Partially revert aed8e2b166 Fill in payment computation shortages (#5941)

- Do not attempt to fill in payment computation shortages. Fixes, tests,
  and optimizations are left intact.

src/test/app/Loan_test.cpp

@@ -1999,6 +1999,7 @@ protected:
                             state.paymentRemaining,
                             broker.params.managementFeeRate);
 
+#if LOANFILLSHORTAGE
                     BEAST_EXPECT(
                         paymentComponents.trackedValueDelta ==
                             roundedPeriodicPayment ||
@@ -2006,6 +2007,11 @@ protected:
                              detail::PaymentSpecialCase::final &&
                          paymentComponents.trackedValueDelta <
                              roundedPeriodicPayment));
+#else
+                    BEAST_EXPECT(
+                        paymentComponents.trackedValueDelta <=
+                        roundedPeriodicPayment);
+#endif
 
                     ripple::LoanState const nextTrueState =
                         calculateRawLoanState(

src/xrpld/app/misc/detail/LendingHelpers.cpp

@@ -1208,6 +1208,7 @@ computePaymentComponents(
             "ripple::detail::computePaymentComponents",
             "excess non-negative");
     };
+#if LOANFILLSHORTAGE
     auto giveTo =
         [](Number& component, Number& shortage, Number const& maximum) {
             if (shortage > beast::zero)
@@ -1225,12 +1226,14 @@ computePaymentComponents(
                 "ripple::detail::computePaymentComponents",
                 "excess non-negative");
         };
+#endif
     auto addressExcess = [&takeFrom](LoanDeltas& deltas, Number& excess) {
         // This order is based on where errors are the least problematic
         takeFrom(deltas.interestDueDelta, excess);
         takeFrom(deltas.managementFeeDueDelta, excess);
         takeFrom(deltas.principalDelta, excess);
     };
+#if LOANFILLSHORTAGE
     auto addressShortage = [&giveTo](
                                LoanDeltas& deltas,
                                Number& shortage,
@@ -1240,6 +1243,7 @@ computePaymentComponents(
         giveTo(
             deltas.managementFeeDueDelta, shortage, current.managementFeeDue);
     };
+#endif
     Number totalOverpayment =
         deltas.valueDelta() - currentLedgerState.valueOutstanding;
     if (totalOverpayment > beast::zero)
@@ -1268,6 +1272,7 @@ computePaymentComponents(
 
         shortage = -excess;
     }
+#if LOANFILLSHORTAGE
     else if (shortage > beast::zero && totalOverpayment < beast::zero)
     {
         // If there's a shortage, and there's room in the loan itself, we can
@@ -1285,6 +1290,16 @@ computePaymentComponents(
         shortage == beast::zero,
         "ripple::detail::computePaymentComponents",
         "no shortage or excess");
+#else
+    // The shortage should never be negative, which indicates that the
+    // parts are trying to take more than the whole payment. The
+    // shortage may be positive, which indicates that we're not going to
+    // take the whole payment amount.
+    XRPL_ASSERT_PARTS(
+        shortage >= beast::zero,
+        "ripple::detail::computePaymentComponents",
+        "no shortage or excess");
+#endif
 #if LOANCOMPLETE
     /*
     // This used to be part of the above assert. It will eventually be removed