Merge bitcoin/bitcoin#29906: Disable util::Result copying and assignment

6a8b2befeab25e4e92d8e947a23e78014695e06c refactor: Avoid copying util::Result values (Ryan Ofsky)
834f65e82405bbed336f98996bc8cef366bbed0f refactor: Drop util::Result operator= (Ryan Ofsky)

Pull request description:

  This PR just contains the first two commits of #25665.

  It disables copying of `util::Result` objects because unnecessary copies are inefficient and not possible after #25665, which makes `util::Result` object move-only.

  It disables the assignment operator and replaces it with an `Update()` method, because #25665 adds more information to `util::Result` objects (warning and error messages and failure values) and having an assignment operator that overwrites data instead of merging it would make it easy to accidentally erase existing information while trying to assign new information.

ACKs for top commit:
  stickies-v:
    re-ACK 6a8b2befeab25e4e92d8e947a23e78014695e06c
  achow101:
    ACK 6a8b2befeab25e4e92d8e947a23e78014695e06c
  furszy:
    re-ACK https://github.com/bitcoin/bitcoin/commit/6a8b2befeab25e4e92d8e947a23e78014695e06c

Tree-SHA512: 3f21af9031d50d6c68cca69133de03080f69b1ddcf8b140bdeb762069f14645209b2586037236d15b6ebd8973af0fbefd7e83144aeb7b84078a4cb4df812f984

1 files changed, 10 insertions, 6 deletions

diff --git a/src/test/mempool_tests.cpp b/src/test/mempool_tests.cpp
index 217e4a6d22..9f8d434213 100644
--- a/src/test/mempool_tests.cpp
+++ b/src/test/mempool_tests.cpp
@@ -202,9 +202,11 @@ BOOST_AUTO_TEST_CASE(MempoolIndexingTest)
     tx7.vout[1].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
     tx7.vout[1].nValue = 1 * COIN;
 
-    auto ancestors_calculated{pool.CalculateMemPoolAncestors(entry.Fee(2000000LL).FromTx(tx7), CTxMemPool::Limits::NoLimits())};
-    BOOST_REQUIRE(ancestors_calculated.has_value());
-    BOOST_CHECK(*ancestors_calculated == setAncestors);
+    {
+        auto ancestors_calculated{pool.CalculateMemPoolAncestors(entry.Fee(2000000LL).FromTx(tx7), CTxMemPool::Limits::NoLimits())};
+        BOOST_REQUIRE(ancestors_calculated.has_value());
+        BOOST_CHECK(*ancestors_calculated == setAncestors);
+    }
 
     pool.addUnchecked(entry.FromTx(tx7), setAncestors);
     BOOST_CHECK_EQUAL(pool.size(), 7U);
@@ -260,9 +262,11 @@ BOOST_AUTO_TEST_CASE(MempoolIndexingTest)
     tx10.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
     tx10.vout[0].nValue = 10 * COIN;
 
-    ancestors_calculated = pool.CalculateMemPoolAncestors(entry.Fee(200000LL).Time(NodeSeconds{4s}).FromTx(tx10), CTxMemPool::Limits::NoLimits());
-    BOOST_REQUIRE(ancestors_calculated);
-    BOOST_CHECK(*ancestors_calculated == setAncestors);
+    {
+        auto ancestors_calculated{pool.CalculateMemPoolAncestors(entry.Fee(200000LL).Time(NodeSeconds{4s}).FromTx(tx10), CTxMemPool::Limits::NoLimits())};
+        BOOST_REQUIRE(ancestors_calculated);
+        BOOST_CHECK(*ancestors_calculated == setAncestors);
+    }
 
     pool.addUnchecked(entry.FromTx(tx10), setAncestors);