diff --git a/std/datetime/systime.d b/std/datetime/systime.d
index 305f10c16..687c02766 100644
--- a/std/datetime/systime.d
+++ b/std/datetime/systime.d
@@ -419,7 +419,7 @@ public:
                        given $(REF DateTime,std,datetime,date) is assumed to
                        be in the given time zone.
       +/
-    this(scope const DateTime dateTime, immutable TimeZone tz = null) @safe nothrow
+    this(DateTime dateTime, immutable TimeZone tz = null) @safe nothrow
     {
         try
             this(dateTime, Duration.zero, tz);
@@ -446,6 +446,11 @@ public:
         test(DateTime(1, 1, 1, 0, 0, 0), new immutable SimpleTimeZone(dur!"minutes"(-60)), 36_000_000_000L);
         test(DateTime(1, 1, 1, 0, 0, 0), new immutable SimpleTimeZone(Duration.zero), 0);
         test(DateTime(1, 1, 1, 0, 0, 0), new immutable SimpleTimeZone(dur!"minutes"(60)), -36_000_000_000L);
+
+        static void testScope(scope ref DateTime dt) @safe
+        {
+            auto st = SysTime(dt);
+        }
     }
 
     /++
@@ -465,7 +470,7 @@ public:
             $(REF DateTimeException,std,datetime,date) if `fracSecs` is negative or if it's
             greater than or equal to one second.
       +/
-    this(scope const DateTime dateTime, scope const Duration fracSecs, immutable TimeZone tz = null) @safe
+    this(DateTime dateTime, Duration fracSecs, immutable TimeZone tz = null) @safe
     {
         enforce(fracSecs >= Duration.zero, new DateTimeException("A SysTime cannot have negative fractional seconds."));
         enforce(fracSecs < seconds(1), new DateTimeException("Fractional seconds must be less than one second."));
@@ -503,6 +508,11 @@ public:
 
         assertThrown!DateTimeException(SysTime(DateTime.init, hnsecs(-1), UTC()));
         assertThrown!DateTimeException(SysTime(DateTime.init, seconds(1), UTC()));
+
+        static void testScope(scope ref DateTime dt, scope ref Duration d) @safe
+        {
+            auto st = SysTime(dt, d);
+        }
     }
 
     /++
@@ -517,7 +527,7 @@ public:
                    given $(REF Date,std,datetime,date) is assumed to be in the
                    given time zone.
       +/
-    this(scope const Date date, immutable TimeZone tz = null) @safe nothrow
+    this(Date date, immutable TimeZone tz = null) @safe nothrow
     {
         _timezone = tz is null ? LocalTime() : tz;
 
@@ -545,6 +555,11 @@ public:
         test(Date(1, 1, 1), UTC(), 0);
         test(Date(1, 1, 2), UTC(), 864000000000);
         test(Date(0, 12, 31), UTC(), -864000000000);
+
+        static void testScope(scope ref Date d) @safe
+        {
+            auto st = SysTime(d);
+        }
     }
 
     /++
@@ -587,28 +602,37 @@ public:
         }
     }
 
+
     /++
         Params:
             rhs = The $(LREF SysTime) to assign to this one.
+
+        Returns: The `this` of this `SysTime`.
       +/
-    ref SysTime opAssign(const ref SysTime rhs) return @safe pure nothrow
+    ref SysTime opAssign()(auto ref const(SysTime) rhs) return @safe pure nothrow scope
     {
         _stdTime = rhs._stdTime;
         _timezone = rhs._timezone;
         return this;
     }
 
-    /++
-        Params:
-            rhs = The $(LREF SysTime) to assign to this one.
-      +/
-    ref SysTime opAssign(SysTime rhs) scope return @safe pure nothrow
+    @safe unittest
     {
-        _stdTime = rhs._stdTime;
-        _timezone = rhs._timezone;
-        return this;
+        SysTime st;
+        st = SysTime(DateTime(2012, 12, 21, 1, 2, 3), UTC());
+        assert(st == SysTime(DateTime(2012, 12, 21, 1, 2, 3), UTC()));
+
+        const other = SysTime(DateTime(19, 1, 7, 13, 14, 15), LocalTime());
+        st = other;
+        assert(st == other);
+
+        static void testScope(scope ref SysTime left, const scope SysTime right) @safe
+        {
+            left = right;
+        }
     }
 
+
     /++
         Checks for equality between this $(LREF SysTime) and the given
         $(LREF SysTime).
@@ -616,13 +640,7 @@ public:
         Note that the time zone is ignored. Only the internal
         std times (which are in UTC) are compared.
      +/
-    bool opEquals(const SysTime rhs) @safe const pure nothrow
-    {
-        return opEquals(rhs);
-    }
-
-    /// ditto
-    bool opEquals(const ref SysTime rhs) @safe const pure nothrow
+    bool opEquals()(auto ref const(SysTime) rhs) @safe const pure nothrow scope
     {
         return _stdTime == rhs._stdTime;
     }
@@ -658,18 +676,25 @@ public:
 
         auto st = SysTime(DateTime(1999, 7, 6, 12, 33, 30));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 33, 30));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 33, 30));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 33, 30));
         assert(st == st);
         assert(st == cst);
-        //assert(st == ist);
+        assert(st == ist);
         assert(cst == st);
         assert(cst == cst);
-        //assert(cst == ist);
-        //assert(ist == st);
-        //assert(ist == cst);
-        //assert(ist == ist);
+        assert(cst == ist);
+        assert(ist == st);
+        assert(ist == cst);
+        assert(ist == ist);
+
+        static void testScope(scope ref SysTime left, const scope SysTime right) @safe
+        {
+            assert(left == right);
+            assert(right == left);
+        }
     }
 
+
     /++
         Compares this $(LREF SysTime) with the given $(LREF SysTime).
 
@@ -682,7 +707,7 @@ public:
             $(TR $(TD this &gt; rhs) $(TD &gt; 0))
             )
      +/
-    int opCmp(scope const SysTime rhs) @safe const pure nothrow
+    int opCmp()(auto ref const(SysTime) rhs) @safe const pure nothrow scope
     {
         if (_stdTime < rhs._stdTime)
             return -1;
@@ -746,22 +771,29 @@ public:
 
         auto st = SysTime(DateTime(1999, 7, 6, 12, 33, 30));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 33, 30));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 33, 30));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 33, 30));
         assert(st.opCmp(st) == 0);
         assert(st.opCmp(cst) == 0);
-        //assert(st.opCmp(ist) == 0);
+        assert(st.opCmp(ist) == 0);
         assert(cst.opCmp(st) == 0);
         assert(cst.opCmp(cst) == 0);
-        //assert(cst.opCmp(ist) == 0);
-        //assert(ist.opCmp(st) == 0);
-        //assert(ist.opCmp(cst) == 0);
-        //assert(ist.opCmp(ist) == 0);
+        assert(cst.opCmp(ist) == 0);
+        assert(ist.opCmp(st) == 0);
+        assert(ist.opCmp(cst) == 0);
+        assert(ist.opCmp(ist) == 0);
+
+        static void testScope(scope ref SysTime left, const scope SysTime right) @safe
+        {
+            assert(left < right);
+            assert(right > left);
+        }
     }
 
-    /**
-     * Returns: A hash of the $(LREF SysTime)
-     */
-    size_t toHash() const @nogc pure nothrow @safe
+
+    /++
+        Returns: A hash of the $(LREF SysTime).
+     +/
+    size_t toHash() const @nogc pure nothrow @safe scope
     {
         static if (is(size_t == ulong))
             return _stdTime;
@@ -798,13 +830,19 @@ public:
         immutable zone = new SimpleTimeZone(dur!"minutes"(60));
         assert(SysTime(DateTime(2000, 1, 1, 1), zone).toHash == SysTime(DateTime(2000, 1, 1), UTC()).toHash);
         assert(SysTime(DateTime(2000, 1, 1), zone).toHash != SysTime(DateTime(2000, 1, 1), UTC()).toHash);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toHash();
+        }
     }
 
+
     /++
         Year of the Gregorian Calendar. Positive numbers are A.D. Non-positive
         are B.C.
      +/
-    @property short year() @safe const nothrow
+    @property short year() @safe const nothrow scope
     {
         return (cast(Date) this).year;
     }
@@ -838,9 +876,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.year == 1999);
-        //assert(ist.year == 1999);
+        assert(ist.year == 1999);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.year;
+        }
     }
 
     /++
@@ -854,7 +897,7 @@ public:
             $(REF DateTimeException,std,datetime,date) if the new year is not
             a leap year and the resulting date would be on February 29th.
      +/
-    @property void year(int year) @safe
+    @property void year(int year) @safe scope
     {
         auto hnsecs = adjTime;
         auto days = splitUnitsFromHNSecs!"days"(hnsecs) + 1;
@@ -886,7 +929,7 @@ public:
     {
         import std.range : chain;
 
-        static void test(SysTime st, int year, scope const SysTime expected)
+        static void test(SysTime st, int year, SysTime expected)
         {
             st.year = year;
             assert(st == expected);
@@ -926,9 +969,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.year = 7));
-        //static assert(!__traits(compiles, ist.year = 7));
+        static assert(!__traits(compiles, ist.year = 7));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.year = 42;
+        }
     }
 
     /++
@@ -937,7 +985,7 @@ public:
         Throws:
             $(REF DateTimeException,std,datetime,date) if `isAD` is true.
      +/
-    @property ushort yearBC() @safe const
+    @property ushort yearBC() @safe const scope
     {
         return (cast(Date) this).yearBC;
     }
@@ -967,11 +1015,16 @@ public:
 
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         st.year = 12;
         assert(st.year == 12);
         static assert(!__traits(compiles, cst.year = 12));
-        //static assert(!__traits(compiles, ist.year = 12));
+        static assert(!__traits(compiles, ist.year = 12));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.yearBC;
+        }
     }
 
 
@@ -985,7 +1038,7 @@ public:
             $(REF DateTimeException,std,datetime,date) if a non-positive value
             is given.
      +/
-    @property void yearBC(int year) @safe
+    @property void yearBC(int year) @safe scope
     {
         auto hnsecs = adjTime;
         auto days = splitUnitsFromHNSecs!"days"(hnsecs) + 1;
@@ -1016,7 +1069,7 @@ public:
     @safe unittest
     {
         import std.range : chain;
-        static void test(SysTime st, int year, scope const SysTime expected)
+        static void test(SysTime st, int year, SysTime expected)
         {
             st.yearBC = year;
             assert(st == expected, format("SysTime: %s", st));
@@ -1063,17 +1116,23 @@ public:
 
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         st.yearBC = 12;
         assert(st.yearBC == 12);
         static assert(!__traits(compiles, cst.yearBC = 12));
-        //static assert(!__traits(compiles, ist.yearBC = 12));
+        static assert(!__traits(compiles, ist.yearBC = 12));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.yearBC = 42;
+        }
     }
 
+
     /++
         Month of a Gregorian Year.
      +/
-    @property Month month() @safe const nothrow
+    @property Month month() @safe const nothrow scope
     {
         return (cast(Date) this).month;
     }
@@ -1118,9 +1177,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.month == 7);
-        //assert(ist.month == 7);
+        assert(ist.month == 7);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.month;
+        }
     }
 
 
@@ -1134,7 +1198,7 @@ public:
             $(REF DateTimeException,std,datetime,date) if the given month is
             not a valid month.
      +/
-    @property void month(Month month) @safe
+    @property void month(Month month) @safe scope
     {
         auto hnsecs = adjTime;
         auto days = splitUnitsFromHNSecs!"days"(hnsecs) + 1;
@@ -1157,7 +1221,7 @@ public:
         import std.algorithm.iteration : filter;
         import std.range : chain;
 
-        static void test(SysTime st, Month month, scope const SysTime expected)
+        static void test(SysTime st, Month month, SysTime expected)
         {
             st.month = cast(Month) month;
             assert(st == expected);
@@ -1226,15 +1290,20 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        static assert(!__traits(compiles, cst.month = 12));
-        //static assert(!__traits(compiles, ist.month = 12));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        static assert(!__traits(compiles, cst.month = Month.dec));
+        static assert(!__traits(compiles, ist.month = Month.dec));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.month = Month.dec;
+        }
     }
 
     /++
         Day of a Gregorian Month.
      +/
-    @property ubyte day() @safe const nothrow
+    @property ubyte day() @safe const nothrow scope
     {
         return (cast(Date) this).day;
     }
@@ -1280,9 +1349,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
          assert(cst.day == 6);
-        //assert(ist.day == 6);
+        assert(ist.day == 6);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.day;
+        }
     }
 
 
@@ -1296,7 +1370,7 @@ public:
             $(REF DateTimeException,std,datetime,date) if the given day is not
             a valid day of the current month.
      +/
-    @property void day(int day) @safe
+    @property void day(int day) @safe scope
     {
         auto hnsecs = adjTime;
         auto days = splitUnitsFromHNSecs!"days"(hnsecs) + 1;
@@ -1380,16 +1454,21 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.day = 27));
-        //static assert(!__traits(compiles, ist.day = 27));
+        static assert(!__traits(compiles, ist.day = 27));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.day = 12;
+        }
     }
 
 
     /++
         Hours past midnight.
      +/
-    @property ubyte hour() @safe const nothrow
+    @property ubyte hour() @safe const nothrow scope
     {
         auto hnsecs = adjTime;
         auto days = splitUnitsFromHNSecs!"days"(hnsecs) + 1;
@@ -1439,9 +1518,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.hour == 12);
-        //assert(ist.hour == 12);
+        assert(ist.hour == 12);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.hour;
+        }
     }
 
 
@@ -1455,7 +1539,7 @@ public:
             $(REF DateTimeException,std,datetime,date) if the given hour are
             not a valid hour of the day.
      +/
-    @property void hour(int hour) @safe
+    @property void hour(int hour) @safe scope
     {
         enforceValid!"hours"(hour);
 
@@ -1498,16 +1582,21 @@ public:
         assertThrown!DateTimeException(st.hour = 60);
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.hour = 27));
-        //static assert(!__traits(compiles, ist.hour = 27));
+        static assert(!__traits(compiles, ist.hour = 27));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.hour = 12;
+        }
     }
 
 
     /++
         Minutes past the current hour.
      +/
-    @property ubyte minute() @safe const nothrow
+    @property ubyte minute() @safe const nothrow scope
     {
         auto hnsecs = adjTime;
         auto days = splitUnitsFromHNSecs!"days"(hnsecs) + 1;
@@ -1559,9 +1648,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.minute == 30);
-        //assert(ist.minute == 30);
+        assert(ist.minute == 30);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.minute;
+        }
     }
 
 
@@ -1575,7 +1669,7 @@ public:
             $(REF DateTimeException,std,datetime,date) if the given minute are
             not a valid minute of an hour.
      +/
-    @property void minute(int minute) @safe
+    @property void minute(int minute) @safe scope
     {
         enforceValid!"minutes"(minute);
 
@@ -1621,16 +1715,21 @@ public:
         assertThrown!DateTimeException(st.minute = 60);
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.minute = 27));
-        //static assert(!__traits(compiles, ist.minute = 27));
+        static assert(!__traits(compiles, ist.minute = 27));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.minute = 12;
+        }
     }
 
 
     /++
         Seconds past the current minute.
      +/
-    @property ubyte second() @safe const nothrow
+    @property ubyte second() @safe const nothrow scope
     {
         auto hnsecs = adjTime;
         auto days = splitUnitsFromHNSecs!"days"(hnsecs) + 1;
@@ -1683,9 +1782,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.second == 33);
-        //assert(ist.second == 33);
+        assert(ist.second == 33);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.second;
+        }
     }
 
 
@@ -1699,7 +1803,7 @@ public:
             $(REF DateTimeException,std,datetime,date) if the given second are
             not a valid second of a minute.
      +/
-    @property void second(int second) @safe
+    @property void second(int second) @safe scope
     {
         enforceValid!"seconds"(second);
 
@@ -1747,9 +1851,14 @@ public:
         assertThrown!DateTimeException(st.second = 60);
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.seconds = 27));
-        //static assert(!__traits(compiles, ist.seconds = 27));
+        static assert(!__traits(compiles, ist.seconds = 27));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.second = 12;
+        }
     }
 
 
@@ -1757,7 +1866,7 @@ public:
         Fractional seconds past the second (i.e. the portion of a
         $(LREF SysTime) which is less than a second).
      +/
-    @property Duration fracSecs() scope @safe const nothrow
+    @property Duration fracSecs() @safe const nothrow scope
     {
         auto hnsecs = removeUnitsFromHNSecs!"days"(adjTime);
 
@@ -1815,9 +1924,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.fracSecs == Duration.zero);
-        //assert(ist.fracSecs == Duration.zero);
+        assert(ist.fracSecs == Duration.zero);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.fracSecs;
+        }
     }
 
 
@@ -1833,7 +1947,7 @@ public:
             $(REF DateTimeException,std,datetime,date) if the given duration
             is negative or if it's greater than or equal to one second.
      +/
-    @property void fracSecs(Duration fracSecs) @safe
+    @property void fracSecs(Duration fracSecs) @safe scope
     {
         enforce(fracSecs >= Duration.zero, new DateTimeException("A SysTime cannot have negative fractional seconds."));
         enforce(fracSecs < seconds(1), new DateTimeException("Fractional seconds must be less than one second."));
@@ -1898,9 +2012,14 @@ public:
         assertThrown!DateTimeException(st.fracSecs = seconds(1));
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.fracSecs = msecs(7)));
-        //static assert(!__traits(compiles, ist.fracSecs = msecs(7)));
+        static assert(!__traits(compiles, ist.fracSecs = msecs(7)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.fracSecs = Duration.zero;
+        }
     }
 
 
@@ -1908,7 +2027,7 @@ public:
         The total hnsecs from midnight, January 1st, 1 A.D. UTC. This is the
         internal representation of $(LREF SysTime).
      +/
-    @property long stdTime() @safe const pure nothrow
+    @property long stdTime() @safe const pure nothrow scope
     {
         return _stdTime;
     }
@@ -1923,9 +2042,14 @@ public:
         assert(SysTime(DateTime(1970, 1, 1, 0, 0, 0), UTC()).stdTime == 621_355_968_000_000_000L);
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.stdTime > 0);
-        //assert(ist.stdTime > 0);
+        assert(ist.stdTime > 0);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.stdTime;
+        }
     }
 
 
@@ -1936,7 +2060,7 @@ public:
         Params:
             stdTime = The number of hnsecs since January 1st, 1 A.D. UTC.
      +/
-    @property void stdTime(long stdTime) @safe pure nothrow
+    @property void stdTime(long stdTime) @safe pure nothrow scope
     {
         _stdTime = stdTime;
     }
@@ -1944,7 +2068,7 @@ public:
     @safe unittest
     {
         import core.time;
-        static void test(long stdTime, scope const SysTime expected, size_t line = __LINE__)
+        static void test(long stdTime, SysTime expected, size_t line = __LINE__)
         {
             auto st = SysTime(0, UTC());
             st.stdTime = stdTime;
@@ -1958,9 +2082,14 @@ public:
         test(621_355_968_000_000_000L, SysTime(DateTime(1970, 1, 1, 0, 0, 0), UTC()));
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.stdTime = 27));
-        //static assert(!__traits(compiles, ist.stdTime = 27));
+        static assert(!__traits(compiles, ist.stdTime = 27));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.stdTime = 42;
+        }
     }
 
 
@@ -1971,11 +2100,22 @@ public:
         hours - adjust the time to this $(LREF SysTime)'s time zone before
         returning.
       +/
-    @property immutable(TimeZone) timezone() @safe const pure nothrow
+    @property immutable(TimeZone) timezone() @safe const pure nothrow scope
     {
         return _timezone;
     }
 
+    @safe unittest
+    {
+        assert(SysTime.init.timezone is InitTimeZone());
+        assert(SysTime(DateTime.init, UTC()).timezone is UTC());
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.timezone;
+        }
+    }
+
 
     /++
         The current time zone of this $(LREF SysTime). It's internal time is
@@ -1988,7 +2128,7 @@ public:
             timezone = The $(REF _TimeZone,std,datetime,_timezone) to set this
                        $(LREF SysTime)'s time zone to.
       +/
-    @property void timezone(immutable TimeZone timezone) @safe pure nothrow
+    @property void timezone(immutable TimeZone timezone) @safe pure nothrow scope
     {
         if (timezone is null)
             _timezone = LocalTime();
@@ -1996,11 +2136,25 @@ public:
             _timezone = timezone;
     }
 
+    @safe unittest
+    {
+        SysTime st;
+        st.timezone = null;
+        assert(st.timezone is LocalTime());
+        st.timezone = UTC();
+        assert(st.timezone is UTC());
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.timezone = UTC();
+        }
+    }
+
 
     /++
         Returns whether DST is in effect for this $(LREF SysTime).
       +/
-    @property bool dstInEffect() @safe const nothrow
+    @property bool dstInEffect() @safe const nothrow scope
     {
         return _timezone.dstInEffect(_stdTime);
     }
@@ -2011,6 +2165,11 @@ public:
     @safe unittest
     {
         assert(!SysTime.init.dstInEffect);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.dstInEffect;
+        }
     }
 
 
@@ -2018,7 +2177,7 @@ public:
         Returns what the offset from UTC is for this $(LREF SysTime).
         It includes the DST offset in effect at that time (if any).
       +/
-    @property Duration utcOffset() @safe const nothrow
+    @property Duration utcOffset() @safe const nothrow scope
     {
         return _timezone.utcOffsetAt(_stdTime);
     }
@@ -2029,6 +2188,11 @@ public:
     @safe unittest
     {
         assert(SysTime.init.utcOffset == Duration.zero);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.utcOffset;
+        }
     }
 
 
@@ -2036,7 +2200,7 @@ public:
         Returns a $(LREF SysTime) with the same std time as this one, but with
         $(REF LocalTime,std,datetime,timezone) as its time zone.
       +/
-    SysTime toLocalTime() @safe const pure nothrow
+    SysTime toLocalTime() @safe const pure nothrow scope
     {
         return SysTime(_stdTime, LocalTime());
     }
@@ -2062,6 +2226,11 @@ public:
             assert(sysTime.toLocalTime().timezone !is UTC());
             assert(sysTime.toLocalTime().timezone !is stz);
         }
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toLocalTime();
+        }
     }
 
 
@@ -2069,7 +2238,7 @@ public:
         Returns a $(LREF SysTime) with the same std time as this one, but with
         `UTC` as its time zone.
       +/
-    SysTime toUTC() @safe const pure nothrow
+    SysTime toUTC() @safe const pure nothrow scope
     {
         return SysTime(_stdTime, UTC());
     }
@@ -2083,6 +2252,11 @@ public:
         assert(sysTime.toUTC().timezone is UTC());
         assert(sysTime.toUTC().timezone !is LocalTime());
         assert(sysTime.toUTC().timezone !is sysTime.timezone);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toUTC();
+        }
     }
 
 
@@ -2090,7 +2264,7 @@ public:
         Returns a $(LREF SysTime) with the same std time as this one, but with
         given time zone as its time zone.
       +/
-    SysTime toOtherTZ(immutable TimeZone tz) @safe const pure nothrow
+    SysTime toOtherTZ(immutable TimeZone tz) @safe const pure nothrow scope
     {
         if (tz is null)
             return SysTime(_stdTime, LocalTime());
@@ -2108,6 +2282,12 @@ public:
         assert(sysTime.toOtherTZ(stz).timezone is stz);
         assert(sysTime.toOtherTZ(stz).timezone !is LocalTime());
         assert(sysTime.toOtherTZ(stz).timezone !is UTC());
+        assert(sysTime.toOtherTZ(null).timezone is LocalTime());
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toOtherTZ(null);
+        }
     }
 
 
@@ -2140,7 +2320,7 @@ public:
             A signed integer representing the unix time which is equivalent to
             this SysTime.
       +/
-    T toUnixTime(T = time_t)() @safe const pure nothrow
+    T toUnixTime(T = time_t)() @safe const pure nothrow scope
         if (is(T == int) || is(T == long))
     {
         return stdTimeToUnixTime!T(_stdTime);
@@ -2163,6 +2343,11 @@ public:
 
         auto ca = SysTime(DateTime(2007, 12, 22, 8, 14, 45), pst);
         assert(ca.toUnixTime() == 1_198_340_085);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toUnixTime();
+        }
     }
 
     @safe unittest
@@ -2252,7 +2437,7 @@ public:
         `tv_sec`. (so `int.max` if it goes over and `int.min` if it
         goes under).
       +/
-    timeval toTimeVal() @safe const pure nothrow
+    timeval toTimeVal() @safe const pure nothrow scope
     {
         immutable tv_sec = toUnixTime!(typeof(timeval.tv_sec))();
         immutable fracHNSecs = removeUnitsFromHNSecs!"seconds"(_stdTime - 621_355_968_000_000_000L);
@@ -2281,6 +2466,11 @@ public:
         assert(SysTime(DateTime(1969, 12, 31, 23, 59, 59), msecs(999), UTC()).toTimeVal() == timeval(0, -1000));
         assert(SysTime(DateTime(1969, 12, 31, 23, 59, 59), UTC()).toTimeVal() == timeval(-1, 0));
         assert(SysTime(DateTime(1969, 12, 31, 23, 59, 58), usecs(17), UTC()).toTimeVal() == timeval(-1, -999_983));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toTimeVal();
+        }
     }
 
 
@@ -2292,11 +2482,11 @@ public:
 
             $(BLUE This function is Posix-Only.)
           +/
-        timespec toTimeSpec() @safe const pure nothrow;
+        timespec toTimeSpec() @safe const pure nothrow scope;
     }
     else version(Posix)
     {
-        timespec toTimeSpec() @safe const pure nothrow
+        timespec toTimeSpec() @safe const pure nothrow scope
         {
             immutable tv_sec = toUnixTime!(typeof(timespec.tv_sec))();
             immutable fracHNSecs = removeUnitsFromHNSecs!"seconds"(_stdTime - 621_355_968_000_000_000L);
@@ -2332,13 +2522,18 @@ public:
                    timespec(-1, 0));
             assert(SysTime(DateTime(1969, 12, 31, 23, 59, 58), usecs(17), UTC()).toTimeSpec() ==
                    timespec(-1, -999_983_000));
+
+            static void testScope(scope ref SysTime st) @safe
+            {
+                auto result = st.toTimeSpec();
+            }
         }
     }
 
     /++
         Returns a `tm` which represents this $(LREF SysTime).
       +/
-    tm toTM() @safe const nothrow
+    tm toTM() @safe const nothrow scope
     {
         auto dateTime = cast(DateTime) this;
         tm timeInfo;
@@ -2446,6 +2641,11 @@ public:
                 assert(to!string(timeInfo.tm_zone) == "SysTime.init's timezone");
             }
         }
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toTM();
+        }
     }
 
 
@@ -2468,7 +2668,7 @@ public:
             allowOverflow = Whether the days should be allowed to overflow,
                             causing the month to increment.
       +/
-    ref SysTime add(string units)(long value, AllowDayOverflow allowOverflow = AllowDayOverflow.yes) @safe nothrow
+    ref SysTime add(string units)(long value, AllowDayOverflow allowOverflow = AllowDayOverflow.yes) @safe nothrow scope
         if (units == "years" || units == "months")
     {
         auto hnsecs = adjTime;
@@ -2714,9 +2914,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.add!"years"(4)));
-        //static assert(!__traits(compiles, ist.add!"years"(4)));
+        static assert(!__traits(compiles, ist.add!"years"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.add!"years"(42);
+        }
     }
 
     // Test add!"years"() with AllowDayOverflow.no
@@ -3267,9 +3472,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.add!"months"(4)));
-        //static assert(!__traits(compiles, ist.add!"months"(4)));
+        static assert(!__traits(compiles, ist.add!"months"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.add!"months"(42);
+        }
     }
 
     // Test add!"months"() with AllowDayOverflow.no
@@ -3634,8 +3844,9 @@ public:
             allowOverflow = Whether the days should be allowed to overflow,
                             causing the month to increment.
       +/
-    ref SysTime roll(string units)(long value, AllowDayOverflow allowOverflow = AllowDayOverflow.yes) @safe nothrow
-        if (units == "years")
+    ref SysTime roll(string units)
+                    (long value, AllowDayOverflow allowOverflow = AllowDayOverflow.yes) @safe nothrow scope
+    if (units == "years")
     {
         return add!"years"(value, allowOverflow);
     }
@@ -3674,16 +3885,22 @@ public:
     {
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         st.roll!"years"(4);
         static assert(!__traits(compiles, cst.roll!"years"(4)));
-        //static assert(!__traits(compiles, ist.roll!"years"(4)));
+        static assert(!__traits(compiles, ist.roll!"years"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.roll!"years"(42);
+        }
     }
 
 
     // Shares documentation with "years" overload.
-    ref SysTime roll(string units)(long value, AllowDayOverflow allowOverflow = AllowDayOverflow.yes) @safe nothrow
-        if (units == "months")
+    ref SysTime roll(string units)
+                    (long value, AllowDayOverflow allowOverflow = AllowDayOverflow.yes) @safe nothrow scope
+    if (units == "months")
     {
         auto hnsecs = adjTime;
         auto days = splitUnitsFromHNSecs!"days"(hnsecs) + 1;
@@ -4083,9 +4300,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.roll!"months"(4)));
-        //static assert(!__traits(compiles, ist.roll!"months"(4)));
+        static assert(!__traits(compiles, ist.roll!"months"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.roll!"months"(42);
+        }
     }
 
     // Test roll!"months"() with AllowDayOverflow.no
@@ -4484,7 +4706,7 @@ public:
             value = The number of $(D_PARAM units) to add to this
                     $(LREF SysTime).
       +/
-    ref SysTime roll(string units)(long value) @safe nothrow
+    ref SysTime roll(string units)(long value) @safe nothrow scope
         if (units == "days")
     {
         auto hnsecs = adjTime;
@@ -4837,14 +5059,19 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.roll!"days"(4)));
-        //static assert(!__traits(compiles, ist.roll!"days"(4)));
+        static assert(!__traits(compiles, ist.roll!"days"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.roll!"days"(42);
+        }
     }
 
 
     // Shares documentation with "days" version.
-    ref SysTime roll(string units)(long value) @safe nothrow
+    ref SysTime roll(string units)(long value) @safe nothrow scope
         if (units == "hours" || units == "minutes" || units == "seconds")
     {
         try
@@ -4889,14 +5116,11 @@ public:
     @safe unittest
     {
         import core.time;
-        static void testST(SysTime orig, int hours, scope const SysTime expected, size_t line = __LINE__) @safe
+        static void testST(SysTime orig, int hours, SysTime expected, size_t line = __LINE__) @safe
         {
             orig.roll!"hours"(hours);
             if (orig != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -5101,23 +5325,25 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.roll!"hours"(4)));
-        //static assert(!__traits(compiles, ist.roll!"hours"(4)));
+        static assert(!__traits(compiles, ist.roll!"hours"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.roll!"hours"(42);
+        }
     }
 
     // Test roll!"minutes"().
     @safe unittest
     {
         import core.time;
-        static void testST(SysTime orig, int minutes, scope const SysTime expected, size_t line = __LINE__) @safe
+        static void testST(SysTime orig, int minutes, SysTime expected, size_t line = __LINE__) @safe
         {
             orig.roll!"minutes"(minutes);
             if (orig != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -5315,23 +5541,25 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.roll!"minutes"(4)));
-        //static assert(!__traits(compiles, ist.roll!"minutes"(4)));
+        static assert(!__traits(compiles, ist.roll!"minutes"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.roll!"minutes"(42);
+        }
     }
 
     // Test roll!"seconds"().
     @safe unittest
     {
         import core.time;
-        static void testST(SysTime orig, int seconds, scope const SysTime expected, size_t line = __LINE__) @safe
+        static void testST(SysTime orig, int seconds, SysTime expected, size_t line = __LINE__) @safe
         {
             orig.roll!"seconds"(seconds);
             if (orig != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -5507,14 +5735,19 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.roll!"seconds"(4)));
-        //static assert(!__traits(compiles, ist.roll!"seconds"(4)));
+        static assert(!__traits(compiles, ist.roll!"seconds"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.roll!"seconds"(42);
+        }
     }
 
 
     // Shares documentation with "days" version.
-    ref SysTime roll(string units)(long value) @safe nothrow
+    ref SysTime roll(string units)(long value) @safe nothrow scope
         if (units == "msecs" || units == "usecs" || units == "hnsecs")
     {
         auto hnsecs = adjTime;
@@ -5545,14 +5778,11 @@ public:
     @safe unittest
     {
         import core.time;
-        static void testST(SysTime orig, int milliseconds, scope const SysTime expected, size_t line = __LINE__) @safe
+        static void testST(SysTime orig, int milliseconds, SysTime expected, size_t line = __LINE__) @safe
         {
             orig.roll!"msecs"(milliseconds);
             if (orig != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -5645,23 +5875,25 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        static assert(!__traits(compiles, cst.addMSecs(4)));
-        //static assert(!__traits(compiles, ist.addMSecs(4)));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        static assert(!__traits(compiles, cst.roll!"msecs"(4)));
+        static assert(!__traits(compiles, ist.roll!"msecs"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.roll!"msecs"(42);
+        }
     }
 
     // Test roll!"usecs"().
     @safe unittest
     {
         import core.time;
-        static void testST(SysTime orig, long microseconds, scope const SysTime expected, size_t line = __LINE__) @safe
+        static void testST(SysTime orig, long microseconds, SysTime expected, size_t line = __LINE__) @safe
         {
             orig.roll!"usecs"(microseconds);
             if (orig != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -5778,23 +6010,25 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.roll!"usecs"(4)));
-        //static assert(!__traits(compiles, ist.roll!"usecs"(4)));
+        static assert(!__traits(compiles, ist.roll!"usecs"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.roll!"usecs"(42);
+        }
     }
 
     // Test roll!"hnsecs"().
     @safe unittest
     {
         import core.time;
-        static void testST(SysTime orig, long hnsecs, scope const SysTime expected, size_t line = __LINE__) @safe
+        static void testST(SysTime orig, long hnsecs, SysTime expected, size_t line = __LINE__) @safe
         {
             orig.roll!"hnsecs"(hnsecs);
             if (orig != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -5923,9 +6157,14 @@ public:
         }
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.roll!"hnsecs"(4)));
-        //static assert(!__traits(compiles, ist.roll!"hnsecs"(4)));
+        static assert(!__traits(compiles, ist.roll!"hnsecs"(4)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.roll!"hnsecs"(42);
+        }
     }
 
 
@@ -5945,7 +6184,7 @@ public:
             duration = The $(REF Duration, core,time) to add to or subtract from
                        this $(LREF SysTime).
       +/
-    SysTime opBinary(string op)(Duration duration) @safe const pure nothrow
+    SysTime opBinary(string op)(Duration duration) @safe const pure nothrow scope
         if (op == "+" || op == "-")
     {
         SysTime retval = SysTime(this._stdTime, this._timezone);
@@ -6012,15 +6251,11 @@ public:
         assert(st - dur!"hnsecs"(-7) == SysTime(DateTime(1999, 7, 6, 12, 30, 33), hnsecs(2_345_685)));
         assert(st - dur!"hnsecs"(7) == SysTime(DateTime(1999, 7, 6, 12, 30, 33), hnsecs(2_345_671)));
 
-        static void testST(scope const SysTime orig,
-                           long hnsecs, scope const SysTime expected, size_t line = __LINE__) @safe
+        static void testST(SysTime orig, long hnsecs, SysTime expected, size_t line = __LINE__) @safe
         {
             auto result = orig + dur!"hnsecs"(hnsecs);
             if (result != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed. actual [%s] != expected [%s]", result, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed. actual [%s] != expected [%s]", result, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -6140,11 +6375,16 @@ public:
 
         auto duration = dur!"seconds"(12);
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst + duration == SysTime(DateTime(1999, 7, 6, 12, 30, 45)));
-        //assert(ist + duration == SysTime(DateTime(1999, 7, 6, 12, 30, 45)));
+        assert(ist + duration == SysTime(DateTime(1999, 7, 6, 12, 30, 45)));
         assert(cst - duration == SysTime(DateTime(1999, 7, 6, 12, 30, 21)));
-        //assert(ist - duration == SysTime(DateTime(1999, 7, 6, 12, 30, 21)));
+        assert(ist - duration == SysTime(DateTime(1999, 7, 6, 12, 30, 21)));
+
+        static void testScope(scope ref SysTime st, scope ref Duration d) @safe
+        {
+            auto result = st + d;
+        }
     }
 
 
@@ -6164,7 +6404,7 @@ public:
             duration = The $(REF Duration, core,time) to add to or subtract from
                        this $(LREF SysTime).
       +/
-    ref SysTime opOpAssign(string op)(Duration duration) @safe pure nothrow
+    ref SysTime opOpAssign(string op)(Duration duration) @safe pure nothrow scope
         if (op == "+" || op == "-")
     {
         immutable hnsecs = duration.total!"hnsecs";
@@ -6212,19 +6452,13 @@ public:
         assert(before - dur!"hnsecs"(-7) == SysTime(DateTime(1999, 7, 6, 12, 30, 33), hnsecs(7)));
         assert(before - dur!"hnsecs"(7) == SysTime(DateTime(1999, 7, 6, 12, 30, 32), hnsecs(9_999_993)));
 
-        static void testST(SysTime orig, long hnsecs, scope const SysTime expected, size_t line = __LINE__) @safe
+        static void testST(SysTime orig, long hnsecs, SysTime expected, size_t line = __LINE__) @safe
         {
             auto r = orig += dur!"hnsecs"(hnsecs);
             if (orig != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed 1. actual [%s] != expected [%s]", orig, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed 1. actual [%s] != expected [%s]", orig, expected), __FILE__, line);
             if (r != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed 2. actual [%s] != expected [%s]", r, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed 2. actual [%s] != expected [%s]", r, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -6350,11 +6584,17 @@ public:
 
         auto duration = dur!"seconds"(12);
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst += duration));
-        //static assert(!__traits(compiles, ist += duration));
+        static assert(!__traits(compiles, ist += duration));
         static assert(!__traits(compiles, cst -= duration));
-        //static assert(!__traits(compiles, ist -= duration));
+        static assert(!__traits(compiles, ist -= duration));
+
+        static void testScope(scope ref SysTime st, scope ref Duration d) @safe
+        {
+            auto result1 = st += d;
+            auto result2 = st -= d;
+        }
     }
 
 
@@ -6368,7 +6608,7 @@ public:
         $(TR $(TD SysTime) $(TD -) $(TD SysTime) $(TD -->) $(TD duration))
         )
       +/
-    Duration opBinary(string op)(scope const SysTime rhs) @safe const pure nothrow
+    Duration opBinary(string op)(SysTime rhs) @safe const pure nothrow scope
         if (op == "-")
     {
         return dur!"hnsecs"(_stdTime - rhs._stdTime);
@@ -6450,18 +6690,23 @@ public:
 
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(st - st == Duration.zero);
         assert(cst - st == Duration.zero);
-        //assert(ist - st == Duration.zero);
+        assert(ist - st == Duration.zero);
 
         assert(st - cst == Duration.zero);
         assert(cst - cst == Duration.zero);
-        //assert(ist - cst == Duration.zero);
+        assert(ist - cst == Duration.zero);
 
-        //assert(st - ist == Duration.zero);
-        //assert(cst - ist == Duration.zero);
-        //assert(ist - ist == Duration.zero);
+        assert(st - ist == Duration.zero);
+        assert(cst - ist == Duration.zero);
+        assert(ist - ist == Duration.zero);
+
+        static void testScope(scope ref SysTime left, scope ref SysTime right) @safe
+        {
+            auto result = left - right;
+        }
     }
 
 
@@ -6486,7 +6731,7 @@ public:
         Params:
             rhs = The $(LREF SysTime) to subtract from this one.
       +/
-    int diffMonths(scope const SysTime rhs) @safe const nothrow
+    int diffMonths(scope SysTime rhs) @safe const nothrow scope
     {
         return (cast(Date) this).diffMonths(cast(Date) rhs);
     }
@@ -6515,25 +6760,30 @@ public:
         import core.time;
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(st.diffMonths(st) == 0);
         assert(cst.diffMonths(st) == 0);
-        //assert(ist.diffMonths(st) == 0);
+        assert(ist.diffMonths(st) == 0);
 
         assert(st.diffMonths(cst) == 0);
         assert(cst.diffMonths(cst) == 0);
-        //assert(ist.diffMonths(cst) == 0);
+        assert(ist.diffMonths(cst) == 0);
 
-        //assert(st.diffMonths(ist) == 0);
-        //assert(cst.diffMonths(ist) == 0);
-        //assert(ist.diffMonths(ist) == 0);
+        assert(st.diffMonths(ist) == 0);
+        assert(cst.diffMonths(ist) == 0);
+        assert(ist.diffMonths(ist) == 0);
+
+        static void testScope(scope ref SysTime left, scope ref SysTime right) @safe
+        {
+            auto result = left.diffMonths(right);
+        }
     }
 
 
     /++
         Whether this $(LREF SysTime) is in a leap year.
      +/
-    @property bool isLeapYear() @safe const nothrow
+    @property bool isLeapYear() @safe const nothrow scope
     {
         return (cast(Date) this).isLeapYear;
     }
@@ -6543,17 +6793,22 @@ public:
         import core.time;
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(!st.isLeapYear);
         assert(!cst.isLeapYear);
-        //assert(!ist.isLeapYear);
+        assert(!ist.isLeapYear);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.isLeapYear;
+        }
     }
 
 
     /++
         Day of the week this $(LREF SysTime) is on.
       +/
-    @property DayOfWeek dayOfWeek() @safe const nothrow
+    @property DayOfWeek dayOfWeek() @safe const nothrow scope
     {
         return getDayOfWeek(dayOfGregorianCal);
     }
@@ -6563,17 +6818,22 @@ public:
         import core.time;
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(st.dayOfWeek == DayOfWeek.tue);
         assert(cst.dayOfWeek == DayOfWeek.tue);
-        //assert(ist.dayOfWeek == DayOfWeek.tue);
+        assert(ist.dayOfWeek == DayOfWeek.tue);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.dayOfWeek;
+        }
     }
 
 
     /++
         Day of the year this $(LREF SysTime) is on.
       +/
-    @property ushort dayOfYear() @safe const nothrow
+    @property ushort dayOfYear() @safe const nothrow scope
     {
         return (cast(Date) this).dayOfYear;
     }
@@ -6594,10 +6854,15 @@ public:
         import core.time;
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(st.dayOfYear == 187);
         assert(cst.dayOfYear == 187);
-        //assert(ist.dayOfYear == 187);
+        assert(ist.dayOfYear == 187);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.dayOfYear;
+        }
     }
 
 
@@ -6608,7 +6873,7 @@ public:
             day = The day of the year to set which day of the year this
                   $(LREF SysTime) is on.
       +/
-    @property void dayOfYear(int day) @safe
+    @property void dayOfYear(int day) @safe scope
     {
         immutable hnsecs = adjTime;
         immutable days = convert!("hnsecs", "days")(hnsecs);
@@ -6627,18 +6892,23 @@ public:
         import core.time;
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         st.dayOfYear = 12;
         assert(st.dayOfYear == 12);
         static assert(!__traits(compiles, cst.dayOfYear = 12));
-        //static assert(!__traits(compiles, ist.dayOfYear = 12));
+        static assert(!__traits(compiles, ist.dayOfYear = 12));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.dayOfYear = 42;
+        }
     }
 
 
     /++
         The Xth day of the Gregorian Calendar that this $(LREF SysTime) is on.
      +/
-    @property int dayOfGregorianCal() @safe const nothrow
+    @property int dayOfGregorianCal() @safe const nothrow scope
     {
         immutable adjustedTime = adjTime;
 
@@ -6836,9 +7106,14 @@ public:
         assert(SysTime(DateTime(-3760, 9, 7, 0, 0, 0)).dayOfGregorianCal == -1_373_427);
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.dayOfGregorianCal == 729_941);
-        //assert(ist.dayOfGregorianCal == 729_941);
+        assert(ist.dayOfGregorianCal == 729_941);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.dayOfGregorianCal;
+        }
     }
 
 
@@ -7012,7 +7287,7 @@ public:
             days = The day of the Gregorian Calendar to set this $(LREF SysTime)
                    to.
      +/
-    @property void dayOfGregorianCal(int days) @safe nothrow
+    @property void dayOfGregorianCal(int days) @safe nothrow scope
     {
         auto hnsecs = adjTime;
         hnsecs = removeUnitsFromHNSecs!"days"(hnsecs);
@@ -7066,14 +7341,11 @@ public:
     @safe unittest
     {
         import core.time;
-        void testST(SysTime orig, int day, scope const SysTime expected, size_t line = __LINE__) @safe
+        void testST(SysTime orig, int day, SysTime expected, size_t line = __LINE__) @safe
         {
             orig.dayOfGregorianCal = day;
             if (orig != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed. actual [%s] != expected [%s]", orig, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -7106,14 +7378,11 @@ public:
 
         auto st = SysTime(DateTime(1, 1, 1, 12, 2, 9), msecs(212));
 
-        void testST2(int day, scope const SysTime expected, size_t line = __LINE__) @safe
+        void testST2(int day, SysTime expected, size_t line = __LINE__) @safe
         {
             st.dayOfGregorianCal = day;
             if (st != expected)
-            {
-                string s = expected.toSimpleString();
-                throw new AssertError(format("Failed. actual [%s] != expected [%s]", st, s), __FILE__, line);
-            }
+                throw new AssertError(format("Failed. actual [%s] != expected [%s]", st, expected), __FILE__, line);
         }
 
         // Test A.D.
@@ -7264,9 +7533,14 @@ public:
         testST2(-735_173, SysTime(DateTime(-2012, 3, 1, 12, 2, 9), msecs(212)));
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         static assert(!__traits(compiles, cst.dayOfGregorianCal = 7));
-        //static assert(!__traits(compiles, ist.dayOfGregorianCal = 7));
+        static assert(!__traits(compiles, ist.dayOfGregorianCal = 7));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            st.dayOfGregorianCal = 42;
+        }
     }
 
 
@@ -7276,7 +7550,7 @@ public:
         See_Also:
             $(HTTP en.wikipedia.org/wiki/ISO_week_date, ISO Week Date).
       +/
-    @property ubyte isoWeek() @safe const nothrow
+    @property ubyte isoWeek() @safe const nothrow scope
     {
         return (cast(Date) this).isoWeek;
     }
@@ -7296,12 +7570,20 @@ public:
         assert(ist.isoWeek == 41);
     }
 
+    @safe unittest
+    {
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.isoWeek;
+        }
+    }
+
 
     /++
         $(LREF SysTime) for the last day in the month that this Date is in.
         The time portion of endOfMonth is always 23:59:59.9999999.
       +/
-    @property SysTime endOfMonth() @safe const nothrow
+    @property SysTime endOfMonth() @safe const nothrow scope
     {
         immutable hnsecs = adjTime;
         immutable days = getUnitsFromHNSecs!"days"(hnsecs);
@@ -7382,16 +7664,21 @@ public:
                SysTime(DateTime(-1999, 12, 31, 23, 59, 59), hnsecs(9_999_999)));
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.endOfMonth == SysTime(DateTime(1999, 7, 31, 23, 59, 59), hnsecs(9_999_999)));
-        //assert(ist.endOfMonth == SysTime(DateTime(1999, 7, 31, 23, 59, 59), hnsecs(9_999_999)));
+        assert(ist.endOfMonth == SysTime(DateTime(1999, 7, 31, 23, 59, 59), hnsecs(9_999_999)));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.endOfMonth;
+        }
     }
 
 
     /++
         The last day in the month that this $(LREF SysTime) is in.
       +/
-    @property ubyte daysInMonth() @safe const nothrow
+    @property ubyte daysInMonth() @safe const nothrow scope
     {
         return Date(dayOfGregorianCal).daysInMonth;
     }
@@ -7442,16 +7729,21 @@ public:
         assert(SysTime(DateTime(-1999, 12, 1, 12, 52, 13)).daysInMonth == 31);
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.daysInMonth == 31);
-        //assert(ist.daysInMonth == 31);
+        assert(ist.daysInMonth == 31);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.daysInMonth;
+        }
     }
 
 
     /++
         Whether the current year is a date in A.D.
       +/
-    @property bool isAD() @safe const nothrow
+    @property bool isAD() @safe const nothrow scope
     {
         return adjTime >= 0;
     }
@@ -7479,9 +7771,14 @@ public:
         assert(!SysTime(DateTime(-2010, 7, 4, 12, 2, 2)).isAD);
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.isAD);
-        //assert(ist.isAD);
+        assert(ist.isAD);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.isAD;
+        }
     }
 
 
@@ -7492,7 +7789,7 @@ public:
         this function returns 2_450_173, while from noon onward, the Julian
         day number would be 2_450_174, so this function returns 2_450_174.
       +/
-    @property long julianDay() @safe const nothrow
+    @property long julianDay() @safe const nothrow scope
     {
         immutable jd = dayOfGregorianCal + 1_721_425;
         return hour < 12 ? jd - 1 : jd;
@@ -7526,9 +7823,14 @@ public:
         assert(SysTime(DateTime(2010, 8, 24, 12, 0, 0)).julianDay == 2_455_433);
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.julianDay == 2_451_366);
-        //assert(ist.julianDay == 2_451_366);
+        assert(ist.julianDay == 2_451_366);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.julianDay;
+        }
     }
 
 
@@ -7537,7 +7839,7 @@ public:
         any time on this date (since, the modified Julian day changes at
         midnight).
       +/
-    @property long modJulianDay() @safe const nothrow
+    @property long modJulianDay() @safe const nothrow scope
     {
         return dayOfGregorianCal + 1_721_425 - 2_400_001;
     }
@@ -7552,16 +7854,21 @@ public:
         assert(SysTime(DateTime(2010, 8, 24, 12, 0, 0)).modJulianDay == 55_432);
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cst.modJulianDay == 51_365);
-        //assert(ist.modJulianDay == 51_365);
+        assert(ist.modJulianDay == 51_365);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.modJulianDay;
+        }
     }
 
 
     /++
         Returns a $(REF Date,std,datetime,date) equivalent to this $(LREF SysTime).
       +/
-    Date opCast(T)() scope @trusted const nothrow
+    Date opCast(T)() @safe const nothrow scope
         if (is(Unqual!T == Date))
     {
         return Date(dayOfGregorianCal);
@@ -7587,9 +7894,14 @@ public:
         assert(cast(Date) SysTime(DateTime(-2001, 1, 1, 14, 12, 11)) == Date(-2001, 1, 1));
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cast(Date) cst != Date.init);
-        //assert(cast(Date) ist != Date.init);
+        assert(cast(Date) ist != Date.init);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = cast(Date) st;
+        }
     }
 
 
@@ -7597,7 +7909,7 @@ public:
         Returns a $(REF DateTime,std,datetime,date) equivalent to this
         $(LREF SysTime).
       +/
-    DateTime opCast(T)() @safe const nothrow
+    DateTime opCast(T)() @safe const nothrow scope
         if (is(Unqual!T == DateTime))
     {
         try
@@ -7648,9 +7960,14 @@ public:
                DateTime(2011, 1, 13, 8, 17, 2));
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cast(DateTime) cst != DateTime.init);
-        //assert(cast(DateTime) ist != DateTime.init);
+        assert(cast(DateTime) ist != DateTime.init);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = cast(DateTime) st;
+        }
     }
 
 
@@ -7658,7 +7975,7 @@ public:
         Returns a $(REF TimeOfDay,std,datetime,date) equivalent to this
         $(LREF SysTime).
       +/
-    TimeOfDay opCast(T)() @safe const nothrow
+    TimeOfDay opCast(T)() @safe const nothrow scope
         if (is(Unqual!T == TimeOfDay))
     {
         try
@@ -7699,9 +8016,14 @@ public:
         assert(cast(TimeOfDay) SysTime(DateTime(-2001, 1, 1, 14, 12, 11)) == TimeOfDay(14, 12, 11));
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         assert(cast(TimeOfDay) cst != TimeOfDay.init);
-        //assert(cast(TimeOfDay) ist != TimeOfDay.init);
+        assert(cast(TimeOfDay) ist != TimeOfDay.init);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = cast(TimeOfDay) st;
+        }
     }
 
 
@@ -7710,12 +8032,20 @@ public:
     // It may be a good idea to keep it though, since casting from a type to itself
     // should be allowed, and it doesn't work without this opCast() since opCast()
     // has already been defined for other types.
-    SysTime opCast(T)() @safe const pure nothrow
+    SysTime opCast(T)() @safe const pure nothrow scope
         if (is(Unqual!T == SysTime))
     {
         return SysTime(_stdTime, _timezone);
     }
 
+    @safe unittest
+    {
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = cast(SysTime) st;
+        }
+    }
+
 
     /++
         Converts this $(LREF SysTime) to a string with the format
@@ -7754,7 +8084,7 @@ public:
         Returns:
             A `string` when not using an output range; `void` otherwise.
       +/
-    string toISOString() @safe const nothrow
+    string toISOString() @safe const nothrow scope
     {
         import std.array : appender;
         auto app = appender!string();
@@ -7767,7 +8097,7 @@ public:
     }
 
     /// ditto
-    void toISOString(W)(ref W writer) const
+    void toISOString(W)(ref W writer) const scope
     if (isOutputRange!(W, char))
     {
         immutable adjustedTime = adjTime;
@@ -7877,9 +8207,14 @@ public:
         assert(SysTime(DateTime(-10000, 10, 20, 1, 1, 1), hnsecs(507890)).toISOString() == "-100001020T010101.050789");
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        assert(cast(TimeOfDay) cst != TimeOfDay.init);
-        //assert(cast(TimeOfDay) ist != TimeOfDay.init);
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        assert(cst.toISOString() == "19990706T123033");
+        assert(ist.toISOString() == "19990706T123033");
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toISOString();
+        }
     }
 
 
@@ -7909,7 +8244,7 @@ public:
         Returns:
             A `string` when not using an output range; `void` otherwise.
       +/
-    string toISOExtString() @safe const nothrow
+    string toISOExtString() @safe const nothrow scope
     {
         import std.array : appender;
         auto app = appender!string();
@@ -7922,7 +8257,7 @@ public:
     }
 
     /// ditto
-    void toISOExtString(W)(ref W writer) const
+    void toISOExtString(W)(ref W writer) const scope
     if (isOutputRange!(W, char))
     {
         immutable adjustedTime = adjTime;
@@ -8038,9 +8373,14 @@ public:
                "-10000-10-20T01:01:01.050789");
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        assert(cast(TimeOfDay) cst != TimeOfDay.init);
-        //assert(cast(TimeOfDay) ist != TimeOfDay.init);
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        assert(cst.toISOExtString() == "1999-07-06T12:30:33");
+        assert(ist.toISOExtString() == "1999-07-06T12:30:33");
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toISOExtString();
+        }
     }
 
     /++
@@ -8068,7 +8408,7 @@ public:
         Returns:
             A `string` when not using an output range; `void` otherwise.
       +/
-    string toSimpleString() scope @trusted const nothrow
+    string toSimpleString() @safe const nothrow scope
     {
         import std.array : appender;
         auto app = appender!string();
@@ -8081,7 +8421,7 @@ public:
     }
 
     /// ditto
-    void toSimpleString(W)(ref W writer) const
+    void toSimpleString(W)(ref W writer) const scope
     if (isOutputRange!(W, char))
     {
         immutable adjustedTime = adjTime;
@@ -8198,9 +8538,14 @@ public:
                "-10000-Oct-20 01:01:01.050789");
 
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        assert(cast(TimeOfDay) cst != TimeOfDay.init);
-        //assert(cast(TimeOfDay) ist != TimeOfDay.init);
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        assert(cst.toSimpleString() == "1999-Jul-06 12:30:33");
+        assert(ist.toSimpleString() == "1999-Jul-06 12:30:33");
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toSimpleString();
+        }
     }
 
 
@@ -8233,13 +8578,13 @@ public:
         Returns:
             A `string` when not using an output range; `void` otherwise.
       +/
-    string toString() @safe const nothrow
+    string toString() @safe const nothrow scope
     {
         return toSimpleString();
     }
 
     /// ditto
-    void toString(W)(ref W writer) const
+    void toString(W)(ref W writer) const scope
     if (isOutputRange!(W, char))
     {
         toSimpleString(writer);
@@ -8250,10 +8595,15 @@ public:
         import core.time;
         auto st = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
         const cst = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        //immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
-        assert(st.toString());
-        assert(cst.toString());
-        //assert(ist.toString());
+        immutable ist = SysTime(DateTime(1999, 7, 6, 12, 30, 33));
+        static assert(__traits(compiles, st.toString()));
+        static assert(__traits(compiles, cst.toString()));
+        static assert(__traits(compiles, ist.toString()));
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = st.toString();
+        }
     }
 
 
@@ -8544,6 +8894,11 @@ public:
         test("20101222T172201.1234567+01:00", SysTime(DateTime(2010, 12, 22, 17, 22, 01), hnsecs(1_234_567), east60));
         test("20101222T172201.0000000+01:30", SysTime(DateTime(2010, 12, 22, 17, 22, 01), east90));
         test("20101222T172201.45+08:00", SysTime(DateTime(2010, 12, 22, 17, 22, 01), hnsecs(4_500_000), east480));
+
+        static void testScope(scope ref string str) @safe
+        {
+            auto result = SysTime.fromISOString(str);
+        }
     }
 
     // bug# 17801
@@ -8786,6 +9141,11 @@ public:
         test("2010-12-22T17:22:01.0+01", SysTime(DateTime(2010, 12, 22, 17, 22, 01), east60));
         test("2010-12-22T17:22:01.0000000+01:30", SysTime(DateTime(2010, 12, 22, 17, 22, 01), east90));
         test("2010-12-22T17:22:01.45+08:00", SysTime(DateTime(2010, 12, 22, 17, 22, 01), hnsecs(4_500_000), east480));
+
+        static void testScope(scope ref string str) @safe
+        {
+            auto result = SysTime.fromISOExtString(str);
+        }
     }
 
     // bug# 17801
@@ -9032,6 +9392,11 @@ public:
         test("2010-Dec-22 17:22:01.0+01", SysTime(DateTime(2010, 12, 22, 17, 22, 01), east60));
         test("2010-Dec-22 17:22:01.0000000+01:30", SysTime(DateTime(2010, 12, 22, 17, 22, 01), east90));
         test("2010-Dec-22 17:22:01.45+08:00", SysTime(DateTime(2010, 12, 22, 17, 22, 01), hnsecs(4_500_000), east480));
+
+        static void testScope(scope ref string str) @safe
+        {
+            auto result = SysTime.fromSimpleString(str);
+        }
     }
 
     // bug# 17801
@@ -9398,7 +9763,7 @@ version(StdDdoc)
             unlikely to happen given that `SysTime.max` is in 29,228 A.D. and
             the maximum `SYSTEMTIME` is in 30,827 A.D.
       +/
-    SysTime SYSTEMTIMEToSysTime(const SYSTEMTIME* st, immutable TimeZone tz = LocalTime()) @safe;
+    SysTime SYSTEMTIMEToSysTime(const scope SYSTEMTIME* st, immutable TimeZone tz = LocalTime()) @safe;
 
 
     /++
@@ -9418,7 +9783,7 @@ version(StdDdoc)
             $(LREF SysTime) will not fit in a `SYSTEMTIME`. This will only
             happen if the $(LREF SysTime)'s date is prior to 1601 A.D.
       +/
-    SYSTEMTIME SysTimeToSYSTEMTIME(scope const SysTime sysTime) @safe;
+    SYSTEMTIME SysTimeToSYSTEMTIME(scope SysTime sysTime) @safe;
 
 
     /++
@@ -9485,11 +9850,11 @@ version(StdDdoc)
             $(REF DateTimeException,std,datetime,date) if the given
             $(LREF SysTime) will not fit in a `FILETIME`.
       +/
-    FILETIME SysTimeToFILETIME(SysTime sysTime) @safe;
+    FILETIME SysTimeToFILETIME(scope SysTime sysTime) @safe;
 }
 else version(Windows)
 {
-    SysTime SYSTEMTIMEToSysTime(const SYSTEMTIME* st, immutable TimeZone tz = LocalTime()) @safe
+    SysTime SYSTEMTIMEToSysTime(const scope SYSTEMTIME* st, immutable TimeZone tz = LocalTime()) @safe
     {
         const max = SysTime.max;
 
@@ -9545,10 +9910,15 @@ else version(Windows)
         auto converted = SYSTEMTIMEToSysTime(&st, UTC());
         import core.time : abs;
         assert(abs((converted - sysTime)) <= dur!"seconds"(2));
+
+        static void testScope(scope SYSTEMTIME* st) @safe
+        {
+            auto result = SYSTEMTIMEToSysTime(st);
+        }
     }
 
 
-    SYSTEMTIME SysTimeToSYSTEMTIME(scope const SysTime sysTime) @safe
+    SYSTEMTIME SysTimeToSYSTEMTIME(scope SysTime sysTime) @safe
     {
         immutable dt = cast(DateTime) sysTime;
 
@@ -9585,6 +9955,11 @@ else version(Windows)
         assert(st.wMinute == result.wMinute);
         assert(st.wSecond == result.wSecond);
         assert(st.wMilliseconds == result.wMilliseconds);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = SysTimeToSYSTEMTIME(st);
+        }
     }
 
     private enum hnsecsFrom1601 = 504_911_232_000_000_000L;
@@ -9622,6 +9997,11 @@ else version(Windows)
 
         import core.time : abs;
         assert(abs((converted - sysTime)) <= dur!"seconds"(2));
+
+        static void testScope(scope FILETIME* ft) @safe
+        {
+            auto result = FILETIMEToSysTime(ft);
+        }
     }
 
 
@@ -9640,7 +10020,7 @@ else version(Windows)
         return ft;
     }
 
-    FILETIME SysTimeToFILETIME(SysTime sysTime) @safe
+    FILETIME SysTimeToFILETIME(scope SysTime sysTime) @safe
     {
         return stdTimeToFILETIME(sysTime.stdTime);
     }
@@ -9658,6 +10038,11 @@ else version(Windows)
 
         assert(ft.dwLowDateTime == result.dwLowDateTime);
         assert(ft.dwHighDateTime == result.dwHighDateTime);
+
+        static void testScope(scope ref SysTime st) @safe
+        {
+            auto result = SysTimeToFILETIME(st);
+        }
     }
 }
 
@@ -9708,6 +10093,14 @@ SysTime DosFileTimeToSysTime(DosFileTime dft, immutable TimeZone tz = LocalTime(
     assert(DosFileTimeToSysTime(0x3E3F8456) == SysTime(DateTime(2011, 1, 31, 16, 34, 44)));
 }
 
+@safe unittest
+{
+    static void testScope(scope ref DosFileTime dft) @safe
+    {
+        auto result = DosFileTimeToSysTime(dft);
+    }
+}
+
 
 /++
     Converts from $(LREF SysTime) to DOS file date/time.
@@ -9719,7 +10112,7 @@ SysTime DosFileTimeToSysTime(DosFileTime dft, immutable TimeZone tz = LocalTime(
         $(REF DateTimeException,std,datetime,date) if the given
         $(LREF SysTime) cannot be converted to a `DosFileTime`.
   +/
-DosFileTime SysTimeToDosFileTime(SysTime sysTime) @safe
+DosFileTime SysTimeToDosFileTime(scope SysTime sysTime) @safe
 {
     auto dateTime = cast(DateTime) sysTime;
 
@@ -9750,6 +10143,14 @@ DosFileTime SysTimeToDosFileTime(SysTime sysTime) @safe
     assert(SysTimeToDosFileTime(SysTime(DateTime(2011, 1, 31, 16, 34, 44))) == 0x3E3F8456);
 }
 
+@safe unittest
+{
+    static void testScope(scope ref SysTime st) @safe
+    {
+        auto result = SysTimeToDosFileTime(st);
+    }
+}
+
 
 /++
     The given array of `char` or random-access range of `char` or
@@ -9794,7 +10195,7 @@ SysTime parseRFC822DateTime()(scope const char[] value) @safe
 }
 
 /++ Ditto +/
-SysTime parseRFC822DateTime(R)(scope R value) @trusted
+SysTime parseRFC822DateTime(R)(scope R value)
 if (isRandomAccessRange!R && hasSlicing!R && hasLength!R &&
     (is(Unqual!(ElementType!R) == char) || is(Unqual!(ElementType!R) == ubyte)))
 {
@@ -10304,6 +10705,11 @@ version(unittest) void testBadParse822(alias cr)(string str, size_t line = __LIN
             testBad((cast(string) currStr) ~ "                                    ");
         }
     }}
+
+    static void testScope(scope ref string str) @safe
+    {
+        auto result = parseRFC822DateTime(str);
+    }
 }
 
 // Obsolete Format per section 4.3 of RFC 5322.
@@ -10590,7 +10996,7 @@ void fracSecsToISOString(W)(ref W writer, int hnsecs)
     Returns a Duration corresponding to to the given ISO string of
     fractional seconds.
   +/
-static Duration fracSecsFromISOString(S)(scope const S isoString) @trusted pure
+static Duration fracSecsFromISOString(S)(scope const S isoString) @safe pure
 if (isSomeString!S)
 {
     import std.algorithm.searching : all;