compiler warning on building src/test/test_bitcoin-validation_chainstate_tests.o #23101

1. 
   katesalazar commented at 5:11 pm on September 26, 2021: contributor

   Is your feature request related to a problem? Please describe.

   Warning on building using g++ 8.3.

    0 1 In file included from ./txdb.h:11,
    1 2                  from ./validation.h:26,
    2 3                  from ./test/util/chainstate.h:13,
    3 4                  from test/validation_chainstate_tests.cpp:11:
    4 5 ./chain.h: In member function ‘void validation_chainstate_tests::chainstate_update_tip::test_method()’:
    5 6 ./chain.h:422:27: warning: ‘background_cs’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    6 7          return vChain.size() > 0 ? vChain[vChain.size() - 1] : nullptr;
    7 8                 ~~~~~~~~~~~^~
    8 9 test/validation_chainstate_tests.cpp:109:18: note: ‘background_cs’ was declared here
    910      CChainState* background_cs;
   1011                   ^~~~~~~~~~~~~
   1112
   

   Describe the solution you’d like

   Able to build without warnings.

   Describe alternatives you’ve considered

   N/A.

   Additional context

   cd src/ && make test/test_bitcoin-validation_chainstate_tests.o

   Bisecting this warning, I ended up in revision 673a5bd3377929a0 by @jamesob.

   Thank you very much and please excuse the noise.

2. katesalazar added the label Feature on Sep 26, 2021
3. hebasto removed the label Feature on Sep 26, 2021
4. 
   MarcoFalke commented at 7:36 am on September 27, 2021: member

   Can be fixed with:

    0diff --git a/src/test/validation_chainstate_tests.cpp b/src/test/validation_chainstate_tests.cpp
    1index 726c9ebbb..9bb08f774 100644
    2--- a/src/test/validation_chainstate_tests.cpp
    3+++ b/src/test/validation_chainstate_tests.cpp
    4@@ -107,20 +107,21 @@ BOOST_FIXTURE_TEST_CASE(chainstate_update_tip, TestChain100Setup)
    5 
    6     curr_tip = ::g_best_block;
    7 
    8-    CChainState* background_cs;
    9-
   10     BOOST_CHECK_EQUAL(chainman.GetAll().size(), 2);
   11-    for (CChainState* cs : chainman.GetAll()) {
   12-        if (cs != &chainman.ActiveChainstate()) {
   13-            background_cs = cs;
   14+
   15+    CChainState& background_cs{*[&] {
   16+        for (CChainState* cs : chainman.GetAll()) {
   17+            if (cs != &chainman.ActiveChainstate()) {
   18+                return cs;
   19+            }
   20         }
   21-    }
   22-    BOOST_CHECK(background_cs);
   23+        assert(false);
   24+    }()};
   25 
   26     // Create a block to append to the validation chain.
   27     std::vector<CMutableTransaction> noTxns;
   28     CScript scriptPubKey = CScript() << ToByteVector(coinbaseKey.GetPubKey()) << OP_CHECKSIG;
   29-    CBlock validation_block = this->CreateBlock(noTxns, scriptPubKey, *background_cs);
   30+    CBlock validation_block = this->CreateBlock(noTxns, scriptPubKey, background_cs);
   31     auto pblock = std::make_shared<const CBlock>(validation_block);
   32     BlockValidationState state;
   33     CBlockIndex* pindex = nullptr;
   34@@ -133,15 +134,15 @@ BOOST_FIXTURE_TEST_CASE(chainstate_update_tip, TestChain100Setup)
   35         LOCK(::cs_main);
   36         bool checked = CheckBlock(*pblock, state, chainparams.GetConsensus());
   37         BOOST_CHECK(checked);
   38-        bool accepted = background_cs->AcceptBlock(
   39+        bool accepted = background_cs.AcceptBlock(
   40             pblock, state, &pindex, true, nullptr, &newblock);
   41         BOOST_CHECK(accepted);
   42     }
   43     // UpdateTip is called here
   44-    bool block_added = background_cs->ActivateBestChain(state, pblock);
   45+    bool block_added = background_cs.ActivateBestChain(state, pblock);
   46 
   47     // Ensure tip is as expected
   48-    BOOST_CHECK_EQUAL(background_cs->m_chain.Tip()->GetBlockHash(), validation_block.GetHash());
   49+    BOOST_CHECK_EQUAL(background_cs.m_chain.Tip()->GetBlockHash(), validation_block.GetHash());
   50 
   51     // g_best_block should be unchanged after adding a block to the background
   52     // validation chain.
   

5. 
   katesalazar commented at 3:21 pm on September 27, 2021: contributor

   It went away!
6. 
   meshcollider commented at 9:54 am on September 29, 2021: contributor

   @MarcoFalke want to PR the fix?
7. MarcoFalke referenced this in commit fa4d0aacf2 on Sep 29, 2021
8. MarcoFalke closed this on Oct 12, 2021

   ---

9. MarcoFalke referenced this in commit 8df7eee5e1 on Oct 12, 2021
10. rebroad referenced this in commit a2a5392d3c on Oct 13, 2021
11. janus referenced this in commit b7761d1f9b on Nov 11, 2021
12. DrahtBot locked this on Oct 30, 2022

Contributors
katesalazar MarcoFalke meshcollider