move-only: Move settings to the common library

The background of this commit is an ongoing effort to decouple the
libbitcoinkernel library from code that is not strictly required by it.
The settings code belongs into the common library and namespace, since
the kernel library should not depend on it. See doc/design/libraries.md
for more information on this rationale.

Changing the namespace of the moved functions is scripted in the
following commit.

Author: TheCharlatan

src/Makefile.am

@@ -143,6 +143,7 @@ BITCOIN_CORE_H = \
   compat/compat.h \
   compat/cpuid.h \
   compat/endian.h \
+  common/settings.h \
   common/system.h \
   compressor.h \
   consensus/consensus.h \
@@ -309,7 +310,6 @@ BITCOIN_CORE_H = \
   util/readwritefile.h \
   util/result.h \
   util/serfloat.h \
-  util/settings.h \
   util/sock.h \
   util/spanparsing.h \
   util/string.h \
@@ -663,6 +663,7 @@ libbitcoin_common_a_SOURCES = \
   common/init.cpp \
   common/interfaces.cpp \
   common/run_command.cpp \
+  common/settings.cpp \
   common/system.cpp \
   compressor.cpp \
   core_read.cpp \
@@ -733,7 +734,6 @@ libbitcoin_util_a_SOURCES = \
   util/moneystr.cpp \
   util/rbf.cpp \
   util/readwritefile.cpp \
-  util/settings.cpp \
   util/thread.cpp \
   util/threadinterrupt.cpp \
   util/threadnames.cpp \

src/addrdb.cpp

@@ -9,6 +9,7 @@
 #include <chainparams.h>
 #include <clientversion.h>
 #include <common/args.h>
+#include <common/settings.h>
 #include <cstdint>
 #include <hash.h>
 #include <logging.h>
@@ -21,7 +22,6 @@
 #include <univalue.h>
 #include <util/fs.h>
 #include <util/fs_helpers.h>
-#include <util/settings.h>
 #include <util/translation.h>
 
 namespace {

src/common/args.cpp

@@ -6,6 +6,7 @@
 #include <common/args.h>
 
 #include <chainparamsbase.h>
+#include <common/settings.h>
 #include <logging.h>
 #include <sync.h>
 #include <tinyformat.h>
@@ -14,7 +15,6 @@
 #include <util/check.h>
 #include <util/fs.h>
 #include <util/fs_helpers.h>
-#include <util/settings.h>
 #include <util/strencodings.h>
 
 #ifdef WIN32

src/common/args.h

@@ -5,11 +5,11 @@
 #ifndef BITCOIN_COMMON_ARGS_H
 #define BITCOIN_COMMON_ARGS_H
 
+#include <common/settings.h>
 #include <compat/compat.h>
 #include <sync.h>
 #include <util/chaintype.h>
 #include <util/fs.h>
-#include <util/settings.h>
 
 #include <iosfwd>
 #include <list>

src/common/config.cpp

@@ -4,13 +4,13 @@
 
 #include <common/args.h>
 
+#include <common/settings.h>
 #include <logging.h>
 #include <sync.h>
 #include <tinyformat.h>
 #include <univalue.h>
 #include <util/chaintype.h>
 #include <util/fs.h>
-#include <util/settings.h>
 #include <util/string.h>
 
 #include <algorithm>

src/util/settings.cpp renamed to src/common/settings.cpp

@@ -2,15 +2,18 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include <util/fs.h>
-#include <util/settings.h>
+#include <common/settings.h>
 
 #include <tinyformat.h>
 #include <univalue.h>
+#include <util/fs.h>
 
+#include <algorithm>
 #include <fstream>
+#include <iterator>
 #include <map>
 #include <string>
+#include <utility>
 #include <vector>
 
 namespace util {

src/util/settings.h renamed to src/common/settings.h

@@ -2,11 +2,12 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_UTIL_SETTINGS_H
-#define BITCOIN_UTIL_SETTINGS_H
+#ifndef BITCOIN_COMMON_SETTINGS_H
+#define BITCOIN_COMMON_SETTINGS_H
 
 #include <util/fs.h>
 
+#include <cstddef>
 #include <map>
 #include <string>
 #include <vector>
@@ -111,4 +112,4 @@ auto FindKey(Map&& map, Key&& key) -> decltype(&map.at(key))
 
 } // namespace util
 
-#endif // BITCOIN_UTIL_SETTINGS_H
+#endif // BITCOIN_COMMON_SETTINGS_H

src/interfaces/chain.h

@@ -6,8 +6,8 @@
 #define BITCOIN_INTERFACES_CHAIN_H
 
 #include <blockfilter.h>
+#include <common/settings.h>
 #include <primitives/transaction.h> // For CTransactionRef
-#include <util/settings.h>          // For util::SettingsValue
 
 #include <functional>
 #include <memory>

src/interfaces/node.h

@@ -5,13 +5,13 @@
 #ifndef BITCOIN_INTERFACES_NODE_H
 #define BITCOIN_INTERFACES_NODE_H
 
+#include <common/settings.h>
 #include <consensus/amount.h>          // For CAmount
 #include <net.h>                       // For NodeId
 #include <net_types.h>                 // For banmap_t
 #include <netaddress.h>                // For Network
 #include <netbase.h>                   // For ConnectionDirection
 #include <support/allocators/secure.h> // For SecureString
-#include <util/settings.h>             // For util::SettingsValue
 #include <util/translation.h>
 
 #include <functional>

src/qt/test/optiontests.h

@@ -5,9 +5,9 @@
 #ifndef BITCOIN_QT_TEST_OPTIONTESTS_H
 #define BITCOIN_QT_TEST_OPTIONTESTS_H
 
+#include <common/settings.h>
 #include <qt/optionsmodel.h>
 #include <univalue.h>
-#include <util/settings.h>
 
 #include <QObject>