Silence new rustc warning about useless muts

Author: TheBlueMatt

lightning/src/ln/chanmon_update_fail_tests.rs

@@ -12,6 +12,11 @@
 //! There are a bunch of these as their handling is relatively error-prone so they are split out
 //! here. See also the chanmon_fail_consistency fuzz test.
 
+// Older rustc (which we support) refuses to let us call the get_payment_preimage_hash!() macro
+// without the node parameter being mut. This is incorrect, and thus newer rustcs will complain
+// about an unnecessary mut. Just silence the warning.
+#[allow(unused_mut)]
+
 use chain::transaction::OutPoint;
 use ln::channelmanager::{RAACommitmentOrder, PaymentPreimage, PaymentHash, PaymentSecret, PaymentSendFailure};
 use ln::channelmonitor::ChannelMonitorUpdateErr;

lightning/src/ln/mod.rs

@@ -35,12 +35,18 @@ mod channel;
 mod onion_utils;
 mod wire;
 
+// Older rustc (which we support) refuses to let us call the get_payment_preimage_hash!() macro
+// without the node parameter being mut. This is incorrect, and thus newer rustcs will complain
+// about an unnecessary mut. Thus, we silence the unused_mut warning in two test modules below.
+
 #[cfg(test)]
 #[macro_use]
 pub(crate) mod functional_test_utils;
 #[cfg(test)]
+#[allow(unused_mut)]
 mod functional_tests;
 #[cfg(test)]
+#[allow(unused_mut)]
 mod chanmon_update_fail_tests;
 #[cfg(test)]
 mod reorg_tests;