Long live Q_UNREACHABLE_RETURN()!

This is a combination of Q_UNREACHABLE() with a return statement.

ATM, the return statement is unconditionally included. If we notice
that some compilers warn about return after __builtin_unreachable(),
then we can map Q_UNREACHABLE_RETURN(...) to Q_UNREACHABLE() without
having to touch all the code that uses explicit Q_UNREACHABLE() +
return.

The fact that Boost has BOOST_UNREACHABLE_RETURN() indicates that
there are compilers that complain about a lack of return after
Q_UNREACHABLE (we know that MSVC, ICC, and GHS are among them), as
well as compilers that complained about a return being present
(Coverity). Take this opportunity to properly adapt to Coverity, by
leaving out the return statement on this compiler.

Apply the macro around the code base, using a clang-tidy transformer
rule:

    const std::string unr = "unr", val = "val", ret = "ret";
    auto makeUnreachableReturn = cat("Q_UNREACHABLE_RETURN(",
                                    ifBound(val, cat(node(val)), cat("")),
                                    ")");
    auto ignoringSwitchCases = [](auto stmt) {
        return anyOf(stmt, switchCase(subStmt(stmt)));
    };

    makeRule(
       stmt(ignoringSwitchCases(stmt(isExpandedFromMacro("Q_UNREACHABLE")).bind(unr)),
            nextStmt(returnStmt(optionally(hasReturnValue(expr().bind(val)))).bind(ret))),
       {changeTo(node(unr), cat(makeUnreachableReturn,
                                ";")),  // TODO: why is the ; lost w/o this?
        changeTo(node(ret), cat(""))},
       cat("use ", makeUnreachableReturn))
    );

where nextStmt() is copied from some upstream clang-tidy check's
private implementation and subStmt() is a private matcher that gives
access to SwitchCase's SubStmt.

A.k.a. qt-use-unreachable-return.

There were some false positives, suppressed them with NOLINTNEXTLINE.

They're not really false positiives, it's just that Clang sees the
world in one way and if conditonal compilation (#if) differs for other
compilers, Clang doesn't know better. This is an artifact of matching
two consecutive statements.

I haven't figured out how to remove the empty line left by the
deletion of the return statement, if it, indeed, was on a separate
line, so post-processed the patch to remove all the lines matching
^\+ *$ from the diff:

  git commit -am meep
  git reset --hard HEAD^
  git diff HEAD..HEAD@{1} | sed '/^\+ *$/d' | recountdiff - | patch -p1

[ChangeLog][QtCore][QtAssert] Added Q_UNREACHABLE_RETURN() macro.

Change-Id: I9782939f16091c964f25b7826e1c0dbd13a71305
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

55 files changed, 154 insertions, 221 deletions

diff --git a/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp b/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp
index 4d6f566bf8..096e36dc72 100644
--- a/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp
+++ b/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp
@@ -667,6 +667,19 @@ bool readConfiguration(const QFile &file)
    }
 //! [qunreachable-switch]
 
+//! [qunreachable-return]
+   switch (shape) {
+       case Rectangle:
+           return rectangle();
+       case Triangle:
+           return triangle();
+       case Circle:
+           return circle();
+       case NumShapes:
+           Q_UNREACHABLE_RETURN(nullptr);
+   }
+//! [qunreachable-return]
+
 //! [qt-version-check]
 #include <QtGlobal>
 
diff --git a/src/corelib/global/qassert.cpp b/src/corelib/global/qassert.cpp
index 2e340ebbb2..4165429d4b 100644
--- a/src/corelib/global/qassert.cpp
+++ b/src/corelib/global/qassert.cpp
@@ -195,7 +195,25 @@ void qBadAlloc()
 
     In debug builds the condition is enforced by an assert to facilitate debugging.
 
-    \sa Q_ASSERT(), Q_ASSUME(), qFatal()
+    \note Use the macro Q_UNREACHABLE_RETURN() to insert return statements for
+    compilers that need them, without causing warnings for compilers that
+    complain about its presence.
+
+    \sa Q_ASSERT(), Q_ASSUME(), qFatal(), Q_UNREACHABLE_RETURN()
 */
 
+/*!
+    \macro void Q_UNREACHABLE_RETURN(...)
+    \relates <QtAssert>
+    \since 6.5
+
+    This is equivalent to
+    \code
+    Q_UNREACHABLE();
+    return __VA_ARGS__;
+    \endcode
+    except it omits the return on compilers that would warn about it.
+
+    \sa Q_UNREACHABLE()
+*/
 QT_END_NAMESPACE
diff --git a/src/corelib/global/qassert.h b/src/corelib/global/qassert.h
index c7ee13176a..28c6b6c8fc 100644
--- a/src/corelib/global/qassert.h
+++ b/src/corelib/global/qassert.h
@@ -70,6 +70,14 @@ inline T *q_check_ptr(T *p) { Q_CHECK_PTR(p); return p; }
         Q_UNREACHABLE_IMPL();\
     } while (false)
 
+#ifndef Q_UNREACHABLE_RETURN
+#  ifdef Q_COMPILER_COMPLAINS_ABOUT_RETURN_AFTER_UNREACHABLE
+#    define Q_UNREACHABLE_RETURN(...) Q_UNREACHABLE()
+#  else
+#    define Q_UNREACHABLE_RETURN(...) do { Q_UNREACHABLE(); return __VA_ARGS__; } while (0)
+#  endif
+#endif
+
 #define Q_ASSUME(Expr) \
     [] (bool valueOfExpression) {\
         Q_ASSERT_X(valueOfExpression, "Q_ASSUME()", "Assumption in Q_ASSUME(\"" #Expr "\") was not correct");\
diff --git a/src/corelib/global/qcompilerdetection.h b/src/corelib/global/qcompilerdetection.h
index 6dd76ce30a..35d0c5816b 100644
--- a/src/corelib/global/qcompilerdetection.h
+++ b/src/corelib/global/qcompilerdetection.h
@@ -49,6 +49,7 @@
 
 #if defined(__COVERITY__)
 #  define Q_CC_COVERITY
+#  define Q_COMPILER_COMPLAINS_ABOUT_RETURN_AFTER_UNREACHABLE
 #endif
 
 /* Symantec C++ is now Digital Mars */
diff --git a/src/corelib/global/qcompilerdetection.qdoc b/src/corelib/global/qcompilerdetection.qdoc
index 05a4b89f1d..377323a5eb 100644
--- a/src/corelib/global/qcompilerdetection.qdoc
+++ b/src/corelib/global/qcompilerdetection.qdoc
@@ -180,7 +180,7 @@
     This is useful since a missing break statement is often a bug, and some
     compilers can be configured to emit warnings when one is not found.
 
-    \sa Q_UNREACHABLE()
+    \sa Q_UNREACHABLE(), Q_UNREACHABLE_RETURN()
 */
 
 /*!
diff --git a/src/corelib/io/qprocess.cpp b/src/corelib/io/qprocess.cpp
index c838b665b7..1af592d39d 100644
--- a/src/corelib/io/qprocess.cpp
+++ b/src/corelib/io/qprocess.cpp
@@ -1903,8 +1903,7 @@ void QProcess::setProcessState(ProcessState state)
 */
 auto QProcess::setupChildProcess() -> Use_setChildProcessModifier_Instead
 {
-    Q_UNREACHABLE();
-    return {};
+    Q_UNREACHABLE_RETURN({});
 }
 #endif
 
diff --git a/src/corelib/io/qurl.cpp b/src/corelib/io/qurl.cpp
index 3cebb68561..591ed7fe87 100644
--- a/src/corelib/io/qurl.cpp
+++ b/src/corelib/io/qurl.cpp
@@ -3495,8 +3495,7 @@ static QString errorMessage(QUrlPrivate::ErrorCode errorCode, const QString &err
     case QUrlPrivate::NoError:
         Q_ASSERT_X(false, "QUrl::errorString",
                    "Impossible: QUrl::errorString should have treated this condition");
-        Q_UNREACHABLE();
-        return QString();
+        Q_UNREACHABLE_RETURN(QString());
 
     case QUrlPrivate::InvalidSchemeError: {
         auto msg = "Invalid scheme (character '%1' not permitted)"_L1;
@@ -3554,8 +3553,7 @@ static QString errorMessage(QUrlPrivate::ErrorCode errorCode, const QString &err
     }
 
     Q_ASSERT_X(false, "QUrl::errorString", "Cannot happen, unknown error");
-    Q_UNREACHABLE();
-    return QString();
+    Q_UNREACHABLE_RETURN(QString());
 }
 
 static inline void appendComponentIfPresent(QString &msg, bool present, const char *componentName,
diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index 5ad7967605..1047c8c0aa 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -2006,8 +2006,7 @@ static bool convertToEnum(QMetaType fromType, const void *from, QMetaType toType
         *static_cast<qint64 *>(to) = value;
         return true;
     default:
-        Q_UNREACHABLE();
-        return false;
+        Q_UNREACHABLE_RETURN(false);
     }
 }
 
diff --git a/src/corelib/kernel/qpropertyprivate.h b/src/corelib/kernel/qpropertyprivate.h
index 966821fa67..4387f0fbeb 100644
--- a/src/corelib/kernel/qpropertyprivate.h
+++ b/src/corelib/kernel/qpropertyprivate.h
@@ -194,8 +194,7 @@ struct BindingFunctionVTable
                     return true;
                 } else {
                     // Our code will never instantiate this
-                    Q_UNREACHABLE();
-                    return false;
+                    Q_UNREACHABLE_RETURN(false);
                 }
             },
             /*destroy*/[](void *f){ static_cast<Callable *>(f)->~Callable(); },
diff --git a/src/corelib/kernel/qvariant.cpp b/src/corelib/kernel/qvariant.cpp
index 5e949487db..3fb80f203e 100644
--- a/src/corelib/kernel/qvariant.cpp
+++ b/src/corelib/kernel/qvariant.cpp
@@ -2261,8 +2261,7 @@ static bool integralEquals(uint promotedType, const QVariant::Private *d1, const
     if (promotedType == QMetaType::ULongLong)
         return qulonglong(l1) == qulonglong(l2);
 
-    Q_UNREACHABLE();
-    return 0;
+    Q_UNREACHABLE_RETURN(0);
 }
 
 namespace {
@@ -2306,8 +2305,7 @@ static std::optional<int> integralCompare(uint promotedType, const QVariant::Pri
     if (promotedType == QMetaType::ULongLong)
         return spaceShip<qulonglong>(l1, l2);
 
-    Q_UNREACHABLE();
-    return 0;
+    Q_UNREACHABLE_RETURN(0);
 }
 
 static std::optional<int> numericCompare(const QVariant::Private *d1, const QVariant::Private *d2)
diff --git a/src/corelib/serialization/qcborstreamreader.cpp b/src/corelib/serialization/qcborstreamreader.cpp
index 5f6c0feb49..86fb1f0d7e 100644
--- a/src/corelib/serialization/qcborstreamreader.cpp
+++ b/src/corelib/serialization/qcborstreamreader.cpp
@@ -36,13 +36,11 @@ QT_WARNING_POP
 
 static CborError _cbor_value_dup_string(const CborValue *, void **, size_t *, CborValue *)
 {
-    Q_UNREACHABLE();
-    return CborErrorInternalError;
+    Q_UNREACHABLE_RETURN(CborErrorInternalError);
 }
 [[maybe_unused]] static CborError cbor_value_get_half_float_as_float(const CborValue *, float *)
 {
-    Q_UNREACHABLE();
-    return CborErrorInternalError;
+    Q_UNREACHABLE_RETURN(CborErrorInternalError);
 }
 
 // confirm our constants match TinyCBOR's
diff --git a/src/corelib/serialization/qcborstreamwriter.cpp b/src/corelib/serialization/qcborstreamwriter.cpp
index 0e445451bc..a2ddc15161 100644
--- a/src/corelib/serialization/qcborstreamwriter.cpp
+++ b/src/corelib/serialization/qcborstreamwriter.cpp
@@ -29,14 +29,12 @@ QT_WARNING_POP
 // but never defined
 [[maybe_unused]] static CborError cbor_encoder_close_container_checked(CborEncoder*, const CborEncoder*)
 {
-    Q_UNREACHABLE();
-    return CborErrorInternalError;
+    Q_UNREACHABLE_RETURN(CborErrorInternalError);
 }
 
 [[maybe_unused]] static CborError cbor_encode_float_as_half_float(CborEncoder *, float)
 {
-    Q_UNREACHABLE();
-    return CborErrorInternalError;
+    Q_UNREACHABLE_RETURN(CborErrorInternalError);
 }
 
 Q_DECLARE_TYPEINFO(CborEncoder, Q_PRIMITIVE_TYPE);
diff --git a/src/corelib/serialization/qjsoncbor.cpp b/src/corelib/serialization/qjsoncbor.cpp
index 67db3d7d6c..ad0e95061c 100644
--- a/src/corelib/serialization/qjsoncbor.cpp
+++ b/src/corelib/serialization/qjsoncbor.cpp
@@ -576,8 +576,7 @@ QVariant QCborValue::toVariant() const
     if (isSimpleType())
         return QVariant::fromValue(toSimpleType());
 
-    Q_UNREACHABLE();
-    return QVariant();
+    Q_UNREACHABLE_RETURN(QVariant());
 }
 
 /*!
diff --git a/src/corelib/serialization/qjsonvalue.cpp b/src/corelib/serialization/qjsonvalue.cpp
index 5383addb70..49fc0d85d1 100644
--- a/src/corelib/serialization/qjsonvalue.cpp
+++ b/src/corelib/serialization/qjsonvalue.cpp
@@ -1097,8 +1097,7 @@ size_t qHash(const QJsonValue &value, size_t seed)
     case QJsonValue::Undefined:
         return seed;
     }
-    Q_UNREACHABLE();
-    return 0;
+    Q_UNREACHABLE_RETURN(0);
 }
 
 #if !defined(QT_NO_DEBUG_STREAM) && !defined(QT_JSON_READONLY)
diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index 33292d9ca2..29728fcf51 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -541,8 +541,7 @@ static const char *zlibOpAsString(ZLibOp op)
     case ZLibOp::Compression: return "qCompress";
     case ZLibOp::Decompression: return "qUncompress";
     }
-    Q_UNREACHABLE();
-    return nullptr;
+    Q_UNREACHABLE_RETURN(nullptr);
 }
 
 Q_DECL_COLD_FUNCTION
@@ -2908,8 +2907,7 @@ QByteArray QByteArray::mid(qsizetype pos, qsizetype len) const
     case QContainerImplHelper::Subset:
         return QByteArray(d.data() + p, l);
     }
-    Q_UNREACHABLE();
-    return QByteArray();
+    Q_UNREACHABLE_RETURN(QByteArray());
 }
 
 /*!
diff --git a/src/corelib/text/qlocale_tools.cpp b/src/corelib/text/qlocale_tools.cpp
index ca6f954bed..f3e664ea41 100644
--- a/src/corelib/text/qlocale_tools.cpp
+++ b/src/corelib/text/qlocale_tools.cpp
@@ -570,8 +570,7 @@ QString qulltoa(qulonglong number, int base, const QStringView zero)
             number /= base;
         }
     } else { // zero should always be either a non-surrogate or a surrogate pair:
-        Q_UNREACHABLE();
-        return QString();
+        Q_UNREACHABLE_RETURN(QString());
     }
 
     return QString(reinterpret_cast<QChar *>(p), end - p);
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index e77ff3f3d0..394e1d2c89 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -5025,8 +5025,7 @@ QString QString::mid(qsizetype position, qsizetype n) const
     case QContainerImplHelper::Subset:
         return QString(constData() + p, l);
     }
-    Q_UNREACHABLE();
-    return QString();
+    Q_UNREACHABLE_RETURN(QString());
 }
 
 /*!
diff --git a/src/corelib/text/qstringalgorithms_p.h b/src/corelib/text/qstringalgorithms_p.h
index 513e2b8cbc..0b8118a858 100644
--- a/src/corelib/text/qstringalgorithms_p.h
+++ b/src/corelib/text/qstringalgorithms_p.h
@@ -47,8 +47,7 @@ template <typename StringType> struct QStringAlgorithms
     static inline StringType trimmed_helper_inplace(const NakedStringType &, const Char *, const Char *)
     {
         // can't happen
-        Q_UNREACHABLE();
-        return StringType();
+        Q_UNREACHABLE_RETURN(StringType());
     }
 
     static inline void trimmed_helper_positions(const Char *&begin, const Char *&end)
diff --git a/src/corelib/thread/qfutex_p.h b/src/corelib/thread/qfutex_p.h
index 9363cc02de..48f03f5ed0 100644
--- a/src/corelib/thread/qfutex_p.h
+++ b/src/corelib/thread/qfutex_p.h
@@ -24,7 +24,7 @@ namespace QtDummyFutex {
     constexpr inline bool futexAvailable() { return false; }
     template <typename Atomic>
     inline bool futexWait(Atomic &, typename Atomic::Type, int = 0)
-    { Q_UNREACHABLE(); return false; }
+    { Q_UNREACHABLE_RETURN(false); }
     template <typename Atomic> inline void futexWakeOne(Atomic &)
     { Q_UNREACHABLE(); }
     template <typename Atomic> inline void futexWakeAll(Atomic &)
diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index 46a33d55c7..21f252a70d 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -2841,8 +2841,7 @@ static inline bool usesSameOffset(const QDateTimeData &a, const QDateTimeData &b
         Q_ASSERT(!a.isShort() && !b.isShort());
         return a->m_offsetFromUtc == b->m_offsetFromUtc;
     }
-    Q_UNREACHABLE();
-    return false;
+    Q_UNREACHABLE_RETURN(false);
 }
 
 // Refresh the LocalTime or TimeZone validity and offset
@@ -3805,8 +3804,7 @@ qint64 QDateTime::toMSecsSinceEpoch() const
 #endif
         return 0;
     }
-    Q_UNREACHABLE();
-    return 0;
+    Q_UNREACHABLE_RETURN(0);
 }
 
 /*!
diff --git a/src/corelib/time/qdatetimeparser.cpp b/src/corelib/time/qdatetimeparser.cpp
index a90fb46046..ab784912e5 100644
--- a/src/corelib/time/qdatetimeparser.cpp
+++ b/src/corelib/time/qdatetimeparser.cpp
@@ -1441,8 +1441,7 @@ QDateTimeParser::scanString(const QDateTime &defaultValue, bool fixup) const
             // Don't care about date or spec, so pick a safe spec:
             return StateNode(QDateTime(date, time, Qt::UTC), state, padding, conflicts);
         default:
-            Q_UNREACHABLE();
-            return StateNode();
+            Q_UNREACHABLE_RETURN(StateNode());
         }
     }
 
@@ -2253,8 +2252,7 @@ QString QDateTimeParser::getAmPmText(AmPm ap, Case cs) const
     case LowerCase: return raw.toLower();
     case NativeCase: return raw;
     }
-    Q_UNREACHABLE();
-    return raw;
+    Q_UNREACHABLE_RETURN(raw);
 }
 
 /*
diff --git a/src/corelib/tools/qatomicscopedvaluerollback_p.h b/src/corelib/tools/qatomicscopedvaluerollback_p.h
index a0f088ec45..147156d585 100644
--- a/src/corelib/tools/qatomicscopedvaluerollback_p.h
+++ b/src/corelib/tools/qatomicscopedvaluerollback_p.h
@@ -43,6 +43,7 @@ class [[nodiscard]] QAtomicScopedValueRollback
         }
         // GCC 8.x does not tread __builtin_unreachable() as constexpr
 #if !defined(Q_CC_GNU_ONLY) || (Q_CC_GNU >= 900)
+        // NOLINTNEXTLINE(qt-use-unreachable-return): Triggers on Clang, breaking GCC 8
         Q_UNREACHABLE();
 #endif
         return std::memory_order_seq_cst;
diff --git a/src/corelib/tools/qfreelist_p.h b/src/corelib/tools/qfreelist_p.h
index c06c569d23..6bbde5b4b6 100644
--- a/src/corelib/tools/qfreelist_p.h
+++ b/src/corelib/tools/qfreelist_p.h
@@ -124,8 +124,7 @@ class QFreeList
                 return i;
             x -= size;
         }
-        Q_UNREACHABLE();
-        return -1;
+        Q_UNREACHABLE_RETURN(-1);
     }
 
     // allocate a block of the given \a size, initialized starting with the given \a offset
diff --git a/src/corelib/tools/qhash.cpp b/src/corelib/tools/qhash.cpp
index 9b69c79389..bac2a01afc 100644
--- a/src/corelib/tools/qhash.cpp
+++ b/src/corelib/tools/qhash.cpp
@@ -107,6 +107,7 @@ private:
     StateResult result = { 0, OverriddenByEnvironment };
 #ifdef QT_BOOTSTRAPPED
     Q_UNUSED(which);
+    // NOLINTNEXTLINE(qt-use-unreachable-return): triggers on QT_BOOTSTRAPPED, breaking #else case
     Q_UNREACHABLE();
 #else
     // can't use qEnvironmentVariableIntValue (reentrancy)
diff --git a/src/gui/image/qimage_conversions.cpp b/src/gui/image/qimage_conversions.cpp
index fa75bed3c8..d13bef7190 100644
--- a/src/gui/image/qimage_conversions.cpp
+++ b/src/gui/image/qimage_conversions.cpp
@@ -1033,8 +1033,7 @@ static inline uint qUnpremultiplyRgb30(uint rgb30)
     case 3:
         return rgb30;
     }
-    Q_UNREACHABLE();
-    return 0;
+    Q_UNREACHABLE_RETURN(0);
 }
 
 template<bool rgbswap>
diff --git a/src/gui/kernel/qshortcutmap.cpp b/src/gui/kernel/qshortcutmap.cpp
index e3236a0086..ed03f00542 100644
--- a/src/gui/kernel/qshortcutmap.cpp
+++ b/src/gui/kernel/qshortcutmap.cpp
@@ -313,8 +313,7 @@ bool QShortcutMap::tryShortcut(QKeyEvent *e)
         return identicalMatches > 0;
     }
     }
-    Q_UNREACHABLE();
-    return false;
+    Q_UNREACHABLE_RETURN(false);
 }
 
 /*! \internal
diff --git a/src/gui/painting/qdrawhelper.cpp b/src/gui/painting/qdrawhelper.cpp
index 35c44b8286..e5d322e1dc 100644
--- a/src/gui/painting/qdrawhelper.cpp
+++ b/src/gui/painting/qdrawhelper.cpp
@@ -50,8 +50,7 @@ constexpr int half_point = 1 << 15;
 template <QPixelLayout::BPP bpp> static
 inline uint QT_FASTCALL fetch1Pixel(const uchar *, int)
 {
-    Q_UNREACHABLE();
-    return 0;
+    Q_UNREACHABLE_RETURN(0);
 }
 
 template <>
@@ -4917,8 +4916,7 @@ void qBlendTexture(int count, const QSpan *spans, void *userData)
     ProcessSpans proc;
     switch (data->rasterBuffer->format) {
     case QImage::Format_Invalid:
-        Q_UNREACHABLE();
-        return;
+        Q_UNREACHABLE_RETURN();
     case QImage::Format_ARGB32_Premultiplied:
         proc = processTextureSpansARGB32PM[blendType];
         break;
diff --git a/src/gui/painting/qpixellayout.cpp b/src/gui/painting/qpixellayout.cpp
index 025bb168f5..871fd1014d 100644
--- a/src/gui/painting/qpixellayout.cpp
+++ b/src/gui/painting/qpixellayout.cpp
@@ -212,8 +212,7 @@ inline void QT_FASTCALL storePixel<QPixelLayout::BPP24>(uchar *dest, int index,
 template <QPixelLayout::BPP bpp> static
 inline uint QT_FASTCALL fetchPixel(const uchar *, int)
 {
-    Q_UNREACHABLE();
-    return 0;
+    Q_UNREACHABLE_RETURN(0);
 }
 
 template <>
diff --git a/src/gui/painting/webgradients.cpp b/src/gui/painting/webgradients.cpp
index 5924fe6e60..fd5031349e 100644
--- a/src/gui/painting/webgradients.cpp
+++ b/src/gui/painting/webgradients.cpp
@@ -346,8 +346,7 @@ static QList<QGradientStop> qt_preset_gradient_stops(QGradient::Preset preset)
     case QGradient::NumPresets:
         Q_UNREACHABLE();
     }
-    Q_UNREACHABLE();
-    return {};
+    Q_UNREACHABLE_RETURN({});
 }
 
 static constexpr QGradient::QGradientData qt_preset_gradient_data[] = {
diff --git a/src/gui/rhi/qrhi.cpp b/src/gui/rhi/qrhi.cpp
index 3821062c8e..a52b953a37 100644
--- a/src/gui/rhi/qrhi.cpp
+++ b/src/gui/rhi/qrhi.cpp
@@ -1435,8 +1435,7 @@ QRhiVertexInputAttribute::Format QRhiImplementation::shaderDescVariableFormatToV
         return QRhiVertexInputAttribute::UInt;
 
     default:
-        Q_UNREACHABLE();
-        return QRhiVertexInputAttribute::Float;
+        Q_UNREACHABLE_RETURN(QRhiVertexInputAttribute::Float);
     }
 }
 
@@ -1478,8 +1477,7 @@ quint32 QRhiImplementation::byteSizePerVertexForVertexInputFormat(QRhiVertexInpu
         return sizeof(qint32);
 
     default:
-        Q_UNREACHABLE();
-        return 1;
+        Q_UNREACHABLE_RETURN(1);
     }
 }
 
@@ -4120,8 +4118,7 @@ bool operator==(const QRhiShaderResourceBinding &a, const QRhiShaderResourceBind
         }
         break;
     default:
-        Q_UNREACHABLE();
-        return false;
+        Q_UNREACHABLE_RETURN(false);
     }
 
     return true;
@@ -5100,8 +5097,7 @@ static const char *resourceTypeStr(QRhiResource *res)
         return "CommandBuffer";
     }
 
-    Q_UNREACHABLE();
-    return "";
+    Q_UNREACHABLE_RETURN("");
 }
 
 QRhiImplementation::~QRhiImplementation()
@@ -5629,8 +5625,7 @@ const char *QRhi::backendName(Implementation impl)
         return "Metal";
     }
 
-    Q_UNREACHABLE();
-    return "Unknown";
+    Q_UNREACHABLE_RETURN("Unknown");
 }
 
 /*!
@@ -5691,8 +5686,7 @@ static inline const char *deviceTypeStr(QRhiDriverInfo::DeviceType type)
         return "Cpu";
     }
 
-    Q_UNREACHABLE();
-    return nullptr;
+    Q_UNREACHABLE_RETURN(nullptr);
 }
 QDebug operator<<(QDebug dbg, const QRhiDriverInfo &info)
 {
@@ -7768,8 +7762,7 @@ QRhiPassResourceTracker::BufferStage QRhiPassResourceTracker::toPassTrackerBuffe
     if (stages.testFlag(QRhiShaderResourceBinding::GeometryStage))
         return QRhiPassResourceTracker::BufGeometryStage;
 
-    Q_UNREACHABLE();
-    return QRhiPassResourceTracker::BufVertexStage;
+    Q_UNREACHABLE_RETURN(QRhiPassResourceTracker::BufVertexStage);
 }
 
 QRhiPassResourceTracker::TextureStage QRhiPassResourceTracker::toPassTrackerTextureStage(QRhiShaderResourceBinding::StageFlags stages)
@@ -7788,8 +7781,7 @@ QRhiPassResourceTracker::TextureStage QRhiPassResourceTracker::toPassTrackerText
     if (stages.testFlag(QRhiShaderResourceBinding::GeometryStage))
         return QRhiPassResourceTracker::TexGeometryStage;
 
-    Q_UNREACHABLE();
-    return QRhiPassResourceTracker::TexVertexStage;
+    Q_UNREACHABLE_RETURN(QRhiPassResourceTracker::TexVertexStage);
 }
 
 QT_END_NAMESPACE
diff --git a/src/gui/rhi/qrhigles2.cpp b/src/gui/rhi/qrhigles2.cpp
index a45915495e..a8b7919647 100644
--- a/src/gui/rhi/qrhigles2.cpp
+++ b/src/gui/rhi/qrhigles2.cpp
@@ -1232,8 +1232,7 @@ bool QRhiGles2::isFeatureSupported(QRhi::Feature feature) const
     case QRhi::NonFillPolygonMode:
         return !caps.gles;
     default:
-        Q_UNREACHABLE();
-        return false;
+        Q_UNREACHABLE_RETURN(false);
     }
 }
 
@@ -1271,8 +1270,7 @@ int QRhiGles2::resourceLimit(QRhi::ResourceLimit limit) const
     case QRhi::MaxVertexOutputs:
         return caps.maxVertexOutputs;
     default:
-        Q_UNREACHABLE();
-        return 0;
+        Q_UNREACHABLE_RETURN(0);
     }
 }
 
@@ -2356,8 +2354,7 @@ static inline GLenum toGlTopology(QRhiGraphicsPipeline::Topology t)
     case QRhiGraphicsPipeline::Patches:
         return GL_PATCHES;
     default:
-        Q_UNREACHABLE();
-        return GL_TRIANGLES;
+        Q_UNREACHABLE_RETURN(GL_TRIANGLES);
     }
 }
 
@@ -2369,8 +2366,7 @@ static inline GLenum toGlCullMode(QRhiGraphicsPipeline::CullMode c)
     case QRhiGraphicsPipeline::Back:
         return GL_BACK;
     default:
-        Q_UNREACHABLE();
-        return GL_BACK;
+        Q_UNREACHABLE_RETURN(GL_BACK);
     }
 }
 
@@ -2382,8 +2378,7 @@ static inline GLenum toGlFrontFace(QRhiGraphicsPipeline::FrontFace f)
     case QRhiGraphicsPipeline::CW:
         return GL_CW;
     default:
-        Q_UNREACHABLE();
-        return GL_CCW;
+        Q_UNREACHABLE_RETURN(GL_CCW);
     }
 }
 
@@ -2427,8 +2422,7 @@ static inline GLenum toGlBlendFactor(QRhiGraphicsPipeline::BlendFactor f)
         qWarning("Unsupported blend factor %d", f);
         return GL_ZERO;
     default:
-        Q_UNREACHABLE();
-        return GL_ZERO;
+        Q_UNREACHABLE_RETURN(GL_ZERO);
     }
 }
 
@@ -2446,8 +2440,7 @@ static inline GLenum toGlBlendOp(QRhiGraphicsPipeline::BlendOp op)
     case QRhiGraphicsPipeline::Max:
         return GL_MAX;
     default:
-        Q_UNREACHABLE();
-        return GL_FUNC_ADD;
+        Q_UNREACHABLE_RETURN(GL_FUNC_ADD);
     }
 }
 
@@ -2471,8 +2464,7 @@ static inline GLenum toGlCompareOp(QRhiGraphicsPipeline::CompareOp op)
     case QRhiGraphicsPipeline::Always:
         return GL_ALWAYS;
     default:
-        Q_UNREACHABLE();
-        return GL_ALWAYS;
+        Q_UNREACHABLE_RETURN(GL_ALWAYS);
     }
 }
 
@@ -2496,8 +2488,7 @@ static inline GLenum toGlStencilOp(QRhiGraphicsPipeline::StencilOp op)
     case QRhiGraphicsPipeline::DecrementAndWrap:
         return GL_DECR_WRAP;
     default:
-        Q_UNREACHABLE();
-        return GL_KEEP;
+        Q_UNREACHABLE_RETURN(GL_KEEP);
     }
 }
 
@@ -2509,8 +2500,7 @@ static inline GLenum toGlPolygonMode(QRhiGraphicsPipeline::PolygonMode mode)
     case QRhiGraphicsPipeline::PolygonMode::Line:
         return GL_LINE;
     default:
-        Q_UNREACHABLE();
-        return GL_FILL;
+        Q_UNREACHABLE_RETURN(GL_FILL);
     }
 }
 
@@ -2528,8 +2518,7 @@ static inline GLenum toGlMinFilter(QRhiSampler::Filter f, QRhiSampler::Filter m)
         else
             return m == QRhiSampler::Nearest ? GL_LINEAR_MIPMAP_NEAREST : GL_LINEAR_MIPMAP_LINEAR;
     default:
-        Q_UNREACHABLE();
-        return GL_LINEAR;
+        Q_UNREACHABLE_RETURN(GL_LINEAR);
     }
 }
 
@@ -2541,8 +2530,7 @@ static inline GLenum toGlMagFilter(QRhiSampler::Filter f)
     case QRhiSampler::Linear:
         return GL_LINEAR;
     default:
-        Q_UNREACHABLE();
-        return GL_LINEAR;
+        Q_UNREACHABLE_RETURN(GL_LINEAR);
     }
 }
 
@@ -2556,8 +2544,7 @@ static inline GLenum toGlWrapMode(QRhiSampler::AddressMode m)
     case QRhiSampler::Mirror:
         return GL_MIRRORED_REPEAT;
     default:
-        Q_UNREACHABLE();
-        return GL_CLAMP_TO_EDGE;
+        Q_UNREACHABLE_RETURN(GL_CLAMP_TO_EDGE);
     }
 }
 
@@ -2581,8 +2568,7 @@ static inline GLenum toGlTextureCompareFunc(QRhiSampler::CompareOp op)
     case QRhiSampler::Always:
         return GL_ALWAYS;
     default:
-        Q_UNREACHABLE();
-        return GL_NEVER;
+        Q_UNREACHABLE_RETURN(GL_NEVER);
     }
 }
 
@@ -4275,8 +4261,7 @@ static inline GLenum toGlShaderType(QRhiShaderStage::Type type)
     case QRhiShaderStage::Compute:
         return GL_COMPUTE_SHADER;
     default:
-        Q_UNREACHABLE();
-        return GL_VERTEX_SHADER;
+        Q_UNREACHABLE_RETURN(GL_VERTEX_SHADER);
     }
 }
 
@@ -4558,8 +4543,7 @@ static inline QShader::Stage toShaderStage(QRhiShaderStage::Type type)
     case QRhiShaderStage::Compute:
         return QShader::ComputeStage;
     default:
-        Q_UNREACHABLE();
-        return QShader::VertexStage;
+        Q_UNREACHABLE_RETURN(QShader::VertexStage);
     }
 }
 
@@ -5526,8 +5510,7 @@ bool QGles2GraphicsPipeline::create()
         default:
             break;
         }
-        Q_UNREACHABLE();
-        return VtxIdx;
+        Q_UNREACHABLE_RETURN(VtxIdx);
     };
     QShaderDescription desc[LastIdx];
     QShader::SeparateToCombinedImageSamplerMappingList samplerMappingList[LastIdx];
diff --git a/src/gui/rhi/qrhinull.cpp b/src/gui/rhi/qrhinull.cpp
index b0c3c559c4..88afb004f7 100644
--- a/src/gui/rhi/qrhinull.cpp
+++ b/src/gui/rhi/qrhinull.cpp
@@ -135,8 +135,7 @@ int QRhiNull::resourceLimit(QRhi::ResourceLimit limit) const
         return 32;
     }
 
-    Q_UNREACHABLE();
-    return 0;
+    Q_UNREACHABLE_RETURN(0);
 }
 
 const QRhiNativeHandles *QRhiNull::nativeHandles()
diff --git a/src/gui/rhi/qrhivulkan.cpp b/src/gui/rhi/qrhivulkan.cpp
index daf934f1d3..a04b9e8e0a 100644
--- a/src/gui/rhi/qrhivulkan.cpp
+++ b/src/gui/rhi/qrhivulkan.cpp
@@ -1016,8 +1016,7 @@ static inline VkFormat toVkTextureFormat(QRhiTexture::Format format, QRhiTexture
         return srgb ? VK_FORMAT_ASTC_12x12_SRGB_BLOCK : VK_FORMAT_ASTC_12x12_UNORM_BLOCK;
 
     default:
-        Q_UNREACHABLE();
-        return VK_FORMAT_R8G8B8A8_UNORM;
+        Q_UNREACHABLE_RETURN(VK_FORMAT_R8G8B8A8_UNORM);
     }
 }
 
@@ -3813,8 +3812,7 @@ VkSampleCountFlagBits QRhiVulkan::effectiveSampleCount(int sampleCount)
             return qvk_sampleCount.mask;
     }
 
-    Q_UNREACHABLE();
-    return VK_SAMPLE_COUNT_1_BIT;
+    Q_UNREACHABLE_RETURN(VK_SAMPLE_COUNT_1_BIT);
 }
 
 void QRhiVulkan::enqueueTransitionPassResources(QVkCommandBuffer *cbD)
@@ -4336,8 +4334,7 @@ bool QRhiVulkan::isFeatureSupported(QRhi::Feature feature) const
     case QRhi::NonFillPolygonMode:
         return caps.nonFillPolygonMode;
     default:
-        Q_UNREACHABLE();
-        return false;
+        Q_UNREACHABLE_RETURN(false);
     }
 }
 
@@ -4375,8 +4372,7 @@ int QRhiVulkan::resourceLimit(QRhi::ResourceLimit limit) const
     case QRhi::MaxVertexOutputs:
         return physDevProperties.limits.maxVertexOutputComponents / 4;
     default:
-        Q_UNREACHABLE();
-        return 0;
+        Q_UNREACHABLE_RETURN(0);
     }
 }
 
@@ -5258,8 +5254,7 @@ static inline VkFilter toVkFilter(QRhiSampler::Filter f)
     case QRhiSampler::Linear:
         return VK_FILTER_LINEAR;
     default:
-        Q_UNREACHABLE();
-        return VK_FILTER_NEAREST;
+        Q_UNREACHABLE_RETURN(VK_FILTER_NEAREST);
     }
 }
 
@@ -5273,8 +5268,7 @@ static inline VkSamplerMipmapMode toVkMipmapMode(QRhiSampler::Filter f)
     case QRhiSampler::Linear:
         return VK_SAMPLER_MIPMAP_MODE_LINEAR;
     default:
-        Q_UNREACHABLE();
-        return VK_SAMPLER_MIPMAP_MODE_NEAREST;
+        Q_UNREACHABLE_RETURN(VK_SAMPLER_MIPMAP_MODE_NEAREST);
     }
 }
 
@@ -5288,8 +5282,7 @@ static inline VkSamplerAddressMode toVkAddressMode(QRhiSampler::AddressMode m)
     case QRhiSampler::Mirror:
         return VK_SAMPLER_ADDRESS_MODE_MIRRORED_REPEAT;
     default:
-        Q_UNREACHABLE();
-        return VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
+        Q_UNREACHABLE_RETURN(VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE);
     }
 }
 
@@ -5309,8 +5302,7 @@ static inline VkShaderStageFlagBits toVkShaderStage(QRhiShaderStage::Type type)
     case QRhiShaderStage::Geometry:
         return VK_SHADER_STAGE_GEOMETRY_BIT;
     default:
-        Q_UNREACHABLE();
-        return VK_SHADER_STAGE_VERTEX_BIT;
+        Q_UNREACHABLE_RETURN(VK_SHADER_STAGE_VERTEX_BIT);
     }
 }
 
@@ -5348,8 +5340,7 @@ static inline VkFormat toVkAttributeFormat(QRhiVertexInputAttribute::Format form
     case QRhiVertexInputAttribute::SInt:
         return VK_FORMAT_R32_SINT;
     default:
-        Q_UNREACHABLE();
-        return VK_FORMAT_R32G32B32A32_SFLOAT;
+        Q_UNREACHABLE_RETURN(VK_FORMAT_R32G32B32A32_SFLOAT);
     }
 }
 
@@ -5371,8 +5362,7 @@ static inline VkPrimitiveTopology toVkTopology(QRhiGraphicsPipeline::Topology t)
     case QRhiGraphicsPipeline::Patches:
         return VK_PRIMITIVE_TOPOLOGY_PATCH_LIST;
     default:
-        Q_UNREACHABLE();
-        return VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+        Q_UNREACHABLE_RETURN(VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST);
     }
 }
 
@@ -5386,8 +5376,7 @@ static inline VkCullModeFlags toVkCullMode(QRhiGraphicsPipeline::CullMode c)
     case QRhiGraphicsPipeline::Back:
         return VK_CULL_MODE_BACK_BIT;
     default:
-        Q_UNREACHABLE();
-        return VK_CULL_MODE_NONE;
+        Q_UNREACHABLE_RETURN(VK_CULL_MODE_NONE);
     }
 }
 
@@ -5399,8 +5388,7 @@ static inline VkFrontFace toVkFrontFace(QRhiGraphicsPipeline::FrontFace f)
     case QRhiGraphicsPipeline::CW:
         return VK_FRONT_FACE_CLOCKWISE;
     default:
-        Q_UNREACHABLE();
-        return VK_FRONT_FACE_COUNTER_CLOCKWISE;
+        Q_UNREACHABLE_RETURN(VK_FRONT_FACE_COUNTER_CLOCKWISE);
     }
 }
 
@@ -5460,8 +5448,7 @@ static inline VkBlendFactor toVkBlendFactor(QRhiGraphicsPipeline::BlendFactor f)
     case QRhiGraphicsPipeline::OneMinusSrc1Alpha:
         return VK_BLEND_FACTOR_ONE_MINUS_SRC1_ALPHA;
     default:
-        Q_UNREACHABLE();
-        return VK_BLEND_FACTOR_ZERO;
+        Q_UNREACHABLE_RETURN(VK_BLEND_FACTOR_ZERO);
     }
 }
 
@@ -5479,8 +5466,7 @@ static inline VkBlendOp toVkBlendOp(QRhiGraphicsPipeline::BlendOp op)
     case QRhiGraphicsPipeline::Max:
         return VK_BLEND_OP_MAX;
     default:
-        Q_UNREACHABLE();
-        return VK_BLEND_OP_ADD;
+        Q_UNREACHABLE_RETURN(VK_BLEND_OP_ADD);
     }
 }
 
@@ -5504,8 +5490,7 @@ static inline VkCompareOp toVkCompareOp(QRhiGraphicsPipeline::CompareOp op)
     case QRhiGraphicsPipeline::Always:
         return VK_COMPARE_OP_ALWAYS;
     default:
-        Q_UNREACHABLE();
-        return VK_COMPARE_OP_ALWAYS;
+        Q_UNREACHABLE_RETURN(VK_COMPARE_OP_ALWAYS);
     }
 }
 
@@ -5529,8 +5514,7 @@ static inline VkStencilOp toVkStencilOp(QRhiGraphicsPipeline::StencilOp op)
     case QRhiGraphicsPipeline::DecrementAndWrap:
         return VK_STENCIL_OP_DECREMENT_AND_WRAP;
     default:
-        Q_UNREACHABLE();
-        return VK_STENCIL_OP_KEEP;
+        Q_UNREACHABLE_RETURN(VK_STENCIL_OP_KEEP);
     }
 }
 
@@ -5542,8 +5526,7 @@ static inline VkPolygonMode toVkPolygonMode(QRhiGraphicsPipeline::PolygonMode mo
     case QRhiGraphicsPipeline::Line:
         return VK_POLYGON_MODE_LINE;
     default:
-        Q_UNREACHABLE();
-        return VK_POLYGON_MODE_FILL;
+        Q_UNREACHABLE_RETURN(VK_POLYGON_MODE_FILL);
     }
 }
 
@@ -5582,8 +5565,7 @@ static inline VkDescriptorType toVkDescriptorType(const QRhiShaderResourceBindin
         return VK_DESCRIPTOR_TYPE_STORAGE_BUFFER;
 
     default:
-        Q_UNREACHABLE();
-        return VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
+        Q_UNREACHABLE_RETURN(VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER);
     }
 }
 
@@ -5625,8 +5607,7 @@ static inline VkCompareOp toVkTextureCompareOp(QRhiSampler::CompareOp op)
     case QRhiSampler::Always:
         return VK_COMPARE_OP_ALWAYS;
     default:
-        Q_UNREACHABLE();
-        return VK_COMPARE_OP_NEVER;
+        Q_UNREACHABLE_RETURN(VK_COMPARE_OP_NEVER);
     }
 }
 
diff --git a/src/gui/text/qtextdocumentlayout.cpp b/src/gui/text/qtextdocumentlayout.cpp
index c95ec4c686..b86b6ca923 100644
--- a/src/gui/text/qtextdocumentlayout.cpp
+++ b/src/gui/text/qtextdocumentlayout.cpp
@@ -1209,8 +1209,7 @@ static inline QTextFormat::Property borderPropertyForEdge(QCss::Edge edge)
     case QCss::RightEdge:
         return QTextFormat::TableCellRightBorder;
     default:
-        Q_UNREACHABLE();
-        return QTextFormat::UserProperty;
+        Q_UNREACHABLE_RETURN(QTextFormat::UserProperty);
     }
 }
 
@@ -1226,8 +1225,7 @@ static inline QTextFormat::Property borderStylePropertyForEdge(QCss::Edge edge)
     case QCss::RightEdge:
         return QTextFormat::TableCellRightBorderStyle;
     default:
-        Q_UNREACHABLE();
-        return QTextFormat::UserProperty;
+        Q_UNREACHABLE_RETURN(QTextFormat::UserProperty);
     }
 }
 
@@ -1243,8 +1241,7 @@ static inline QCss::Edge adjacentEdge(QCss::Edge edge)
     case QCss::LeftEdge:
         return QCss::RightEdge;
     default:
-        Q_UNREACHABLE();
-        return QCss::NumEdges;
+        Q_UNREACHABLE_RETURN(QCss::NumEdges);
     }
 }
 
@@ -1323,8 +1320,7 @@ static inline bool sharesAxis(const QTextTableCell &cell, QCss::Edge edge,
         return cell.column() + cell.columnSpan() ==
                 competingCell.column() + (competingCellEdge == QCss::LeftEdge ? 0 : competingCell.columnSpan());
     default:
-        Q_UNREACHABLE();
-        return false;
+        Q_UNREACHABLE_RETURN(false);
     }
 }
 
diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp
index 1c1da979c8..27284d8d5a 100644
--- a/src/gui/text/qtextengine.cpp
+++ b/src/gui/text/qtextengine.cpp
@@ -1395,8 +1395,7 @@ void QTextEngine::shapeText(int item) const
     }
 
     if (Q_UNLIKELY(!ensureSpace(itemLength))) {
-        Q_UNREACHABLE(); // ### report OOM error somehow
-        return;
+        Q_UNREACHABLE_RETURN(); // ### report OOM error somehow
     }
 
     QFontEngine *fontEngine = this->fontEngine(si, &si.ascent, &si.descent, &si.leading);
diff --git a/src/network/access/http2/hpacktable.cpp b/src/network/access/http2/hpacktable.cpp
index 0b69ee86a9..74a09a207f 100644
--- a/src/network/access/http2/hpacktable.cpp
+++ b/src/network/access/http2/hpacktable.cpp
@@ -346,8 +346,7 @@ quint32 FieldLookupTable::indexOfChunk(const Chunk *chunk) const
             return quint32(i);
     }
 
-    Q_UNREACHABLE();
-    return 0;
+    Q_UNREACHABLE_RETURN(0);
 }
 
 quint32 FieldLookupTable::keyToIndex(const SearchEntry &key) const
diff --git a/src/network/ssl/qssldiffiehellmanparameters.cpp b/src/network/ssl/qssldiffiehellmanparameters.cpp
index 04add93116..b2c112bbf9 100644
--- a/src/network/ssl/qssldiffiehellmanparameters.cpp
+++ b/src/network/ssl/qssldiffiehellmanparameters.cpp
@@ -241,8 +241,7 @@ QString QSslDiffieHellmanParameters::errorString() const noexcept
         return QCoreApplication::translate("QSslDiffieHellmanParameter", "The given Diffie-Hellman parameters are deemed unsafe");
     }
 
-    Q_UNREACHABLE();
-    return QString();
+    Q_UNREACHABLE_RETURN(QString());
 }
 
 /*!
diff --git a/src/network/ssl/qtlsbackend.cpp b/src/network/ssl/qtlsbackend.cpp
index bc5b492d0f..d1157e5838 100644
--- a/src/network/ssl/qtlsbackend.cpp
+++ b/src/network/ssl/qtlsbackend.cpp
@@ -1382,8 +1382,7 @@ QByteArray TlsKey::pemHeader() const
     else if (algorithm() == QSsl::Dh)
         return QByteArrayLiteral("-----BEGIN PRIVATE KEY-----");
 
-    Q_UNREACHABLE();
-    return {};
+    Q_UNREACHABLE_RETURN({});
 }
 
 /*!
@@ -1404,8 +1403,7 @@ QByteArray TlsKey::pemFooter() const
     else if (algorithm() == QSsl::Dh)
         return QByteArrayLiteral("-----END PRIVATE KEY-----");
 
-    Q_UNREACHABLE();
-    return {};
+    Q_UNREACHABLE_RETURN({});
 }
 
 /*!
diff --git a/src/opengl/qopenglframebufferobject.cpp b/src/opengl/qopenglframebufferobject.cpp
index 9aa89350ec..64b07e661f 100644
--- a/src/opengl/qopenglframebufferobject.cpp
+++ b/src/opengl/qopenglframebufferobject.cpp
@@ -1414,8 +1414,7 @@ static QImage qt_gl_read_framebuffer(const QSize &size, GLenum internal_format,
         return qt_gl_read_framebuffer_rgba8(size, include_alpha, ctx).mirrored(false, flip);
     }
 
-    Q_UNREACHABLE();
-    return QImage();
+    Q_UNREACHABLE_RETURN(QImage());
 }
 
 Q_OPENGL_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, bool include_alpha)
diff --git a/src/opengl/qopengltexture.cpp b/src/opengl/qopengltexture.cpp
index 8dc30cca61..6700f0e383 100644
--- a/src/opengl/qopengltexture.cpp
+++ b/src/opengl/qopengltexture.cpp
@@ -431,8 +431,7 @@ static bool isSizedTextureFormat(QOpenGLTexture::TextureFormat internalFormat)
         return false;
     }
 
-    Q_UNREACHABLE();
-    return false;
+    Q_UNREACHABLE_RETURN(false);
 }
 
 static bool isTextureTargetMultisample(QOpenGLTexture::Target target)
@@ -456,8 +455,7 @@ static bool isTextureTargetMultisample(QOpenGLTexture::Target target)
         return false;
     }
 
-    Q_UNREACHABLE();
-    return false;
+    Q_UNREACHABLE_RETURN(false);
 }
 
 bool QOpenGLTexturePrivate::isUsingImmutableStorage() const
@@ -756,8 +754,7 @@ static QOpenGLTexture::PixelFormat pixelFormatCompatibleWithInternalFormat(QOpen
         return QOpenGLTexture::LuminanceAlpha;
     }
 
-    Q_UNREACHABLE();
-    return QOpenGLTexture::NoSourceFormat;
+    Q_UNREACHABLE_RETURN(QOpenGLTexture::NoSourceFormat);
 }
 
 static QOpenGLTexture::PixelType pixelTypeCompatibleWithInternalFormat(QOpenGLTexture::TextureFormat internalFormat)
@@ -936,8 +933,7 @@ static QOpenGLTexture::PixelType pixelTypeCompatibleWithInternalFormat(QOpenGLTe
         return QOpenGLTexture::UInt8;
     }
 
-    Q_UNREACHABLE();
-    return QOpenGLTexture::NoPixelType;
+    Q_UNREACHABLE_RETURN(QOpenGLTexture::NoPixelType);
 }
 
 static bool isCompressedFormat(QOpenGLTexture::TextureFormat internalFormat)
@@ -1080,8 +1076,7 @@ static bool isCompressedFormat(QOpenGLTexture::TextureFormat internalFormat)
         return false;
     }
 
-    Q_UNREACHABLE();
-    return false;
+    Q_UNREACHABLE_RETURN(false);
 }
 
 void QOpenGLTexturePrivate::allocateMutableStorage(QOpenGLTexture::PixelFormat pixelFormat, QOpenGLTexture::PixelType pixelType)
diff --git a/src/plugins/networkinformation/networkmanager/qnetworkmanagernetworkinformationbackend.cpp b/src/plugins/networkinformation/networkmanager/qnetworkmanagernetworkinformationbackend.cpp
index 67129af2de..6ee84e06f8 100644
--- a/src/plugins/networkinformation/networkmanager/qnetworkmanagernetworkinformationbackend.cpp
+++ b/src/plugins/networkinformation/networkmanager/qnetworkmanagernetworkinformationbackend.cpp
@@ -94,8 +94,7 @@ bool isMeteredFromNMMetered(QNetworkManagerInterface::NMMetered metered)
     case QNetworkManagerInterface::NM_METERED_UNKNOWN:
         return false;
     }
-    Q_UNREACHABLE();
-    return false;
+    Q_UNREACHABLE_RETURN(false);
 }
 } // unnamed namespace
 
diff --git a/src/plugins/platforminputcontexts/compose/qcomposeplatforminputcontext.cpp b/src/plugins/platforminputcontexts/compose/qcomposeplatforminputcontext.cpp
index 7e66e5fae8..3e74189076 100644
--- a/src/plugins/platforminputcontexts/compose/qcomposeplatforminputcontext.cpp
+++ b/src/plugins/platforminputcontexts/compose/qcomposeplatforminputcontext.cpp
@@ -108,8 +108,7 @@ bool QComposeInputContext::filterEvent(const QEvent *event)
     case XKB_COMPOSE_NOTHING:
         return false;
     default:
-        Q_UNREACHABLE();
-        return false;
+        Q_UNREACHABLE_RETURN(false);
     }
 }
 
diff --git a/src/plugins/platforms/linuxfb/qlinuxfbdrmscreen.cpp b/src/plugins/platforms/linuxfb/qlinuxfbdrmscreen.cpp
index 9cb232e13d..56b28ba48c 100644
--- a/src/plugins/platforms/linuxfb/qlinuxfbdrmscreen.cpp
+++ b/src/plugins/platforms/linuxfb/qlinuxfbdrmscreen.cpp
@@ -125,8 +125,7 @@ void QLinuxFbDevice::close()
 
 void *QLinuxFbDevice::nativeDisplay() const
 {
-    Q_UNREACHABLE();
-    return nullptr;
+    Q_UNREACHABLE_RETURN(nullptr);
 }
 
 QPlatformScreen *QLinuxFbDevice::createScreen(const QKmsOutput &output)
diff --git a/src/printsupport/kernel/qcups.cpp b/src/printsupport/kernel/qcups.cpp
index 5d1d4e5c98..f4d3263f48 100644
--- a/src/printsupport/kernel/qcups.cpp
+++ b/src/printsupport/kernel/qcups.cpp
@@ -89,8 +89,7 @@ static inline QString jobHoldToString(const QCUPSSupport::JobHoldUntil jobHold,
     case QCUPSSupport::NoHold:
         return QString();
     }
-    Q_UNREACHABLE();
-    return QString();
+    Q_UNREACHABLE_RETURN(QString());
 }
 
 QCUPSSupport::JobHoldUntilWithTime QCUPSSupport::parseJobHoldUntil(const QString &jobHoldUntil)
@@ -176,8 +175,7 @@ static inline QString bannerPageToString(const QCUPSSupport::BannerPage bannerPa
     case QCUPSSupport::Secret:       return QStringLiteral("secret");
     case QCUPSSupport::TopSecret:    return QStringLiteral("topsecret");
     }
-    Q_UNREACHABLE();
-    return QString();
+    Q_UNREACHABLE_RETURN(QString());
 }
 
 static inline QCUPSSupport::BannerPage stringToBannerPage(const QString &bannerPage)
diff --git a/src/testlib/qabstracttestlogger.cpp b/src/testlib/qabstracttestlogger.cpp
index d329386745..08fdade90b 100644
--- a/src/testlib/qabstracttestlogger.cpp
+++ b/src/testlib/qabstracttestlogger.cpp
@@ -351,8 +351,7 @@ void QAbstractTestLogger::addMessage(QtMsgType type, const QMessageLogContext &c
         case QtWarningMsg: return QAbstractTestLogger::QWarning;
         case QtFatalMsg: return QAbstractTestLogger::QFatal;
         }
-        Q_UNREACHABLE();
-        return QAbstractTestLogger::QFatal;
+        Q_UNREACHABLE_RETURN(QAbstractTestLogger::QFatal);
     }();
 
     QString formattedMessage = qFormatLogMessage(type, context, message);
diff --git a/src/testlib/qplaintestlogger.cpp b/src/testlib/qplaintestlogger.cpp
index 75443c96dc..dd5282cdb1 100644
--- a/src/testlib/qplaintestlogger.cpp
+++ b/src/testlib/qplaintestlogger.cpp
@@ -62,8 +62,7 @@ namespace QTest {
         case QAbstractTestLogger::BlacklistedXFail:
             return "BXFAIL ";
         }
-        Q_UNREACHABLE();
-        return nullptr;
+        Q_UNREACHABLE_RETURN(nullptr);
     }
 
     static const char *benchmarkResult2String()
@@ -89,8 +88,7 @@ namespace QTest {
         case QAbstractTestLogger::Warn:
             return "WARNING";
         }
-        Q_UNREACHABLE();
-        return nullptr;
+        Q_UNREACHABLE_RETURN(nullptr);
     }
 
     template <typename T>
diff --git a/src/testlib/qtestcase.cpp b/src/testlib/qtestcase.cpp
index d3858267bc..cd8b6edeb7 100644
--- a/src/testlib/qtestcase.cpp
+++ b/src/testlib/qtestcase.cpp
@@ -1230,8 +1230,7 @@ class WatchDog : public QThread
             waitCondition.wait(m, expectationChanged);
             return true;
         }
-        Q_UNREACHABLE();
-        return false;
+        Q_UNREACHABLE_RETURN(false);
     }
 
 public:
diff --git a/src/testlib/qtestresult.cpp b/src/testlib/qtestresult.cpp
index 556cafd4d4..00799a02da 100644
--- a/src/testlib/qtestresult.cpp
+++ b/src/testlib/qtestresult.cpp
@@ -599,8 +599,7 @@ static const char *macroNameForOp(QTest::ComparisonOperation op)
     case ComparisonOperation::GreaterThanOrEqual:
         return "QCOMPARE_GE";
     }
-    Q_UNREACHABLE();
-    return "";
+    Q_UNREACHABLE_RETURN("");
 }
 
 static const char *failureMessageForOp(QTest::ComparisonOperation op)
@@ -622,8 +621,7 @@ static const char *failureMessageForOp(QTest::ComparisonOperation op)
     case ComparisonOperation::GreaterThanOrEqual:
         return "Left value is expected to be greater than or equal to right value, but is not";
     }
-    Q_UNREACHABLE();
-    return "";
+    Q_UNREACHABLE_RETURN("");
 }
 
 bool QTestResult::reportResult(bool success, qxp::function_ref<const char *()> lhs,
diff --git a/src/tools/moc/generator.cpp b/src/tools/moc/generator.cpp
index d111380b8f..4c8a73043c 100644
--- a/src/tools/moc/generator.cpp
+++ b/src/tools/moc/generator.cpp
@@ -1554,8 +1554,7 @@ static CborError jsonValueToCbor(CborEncoder *parent, const QJsonValue &v)
         return cbor_encode_double(parent, d);
     }
     }
-    Q_UNREACHABLE();
-    return CborUnknownError;
+    Q_UNREACHABLE_RETURN(CborUnknownError);
 }
 
 void Generator::generatePluginMetaData()
diff --git a/src/widgets/dialogs/qinputdialog.cpp b/src/widgets/dialogs/qinputdialog.cpp
index 80e329bcfe..89ea6e6746 100644
--- a/src/widgets/dialogs/qinputdialog.cpp
+++ b/src/widgets/dialogs/qinputdialog.cpp
@@ -38,8 +38,7 @@ static const char *candidateSignal(int which)
     case NumCandidateSignals:
         break;
     };
-    Q_UNREACHABLE();
-    return nullptr;
+    Q_UNREACHABLE_RETURN(nullptr);
 }
 
 static const char *signalForMember(const char *member)
diff --git a/src/widgets/dialogs/qwizard.cpp b/src/widgets/dialogs/qwizard.cpp
index 884517d53f..1716d8182b 100644
--- a/src/widgets/dialogs/qwizard.cpp
+++ b/src/widgets/dialogs/qwizard.cpp
@@ -129,8 +129,7 @@ static const char *changed_signal(int which)
     case 6: return SIGNAL(valueChanged(int));
     };
     static_assert(7 == NFallbackDefaultProperties);
-    Q_UNREACHABLE();
-    return nullptr;
+    Q_UNREACHABLE_RETURN(nullptr);
 }
 
 class QWizardDefaultProperty
@@ -1350,8 +1349,7 @@ static QString object_name_for_button(QWizard::WizardButton which)
     //case QWizard::NButtons:
         ;
     }
-    Q_UNREACHABLE();
-    return QString();
+    Q_UNREACHABLE_RETURN(QString());
 }
 
 bool QWizardPrivate::ensureButton(QWizard::WizardButton which) const
diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index 90c3b282ee..e231345437 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -3723,8 +3723,7 @@ static Qt::SortOrder flipOrder(Qt::SortOrder order)
     case Qt::DescendingOrder:
         return Qt::AscendingOrder;
     };
-    Q_UNREACHABLE();
-    return Qt::AscendingOrder;
+    Q_UNREACHABLE_RETURN(Qt::AscendingOrder);
 };
 
 void QHeaderViewPrivate::flipSortIndicator(int section)
diff --git a/tests/auto/corelib/global/qtendian/tst_qtendian.cpp b/tests/auto/corelib/global/qtendian/tst_qtendian.cpp
index 401367ecaa..885e693c8d 100644
--- a/tests/auto/corelib/global/qtendian/tst_qtendian.cpp
+++ b/tests/auto/corelib/global/qtendian/tst_qtendian.cpp
@@ -430,8 +430,7 @@ void tst_QtEndian::endianBitfieldUnions()
             testBitfieldUnion<qint32_le_bitfield_union, qint32_le_bitfield_member>();
             return;
         }
-        Q_UNREACHABLE();
-        return;
+        Q_UNREACHABLE_RETURN();
     case QSysInfo::BigEndian:
         switch (signedness) {
         case Unsigned:
@@ -441,8 +440,7 @@ void tst_QtEndian::endianBitfieldUnions()
             testBitfieldUnion<qint32_be_bitfield_union, qint32_be_bitfield_member>();
             return;
         }
-        Q_UNREACHABLE();
-        return;
+        Q_UNREACHABLE_RETURN();
     }
 }
 
diff --git a/tests/auto/other/qobjectrace/tst_qobjectrace.cpp b/tests/auto/other/qobjectrace/tst_qobjectrace.cpp
index 1dbaf33e32..90b1b5c29a 100644
--- a/tests/auto/other/qobjectrace/tst_qobjectrace.cpp
+++ b/tests/auto/other/qobjectrace/tst_qobjectrace.cpp
@@ -309,8 +309,7 @@ public slots:
             break;
         }
 
-        Q_UNREACHABLE();
-        return false;
+        Q_UNREACHABLE_RETURN(false);
     }
 
 private:
diff --git a/tests/benchmarks/corelib/tools/qcryptographichash/tst_bench_qcryptographichash.cpp b/tests/benchmarks/corelib/tools/qcryptographichash/tst_bench_qcryptographichash.cpp
index 719ba7a8c1..85bf863f9d 100644
--- a/tests/benchmarks/corelib/tools/qcryptographichash/tst_bench_qcryptographichash.cpp
+++ b/tests/benchmarks/corelib/tools/qcryptographichash/tst_bench_qcryptographichash.cpp
@@ -80,8 +80,7 @@ const char *algoname(int i)
     case QCryptographicHash::Blake2s_256:
         return "blake2s_256-";
     }
-    Q_UNREACHABLE();
-    return nullptr;
+    Q_UNREACHABLE_RETURN(nullptr);
 }
 
 tst_QCryptographicHash::tst_QCryptographicHash()