refactor: Rely on returned value of GetCoin instead of parameter

Also removed the unused coin parameter of GetCoin.

Co-authored-by: Andrew Toth <andrewstoth@gmail.com>

src/test/fuzz/coins_view.cpp

@@ -162,22 +162,20 @@ FUZZ_TARGET(coins_view, .init = initialize_coins_view)
         const bool exists_using_access_coin = !(coin_using_access_coin == EMPTY_COIN);
         const bool exists_using_have_coin = coins_view_cache.HaveCoin(random_out_point);
         const bool exists_using_have_coin_in_cache = coins_view_cache.HaveCoinInCache(random_out_point);
-        Coin coin_using_get_coin;
-        const bool exists_using_get_coin = coins_view_cache.GetCoin(random_out_point, coin_using_get_coin).has_value();
-        if (exists_using_get_coin) {
-            assert(coin_using_get_coin == coin_using_access_coin);
+        if (auto coin{coins_view_cache.GetCoin(random_out_point)}) {
+            assert(*coin == coin_using_access_coin);
+            assert(exists_using_access_coin && exists_using_have_coin_in_cache && exists_using_have_coin);
+        } else {
+            assert(!exists_using_access_coin && !exists_using_have_coin_in_cache && !exists_using_have_coin);
         }
-        assert((exists_using_access_coin && exists_using_have_coin_in_cache && exists_using_have_coin && exists_using_get_coin) ||
-               (!exists_using_access_coin && !exists_using_have_coin_in_cache && !exists_using_have_coin && !exists_using_get_coin));
         // If HaveCoin on the backend is true, it must also be on the cache if the coin wasn't spent.
         const bool exists_using_have_coin_in_backend = backend_coins_view.HaveCoin(random_out_point);
         if (!coin_using_access_coin.IsSpent() && exists_using_have_coin_in_backend) {
             assert(exists_using_have_coin);
         }
-        Coin coin_using_backend_get_coin;
-        if (backend_coins_view.GetCoin(random_out_point, coin_using_backend_get_coin)) {
+        if (auto coin{backend_coins_view.GetCoin(random_out_point)}) {
             assert(exists_using_have_coin_in_backend);
-            // Note we can't assert that `coin_using_get_coin == coin_using_backend_get_coin` because the coin in
+            // Note we can't assert that `coin_using_get_coin == *coin` because the coin in
             // the cache may have been modified but not yet flushed.
         } else {
             assert(!exists_using_have_coin_in_backend);

src/test/fuzz/coinscache_sim.cpp

@@ -146,15 +146,11 @@ class CoinsViewBottom final : public CCoinsView
     std::map<COutPoint, Coin> m_data;
 
 public:
-    std::optional<Coin> GetCoin(const COutPoint& outpoint, Coin& coin) const final
+    std::optional<Coin> GetCoin(const COutPoint& outpoint) const final
     {
-        auto it = m_data.find(outpoint);
-        if (it == m_data.end()) {
-            return std::nullopt;
-        } else {
-            coin = it->second;
-            return coin; // TODO GetCoin shouldn't return spent coins
-        }
+        // TODO GetCoin shouldn't return spent coins
+        if (auto it = m_data.find(outpoint); it != m_data.end()) return it->second;
+        return std::nullopt;
     }
 
     bool HaveCoin(const COutPoint& outpoint) const final
@@ -265,17 +261,16 @@ FUZZ_TARGET(coinscache_sim)
                 // Look up in simulation data.
                 auto sim = lookup(outpointidx);
                 // Look up in real caches.
-                Coin realcoin;
-                auto real = caches.back()->GetCoin(data.outpoints[outpointidx], realcoin);
+                auto realcoin = caches.back()->GetCoin(data.outpoints[outpointidx]);
                 // Compare results.
                 if (!sim.has_value()) {
-                    assert(!real || realcoin.IsSpent());
+                    assert(!realcoin || realcoin->IsSpent());
                 } else {
-                    assert(real && !realcoin.IsSpent());
+                    assert(realcoin && !realcoin->IsSpent());
                     const auto& simcoin = data.coins[sim->first];
-                    assert(realcoin.out == simcoin.out);
-                    assert(realcoin.fCoinBase == simcoin.fCoinBase);
-                    assert(realcoin.nHeight == sim->second);
+                    assert(realcoin->out == simcoin.out);
+                    assert(realcoin->fCoinBase == simcoin.fCoinBase);
+                    assert(realcoin->nHeight == sim->second);
                 }
             },
 
@@ -460,16 +455,15 @@ FUZZ_TARGET(coinscache_sim)
 
     // Compare the bottom coinsview (not a CCoinsViewCache) with sim_cache[0].
     for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) {
-        Coin realcoin;
-        auto real = bottom.GetCoin(data.outpoints[outpointidx], realcoin);
+        auto realcoin = bottom.GetCoin(data.outpoints[outpointidx]);
         auto sim = lookup(outpointidx, 0);
         if (!sim.has_value()) {
-            assert(!real || realcoin.IsSpent());
+            assert(!realcoin || realcoin->IsSpent());
         } else {
-            assert(real && !realcoin.IsSpent());
-            assert(realcoin.out == data.coins[sim->first].out);
-            assert(realcoin.fCoinBase == data.coins[sim->first].fCoinBase);
-            assert(realcoin.nHeight == sim->second);
+            assert(realcoin && !realcoin->IsSpent());
+            assert(realcoin->out == data.coins[sim->first].out);
+            assert(realcoin->fCoinBase == data.coins[sim->first].fCoinBase);
+            assert(realcoin->nHeight == sim->second);
         }
     }
 }

src/test/fuzz/tx_pool.cpp

@@ -214,9 +214,8 @@ FUZZ_TARGET(tx_pool_standard, .init = initialize_tx_pool)
     // Helper to query an amount
     const CCoinsViewMemPool amount_view{WITH_LOCK(::cs_main, return &chainstate.CoinsTip()), tx_pool};
     const auto GetAmount = [&](const COutPoint& outpoint) {
-        Coin c;
-        Assert(amount_view.GetCoin(outpoint, c));
-        return c.out.nValue;
+        auto coin{amount_view.GetCoin(outpoint).value()};
+        return coin.out.nValue;
     };
 
     LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 300)