Merge #16710: build: Enable -Wsuggest-override if available

839add1 build: Enable -Wsuggest-override (Hennadii Stepanov)
de5e91c refactor: Add BerkeleyDatabaseVersion() function (Hennadii Stepanov)

Pull request description:

  From GCC [docs](https://gcc.gnu.org/onlinedocs/gcc-9.2.0/gcc/Warning-Options.html):
  > `-Wsuggest-override`
  > Warn about overriding virtual functions that are not marked with the override keyword.

  ~This PR is based on #16722 (the first commit).~ See: bitcoin/bitcoin#16722 (comment)

ACKs for top commit:
  fanquake:
    ACK 839add1
  vasild:
    ACK 839add1
  practicalswift:
    ACK 839add1 assuming Travis is happy: patch looks correct

Tree-SHA512: 1e8cc085da30d41536deff9b181962c1882314ab252c2ad958294087ae1e5a0dfa4886bdbe36f21cf6ae71df776a8420f349f007d4b5b49fd79ba98ce308965a

Author: fanquake

configure.ac

@@ -368,6 +368,10 @@ if test "x$enable_werror" = "xyes"; then
   AX_CHECK_COMPILE_FLAG([-Werror=return-type],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=return-type"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Werror=conditional-uninitialized],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=conditional-uninitialized"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Werror=sign-compare],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=sign-compare"],,[[$CXXFLAG_WERROR]])
+  dnl -Wsuggest-override is broken with GCC before 9.2
+  dnl https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78010
+  AX_CHECK_COMPILE_FLAG([-Werror=suggest-override],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=suggest-override"],,[[$CXXFLAG_WERROR]],
+                        [AC_LANG_SOURCE([[struct A { virtual void f(); }; struct B : A { void f() final; };]])])
 fi
 
 if test "x$CXXFLAGS_overridden" = "xno"; then
@@ -385,6 +389,8 @@ if test "x$CXXFLAGS_overridden" = "xno"; then
   AX_CHECK_COMPILE_FLAG([-Wdate-time],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wdate-time"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wconditional-uninitialized],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wconditional-uninitialized"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wsign-compare],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wsign-compare"],,[[$CXXFLAG_WERROR]])
+  AX_CHECK_COMPILE_FLAG([-Wsuggest-override],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wsuggest-override"],,[[$CXXFLAG_WERROR]],
+                        [AC_LANG_SOURCE([[struct A { virtual void f(); }; struct B : A { void f() final; };]])])
 
   dnl Some compilers (gcc) ignore unknown -Wno-* options, but warn about all
   dnl unknown options if any other warning is produced. Test the -Wfoo case, and

src/Makefile.leveldb.include

@@ -36,7 +36,7 @@ LEVELDB_CPPFLAGS_INT += -DLEVELDB_PLATFORM_POSIX
 endif
 
 leveldb_libleveldb_a_CPPFLAGS = $(AM_CPPFLAGS) $(LEVELDB_CPPFLAGS_INT) $(LEVELDB_CPPFLAGS)
-leveldb_libleveldb_a_CXXFLAGS = $(filter-out -Wconditional-uninitialized -Werror=conditional-uninitialized, $(AM_CXXFLAGS)) $(PIE_FLAGS)
+leveldb_libleveldb_a_CXXFLAGS = $(filter-out -Wconditional-uninitialized -Werror=conditional-uninitialized -Wsuggest-override -Werror=suggest-override, $(AM_CXXFLAGS)) $(PIE_FLAGS)
 
 leveldb_libleveldb_a_SOURCES=
 leveldb_libleveldb_a_SOURCES += leveldb/port/port_stdcxx.h

src/qt/rpcconsole.cpp

@@ -24,7 +24,7 @@
 #include <univalue.h>
 
 #ifdef ENABLE_WALLET
-#include <db_cxx.h>
+#include <wallet/db.h>
 #include <wallet/wallet.h>
 #endif
 
@@ -34,9 +34,10 @@
 #include <QScrollBar>
 #include <QScreen>
 #include <QSettings>
+#include <QString>
+#include <QStringList>
 #include <QTime>
 #include <QTimer>
-#include <QStringList>
 
 // TODO: add a scrollback limit, as there is currently none
 // TODO: make it possible to filter out categories (esp debug messages when implemented)
@@ -480,7 +481,7 @@ RPCConsole::RPCConsole(interfaces::Node& node, const PlatformStyle *_platformSty
 
     // set library version labels
 #ifdef ENABLE_WALLET
-    ui->berkeleyDBVersion->setText(DbEnv::version(nullptr, nullptr, nullptr));
+    ui->berkeleyDBVersion->setText(QString::fromStdString(BerkeleyDatabaseVersion()));
 #else
     ui->label_berkeleyDBVersion->hide();
     ui->berkeleyDBVersion->hide();

src/wallet/db.cpp

@@ -399,7 +399,7 @@ bool BerkeleyBatch::VerifyEnvironment(const fs::path& file_path, bilingual_str&
     std::shared_ptr<BerkeleyEnvironment> env = GetWalletEnv(file_path, walletFile);
     fs::path walletDir = env->Directory();
 
-    LogPrintf("Using BerkeleyDB version %s\n", DbEnv::version(nullptr, nullptr, nullptr));
+    LogPrintf("Using BerkeleyDB version %s\n", BerkeleyDatabaseVersion());
     LogPrintf("Using wallet %s\n", file_path.string());
 
     if (!env->Open(true /* retry */)) {
@@ -916,3 +916,8 @@ void BerkeleyDatabase::ReloadDbEnv()
         env->ReloadDbEnv();
     }
 }
+
+std::string BerkeleyDatabaseVersion()
+{
+    return DbEnv::version(nullptr, nullptr, nullptr);
+}

src/wallet/db.h

@@ -19,7 +19,14 @@
 #include <unordered_map>
 #include <vector>
 
+#if defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsuggest-override"
+#endif
 #include <db_cxx.h>
+#if defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#endif
 
 struct bilingual_str;
 
@@ -402,4 +409,6 @@ class BerkeleyBatch
     bool static Rewrite(BerkeleyDatabase& database, const char* pszSkip = nullptr);
 };
 
+std::string BerkeleyDatabaseVersion();
+
 #endif // BITCOIN_WALLET_DB_H