Merge #20429: refactor: replace (sizeof(a)/sizeof(a[0])) with C++17 std::size

e829c9afbf75e930db6c3fe77a269b0af5e7a3ad refactor: replace sizeof(a)/sizeof(a[0]) by std::size (C++17) (Sebastian Falbesoner)
365539c84691d470b44d35df374d8c049f8c1192 refactor: init vectors via std::{begin,end} to avoid pointer arithmetic (Sebastian Falbesoner)
63d4ee1968144cc3d115f92baef95785abf813ac refactor: iterate arrays via C++11 range-based for loops if idx is not needed (Sebastian Falbesoner)

Pull request description:

  This refactoring PR picks up the idea of #19626 and replaces all occurences of `sizeof(x)/sizeof(x[0])` (or `sizeof(x)/sizeof(*x)`, respectively) with the now-available C++17 [`std::size`](https://en.cppreference.com/w/cpp/iterator/size)  (as [suggested by sipa](https://github.com/bitcoin/bitcoin/pull/19626#issuecomment-666487228)), making the macro `ARRAYLEN` obsolete.

  As preparation for this, two other changes are done to eliminate `sizeof(x)/sizeof(x[0])` usage:
  * all places where arrays are iterated via an index are changed to use C++11 range-based for loops If the index' only purpose is to access the array element (as [suggested by MarcoFalke](https://github.com/bitcoin/bitcoin/pull/19626#discussion_r463404541)).
  * `std::vector` initializations are done via `std::begin` and `std::end` rather than using pointer arithmetic to calculate the end (also [suggested by MarcoFalke](https://github.com/bitcoin/bitcoin/pull/20429#discussion_r567418821)).

ACKs for top commit:
  practicalswift:
    cr ACK e829c9afbf75e930db6c3fe77a269b0af5e7a3ad: patch looks correct
  fanquake:
    ACK e829c9afbf75e930db6c3fe77a269b0af5e7a3ad
  MarcoFalke:
    review ACK e829c9afbf75e930db6c3fe77a269b0af5e7a3ad 🌩

Tree-SHA512: b01d32c04b9e04d562b7717cae00a651ec9a718645047a90761be6959e0cc2adbd67494e058fe894641076711bb09c3b47a047d0275c736f0b2218e1ce0d193d

1 files changed, 4 insertions, 5 deletions

diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp
index 9c06283a58..9073a5050c 100644
--- a/src/test/miner_tests.cpp
+++ b/src/test/miner_tests.cpp
@@ -219,11 +219,10 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
 
     // We can't make transactions until we have inputs
     // Therefore, load 110 blocks :)
-    static_assert(sizeof(blockinfo) / sizeof(*blockinfo) == 110, "Should have 110 blocks to import");
+    static_assert(std::size(blockinfo) == 110, "Should have 110 blocks to import");
     int baseheight = 0;
     std::vector<CTransactionRef> txFirst;
-    for (unsigned int i = 0; i < sizeof(blockinfo)/sizeof(*blockinfo); ++i)
-    {
+    for (const auto& bi : blockinfo) {
         CBlock *pblock = &pblocktemplate->block; // pointer for convenience
         {
             LOCK(cs_main);
@@ -232,7 +231,7 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
             CMutableTransaction txCoinbase(*pblock->vtx[0]);
             txCoinbase.nVersion = 1;
             txCoinbase.vin[0].scriptSig = CScript();
-            txCoinbase.vin[0].scriptSig.push_back(blockinfo[i].extranonce);
+            txCoinbase.vin[0].scriptSig.push_back(bi.extranonce);
             txCoinbase.vin[0].scriptSig.push_back(::ChainActive().Height());
             txCoinbase.vout.resize(1); // Ignore the (optional) segwit commitment added by CreateNewBlock (as the hardcoded nonces don't account for this)
             txCoinbase.vout[0].scriptPubKey = CScript();
@@ -242,7 +241,7 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
             if (txFirst.size() < 4)
                 txFirst.push_back(pblock->vtx[0]);
             pblock->hashMerkleRoot = BlockMerkleRoot(*pblock);
-            pblock->nNonce = blockinfo[i].nonce;
+            pblock->nNonce = bi.nonce;
         }
         std::shared_ptr<const CBlock> shared_pblock = std::make_shared<const CBlock>(*pblock);
         BOOST_CHECK(Assert(m_node.chainman)->ProcessNewBlock(chainparams, shared_pblock, true, nullptr));