Require C++20 for building Stepmania.

src/Background.cpp

@@ -538,7 +538,7 @@ void BackgroundImpl::LoadFromSong( const Song* pSong )
 
 		// Pick the same random items every time the song is played.
 		RandomGen rnd( GetHashForString(pSong->GetSongDir()) );
-		random_shuffle( vsNames.begin(), vsNames.end(), rnd );
+		std::shuffle( vsNames.begin(), vsNames.end(), rnd );
 		int iSize = std::min( (int)g_iNumBackgrounds, (int)vsNames.size() );
 		vsNames.resize( iSize );
 

src/CMakeLists.txt

@@ -87,7 +87,7 @@ else()
                  ${SMDATA_ALL_FILES_HPP})
 endif()
 
-set_property(TARGET "${SM_EXE_NAME}" PROPERTY CXX_STANDARD 11)
+set_property(TARGET "${SM_EXE_NAME}" PROPERTY CXX_STANDARD 20)
 set_property(TARGET "${SM_EXE_NAME}" PROPERTY CXX_STANDARD_REQUIRED ON)
 set_property(TARGET "${SM_EXE_NAME}" PROPERTY CXX_EXTENSIONS ON)
 

src/Command.cpp

@@ -81,7 +81,7 @@ static void SplitWithQuotes( const RString sSource, const char Delimitor, std::v
 
 RString Commands::GetOriginalCommandString() const
 {
-	return std::accumulate(v.begin(), v.end(), RString(), [](RString &res, Command const &c) { return res + c.GetOriginalCommandString(); });
+	return std::accumulate(v.begin(), v.end(), RString(), [](RString const &res, Command const &c) { return res + c.GetOriginalCommandString(); });
 }
 
 void ParseCommands( const RString &sCommands, Commands &vCommandsOut, bool bLegacy )

src/Course.cpp

@@ -368,7 +368,7 @@ static void CourseSortSongs( SongSort sort, std::vector<Song*> &vpPossibleSongs,
 	{
 	DEFAULT_FAIL(sort);
 	case SongSort_Randomize:
-		random_shuffle( vpPossibleSongs.begin(), vpPossibleSongs.end(), rnd );
+		shuffle( vpPossibleSongs.begin(), vpPossibleSongs.end(), rnd );
 		break;
 	case SongSort_MostPlays:
 		if( PROFILEMAN )
@@ -428,7 +428,7 @@ bool Course::GetTrailUnsorted( StepsType st, CourseDifficulty cd, Trail &trail )
 		* will change every time it's viewed, and the displayed order will have no
 		* bearing on what you'll actually play. */
 		tmp_entries = m_vEntries;
-		random_shuffle( tmp_entries.begin(), tmp_entries.end(), rnd );
+		shuffle( tmp_entries.begin(), tmp_entries.end(), rnd );
 	}
 
 	const std::vector<CourseEntry> &entries = m_bShuffle ? tmp_entries:m_vEntries;
@@ -589,8 +589,10 @@ bool Course::GetTrailUnsorted( StepsType st, CourseDifficulty cd, Trail &trail )
 					int iAdd;
 					if( iMaxDist == iMinDist )
 						iAdd = iMaxDist;
-					else
-						iAdd = rnd( iMaxDist - iMinDist ) + iMinDist;
+					else {
+						std::uniform_int_distribution<> dist( iMinDist, iMaxDist );
+						iAdd = dist( rnd );
+					}
 					iLowMeter += iAdd;
 					iHighMeter += iAdd;
 				}
@@ -820,8 +822,10 @@ void Course::GetTrailUnsortedEndless( const std::vector<CourseEntry> &entries, T
 				int iAdd;
 				if( iMaxDist == iMinDist )
 					iAdd = iMaxDist;
-				else
-					iAdd = rnd( iMaxDist - iMinDist ) + iMinDist;
+				else {
+					std::uniform_int_distribution<> dist( iMinDist, iMaxDist );
+					iAdd = dist( rnd );
+				}
 				iLowMeter += iAdd;
 				iHighMeter += iAdd;
 			}

src/CourseUtil.cpp

@@ -304,7 +304,7 @@ void CourseUtil::AutogenOniFromArtist( const RString &sArtistName, RString sArti
 	 * song set changes. */
 	{
 		RandomGen rng( GetHashForString( sArtistName ) + aSongs.size() );
-		random_shuffle( aSongs.begin(), aSongs.end(), rng );
+		shuffle( aSongs.begin(), aSongs.end(), rng );
 	}
 
 	// Only use up to four songs.

src/GameSoundManager.cpp

@@ -318,7 +318,7 @@ static void DoPlayOnceFromDir( RString sPath )
 		{
 			order.push_back(i);
 		}
-		std::random_shuffle(order.begin(), order.end());
+		std::shuffle( order.begin(), order.end(), g_RandomNumberGenerator );
 	}
 
 	int index = order.back();

src/MusicWheel.cpp

@@ -1333,7 +1333,7 @@ void MusicWheel::StartRandom()
 	{
 		// Shuffle and use the roulette wheel.
 		RandomGen rnd;
-		random_shuffle( getWheelItemsData(SORT_ROULETTE).begin(), getWheelItemsData(SORT_ROULETTE).end(), rnd );
+		shuffle( getWheelItemsData(SORT_ROULETTE).begin(), getWheelItemsData(SORT_ROULETTE).end(), rnd );
 		GAMESTATE->m_SortOrder.Set( SORT_ROULETTE );
 	}
 	else

src/NoteDataUtil.cpp

@@ -1535,19 +1535,19 @@ static void GetTrackMapping( StepsType st, NoteDataUtil::TrackMapping tt, int Nu
 				switch(st) {
 					case StepsType_beat_single5:
 					{
-						std::random_shuffle( &iTakeFromTrack[0], &iTakeFromTrack[5], rnd );
-						std::random_shuffle( &iTakeFromTrack[6], &iTakeFromTrack[11], rnd );
+						std::shuffle( &iTakeFromTrack[0], &iTakeFromTrack[5], rnd );
+						std::shuffle( &iTakeFromTrack[6], &iTakeFromTrack[11], rnd );
 						break;
 					}
 					case StepsType_beat_single7:
 					{
-						std::random_shuffle( &iTakeFromTrack[1], &iTakeFromTrack[8], rnd );
-						std::random_shuffle( &iTakeFromTrack[9], &iTakeFromTrack[16], rnd );
+						std::shuffle( &iTakeFromTrack[1], &iTakeFromTrack[8], rnd );
+						std::shuffle( &iTakeFromTrack[9], &iTakeFromTrack[16], rnd );
 						break;
 					}
 					default:
 					{
-						std::random_shuffle( &iTakeFromTrack[0], &iTakeFromTrack[NumTracks], rnd );
+						std::shuffle( &iTakeFromTrack[0], &iTakeFromTrack[NumTracks], rnd );
 						break;
 					}
 				}
@@ -1970,7 +1970,7 @@ static void HyperShuffleNotes( NoteData &inout, int iStartIndex, int iEndIndex)
 		for(int i = iActualTaps; i < iFreeTracks; i++)
 			vtnTargetTaps.push_back(TAP_EMPTY);
 
-		std::random_shuffle(viTargetTracks.begin(), viTargetTracks.end(), g_RandomNumberGenerator);
+		std::shuffle(viTargetTracks.begin(), viTargetTracks.end(), g_RandomNumberGenerator);
 
 		// Go through the tracks in their shuffled order and drop tap notes.
 		for(int i = 0; i < viTargetTracks.size(); i++)

src/OptionRow.cpp

@@ -544,7 +544,7 @@ void OptionRow::SetDestination( Actor::TweenState &ts, bool bTween )
 	if( m_Frame.DestTweenState() != ts )
 	{
 		m_Frame.StopTweening();
-		if( bTween && m_pParentType->TWEEN_SECONDS != 0 )
+		if( bTween && m_pParentType->TWEEN_SECONDS != 0.0f )
 			m_Frame.BeginTweening( m_pParentType->TWEEN_SECONDS );
 		m_Frame.DestTweenState() = ts;
 	}

src/RageUtil.cpp

@@ -29,74 +29,6 @@ void UnicodeUpperLower(wchar_t *, size_t, const unsigned char *);
 
 RandomGen g_RandomNumberGenerator;
 
-MersenneTwister::MersenneTwister( int iSeed ) : m_iNext(0)
-{
-	Reset( iSeed );
-}
-
-void MersenneTwister::Reset( int iSeed )
-{
-	if( iSeed == 0 )
-		iSeed = time(nullptr);
-
-	m_Values[0] = iSeed;
-	m_iNext = 0;
-	for( int i = 1; i < 624; ++i )
-		m_Values[i] = ((69069 * m_Values[i-1]) + 1) & 0xFFFFFFFF;
-
-	GenerateValues();
-}
-
-void MersenneTwister::GenerateValues()
-{
-	static const unsigned mask[] = { 0, 0x9908B0DF };
-
-	for( int i = 0; i < 227; ++i )
-	{
-		int iVal = (m_Values[i] & 0x80000000) | (m_Values[i+1] & 0x7FFFFFFF);
-		int iNext = (i + 397);
-
-		m_Values[i] = m_Values[iNext];
-		m_Values[i] ^= (iVal >> 1);
-		m_Values[i] ^= mask[iVal&1];
-	}
-
-	for( int i = 227; i < 623; ++i )
-	{
-		int iVal = (m_Values[i] & 0x80000000) | (m_Values[i+1] & 0x7FFFFFFF);
-		int iNext = (i + 397) - 624;
-
-		m_Values[i] = m_Values[iNext];
-		m_Values[i] ^= (iVal >> 1);
-		m_Values[i] ^= mask[iVal&1];
-	}
-
-	int iVal = (m_Values[623] & 0x80000000) + (m_Values[0] & 0x7FFFFFFF);
-	int iNext = (623 + 397) - 624;
-	m_Values[623] = m_Values[iNext] ^ (iVal>>1);
-	m_Values[623] ^= mask[iVal&1];
-}
-
-int MersenneTwister::Temper( int iVal )
-{
-	iVal ^= (iVal >> 11);
-	iVal ^= (iVal << 7) & 0x9D2C5680;
-	iVal ^= (iVal << 15) & 0xEFC60000;
-	iVal ^= (iVal >> 18);
-	return iVal;
-}
-
-int MersenneTwister::operator()()
-{
-	if( m_iNext == 624 )
-	{
-		m_iNext = 0;
-		GenerateValues();
-	}
-
-	return Temper( m_Values[m_iNext++] );
-}
-
 /* Extend MersenneTwister into Lua space. This is intended to replace
  * math.randomseed and math.random, so we conform to their behavior. */
 
@@ -109,7 +41,7 @@ namespace
 
 	static int Seed( lua_State *L )
 	{
-		g_LuaPRNG.Reset( IArg(1) );
+		g_LuaPRNG = MersenneTwister( IArg(1) );
 		return 0;
 	}
 
@@ -120,7 +52,8 @@ namespace
 			/* [0..1) */
 			case 0:
 			{
-				double r = double(g_LuaPRNG()) / DIVISOR;
+				std::uniform_real_distribution<> dist( 0, 1 );
+				double r = dist( g_LuaPRNG );
 				lua_pushnumber( L, r );
 				return 1;
 			}
@@ -130,7 +63,8 @@ namespace
 			{
 				int upper = IArg(1);
 				luaL_argcheck( L, 1 <= upper, 1, "interval is empty" );
-				lua_pushnumber( L, g_LuaPRNG(upper) + 1 );
+				std::uniform_int_distribution<> dist( 1, upper );
+				lua_pushnumber( L, dist( g_LuaPRNG ) );
 				return 1;
 			}
 			/* [l..u] */
@@ -139,7 +73,8 @@ namespace
 				int lower = IArg(1);
 				int upper = IArg(2);
 				luaL_argcheck( L, lower < upper, 2, "interval is empty" );
-				lua_pushnumber( L, (int(g_LuaPRNG()) % (upper-lower+1)) + lower );
+				std::uniform_int_distribution<> dist( lower, upper );
+				lua_pushnumber( L, dist( g_LuaPRNG ) );
 				return 1;
 			}
 

src/RageUtil.h

@@ -4,6 +4,7 @@
 #define RAGE_UTIL_H
 
 #include <map>
+#include <random>
 #include <vector>
 #include <sstream>
 #include "global.h"
@@ -230,37 +231,16 @@ inline uint32_t Swap24LE( uint32_t n ) { return Swap24( n ); }
 inline uint16_t Swap16LE( uint16_t n ) { return Swap16( n ); }
 #endif
 
-struct MersenneTwister
+class MersenneTwister : public std::mt19937
 {
-	MersenneTwister( int iSeed = 0 ); // 0 = time()
-	int operator()(); // returns [0,2^31-1]
-	int operator()( int n ) // returns [0,n)
-	{
-		return (*this)() % n;
-	}
-
-	void Reset( int iSeed );
-
-private:
-	static int Temper( int iValue );
-	void GenerateValues();
-
-	int m_Values[624];
-	int m_iNext;
+public:
+	MersenneTwister( int iSeed = 0 ) : std::mt19937( iSeed == 0 ? time( nullptr ) : iSeed ) {}
 };
+
 typedef MersenneTwister RandomGen;
 
 extern RandomGen g_RandomNumberGenerator;
 
-/**
- * @brief Generate a random float between 0 inclusive and 1 exclusive.
- * @return the random float.
- */
-inline float RandomFloat()
-{
-	return g_RandomNumberGenerator() / 2147483648.0f;
-}
-
 /**
  * @brief Return a float between the low and high values.
  * @param fLow the low value, inclusive.
@@ -269,19 +249,30 @@ inline float RandomFloat()
  */
 inline float RandomFloat( float fLow, float fHigh )
 {
-	return SCALE( RandomFloat(), 0.0f, 1.0f, fLow, fHigh );
+	std::uniform_real_distribution<> dist( fLow, fHigh );
+	return dist( g_RandomNumberGenerator );
+}
+
+/**
+ * @brief Generate a random float between 0 inclusive and 1 exclusive.
+ * @return the random float.
+ */
+inline float RandomFloat()
+{
+	return RandomFloat( 0, 1 );
 }
 
 // Returns an integer between nLow and nHigh inclusive
 inline int RandomInt( int nLow, int nHigh )
 {
-	return int( g_RandomNumberGenerator(nHigh - nLow + 1) + nLow );
+	std::uniform_int_distribution<> dist( nLow, nHigh );
+	return dist( g_RandomNumberGenerator );
 }
 
 // Returns an integer between 0 and n-1 inclusive (replacement for rand() % n).
 inline int RandomInt( int n )
 {
-	return int( g_RandomNumberGenerator(n) );
+	return RandomInt( 0, n - 1 );
 }
 
 

src/RandomSample.cpp

@@ -56,7 +56,7 @@ bool RandomSample::LoadSoundDir( RString sDir, int iMaxToLoad )
 	GetDirListing( sDir + "*.ogg", arraySoundFiles );
 	GetDirListing( sDir + "*.wav", arraySoundFiles );
 
-	std::random_shuffle( arraySoundFiles.begin(), arraySoundFiles.end() );
+	std::shuffle( arraySoundFiles.begin(), arraySoundFiles.end(), g_RandomNumberGenerator );
 	const unsigned int newSize = std::min<unsigned int>(arraySoundFiles.size(), static_cast<unsigned int>(iMaxToLoad));
 	arraySoundFiles.resize(newSize);
 

src/ScreenOptionsCourseOverview.cpp

@@ -202,7 +202,7 @@ void ScreenOptionsCourseOverview::ProcessMenuStart( const InputEventPlus &input
 	case CourseOverviewRow_Shuffle:
 		{
 			Course *pCourse = GAMESTATE->m_pCurCourse;
-			random_shuffle( pCourse->m_vEntries.begin(), pCourse->m_vEntries.end() );
+			shuffle( pCourse->m_vEntries.begin(), pCourse->m_vEntries.end(), g_RandomNumberGenerator );
 			Trail *pTrail = pCourse->GetTrailForceRegenCache( GAMESTATE->GetCurrentStyle(input.pn)->m_StepsType );
 			GAMESTATE->m_pCurTrail[PLAYER_1].Set( pTrail );
 			SCREENMAN->PlayStartSound();

src/ScreenOptionsReviewWorkout.cpp

@@ -146,7 +146,7 @@ void ScreenOptionsCourseOverview::ProcessMenuStart( const InputEventPlus &input
 	case ReviewWorkoutRow_Shuffle:
 		{
 			Course *pCourse = GAMESTATE->m_pCurCourse;
-			random_shuffle( pCourse->m_vEntries.begin(), pCourse->m_vEntries.end() );
+			shuffle( pCourse->m_vEntries.begin(), pCourse->m_vEntries.end(), g_RandomNumberGenerator );
 			Trail *pTrail = pCourse->GetTrailForceRegenCache( GAMESTATE->m_pCurStyle->m_StepsType );
 			GAMESTATE->m_pCurTrail[PLAYER_1].Set( pTrail );
 			SCREENMAN->PlayStartSound();

src/ScreenWithMenuElements.cpp

@@ -52,7 +52,7 @@ void ScreenWithMenuElements::Init()
 		}
 	}
 
-	if( TIMER_SECONDS != -1 )
+	if( TIMER_SECONDS != -1.0f )
 	{
 		ASSERT( m_MenuTimer == nullptr );	// don't load twice
 		m_MenuTimer = new MenuTimer;

src/SongManager.cpp

@@ -1585,10 +1585,10 @@ void SongManager::UpdateShuffled()
 {
 	// update shuffled
 	m_pShuffledSongs = m_pSongs;
-	random_shuffle( m_pShuffledSongs.begin(), m_pShuffledSongs.end(), g_RandomNumberGenerator );
+	shuffle( m_pShuffledSongs.begin(), m_pShuffledSongs.end(), g_RandomNumberGenerator );
 
 	m_pShuffledCourses = m_pCourses;
-	random_shuffle( m_pShuffledCourses.begin(), m_pShuffledCourses.end(), g_RandomNumberGenerator );
+	shuffle( m_pShuffledCourses.begin(), m_pShuffledCourses.end(), g_RandomNumberGenerator );
 }
 
 void SongManager::UpdatePreferredSort(RString sPreferredSongs, RString sPreferredCourses)