Adapt to the C++ SIC introduced by P0021: noexcept overloading

C++17 adopts P0021R1[1], which makes noexcept be part of the function
pointer's type and thus be overloadable. It contains some provisions for
allowing a noexcept function pointer to cast implicitly to a non-
noexcept function pointer, but that fails in the presence of templates
and additional overloads that could match the type in question.

Fortunately, the paper proposed a test macro, so we can change our
sources now and be compatible with both C++14 and C++17 rules.

This first failed with Clang 4.0 trunk. This source incompatibility is
not our fault, it's the language's doing.

[1] http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0012r1.html

Task-number: QTBUG-58054
Change-Id: I2bc52f3c7a574209b213fffd14988cf0b875be63
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

4 files changed, 49 insertions, 0 deletions

diff --git a/tests/auto/corelib/kernel/qobject/test/test.pro b/tests/auto/corelib/kernel/qobject/test/test.pro
index f3bc045455..4e77cb48c5 100644
--- a/tests/auto/corelib/kernel/qobject/test/test.pro
+++ b/tests/auto/corelib/kernel/qobject/test/test.pro
@@ -3,5 +3,8 @@ TARGET = ../tst_qobject
 QT = core-private network testlib
 SOURCES = ../tst_qobject.cpp
 
+# Force C++17 if available (needed due to P0012R1)
+contains(QT_CONFIG, c++1z): CONFIG += c++1z
+
 !winrt: TEST_HELPER_INSTALLS = ../signalbug/signalbug
 DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0
diff --git a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
index 91810cdcd8..7b75438b19 100644
--- a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
+++ b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
@@ -120,6 +120,7 @@ private slots:
     void connectCxx0x();
     void connectToStaticCxx0x();
     void connectCxx0xTypeMatching();
+    void connectCxx17Noexcept();
     void connectConvert();
     void connectWithReference();
     void connectManyArguments();
@@ -4757,10 +4758,13 @@ class LotsOfSignalsAndSlots: public QObject
 
     public slots:
         void slot_v() {}
+        void slot_v_noexcept() Q_DECL_NOTHROW {}
         void slot_vi(int) {}
+        void slot_vi_noexcept() Q_DECL_NOTHROW {}
         void slot_vii(int, int) {}
         void slot_viii(int, int, int) {}
         int slot_i() { return 0; }
+        int slot_i_noexcept() Q_DECL_NOTHROW { return 0; }
         int slot_ii(int) { return 0; }
         int slot_iii(int, int) { return 0; }
         int slot_iiii(int, int, int) { return 0; }
@@ -4774,13 +4778,18 @@ class LotsOfSignalsAndSlots: public QObject
         void slot_vPFvvE(fptr) {}
 
         void const_slot_v() const {};
+        void const_slot_v_noexcept() const Q_DECL_NOTHROW {}
         void const_slot_vi(int) const {};
+        void const_slot_vi_noexcept(int) const Q_DECL_NOTHROW {}
 
         static void static_slot_v() {}
+        static void static_slot_v_noexcept() Q_DECL_NOTHROW {}
         static void static_slot_vi(int) {}
+        static void static_slot_vi_noexcept(int) Q_DECL_NOTHROW {}
         static void static_slot_vii(int, int) {}
         static void static_slot_viii(int, int, int) {}
         static int static_slot_i() { return 0; }
+        static int static_slot_i_noexcept() Q_DECL_NOTHROW { return 0; }
         static int static_slot_ii(int) { return 0; }
         static int static_slot_iii(int, int) { return 0; }
         static int static_slot_iiii(int, int, int) { return 0; }
@@ -4943,6 +4952,32 @@ void tst_QObject::connectCxx0xTypeMatching()
 
 }
 
+void receiverFunction_noexcept() Q_DECL_NOTHROW {}
+struct Functor_noexcept { void operator()() Q_DECL_NOTHROW {} };
+void tst_QObject::connectCxx17Noexcept()
+{
+    // this is about connecting signals to slots with the Q_DECL_NOTHROW qualifier
+    // as semantics changed due to http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0012r1.html
+    typedef LotsOfSignalsAndSlots Foo;
+    Foo obj;
+
+    QObject::connect(&obj, &Foo::signal_v, &obj, &Foo::slot_v_noexcept);
+    QObject::connect(&obj, &Foo::signal_v, &obj, &Foo::slot_i_noexcept);
+    QObject::connect(&obj, &Foo::signal_v, &obj, &Foo::slot_vi_noexcept);
+
+    QObject::connect(&obj, &Foo::signal_vii, &Foo::static_slot_v_noexcept);
+    QObject::connect(&obj, &Foo::signal_vii, &Foo::static_slot_i_noexcept);
+    QObject::connect(&obj, &Foo::signal_vii, &Foo::static_slot_vi_noexcept);
+
+    QVERIFY(QObject::connect(&obj, &Foo::signal_vi, &obj, &Foo::const_slot_vi_noexcept));
+    QVERIFY(QObject::connect(&obj, &Foo::signal_vi, &obj, &Foo::const_slot_v_noexcept));
+
+    QObject::connect(&obj, &Foo::signal_v, receiverFunction_noexcept);
+
+    Functor_noexcept fn;
+    QObject::connect(&obj, &Foo::signal_v, fn);
+}
+
 class StringVariant : public QObject
 { Q_OBJECT
 signals:
diff --git a/tests/auto/corelib/kernel/qtimer/qtimer.pro b/tests/auto/corelib/kernel/qtimer/qtimer.pro
index 8afdbb148e..b27d862bc5 100644
--- a/tests/auto/corelib/kernel/qtimer/qtimer.pro
+++ b/tests/auto/corelib/kernel/qtimer/qtimer.pro
@@ -2,3 +2,6 @@ CONFIG += testcase
 TARGET = tst_qtimer
 QT = core testlib
 SOURCES = tst_qtimer.cpp
+
+# Force C++17 if available
+contains(QT_CONFIG, c++1z): CONFIG += c++1z
diff --git a/tests/auto/corelib/kernel/qtimer/tst_qtimer.cpp b/tests/auto/corelib/kernel/qtimer/tst_qtimer.cpp
index fe97695d19..29ff552f6a 100644
--- a/tests/auto/corelib/kernel/qtimer/tst_qtimer.cpp
+++ b/tests/auto/corelib/kernel/qtimer/tst_qtimer.cpp
@@ -767,6 +767,11 @@ class StaticEventLoop
 public:
     static void quitEventLoop()
     {
+        quitEventLoop_noexcept();
+    }
+
+    static void quitEventLoop_noexcept() Q_DECL_NOTHROW
+    {
         QVERIFY(!_e.isNull());
         _e->quit();
         if (_t)
@@ -787,6 +792,9 @@ void tst_QTimer::singleShotToFunctors()
     QTimer::singleShot(0, &StaticEventLoop::quitEventLoop);
     QCOMPARE(_e->exec(), 0);
 
+    QTimer::singleShot(0, &StaticEventLoop::quitEventLoop_noexcept);
+    QCOMPARE(_e->exec(), 0);
+
     QThread t1;
     QObject c1;
     c1.moveToThread(&t1);