Merge pull request #14005 from Chocobo1/cpp17

Bump project requirement to C++17

.github/workflows/ci.yaml

@@ -200,10 +200,10 @@ jobs:
           -Value "set(VCPKG_BUILD_TYPE release)","set(VCPKG_OSX_DEPLOYMENT_TARGET 10.15)"
 
     # NOTE: Avoids a libtorrent ABI issue. See https://github.com/arvidn/libtorrent/issues/4965
-    - name: force AppleClang to compile libtorrent with C++14
+    - name: force AppleClang to compile libtorrent with C++17
       run: |
         (Get-Content -path ${{ env.RUNVCPKG_VCPKG_ROOT }}/ports/libtorrent/portfile.cmake).Replace( `
-          '${FEATURE_OPTIONS}', '${FEATURE_OPTIONS} -DCMAKE_CXX_STANDARD=14') `
+          '${FEATURE_OPTIONS}', '${FEATURE_OPTIONS} -DCMAKE_CXX_STANDARD=17') `
           | Set-Content -Path ${{ env.RUNVCPKG_VCPKG_ROOT }}/ports/libtorrent/portfile.cmake
 
     - name: install dependencies via vcpkg

.travis.yml

@@ -129,7 +129,7 @@ install:
 
       cmake \
         -DCMAKE_BUILD_TYPE=Release \
-        -DCMAKE_CXX_STANDARD=14 \
+        -DCMAKE_CXX_STANDARD=17 \
         -Ddeprecated-functions=OFF \
         -DOPENSSL_ROOT_DIR="$openssl_root_path" \
         ./
@@ -145,7 +145,7 @@ install:
 
       cmake \
         -DCMAKE_BUILD_TYPE=Release \
-        -DCMAKE_CXX_STANDARD=14 \
+        -DCMAKE_CXX_STANDARD=17 \
         -Ddeprecated-functions=ON \
         -DOPENSSL_ROOT_DIR="$openssl_root_path" \
         ./

cmake/Modules/MacroQbtCommonConfig.cmake

@@ -20,22 +20,11 @@ macro(qbt_common_config)
 
     add_library(qbt_common_cfg INTERFACE)
 
-    # Full C++ 14 support is required
+    # Full C++ 17 support is required
     # See also https://cmake.org/cmake/help/latest/prop_gbl/CMAKE_CXX_KNOWN_FEATURES.html
     # for a breakdown of the features that CMake recognizes for each C++ standard
     target_compile_features(qbt_common_cfg INTERFACE
-        cxx_std_14
-        cxx_aggregate_default_initializers
-        cxx_attribute_deprecated
-        cxx_binary_literals
-        cxx_contextual_conversions
-        cxx_decltype_auto
-        cxx_digit_separators
-        cxx_generic_lambdas
-        cxx_lambda_init_captures
-        cxx_relaxed_constexpr
-        cxx_return_type_deduction
-        cxx_variable_templates
+        cxx_std_17
     )
 
     set(QBT_PROJECT_VERSION "${qBittorrent_VERSION_MAJOR}.${qBittorrent_VERSION_MINOR}.${qBittorrent_VERSION_PATCH}")

configure

@@ -5564,18 +5564,18 @@ $as_echo "yes" >&6; }
                  LIBS="$zlib_LIBS $LIBS"
 fi
 
-# Check if already in >= C++14 mode because of the flags returned by one of the above packages
+# Check if already in >= C++17 mode because of the flags returned by one of the above packages
 TMP_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS=""
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler defaults to C++14 or later mode" >&5
-$as_echo_n "checking if compiler defaults to C++14 or later mode... " >&6; }
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler defaults to C++17 or later mode" >&5
+$as_echo_n "checking if compiler defaults to C++17 or later mode... " >&6; }
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
             #ifndef __cplusplus
             #error "This is not a C++ compiler"
-            #elif __cplusplus < 201402L
-            #error "This is not a C++14 compiler"
+            #elif __cplusplus < 201703L
+            #error "This is not a C++17 compiler"
             #endif
 int
 main ()
@@ -5589,27 +5589,27 @@ _ACEOF
 if ac_fn_cxx_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-                   QBT_CXX14_FOUND="yes"
+                   QBT_CXX17_FOUND="yes"
 else
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-                   QBT_CXX14_FOUND="no"
+                   QBT_CXX17_FOUND="no"
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
-# In case of no, check if the compiler can support at least C++14
+# In case of no, check if the compiler can support at least C++17
 # and if yes, enable it leaving a warning to the user
-if test "x$QBT_CXX14_FOUND" = "xno"; then :
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler supports C++14" >&5
-$as_echo_n "checking if compiler supports C++14... " >&6; }
-       CXXFLAGS="-std=c++14"
+if test "x$QBT_CXX17_FOUND" = "xno"; then :
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler supports C++17" >&5
+$as_echo_n "checking if compiler supports C++17... " >&6; }
+       CXXFLAGS="-std=c++17"
        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
             #ifndef __cplusplus
             #error "This is not a C++ compiler"
-            #elif __cplusplus < 201402L
-            #error "This is not a C++14 compiler"
+            #elif __cplusplus < 201703L
+            #error "This is not a C++17 compiler"
             #endif
 int
 main ()
@@ -5623,17 +5623,17 @@ _ACEOF
 if ac_fn_cxx_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-                         { $as_echo "$as_me:${as_lineno-$LINENO}: checking if C++14 is disabled by the set compiler flags" >&5
-$as_echo_n "checking if C++14 is disabled by the set compiler flags... " >&6; }
+                         { $as_echo "$as_me:${as_lineno-$LINENO}: checking if C++17 is disabled by the set compiler flags" >&5
+$as_echo_n "checking if C++17 is disabled by the set compiler flags... " >&6; }
                          # prepend the flag so it won't override conflicting user defined flags
-                         CXXFLAGS="-std=c++14 $TMP_CXXFLAGS"
+                         CXXFLAGS="-std=c++17 $TMP_CXXFLAGS"
                          cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
             #ifndef __cplusplus
             #error "This is not a C++ compiler"
-            #elif __cplusplus < 201402L
-            #error "This is not a C++14 compiler"
+            #elif __cplusplus < 201703L
+            #error "This is not a C++17 compiler"
             #endif
 int
 main ()
@@ -5647,19 +5647,19 @@ _ACEOF
 if ac_fn_cxx_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-                                            QBT_ADD_CONFIG="$QBT_ADD_CONFIG c++14"
-                                            { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: C++14 mode is now force enabled. The C++ mode should match the mode that other libraries were built with, otherwise you'll likely get linking errors." >&5
-$as_echo "$as_me: WARNING: C++14 mode is now force enabled. The C++ mode should match the mode that other libraries were built with, otherwise you'll likely get linking errors." >&2;}
+                                            QBT_ADD_CONFIG="$QBT_ADD_CONFIG c++17"
+                                            { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: C++17 mode is now force enabled. The C++ mode should match the mode that other libraries were built with, otherwise you'll likely get linking errors." >&5
+$as_echo "$as_me: WARNING: C++17 mode is now force enabled. The C++ mode should match the mode that other libraries were built with, otherwise you'll likely get linking errors." >&2;}
 else
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-                                            as_fn_error $? "The compiler supports C++14 but the user or a dependency has explicitly enabled a lower mode." "$LINENO" 5
+                                            as_fn_error $? "The compiler supports C++17 but the user or a dependency has explicitly enabled a lower mode." "$LINENO" 5
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 else
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-                         as_fn_error $? "A compiler supporting C++14 is required." "$LINENO" 5
+                         as_fn_error $? "A compiler supporting C++17 is required." "$LINENO" 5
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
@@ -7034,7 +7034,9 @@ $as_echo X/"$am_mf" |
     { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
 $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
 as_fn_error $? "Something went wrong bootstrapping makefile fragments
-    for automatic dependency tracking.  Try re-running configure with the
+    for automatic dependency tracking.  If GNU make was not used, consider
+    re-running the configure script with MAKE=\"gmake\" (or whatever is
+    necessary).  You can also try re-running configure with the
     '--disable-dependency-tracking' option to at least be able to build
     the package (albeit without support for automatic dependency tracking).
 See \`config.log' for more details" "$LINENO" 5; }
@@ -8351,7 +8353,9 @@ $as_echo X/"$am_mf" |
     { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
 $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
 as_fn_error $? "Something went wrong bootstrapping makefile fragments
-    for automatic dependency tracking.  Try re-running configure with the
+    for automatic dependency tracking.  If GNU make was not used, consider
+    re-running the configure script with MAKE=\"gmake\" (or whatever is
+    necessary).  You can also try re-running configure with the
     '--disable-dependency-tracking' option to at least be able to build
     the package (albeit without support for automatic dependency tracking).
 See \`config.log' for more details" "$LINENO" 5; }

configure.ac

@@ -194,34 +194,34 @@ PKG_CHECK_MODULES(zlib,
                  [CXXFLAGS="$zlib_CFLAGS $CXXFLAGS"
                  LIBS="$zlib_LIBS $LIBS"])
 
-# Check if already in >= C++14 mode because of the flags returned by one of the above packages
+# Check if already in >= C++17 mode because of the flags returned by one of the above packages
 TMP_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS=""
-AC_MSG_CHECKING([if compiler defaults to C++14 or later mode])
-AC_COMPILE_IFELSE([DETECT_CPP14_PROGRAM()],
+AC_MSG_CHECKING([if compiler defaults to C++17 or later mode])
+AC_COMPILE_IFELSE([DETECT_CPP17_PROGRAM()],
                   [AC_MSG_RESULT([yes])
-                   QBT_CXX14_FOUND="yes"],
+                   QBT_CXX17_FOUND="yes"],
                   [AC_MSG_RESULT([no])
-                   QBT_CXX14_FOUND="no"])
+                   QBT_CXX17_FOUND="no"])
 
-# In case of no, check if the compiler can support at least C++14
+# In case of no, check if the compiler can support at least C++17
 # and if yes, enable it leaving a warning to the user
-AS_IF([test "x$QBT_CXX14_FOUND" = "xno"],
-      [AC_MSG_CHECKING([if compiler supports C++14])
-       CXXFLAGS="-std=c++14"
-       AC_COMPILE_IFELSE([DETECT_CPP14_PROGRAM()],
+AS_IF([test "x$QBT_CXX17_FOUND" = "xno"],
+      [AC_MSG_CHECKING([if compiler supports C++17])
+       CXXFLAGS="-std=c++17"
+       AC_COMPILE_IFELSE([DETECT_CPP17_PROGRAM()],
                         [AC_MSG_RESULT([yes])
-                         AC_MSG_CHECKING([if C++14 is disabled by the set compiler flags])
+                         AC_MSG_CHECKING([if C++17 is disabled by the set compiler flags])
                          # prepend the flag so it won't override conflicting user defined flags
-                         CXXFLAGS="-std=c++14 $TMP_CXXFLAGS"
-                         AC_COMPILE_IFELSE([DETECT_CPP14_PROGRAM()],
+                         CXXFLAGS="-std=c++17 $TMP_CXXFLAGS"
+                         AC_COMPILE_IFELSE([DETECT_CPP17_PROGRAM()],
                                            [AC_MSG_RESULT([no])
-                                            QBT_ADD_CONFIG="$QBT_ADD_CONFIG c++14"
-                                            AC_MSG_WARN([C++14 mode is now force enabled. The C++ mode should match the mode that other libraries were built with, otherwise you'll likely get linking errors.])],
+                                            QBT_ADD_CONFIG="$QBT_ADD_CONFIG c++17"
+                                            AC_MSG_WARN([C++17 mode is now force enabled. The C++ mode should match the mode that other libraries were built with, otherwise you'll likely get linking errors.])],
                                            [AC_MSG_RESULT([yes])
-                                            AC_MSG_ERROR([The compiler supports C++14 but the user or a dependency has explicitly enabled a lower mode.])])],
+                                            AC_MSG_ERROR([The compiler supports C++17 but the user or a dependency has explicitly enabled a lower mode.])])],
                         [AC_MSG_RESULT([no])
-                         AC_MSG_ERROR([A compiler supporting C++14 is required.])])
+                         AC_MSG_ERROR([A compiler supporting C++17 is required.])])
       ])
 CXXFLAGS="$TMP_CXXFLAGS"
 

m4/qbittorrent.m4

@@ -37,15 +37,15 @@ AC_DEFUN([FIND_QTDBUS],
                          HAVE_QTDBUS=[false]])
 ])
 
-# DETECT_CPP14_PROGRAM()
-# Detects if at least C++14 mode is enabled.
+# DETECT_CPP17_PROGRAM()
+# Detects if at least C++17 mode is enabled.
 # --------------------------------------
-AC_DEFUN([DETECT_CPP14_PROGRAM],
+AC_DEFUN([DETECT_CPP17_PROGRAM],
        [AC_LANG_PROGRAM([[
             #ifndef __cplusplus
             #error "This is not a C++ compiler"
-            #elif __cplusplus < 201402L
-            #error "This is not a C++14 compiler"
+            #elif __cplusplus < 201703L
+            #error "This is not a C++17 compiler"
             #endif]],
             [[]])
 ])

src/app/qtlocalpeer/qtlocalpeer.cpp

@@ -152,7 +152,7 @@ bool QtLocalPeer::isClient()
 #endif
     if (!res)
         qWarning("QtSingleCoreApplication: listen on local socket failed, %s", qPrintable(server->errorString()));
-    QObject::connect(server, SIGNAL(newConnection()), SLOT(receiveConnection()));
+    connect(server, &QLocalServer::newConnection, this, &QtLocalPeer::receiveConnection);
     return false;
 }
 

src/base/algorithm.h

@@ -32,9 +32,6 @@
 
 namespace Algorithm
 {
-    template <typename ...>
-    using void_t = void;  // replace this with std::void_t in C++17
-
     template <typename T, typename = void>
     struct HasMappedType
         : std::false_type
@@ -42,7 +39,7 @@ namespace Algorithm
     };
 
     template <typename T>
-    struct HasMappedType<T, void_t<typename T::mapped_type>>
+    struct HasMappedType<T, std::void_t<typename T::mapped_type>>
         : std::true_type
     {
     };

src/base/bittorrent/common.h

@@ -30,5 +30,4 @@
 
 #include <QString>
 
-// TODO: Make it inline in C++17
-extern const QString QB_EXT;
+inline const QString QB_EXT {QStringLiteral(".!qB")};

src/base/bittorrent/ltunderlyingtype.h

@@ -30,9 +30,6 @@
 
 #include <type_traits>
 
-template <typename ...>
-using void_t = void;  // replace this with std::void_t in C++17
-
 template <typename T, typename = void>
 struct HasUnderlyingType
     : std::false_type
@@ -40,7 +37,7 @@ struct HasUnderlyingType
 };
 
 template <typename T>
-struct HasUnderlyingType<T, void_t<typename T::underlying_type>>
+struct HasUnderlyingType<T, std::void_t<typename T::underlying_type>>
     : std::true_type
 {
 };

src/base/bittorrent/session.cpp

@@ -291,9 +291,8 @@ namespace
     LowerLimited<T> lowerLimited(T limit, T ret) { return LowerLimited<T>(limit, ret); }
 
     template <typename T>
-    std::function<T (const T&)> clampValue(const T lower, const T upper)
+    auto clampValue(const T lower, const T upper)
     {
-        // TODO: change return type to `auto` when using C++17
         return [lower, upper](const T value) -> T
         {
             if (value < lower)

src/base/bittorrent/torrenthandleimpl.cpp

@@ -69,8 +69,6 @@
 #include "session.h"
 #include "trackerentry.h"
 
-const QString QB_EXT {QStringLiteral(".!qB")};
-
 using namespace BitTorrent;
 
 namespace

src/base/indexrange.h

@@ -37,8 +37,7 @@ class IndexInterval
 public:
     using IndexType = Index;
 
-    // TODO: add constexpr when using C++17
-    IndexInterval(const IndexType first, const IndexType last)
+    constexpr IndexInterval(const IndexType first, const IndexType last)
         : m_first {first}
         , m_last {last}
     {

src/base/settingvalue.h

@@ -48,7 +48,13 @@ public:
 
     T get(const T &defaultValue = {}) const
     {
-        return load(defaultValue);
+        if constexpr (std::is_enum_v<T>) {
+            const auto value = SettingsStorage::instance()->loadValue(m_keyName, {}).toString();
+            return Utils::String::toEnum(value, defaultValue);
+        }
+        else {
+            return SettingsStorage::instance()->loadValue(m_keyName, defaultValue).template value<T>();
+        }
     }
 
     operator T() const
@@ -58,39 +64,14 @@ public:
 
     SettingValue<T> &operator=(const T &value)
     {
-        store(value);
+        if constexpr (std::is_enum_v<T>)
+            SettingsStorage::instance()->storeValue(m_keyName, Utils::String::fromEnum(value));
+        else
+            SettingsStorage::instance()->storeValue(m_keyName, value);
         return *this;
     }
 
 private:
-    // regular load/store pair
-    template <typename U, typename std::enable_if_t<!std::is_enum<U>::value, int> = 0>
-    U load(const U &defaultValue) const
-    {
-        return SettingsStorage::instance()->loadValue(m_keyName, defaultValue)
-            .template value<U>();
-    }
-
-    template <typename U, typename std::enable_if_t<!std::is_enum<U>::value, int> = 0>
-    void store(const U &value)
-    {
-        SettingsStorage::instance()->storeValue(m_keyName, value);
-    }
-
-    // load/store pair for enum type, saves literal value of the enum constant
-    // TODO: merge the load/store functions with `if constexpr` in C++17
-    template <typename U, typename std::enable_if_t<std::is_enum<U>::value, int> = 0>
-    U load(const U defaultValue) const
-    {
-        return Utils::String::toEnum(load(QString {}), defaultValue);
-    }
-
-    template <typename U, typename std::enable_if_t<std::is_enum<U>::value, int> = 0>
-    void store(const U value)
-    {
-        store(Utils::String::fromEnum(value));
-    }
-
     const QString m_keyName;
 };
 

src/base/tristatebool.h

@@ -42,7 +42,7 @@ public:
         *this = boolean ? True : False;
     }
 
-    TriStateBool &operator=(const TriStateBool &other) = default;  // TODO: add constexpr when using C++17
+    constexpr TriStateBool &operator=(const TriStateBool &other) = default;
 
     explicit constexpr operator signed char() const
     {

src/base/utils/io.cpp

@@ -60,18 +60,3 @@ Utils::IO::FileDeviceOutputIterator &Utils::IO::FileDeviceOutputIterator::operat
     }
     return *this;
 }
-
-Utils::IO::FileDeviceOutputIterator &Utils::IO::FileDeviceOutputIterator::operator*()
-{
-    return *this;
-}
-
-Utils::IO::FileDeviceOutputIterator &Utils::IO::FileDeviceOutputIterator::operator++()
-{
-    return *this;
-}
-
-Utils::IO::FileDeviceOutputIterator &Utils::IO::FileDeviceOutputIterator::operator++(int)
-{
-    return *this;
-}

src/base/utils/io.h

@@ -40,19 +40,36 @@ namespace Utils
     {
         // A wrapper class that satisfy LegacyOutputIterator requirement
         class FileDeviceOutputIterator
-            : public std::iterator<std::output_iterator_tag, void, void, void, void>
         {
         public:
+            // std::iterator_traits
+            using iterator_category = std::output_iterator_tag;
+            using difference_type = void;
+            using value_type = void;
+            using pointer = void;
+            using reference = void;
+
             explicit FileDeviceOutputIterator(QFileDevice &device, const int bufferSize = (4 * 1024));
             FileDeviceOutputIterator(const FileDeviceOutputIterator &other) = default;
             ~FileDeviceOutputIterator();
 
             // mimic std::ostream_iterator behavior
             FileDeviceOutputIterator &operator=(char c);
-            // TODO: make these `constexpr` in C++17
-            FileDeviceOutputIterator &operator*();
-            FileDeviceOutputIterator &operator++();
-            FileDeviceOutputIterator &operator++(int);
+
+            constexpr FileDeviceOutputIterator &operator*()
+            {
+                return *this;
+            }
+
+            constexpr FileDeviceOutputIterator &operator++()
+            {
+                return *this;
+            }
+
+            constexpr FileDeviceOutputIterator &operator++(int)
+            {
+                return *this;
+            }
 
         private:
             QFileDevice *m_device;

src/base/utils/string.h

@@ -73,20 +73,20 @@ namespace Utils
 
         QString join(const QVector<QStringRef> &strings, const QString &separator);
 
-        template <typename T, typename std::enable_if_t<std::is_enum<T>::value, int> = 0>
+        template <typename T, typename std::enable_if_t<std::is_enum_v<T>, int> = 0>
         QString fromEnum(const T &value)
         {
-            static_assert(std::is_same<int, typename std::underlying_type_t<T>>::value,
+            static_assert(std::is_same_v<int, typename std::underlying_type_t<T>>,
                           "Enumeration underlying type has to be int.");
 
             const auto metaEnum = QMetaEnum::fromType<T>();
             return QString::fromLatin1(metaEnum.valueToKey(static_cast<int>(value)));
         }
 
-        template <typename T, typename std::enable_if_t<std::is_enum<T>::value, int> = 0>
+        template <typename T, typename std::enable_if_t<std::is_enum_v<T>, int> = 0>
         T toEnum(const QString &serializedValue, const T &defaultValue)
         {
-            static_assert(std::is_same<int, typename std::underlying_type_t<T>>::value,
+            static_assert(std::is_same_v<int, typename std::underlying_type_t<T>>,
                           "Enumeration underlying type has to be int.");
 
             const auto metaEnum = QMetaEnum::fromType<T>();

src/gui/advancedsettings.cpp

@@ -715,12 +715,12 @@ void AdvancedSettings::addRow(const int row, const QString &text, T *widget)
     setCellWidget(row, PROPERTY, label);
     setCellWidget(row, VALUE, widget);
 
-    if (std::is_same<T, QCheckBox>::value)
-        connect(widget, SIGNAL(stateChanged(int)), this, SIGNAL(settingsChanged()));
-    else if (std::is_same<T, QSpinBox>::value)
-        connect(widget, SIGNAL(valueChanged(int)), this, SIGNAL(settingsChanged()));
-    else if (std::is_same<T, QComboBox>::value)
-        connect(widget, SIGNAL(currentIndexChanged(int)), this, SIGNAL(settingsChanged()));
-    else if (std::is_same<T, QLineEdit>::value)
-        connect(widget, SIGNAL(textChanged(QString)), this, SIGNAL(settingsChanged()));
+    if constexpr (std::is_same_v<T, QCheckBox>)
+        connect(widget, &QCheckBox::stateChanged, this, &AdvancedSettings::settingsChanged);
+    else if constexpr (std::is_same_v<T, QSpinBox>)
+        connect(widget, qOverload<int>(&QSpinBox::valueChanged), this, &AdvancedSettings::settingsChanged);
+    else if constexpr (std::is_same_v<T, QComboBox>)
+        connect(widget, qOverload<int>(&QComboBox::currentIndexChanged), this, &AdvancedSettings::settingsChanged);
+    else if constexpr (std::is_same_v<T, QLineEdit>)
+        connect(widget, &QLineEdit::textChanged, this, &AdvancedSettings::settingsChanged);
 }

winconf.pri

@@ -4,10 +4,7 @@ DEFINES += BOOST_ASIO_DISABLE_CONNECTEX
 DEFINES += BOOST_EXCEPTION_DISABLE
 
 DEFINES += TORRENT_USE_LIBCRYPTO
-# TODO: remove the following define as it is not used since OpenSSL >= 1.1
 DEFINES += TORRENT_USE_OPENSSL
-# TODO: remove the following define as it is not used since libtorrent >= 1.2
-DEFINES += TORRENT_DISABLE_RESOLVE_COUNTRIES
 
 DEFINES += NTDDI_VERSION=0x06010000
 DEFINES += _WIN32_WINNT=0x0601
@@ -35,12 +32,15 @@ win32-g++* {
     DEFINES += _FILE_OFFSET_BITS=64
     DEFINES += __USE_W32_SOCKETS
 
+    QMAKE_CXXFLAGS += -std=c++17
+
     RC_FILE = qbittorrent_mingw.rc
 
     LIBS += libadvapi32 libiphlpapi libole32 libpowrprof libshell32 libuser32 libwsock32 libws2_32
 }
 else:win32-msvc* {
     CONFIG -= embed_manifest_exe
+    QMAKE_CXXFLAGS += /std:c++17
     QMAKE_LFLAGS += "/MANIFEST:EMBED /MANIFESTINPUT:$$quote($${PWD}/src/qbittorrent.exe.manifest) /STACK:0x800000"
 
     RC_FILE = qbittorrent.rc