CMake: drop the NOTREACHED macro

- both clang and g++ support __builtin_unreachable(); (as Kevin
   Kofler pointed out) so we don't need the macro to do different things;
 - the compilers have gotten better at detecting unreachable code,
   so instead of inserting macros or fiddly bits, just drop them
   and the unreachable code they comment.

CMakeLists.txt

@@ -228,7 +228,6 @@ if( CMAKE_CXX_COMPILER_ID MATCHES "Clang" )
     )
         string( APPEND CMAKE_CXX_FLAGS " ${CLANG_WARNINGS}" )
     endforeach()
-    set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DNOTREACHED='//'")
 
     # Third-party code where we don't care so much about compiler warnings
     # (because it's uncomfortable to patch) get different flags; use
@@ -246,8 +245,6 @@ else()
     set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wnon-virtual-dtor -Woverloaded-virtual" )
 
     set( SUPPRESS_3RDPARTY_WARNINGS "" )
-
-    set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DNOTREACHED='__builtin_unreachable();'" )
 endif()
 
 # Use mark_thirdparty_code() to reduce warnings from the compiler

src/calamares/CalamaresWindow.cpp

@@ -271,7 +271,6 @@ flavoredWidget( Calamares::Branding::PanelFlavor flavor,
     case Calamares::Branding::PanelFlavor::None:
         return nullptr;
     }
-    NOTREACHED return nullptr;  // All enum values handled above
 }
 
 /** @brief Adds widgets to @p layout if they belong on this @p side

src/libcalamares/geoip/Handler.cpp

@@ -101,7 +101,6 @@ create_interface( Handler::Type t, const QString& selector )
     case Handler::Type::Fixed:
         return std::make_unique< GeoIPFixed >( selector );
     }
-    NOTREACHED return nullptr;
 }
 
 static RegionZonePair

src/libcalamares/partition/PartitionSize.cpp

@@ -139,9 +139,6 @@ PartitionSize::toBytes( qint64 totalSectors, qint64 sectorSize ) const
     case SizeUnit::GiB:
         return toBytes();
     }
-
-    // notreached
-    return -1;
 }
 
 qint64
@@ -179,8 +176,6 @@ PartitionSize::toBytes( qint64 totalBytes ) const
         return toBytes();
     }
 
-    // notreached
-    return -1;
 }
 
 qint64
@@ -211,7 +206,6 @@ PartitionSize::toBytes() const
     case SizeUnit::GiB:
         return CalamaresUtils::GiBtoBytes( static_cast< unsigned long long >( value() ) );
     }
-    NOTREACHED return -1;
 }
 
 bool
@@ -237,7 +231,6 @@ PartitionSize::operator<( const PartitionSize& other ) const
     case SizeUnit::GiB:
         return ( toBytes() < other.toBytes() );
     }
-    NOTREACHED return false;
 }
 
 bool
@@ -263,7 +256,6 @@ PartitionSize::operator>( const PartitionSize& other ) const
     case SizeUnit::GiB:
         return ( toBytes() > other.toBytes() );
     }
-    NOTREACHED return false;
 }
 
 bool
@@ -289,7 +281,6 @@ PartitionSize::operator==( const PartitionSize& other ) const
     case SizeUnit::GiB:
         return ( toBytes() == other.toBytes() );
     }
-    NOTREACHED return false;
 }
 
 }  // namespace Partition

src/libcalamares/utils/Yaml.cpp

@@ -52,9 +52,6 @@ yamlToVariant( const YAML::Node& node )
     case YAML::NodeType::Undefined:
         return QVariant();
     }
-
-    // NOTREACHED
-    return QVariant();
 }
 
 

src/modules/netinstall/Config.cpp

@@ -43,7 +43,6 @@ Config::status() const
     case Status::FailedNetworkError:
         return tr( "Network Installation. (Disabled: Unable to fetch package lists, check your network connection)" );
     }
-    NOTREACHED return QString();
 }
 
 

src/modules/netinstall/NetInstallViewStep.cpp

@@ -47,7 +47,7 @@ NetInstallViewStep::prettyName() const
     return m_sidebarLabel ? m_sidebarLabel->get() : tr( "Package selection" );
 
 #if defined( TABLE_OF_TRANSLATIONS )
-    NOTREACHED
+    __builtin_unreachable();
     // This is a table of "standard" labels for this module. If you use them
     // in the label: sidebar: section of the config file, the existing
     // translations can be used.

src/modules/packagechooser/PackageChooserViewStep.cpp

@@ -110,8 +110,6 @@ PackageChooserViewStep::isNextEnabled() const
         // exactly one OR one or more
         return m_widget->hasSelection();
     }
-
-    NOTREACHED return true;
 }