Merge bitcoin/bitcoin#25060: blockstorage: add LIFETIMEBOUND to GetFirstStoredBlock()::start_time

4cb9d21 blockstorage: add LIFETIMEBOUND to GetFirstStoredBlock()::start_time (Jon Atack)

Pull request description:

  Suggested in bitcoin/bitcoin#25016 (comment), the lifetimebound attribute here indicates that a resource owned by the `start_block` param of `CBlockIndex* BlockManager::GetFirstStoredBlock()` can be retained by the method's return value, which enables detecting the use of out-of-scope stack memory (ASan `stack-use-after-scope`) at compile time.

  See https://releases.llvm.org/12.0.0/tools/clang/docs/AttributeReference.html#lifetimebound and #22278 for related discussion, and #25040 for a similar example.

ACKs for top commit:
  MarcoFalke:
    review ACK 4cb9d21

Tree-SHA512: a3f5ef83ebb6f08555d7c89f2437a682071b4ad77a7aa3326b6d2282c909bf9fcf4dac6bf05ee1d9931f2102cad4a02df5468bde1cf377d7126e84e8541604dc

Author: MacroFake

src/node/blockstorage.h

@@ -5,9 +5,10 @@
 #ifndef BITCOIN_NODE_BLOCKSTORAGE_H
 #define BITCOIN_NODE_BLOCKSTORAGE_H
 
+#include <attributes.h>
 #include <chain.h>
 #include <fs.h>
-#include <protocol.h> // For CMessageHeader::MessageStartChars
+#include <protocol.h>
 #include <sync.h>
 #include <txdb.h>
 
@@ -179,7 +180,7 @@ class BlockManager
     const CBlockIndex* GetLastCheckpoint(const CCheckpointData& data) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     //! Find the first block that is not pruned
-    const CBlockIndex* GetFirstStoredBlock(const CBlockIndex& start_block) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
+    const CBlockIndex* GetFirstStoredBlock(const CBlockIndex& start_block LIFETIMEBOUND) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
     /** True if any block files have ever been pruned. */
     bool m_have_pruned = false;