Align input.prevout and prevout default metadata.

Author: evoskuil

include/bitcoin/system/chain/input.hpp

@@ -161,8 +161,9 @@ class BC_API input
 public:
     /// TODO: prevout destruct requires input destruct.
     /// Public mutable metadata access, copied but not compared for equality.
+    /// Defaults are set so non-population issues usually imply invalidity.
     mutable chain::output::cptr prevout{};
-    mutable chain::prevout metadata{ zero, max_uint32, false, false };
+    mutable chain::prevout metadata{ zero, max_uint32, true, true };
 };
 
 typedef std_vector<input> inputs;

include/bitcoin/system/chain/prevout.hpp

@@ -25,6 +25,7 @@ namespace libbitcoin {
 namespace system {
 namespace chain {
 
+// Defaults are set so non-population issues usually imply invalidity.
 class BC_API prevout final
 {
 public:
@@ -74,7 +75,7 @@ class BC_API prevout final
 
     /// The previous output is of a coinbase transaction.
     /// database: populated, does not require prevout block association.
-    bool coinbase{ false };
+    bool coinbase{ true };
 };
 
 } // namespace chain

test/chain/transaction.cpp

@@ -1342,6 +1342,7 @@ BOOST_AUTO_TEST_CASE(transaction__is_confirmed_double_spend__empty_inputs__false
 
 BOOST_AUTO_TEST_CASE(transaction__is_confirmed_double_spend__default_inputs__false)
 {
+    // input.metadata.spent defaults to true.
     const accessor instance
     {
         0,
@@ -1350,7 +1351,7 @@ BOOST_AUTO_TEST_CASE(transaction__is_confirmed_double_spend__default_inputs__fal
         0
     };
 
-    BOOST_REQUIRE(!instance.is_confirmed_double_spend(42));
+    BOOST_REQUIRE(instance.is_confirmed_double_spend(42));
 }
 
 BOOST_AUTO_TEST_CASE(transaction__is_confirmed_double_spend__unspent_input__false)