Add featureImmediateOfferKilled for tfImmediateOrCancel offers:

Fixes #4115; https://github.com/ripple/rippled/issues/4115

src/ripple/app/tx/impl/CreateOffer.cpp

@@ -1107,6 +1107,12 @@ CreateOffer::applyGuts(Sandbox& sb, Sandbox& sbCancel)
     if (bImmediateOrCancel)
     {
         JLOG(j_.trace()) << "Immediate or cancel: offer canceled";
+        if (!crossed && sb.rules().enabled(featureImmediateOfferKilled))
+            // If the ImmediateOfferKilled amendment is enabled, any
+            // ImmediateOrCancel offer that transfers absolutely no funds
+            // returns tecKILLED rather than tesSUCCESS.  Motivation for the
+            // change is here: https://github.com/ripple/rippled/issues/4115
+            return {tecKILLED, false};
         return {tesSUCCESS, true};
     }
 

src/ripple/protocol/Feature.h

@@ -74,7 +74,7 @@ namespace detail {
 // Feature.cpp. Because it's only used to reserve storage, and determine how
 // large to make the FeatureBitset, it MAY be larger. It MUST NOT be less than
 // the actual number of amendments. A LogicError on startup will verify this.
-static constexpr std::size_t numFeatures = 51;
+static constexpr std::size_t numFeatures = 53;
 
 /** Amendments that this server supports and the default voting behavior.
    Whether they are enabled depends on the Rules defined in the validated
@@ -339,6 +339,7 @@ extern uint256 const fixNFTokenNegOffer;
 extern uint256 const featureNonFungibleTokensV1_1;
 extern uint256 const fixTrustLinesToSelf;
 extern uint256 const fixRemoveNFTokenAutoTrustLine;
+extern uint256 const featureImmediateOfferKilled;
 
 }  // namespace ripple
 

src/ripple/protocol/impl/Feature.cpp

@@ -449,6 +449,7 @@ REGISTER_FIX    (fixNFTokenNegOffer,            Supported::yes, DefaultVote::no)
 REGISTER_FEATURE(NonFungibleTokensV1_1,         Supported::yes, DefaultVote::no);
 REGISTER_FIX    (fixTrustLinesToSelf,           Supported::yes, DefaultVote::no);
 REGISTER_FIX    (fixRemoveNFTokenAutoTrustLine, Supported::yes, DefaultVote::yes);
+REGISTER_FEATURE(ImmediateOfferKilled,          Supported::yes, DefaultVote::no);
 
 // The following amendments have been active for at least two years. Their
 // pre-amendment code has been removed and the identifiers are deprecated.

src/ripple/protocol/impl/TER.cpp

@@ -77,7 +77,7 @@ transResults()
         MAKE_ERROR(tecINVARIANT_FAILED,              "One or more invariants for the transaction were not satisfied."),
         MAKE_ERROR(tecEXPIRED,                       "Expiration time is passed."),
         MAKE_ERROR(tecDUPLICATE,                     "Ledger object already exists."),
-        MAKE_ERROR(tecKILLED,                        "FillOrKill offer killed."),
+        MAKE_ERROR(tecKILLED,                        "No funds transferred and no offer created."),
         MAKE_ERROR(tecHAS_OBLIGATIONS,               "The account cannot be deleted since it has obligations."),
         MAKE_ERROR(tecTOO_SOON,                      "It is too early to attempt the requested operation. Please wait."),
         MAKE_ERROR(tecMAX_SEQUENCE_REACHED,          "The maximum sequence number was reached."),

src/test/app/Offer_test.cpp

@@ -950,9 +950,14 @@ public:
             env(pay(gw, alice, USD(1000)), ter(tesSUCCESS));
 
             // No cross:
+            {
+                TER const expectedCode = features[featureImmediateOfferKilled]
+                    ? static_cast<TER>(tecKILLED)
+                    : static_cast<TER>(tesSUCCESS);
                 env(offer(alice, XRP(1000), USD(1000)),
                     txflags(tfImmediateOrCancel),
-                ter(tesSUCCESS));
+                    ter(expectedCode));
+            }
 
             env.require(
                 balance(alice, startBalance - f - f),
@@ -5165,11 +5170,12 @@ public:
         FeatureBitset const flowCross{featureFlowCross};
         FeatureBitset const takerDryOffer{fixTakerDryOfferRemoval};
         FeatureBitset const rmSmallIncreasedQOffers{fixRmSmallIncreasedQOffers};
+        FeatureBitset const immediateOfferKilled{featureImmediateOfferKilled};
 
-        testAll(all - takerDryOffer);
+        testAll(all - takerDryOffer - immediateOfferKilled);
-        testAll(all - flowCross - takerDryOffer);
+        testAll(all - flowCross - takerDryOffer - immediateOfferKilled);
-        testAll(all - flowCross);
+        testAll(all - flowCross - immediateOfferKilled);
-        testAll(all - rmSmallIncreasedQOffers);
+        testAll(all - rmSmallIncreasedQOffers - immediateOfferKilled);
         testAll(all);
         testFalseAssert();
     }
@@ -5184,11 +5190,12 @@ class Offer_manual_test : public Offer_test
         FeatureBitset const all{supported_amendments()};
         FeatureBitset const flowCross{featureFlowCross};
         FeatureBitset const f1513{fix1513};
+        FeatureBitset const immediateOfferKilled{featureImmediateOfferKilled};
         FeatureBitset const takerDryOffer{fixTakerDryOfferRemoval};
 
-        testAll(all - flowCross - f1513);
+        testAll(all - flowCross - f1513 - immediateOfferKilled);
-        testAll(all - flowCross);
+        testAll(all - flowCross - immediateOfferKilled);
-        testAll(all - f1513);
+        testAll(all - immediateOfferKilled);
         testAll(all);
 
         testAll(all - flowCross - takerDryOffer);