Treat division by 0 as an error in Duration and consolidate code.

Duration should never have checked for division by 0 and thrown a
TimeException when it occurred. The OS/hardware already checks for that,
and it should be considered a logic error. Checking for it and possibly
throwing just slows the code down and makes it so that it can't be @nogc.

This is technically a breaking change, but it will only break code which
doesn't bother to avoid dividing by 0 and then catches TimeException
when it occurs, and such code is likely extremely rare, if it exists at
all. Given the fact that the odds of actually breaking code are
extremely low and that this allows us to make Duration fully @nogc except
for toString, I think that it's worth the risk.

src/core/time.d

@@ -465,7 +465,6 @@ public:
             return -1;
         if(_hnsecs > rhs._hnsecs)
             return 1;
-
         return 0;
     }
 
@@ -681,7 +680,6 @@ public:
             mixin("_hnsecs " ~ op ~ "= rhs._hnsecs;");
         else if(is(_Unqual!D == TickDuration))
             mixin("_hnsecs " ~ op ~ "= rhs.hnsecs;");
-
         return this;
     }
 
@@ -770,26 +768,24 @@ public:
     }
 
 
-    // Note: opBinary!"*" and opBinary!"/" have to be implemented separately
-    // because opBinary!"/" may throw TimeException, and opBinary!"*" is nothrow
-
     /++
-        Multiplies the duration by an integer value.
+        Multiplies or divides the duration by an integer value.
 
         The legal types of arithmetic for $(D Duration) using this operator
         overload are
 
         $(TABLE
         $(TR $(TD Duration) $(TD *) $(TD long) $(TD -->) $(TD Duration))
+        $(TR $(TD Duration) $(TD /) $(TD long) $(TD -->) $(TD Duration))
         )
 
         Params:
             value = The value to multiply this $(D Duration) by.
       +/
     Duration opBinary(string op)(long value) const nothrow @nogc
-        if(op == "*")
+        if(op == "*" || op == "/")
     {
-        return Duration(_hnsecs * value);
+        mixin("return Duration(_hnsecs " ~ op ~ " value);");
     }
 
     unittest
@@ -813,27 +809,45 @@ public:
         }
     }
 
+    unittest
+    {
+        foreach(D; _TypeTuple!(Duration, const Duration, immutable Duration))
+        {
+            assert((cast(D)Duration(5)) / 7 == Duration(0));
+            assert((cast(D)Duration(7)) / 5 == Duration(1));
+
+            assert((cast(D)Duration(5)) / -7 == Duration(0));
+            assert((cast(D)Duration(7)) / -5 == Duration(-1));
+
+            assert((cast(D)Duration(-5)) / 7 == Duration(0));
+            assert((cast(D)Duration(-7)) / 5 == Duration(-1));
+
+            assert((cast(D)Duration(-5)) / -7 == Duration(0));
+            assert((cast(D)Duration(-7)) / -5 == Duration(1));
+        }
+    }
+
 
     /++
-        Multiplies the duration by an integer value as well as
+        Multiplies/Divides the duration by an integer value as well as
         assigning the result to this $(D Duration).
 
         The legal types of arithmetic for $(D Duration) using this operator
         overload are
 
         $(TABLE
         $(TR $(TD Duration) $(TD *) $(TD long) $(TD -->) $(TD Duration))
+        $(TR $(TD Duration) $(TD /) $(TD long) $(TD -->) $(TD Duration))
         )
 
         Params:
-            value = The value to multiply this $(D Duration) by.
+            value = The value to multiply/divide this $(D Duration) by.
       +/
     ref Duration opOpAssign(string op)(long value) nothrow @nogc
-        if(op == "*")
+        if(op == "*" || op == "/")
     {
-        _hnsecs *= value;
-
-       return this;
+        mixin("_hnsecs " ~ op ~ "= value;");
+        return this;
     }
 
     unittest
@@ -868,93 +882,8 @@ public:
         static assert(!__traits(compiles, idur *= 12));
     }
 
-
-    /++
-        Divides the duration by an integer value.
-
-        The legal types of arithmetic for $(D Duration) using this operator
-        overload are
-
-        $(TABLE
-        $(TR $(TD Duration) $(TD /) $(TD long) $(TD -->) $(TD Duration))
-        )
-
-        Params:
-            value = The value to divide from this duration.
-
-        Throws:
-            $(D TimeException) if an attempt to divide by $(D 0) is made.
-      +/
-    Duration opBinary(string op)(long value) const
-        if(op == "/")
-    {
-        if(value == 0)
-            throw new TimeException("Attempted division by 0.");
-
-        return Duration(_hnsecs / value);
-    }
-
-    unittest
-    {
-        //Unfortunately, putting these inside of the foreach loop results in
-        //linker errors regarding multiple definitions and the lambdas.
-        _assertThrown!TimeException((){Duration(5) / 0;}());
-        _assertThrown!TimeException((){Duration(-5) / 0;}());
-        _assertThrown!TimeException((){(cast(const Duration)Duration(5)) / 0;}());
-        _assertThrown!TimeException((){(cast(const Duration)Duration(-5)) / 0;}());
-        _assertThrown!TimeException((){(cast(immutable Duration)Duration(5)) / 0;}());
-        _assertThrown!TimeException((){(cast(immutable Duration)Duration(-5)) / 0;}());
-
-        foreach(D; _TypeTuple!(Duration, const Duration, immutable Duration))
-        {
-            assert((cast(D)Duration(5)) / 7 == Duration(0));
-            assert((cast(D)Duration(7)) / 5 == Duration(1));
-
-            assert((cast(D)Duration(5)) / -7 == Duration(0));
-            assert((cast(D)Duration(7)) / -5 == Duration(-1));
-
-            assert((cast(D)Duration(-5)) / 7 == Duration(0));
-            assert((cast(D)Duration(-7)) / 5 == Duration(-1));
-
-            assert((cast(D)Duration(-5)) / -7 == Duration(0));
-            assert((cast(D)Duration(-7)) / -5 == Duration(1));
-        }
-    }
-
-
-    /++
-        Divides the duration by an integer value as well as
-        assigning the result to this $(D Duration).
-
-        The legal types of arithmetic for $(D Duration) using this operator
-        overload are
-
-        $(TABLE
-        $(TR $(TD Duration) $(TD /) $(TD long) $(TD -->) $(TD Duration))
-        )
-
-        Params:
-            value = The value to divide from this $(D Duration).
-
-        Throws:
-            $(D TimeException) if an attempt to divide by $(D 0) is made.
-      +/
-    ref Duration opOpAssign(string op)(long value)
-        if(op == "/")
-    {
-        if(value == 0)
-            throw new TimeException("Attempted division by 0.");
-
-        _hnsecs /= value;
-
-        return this;
-    }
-
     unittest
     {
-        _assertThrown!TimeException((){Duration(5) /= 0;}());
-        _assertThrown!TimeException((){Duration(-5) /= 0;}());
-
         static void test(Duration actual, long value, Duration expected, size_t line = __LINE__)
         {
             if((actual /= value) != expected)