                       // Byte 0
-                       DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
-                       // Byte 1
-                       ,
-                       // Byte 2
-                       BasicMPP | Wumbo,
-                       // Byte 3
-                       ShutdownAnySegwit,
-                       // Byte 4
-                       OnionMessages,
-                       // Byte 5
-                       ChannelType | SCIDPrivacy,
-                       // Byte 6
-                       ZeroConf,
-               ],
-       });
-       define_context!(NodeContext {
-               required_features: [
-                       // Byte 0
-                       ,
-                       // Byte 1
-                       VariableLengthOnion | StaticRemoteKey | PaymentSecret,
-                       // Byte 2
-                       ,
-                       // Byte 3
-                       ,
-                       // Byte 4
-                       ,
-                       // Byte 5
-                       ,
-                       // Byte 6
-                       ,
-               ],
-               optional_features: [
-                       // Byte 0
-                       DataLossProtect | UpfrontShutdownScript | GossipQueries,
-                       // Byte 1
-                       ,
-                       // Byte 2
-                       BasicMPP | Wumbo,
-                       // Byte 3
-                       ShutdownAnySegwit,
-                       // Byte 4
-                       OnionMessages,
-                       // Byte 5
-                       ChannelType | SCIDPrivacy,
-                       // Byte 6
-                       ZeroConf | Keysend,
-               ],
-       });
-       define_context!(ChannelContext {
-               required_features: [],
-               optional_features: [],
-       });
-       define_context!(InvoiceContext {
-               required_features: [
-                       // Byte 0
-                       ,
-                       // Byte 1
-                       VariableLengthOnion | PaymentSecret,
-                       // Byte 2
-                       ,
-               ],
-               optional_features: [
-                       // Byte 0
-                       ,
-                       // Byte 1
-                       ,
-                       // Byte 2
-                       BasicMPP,
-               ],
-       });
+       define_context!(InitContext, [
+               // Byte 0
+               DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
+               // Byte 1
+               VariableLengthOnion | StaticRemoteKey | PaymentSecret,
+               // Byte 2
+               BasicMPP | Wumbo,
+               // Byte 3
+               ShutdownAnySegwit,
+               // Byte 4
+               OnionMessages,
+               // Byte 5
+               ChannelType | SCIDPrivacy,
+               // Byte 6
+               ZeroConf,
+       ]);
+       define_context!(NodeContext, [
+               // Byte 0
+               DataLossProtect | UpfrontShutdownScript | GossipQueries,
+               // Byte 1
+               VariableLengthOnion | StaticRemoteKey | PaymentSecret,
+               // Byte 2
+               BasicMPP | Wumbo,
+               // Byte 3
+               ShutdownAnySegwit,
+               // Byte 4
+               OnionMessages,
+               // Byte 5
+               ChannelType | SCIDPrivacy,
+               // Byte 6
+               ZeroConf | Keysend,
+       ]);
+       define_context!(ChannelContext, []);
+       define_context!(InvoiceContext, [
+               // Byte 0
+               ,
+               // Byte 1
+               VariableLengthOnion | PaymentSecret,
+               // Byte 2
+               BasicMPP,
+       ]);
        // This isn't a "real" feature context, and is only used in the channel_type field in an
        // `OpenChannel` message.
-       define_context!(ChannelTypeContext {
-               required_features: [
-                       // Byte 0
-                       ,
-                       // Byte 1
-                       StaticRemoteKey,
-                       // Byte 2
-                       ,
-                       // Byte 3
-                       ,
-                       // Byte 4
-                       ,
-                       // Byte 5
-                       SCIDPrivacy,
-                       // Byte 6
-                       ZeroConf,
-               ],
-               optional_features: [
-                       // Byte 0
-                       ,
-                       // Byte 1
-                       ,
-                       // Byte 2
-                       ,
-                       // Byte 3
-                       ,
-                       // Byte 4
-                       ,
-                       // Byte 5
-                       ,
-                       // Byte 6
-                       ,
-               ],
-       });
+       define_context!(ChannelTypeContext, [
+               // Byte 0
+               ,
+               // Byte 1
+               StaticRemoteKey,
+               // Byte 2
+               ,
+               // Byte 3
+               ,
+               // Byte 4
+               ,
+               // Byte 5
+               SCIDPrivacy,
+               // Byte 6
+               ZeroConf,
+       ]);
 
        /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
        /// useful for manipulating feature flags.