unsignedToTempString() code deduplication

druntime/src/core/internal/string.d

@@ -31,38 +31,39 @@ Params:
 Returns:
     The unsigned integer value as a string of characters
 */
-T[] unsignedToTempString(uint radix = 10, bool upperCase = false, T)(ulong value, return scope T[] buf)
-if (radix >= 2 && radix <= 36 &&
-    (is(T == char) || is(T == wchar) || is(T == dchar)))
+T[] unsignedToTempString(uint radix = 10, bool upperCase = false, T, U)(in U value, return scope T[] buf)
+if(__traits(isUnsigned, U))
 {
-    enum baseChar = upperCase ? 'A' : 'a';
-    size_t i = buf.length;
-
-    static if (size_t.sizeof == 4) // 32 bit CPU
+    // Process oversized unsigned on 32 bit CPU?
+    static if (size_t.sizeof == 4 && U.sizeof > 4)
     {
         if (value <= uint.max)
         {
             // use faster 32 bit arithmetic
             uint val = cast(uint) value;
-            do
-            {
-                uint x = void;
-                if (val < radix)
-                {
-                    x = cast(uint)val;
-                    val = 0;
-                }
-                else
-                {
-                    x = cast(uint)(val % radix);
-                    val /= radix;
-                }
-                buf[--i] = cast(char)((radix <= 10 || x < 10) ? x + '0' : x - 10 + baseChar);
-            } while (val);
-            return buf[i .. $];
+            return toTempStringImpl!(radix, upperCase)(val, buf);
         }
     }
 
+    return toTempStringImpl!(radix, upperCase)(cast()value, buf);
+}
+
+///ditto
+//TODO: remove after Phobos will acquire necessary changes
+T[] unsignedToTempString(uint radix = 10, bool upperCase = false, T, V)(in V value, return scope T[] buf)
+if(!__traits(isUnsigned, V))
+{
+    return unsignedToTempString!(radix, upperCase)(cast(ulong)value, buf);
+}
+
+private T[] toTempStringImpl(uint radix, bool upperCase, V, T)(V value, ref scope T[] buf)
+if (radix >= 2 && radix <= 36 &&
+    __traits(isUnsigned, V) &&
+    (is(T == char) || is(T == wchar) || is(T == dchar)))
+{
+    enum baseChar = upperCase ? 'A' : 'a';
+    size_t i = buf.length;
+
     do
     {
         uint x = void;
@@ -117,11 +118,11 @@ auto unsignedToTempString(uint radix = 10)(ulong value)
 unittest
 {
     UnsignedStringBuf buf = void;
-    assert(0.unsignedToTempString(buf) == "0");
-    assert(1.unsignedToTempString(buf) == "1");
-    assert(12.unsignedToTempString(buf) == "12");
-    assert(0x12ABCF .unsignedToTempString!16(buf) == "12abcf");
-    assert(0x12ABCF .unsignedToTempString!(16, true)(buf) == "12ABCF");
+    assert(0u.unsignedToTempString(buf) == "0");
+    assert(1u.unsignedToTempString(buf) == "1");
+    assert(12u.unsignedToTempString(buf) == "12");
+    assert(0x12ABCFu .unsignedToTempString!16(buf) == "12abcf");
+    assert(0x12ABCFu .unsignedToTempString!(16, true)(buf) == "12ABCF");
     assert(long.sizeof.unsignedToTempString(buf) == "8");
     assert(uint.max.unsignedToTempString(buf) == "4294967295");
     assert(ulong.max.unsignedToTempString(buf) == "18446744073709551615");
@@ -146,9 +147,8 @@ alias SignedStringBuf = char[65];
 T[] signedToTempString(uint radix = 10, bool upperCase = false, T)(long value, return scope T[] buf)
 {
     bool neg = value < 0;
-    if (neg)
-        value = cast(ulong)-value;
-    auto r = unsignedToTempString!(radix, upperCase)(value, buf);
+    ulong v = neg ? -value : value;
+    auto r = unsignedToTempString!(radix, upperCase)(v, buf);
     if (neg)
     {
         // about to do a slice without a bounds check