Merge #11303: Fix estimatesmartfee rounding display issue

1789e4675 Force explicit double -> int conversion for CFeeRate constructor (Matt Corallo)
53a6590f4 Make float <-> int casts explicit outside of test, qt, CFeeRate (Matt Corallo)
0b1b9148c Remove countMaskInv caching in bench framework (Matt Corallo)

Pull request description:

  This fixes an issue where estimatesmartfee which matches at the min relay fee will return 999 sat/byte instead of 1000 sat/byte due to a float rounding issue. I went ahead and made all float <-> int conversion outside of test/qt explicit (test only had one or two more, Qt had quite a few, including many in the Qt headers themselves) and added overloads to CFeeRate to force callers to do an explicit round themselves. Easy to test with -Wfloat-conversion.

Tree-SHA512: 66087b08e5dfca67506da54ae057c2f9d86184415e8fa4fa0199e38839e06a3ce96c836fcb7593b7d960065f5240c594ff3a0cfa14333ac528421f5aeac835c9

2 files changed, 9 insertions, 4 deletions

diff --git a/src/policy/feerate.h b/src/policy/feerate.h
index 7e519e3efa..3449cdd699 100644
--- a/src/policy/feerate.h
+++ b/src/policy/feerate.h
@@ -20,10 +20,15 @@ class CFeeRate
 {
 private:
     CAmount nSatoshisPerK; // unit is satoshis-per-1,000-bytes
+
 public:
     /** Fee rate of 0 satoshis per kB */
     CFeeRate() : nSatoshisPerK(0) { }
-    explicit CFeeRate(const CAmount& _nSatoshisPerK): nSatoshisPerK(_nSatoshisPerK) { }
+    template<typename I>
+    CFeeRate(const I _nSatoshisPerK): nSatoshisPerK(_nSatoshisPerK) {
+        // We've previously had bugs creep in from silent double->int conversion...
+        static_assert(std::is_integral<I>::value, "CFeeRate should be used without floats");
+    }
     /** Constructor for a fee rate in satoshis per kB. The size in bytes must not exceed (2^63 - 1)*/
     CFeeRate(const CAmount& nFeePaid, size_t nBytes);
     /**
diff --git a/src/policy/fees.cpp b/src/policy/fees.cpp
index b9476407cf..8056f385ab 100644
--- a/src/policy/fees.cpp
+++ b/src/policy/fees.cpp
@@ -714,7 +714,7 @@ CFeeRate CBlockPolicyEstimator::estimateRawFee(int confTarget, double successThr
     if (median < 0)
         return CFeeRate(0);
 
-    return CFeeRate(median);
+    return CFeeRate(llround(median));
 }
 
 unsigned int CBlockPolicyEstimator::HighestTargetTracked(FeeEstimateHorizon horizon) const
@@ -901,7 +901,7 @@ CFeeRate CBlockPolicyEstimator::estimateSmartFee(int confTarget, FeeCalculation
 
     if (median < 0) return CFeeRate(0); // error condition
 
-    return CFeeRate(median);
+    return CFeeRate(llround(median));
 }
 
 
@@ -1043,5 +1043,5 @@ CAmount FeeFilterRounder::round(CAmount currentMinFee)
     if ((it != feeset.begin() && insecure_rand.rand32() % 3 != 0) || it == feeset.end()) {
         it--;
     }
-    return *it;
+    return static_cast<CAmount>(*it);
 }