19 files changed, 94 insertions, 46 deletions
diff --git a/contrib/devtools/lint-include-guards.sh b/contrib/devtools/lint-include-guards.sh
new file mode 100755
index 0000000000..6a0dd556bb
--- /dev/null
+++ b/contrib/devtools/lint-include-guards.sh
@@ -0,0 +1,29 @@
+#!/bin/bash
+#
+# Copyright (c) 2018 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#
+# Check include guards.
+
+HEADER_ID_PREFIX="BITCOIN_"
+HEADER_ID_SUFFIX="_H"
+
+REGEXP_EXCLUDE_FILES_WITH_PREFIX="src/(crypto/ctaes/|leveldb/|secp256k1/|tinyformat.h|univalue/)"
+
+EXIT_CODE=0
+for HEADER_FILE in $(git ls-files -- "*.h" | grep -vE "^${REGEXP_EXCLUDE_FILES_WITH_PREFIX}")
+do
+    HEADER_ID_BASE=$(cut -f2- -d/ <<< "${HEADER_FILE}" | sed "s/\.h$//g" | tr / _ | tr "[:lower:]" "[:upper:]")
+    HEADER_ID="${HEADER_ID_PREFIX}${HEADER_ID_BASE}${HEADER_ID_SUFFIX}"
+    if [[ $(grep -cE "^#(ifndef|define) ${HEADER_ID}" "${HEADER_FILE}") != 2 ]]; then
+        echo "${HEADER_FILE} seems to be missing the expected include guard:"
+        echo "  #ifndef ${HEADER_ID}"
+        echo "  #define ${HEADER_ID}"
+        echo "  ..."
+        echo "  #endif // ${HEADER_ID}"
+        echo
+        EXIT_CODE=1
+    fi
+done
+exit ${EXIT_CODE}
diff --git a/doc/developer-notes.md b/doc/developer-notes.md
index 7a033b28d4..540f2e8b84 100644
--- a/doc/developer-notes.md
+++ b/doc/developer-notes.md
@@ -606,6 +606,16 @@ namespace {
     source file into account. This allows quoted includes to stand out more when
     the location of the source file actually is relevant.
 
+- Use include guards to avoid the problem of double inclusion. The header file
+  `foo/bar.h` should use the include guard identifier `BITCOIN_FOO_BAR_H`, e.g.
+
+```c++
+#ifndef BITCOIN_FOO_BAR_H
+#define BITCOIN_FOO_BAR_H
+...
+#endif // BITCOIN_FOO_BAR_H
+```
+
 GUI
 -----
 
diff --git a/src/bech32.h b/src/bech32.h
index 7ef7b22213..2e2823e974 100644
--- a/src/bech32.h
+++ b/src/bech32.h
@@ -9,6 +9,9 @@
 //
 // For more information, see BIP 173.
 
+#ifndef BITCOIN_BECH32_H
+#define BITCOIN_BECH32_H
+
 #include <stdint.h>
 #include <string>
 #include <vector>
@@ -23,3 +26,5 @@ std::string Encode(const std::string& hrp, const std::vector<uint8_t>& values);
 std::pair<std::string, std::vector<uint8_t>> Decode(const std::string& str);
 
 } // namespace bech32
+
+#endif // BITCOIN_BECH32_H
diff --git a/src/bench/perf.h b/src/bench/perf.h
index 681bd0c8a2..73ea8b9647 100644
--- a/src/bench/perf.h
+++ b/src/bench/perf.h
@@ -3,8 +3,8 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 /** Functions for measurement of CPU cycles */
-#ifndef H_PERF
-#define H_PERF
+#ifndef BITCOIN_BENCH_PERF_H
+#define BITCOIN_BENCH_PERF_H
 
 #include <stdint.h>
 
@@ -34,4 +34,4 @@ uint64_t perf_cpucycles(void);
 void perf_init(void);
 void perf_fini(void);
 
-#endif // H_PERF
+#endif // BITCOIN_BENCH_PERF_H
diff --git a/src/blockencodings.h b/src/blockencodings.h
index f80821aa65..3a0828b307 100644
--- a/src/blockencodings.h
+++ b/src/blockencodings.h
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_BLOCK_ENCODINGS_H
-#define BITCOIN_BLOCK_ENCODINGS_H
+#ifndef BITCOIN_BLOCKENCODINGS_H
+#define BITCOIN_BLOCKENCODINGS_H
 
 #include <primitives/block.h>
 
@@ -206,4 +206,4 @@ public:
     ReadStatus FillBlock(CBlock& block, const std::vector<CTransactionRef>& vtx_missing);
 };
 
-#endif
+#endif // BITCOIN_BLOCKENCODINGS_H
diff --git a/src/consensus/merkle.h b/src/consensus/merkle.h
index d57bb3412e..0afb73adb5 100644
--- a/src/consensus/merkle.h
+++ b/src/consensus/merkle.h
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_MERKLE
-#define BITCOIN_MERKLE
+#ifndef BITCOIN_CONSENSUS_MERKLE_H
+#define BITCOIN_CONSENSUS_MERKLE_H
 
 #include <stdint.h>
 #include <vector>
@@ -35,4 +35,4 @@ uint256 BlockWitnessMerkleRoot(const CBlock& block, bool* mutated = nullptr);
  */
 std::vector<uint256> BlockMerkleBranch(const CBlock& block, uint32_t position);
 
-#endif
+#endif // BITCOIN_CONSENSUS_MERKLE_H
diff --git a/src/key_io.h b/src/key_io.h
index 6fc9a8059a..d75b5b31c8 100644
--- a/src/key_io.h
+++ b/src/key_io.h
@@ -3,8 +3,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_KEYIO_H
-#define BITCOIN_KEYIO_H
+#ifndef BITCOIN_KEY_IO_H
+#define BITCOIN_KEY_IO_H
 
 #include <chainparams.h>
 #include <key.h>
@@ -26,4 +26,4 @@ CTxDestination DecodeDestination(const std::string& str);
 bool IsValidDestinationString(const std::string& str);
 bool IsValidDestinationString(const std::string& str, const CChainParams& params);
 
-#endif // BITCOIN_KEYIO_H
+#endif // BITCOIN_KEY_IO_H
diff --git a/src/policy/fees.h b/src/policy/fees.h
index 7f80fc92c2..afb4746def 100644
--- a/src/policy/fees.h
+++ b/src/policy/fees.h
@@ -2,8 +2,8 @@
 // Copyright (c) 2009-2017 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
-#ifndef BITCOIN_POLICYESTIMATOR_H
-#define BITCOIN_POLICYESTIMATOR_H
+#ifndef BITCOIN_POLICY_FEES_H
+#define BITCOIN_POLICY_FEES_H
 
 #include <amount.h>
 #include <policy/feerate.h>
@@ -294,4 +294,4 @@ private:
     FastRandomContext insecure_rand;
 };
 
-#endif /*BITCOIN_POLICYESTIMATOR_H */
+#endif // BITCOIN_POLICY_FEES_H
diff --git a/src/qt/test/paymentrequestdata.h b/src/qt/test/paymentrequestdata.h
index 74a2db8ea2..8e5a259f68 100644
--- a/src/qt/test/paymentrequestdata.h
+++ b/src/qt/test/paymentrequestdata.h
@@ -2,6 +2,9 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#ifndef BITCOIN_QT_TEST_PAYMENTREQUESTDATA_H
+#define BITCOIN_QT_TEST_PAYMENTREQUESTDATA_H
+
 //
 // Data for paymentservertests.cpp
 //
@@ -458,3 +461,5 @@ iEBFUrBDJZU+UEezGwr7/zoECjo5ZY3PmtZcM2sILNjyweJF6XVzGqTxUw6pN6sW\
 XR2T3Gy2LzRvhVA25QgGqpz0/juS2BtmNbsZPkN9gMMwKimgzc+PuCzmEKwPK9cQ\
 YQ==\
 ";
+
+#endif // BITCOIN_QT_TEST_PAYMENTREQUESTDATA_H
diff --git a/src/qt/test/rpcnestedtests.h b/src/qt/test/rpcnestedtests.h
index 0ce1c66f44..7b3b38f62e 100644
--- a/src/qt/test/rpcnestedtests.h
+++ b/src/qt/test/rpcnestedtests.h
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_QT_TEST_RPC_NESTED_TESTS_H
-#define BITCOIN_QT_TEST_RPC_NESTED_TESTS_H
+#ifndef BITCOIN_QT_TEST_RPCNESTEDTESTS_H
+#define BITCOIN_QT_TEST_RPCNESTEDTESTS_H
 
 #include <QObject>
 #include <QTest>
@@ -19,4 +19,4 @@ class RPCNestedTests : public QObject
     void rpcNestedTests();
 };
 
-#endif // BITCOIN_QT_TEST_RPC_NESTED_TESTS_H
+#endif // BITCOIN_QT_TEST_RPCNESTEDTESTS_H
diff --git a/src/rpc/client.h b/src/rpc/client.h
index e7cf035d8f..e09e1dedf3 100644
--- a/src/rpc/client.h
+++ b/src/rpc/client.h
@@ -3,8 +3,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_RPCCLIENT_H
-#define BITCOIN_RPCCLIENT_H
+#ifndef BITCOIN_RPC_CLIENT_H
+#define BITCOIN_RPC_CLIENT_H
 
 #include <univalue.h>
 
@@ -19,4 +19,4 @@ UniValue RPCConvertNamedValues(const std::string& strMethod, const std::vector<s
  */
 UniValue ParseNonRFCJSONValue(const std::string& strVal);
 
-#endif // BITCOIN_RPCCLIENT_H
+#endif // BITCOIN_RPC_CLIENT_H
diff --git a/src/rpc/protocol.h b/src/rpc/protocol.h
index ff63bf4901..4a265735d2 100644
--- a/src/rpc/protocol.h
+++ b/src/rpc/protocol.h
@@ -3,8 +3,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_RPCPROTOCOL_H
-#define BITCOIN_RPCPROTOCOL_H
+#ifndef BITCOIN_RPC_PROTOCOL_H
+#define BITCOIN_RPC_PROTOCOL_H
 
 #include <fs.h>
 
@@ -104,4 +104,4 @@ void DeleteAuthCookie();
 /** Parse JSON-RPC batch reply into a vector */
 std::vector<UniValue> JSONRPCProcessBatchReply(const UniValue &in, size_t num);
 
-#endif // BITCOIN_RPCPROTOCOL_H
+#endif // BITCOIN_RPC_PROTOCOL_H
diff --git a/src/rpc/register.h b/src/rpc/register.h
index 49aee2365f..b689740681 100644
--- a/src/rpc/register.h
+++ b/src/rpc/register.h
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_RPCREGISTER_H
-#define BITCOIN_RPCREGISTER_H
+#ifndef BITCOIN_RPC_REGISTER_H
+#define BITCOIN_RPC_REGISTER_H
 
 /** These are in one header file to avoid creating tons of single-function
  * headers for everything under src/rpc/ */
@@ -29,4 +29,4 @@ static inline void RegisterAllCoreRPCCommands(CRPCTable &t)
     RegisterRawTransactionRPCCommands(t);
 }
 
-#endif
+#endif // BITCOIN_RPC_REGISTER_H
diff --git a/src/rpc/server.h b/src/rpc/server.h
index 7fc300f554..373914885c 100644
--- a/src/rpc/server.h
+++ b/src/rpc/server.h
@@ -3,8 +3,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_RPCSERVER_H
-#define BITCOIN_RPCSERVER_H
+#ifndef BITCOIN_RPC_SERVER_H
+#define BITCOIN_RPC_SERVER_H
 
 #include <amount.h>
 #include <rpc/protocol.h>
@@ -206,4 +206,4 @@ std::string JSONRPCExecBatch(const JSONRPCRequest& jreq, const UniValue& vReq);
 // Retrieves any serialization flags requested in command line argument
 int RPCSerializationFlags();
 
-#endif // BITCOIN_RPCSERVER_H
+#endif // BITCOIN_RPC_SERVER_H
diff --git a/src/script/bitcoinconsensus.h b/src/script/bitcoinconsensus.h
index bb94c17528..5973808fa5 100644
--- a/src/script/bitcoinconsensus.h
+++ b/src/script/bitcoinconsensus.h
@@ -3,8 +3,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_BITCOINCONSENSUS_H
-#define BITCOIN_BITCOINCONSENSUS_H
+#ifndef BITCOIN_SCRIPT_BITCOINCONSENSUS_H
+#define BITCOIN_SCRIPT_BITCOINCONSENSUS_H
 
 #include <stdint.h>
 
@@ -80,4 +80,4 @@ EXPORT_SYMBOL unsigned int bitcoinconsensus_version();
 
 #undef EXPORT_SYMBOL
 
-#endif // BITCOIN_BITCOINCONSENSUS_H
+#endif // BITCOIN_SCRIPT_BITCOINCONSENSUS_H
diff --git a/src/versionbits.h b/src/versionbits.h
index 65cf308c79..8962a65057 100644
--- a/src/versionbits.h
+++ b/src/versionbits.h
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_CONSENSUS_VERSIONBITS
-#define BITCOIN_CONSENSUS_VERSIONBITS
+#ifndef BITCOIN_VERSIONBITS_H
+#define BITCOIN_VERSIONBITS_H
 
 #include <chain.h>
 #include <map>
@@ -77,4 +77,4 @@ BIP9Stats VersionBitsStatistics(const CBlockIndex* pindexPrev, const Consensus::
 int VersionBitsStateSinceHeight(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache);
 uint32_t VersionBitsMask(const Consensus::Params& params, Consensus::DeploymentPos pos);
 
-#endif
+#endif // BITCOIN_VERSIONBITS_H
diff --git a/src/wallet/coinselection.h b/src/wallet/coinselection.h
index 4d1a43bc17..2b185879c6 100644
--- a/src/wallet/coinselection.h
+++ b/src/wallet/coinselection.h
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_COINSELECTION_H
-#define BITCOIN_COINSELECTION_H
+#ifndef BITCOIN_WALLET_COINSELECTION_H
+#define BITCOIN_WALLET_COINSELECTION_H
 
 #include <amount.h>
 #include <primitives/transaction.h>
@@ -51,4 +51,4 @@ bool SelectCoinsBnB(std::vector<CInputCoin>& utxo_pool, const CAmount& target_va
 
 // Original coin selection algorithm as a fallback
 bool KnapsackSolver(const CAmount& nTargetValue, std::vector<CInputCoin>& vCoins, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet);
-#endif // BITCOIN_COINSELECTION_H
+#endif // BITCOIN_WALLET_COINSELECTION_H
diff --git a/src/wallet/test/wallet_test_fixture.h b/src/wallet/test/wallet_test_fixture.h
index 663836a955..23575391c4 100644
--- a/src/wallet/test/wallet_test_fixture.h
+++ b/src/wallet/test/wallet_test_fixture.h
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_WALLET_TEST_FIXTURE_H
-#define BITCOIN_WALLET_TEST_FIXTURE_H
+#ifndef BITCOIN_WALLET_TEST_WALLET_TEST_FIXTURE_H
+#define BITCOIN_WALLET_TEST_WALLET_TEST_FIXTURE_H
 
 #include <test/test_bitcoin.h>
 
@@ -18,5 +18,4 @@ struct WalletTestingSetup: public TestingSetup {
     CWallet m_wallet;
 };
 
-#endif
-
+#endif // BITCOIN_WALLET_TEST_WALLET_TEST_FIXTURE_H
diff --git a/src/wallet/walletutil.h b/src/wallet/walletutil.h
index 50ff736402..f12acacd00 100644
--- a/src/wallet/walletutil.h
+++ b/src/wallet/walletutil.h
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_WALLET_UTIL_H
-#define BITCOIN_WALLET_UTIL_H
+#ifndef BITCOIN_WALLET_WALLETUTIL_H
+#define BITCOIN_WALLET_WALLETUTIL_H
 
 #include <chainparamsbase.h>
 #include <util.h>
@@ -11,4 +11,4 @@
 //! Get the path of the wallet directory.
 fs::path GetWalletDir();
 
-#endif // BITCOIN_WALLET_UTIL_H
+#endif // BITCOIN_WALLET_WALLETUTIL_H