fix Issue 7909 - to!(enum)(string) and to!(string)(enum) break when enum is integral

changelog.dd

@@ -6,6 +6,7 @@ $(VERSION 060, ddd mm, 2012, =================================================,
     )
 
     $(LIBBUGSFIXED
+        $(LI $(BUGZILLA 7909): to!enum(string) and to!string(enum) break when enum is integral)
      )
  )
 $(VERSION 059, ddd mm, 2012, =================================================,

std/conv.d

@@ -1048,21 +1048,23 @@ T toImpl(T, S)(S s)
 unittest
 {
     debug(conv) scope(success) writeln("unittest @", __FILE__, ":", __LINE__, " succeeded.");
-    enum E { a, b, c }
-    assert(to! string(E.a) == "a"c);
-    assert(to!wstring(E.b) == "b"w);
-    assert(to!dstring(E.c) == "c"d);
 
-    enum F : real { x = 1.414, y = 1.732, z = 2.236 }
+    enum EU { a = 0, b = 1, c = 2 }     // base type is unsigned
-    assert(to! string(F.x) == "x"c);
+    enum EI { a = -1, b = 0, c = 1 }    // base type is signed (bug 7909)
-    assert(to!wstring(F.y) == "y"w);
+    enum EF : real { a = 1.414, b = 1.732, c = 2.236 }
-    assert(to!dstring(F.z) == "z"d);
+
+    foreach (E; TypeTuple!(EU, EI, EF))
+    {
+        assert(to! string(E.a) == "a"c);
+        assert(to!wstring(E.a) == "a"w);
+        assert(to!dstring(E.a) == "a"d);
+    }
 
     // Test an value not corresponding to an enum member.
-    auto o = cast(E)5;
+    auto o = cast(EU)5;
-    assert(to! string(o) == "cast(E)5"c);
+    assert(to! string(o) == "cast(EU)5"c);
-    assert(to!wstring(o) == "cast(E)5"w);
+    assert(to!wstring(o) == "cast(EU)5"w);
-    assert(to!dstring(o) == "cast(E)5"d);
+    assert(to!dstring(o) == "cast(EU)5"d);
 }
 
 /// ditto

std/traits.d

@@ -2700,7 +2700,7 @@ unittest
 
 /*
  */
-template BooleanTypeOf(T)
+template BooleanTypeOf(T) if (!is(T == enum))
 {
            inout(bool) idx(        inout(bool) );
     shared(inout bool) idx( shared(inout bool) );
@@ -2734,7 +2734,7 @@ unittest
 
 /*
  */
-template IntegralTypeOf(T)
+template IntegralTypeOf(T) if (!is(T == enum))
 {
            inout(  byte) idx(        inout(  byte) );
            inout( ubyte) idx(        inout( ubyte) );
@@ -2793,7 +2793,7 @@ unittest
 
 /*
  */
-template FloatingPointTypeOf(T)
+template FloatingPointTypeOf(T) if (!is(T == enum))
 {
            inout( float) idx(        inout( float) );
            inout(double) idx(        inout(double) );
@@ -2832,7 +2832,7 @@ unittest
 
 /*
  */
-template NumericTypeOf(T)
+template NumericTypeOf(T) if (!is(T == enum))
 {
     static if (is(IntegralTypeOf!T X))
         alias X NumericTypeOf;
@@ -2860,7 +2860,7 @@ unittest
 
 /*
  */
-template UnsignedTypeOf(T)
+template UnsignedTypeOf(T) if (!is(T == enum))
 {
     static if (is(IntegralTypeOf!T X) &&
                staticIndexOf!(Unqual!X, UnsignedIntTypeList) >= 0)
@@ -2869,7 +2869,7 @@ template UnsignedTypeOf(T)
         static assert(0, T.stringof~" is not an unsigned type.");
 }
 
-template SignedTypeOf(T)
+template SignedTypeOf(T) if (!is(T == enum))
 {
     static if (is(IntegralTypeOf!T X) &&
                staticIndexOf!(Unqual!X, SignedIntTypeList) >= 0)
@@ -2882,7 +2882,7 @@ template SignedTypeOf(T)
 
 /*
  */
-template CharTypeOf(T)
+template CharTypeOf(T) if (!is(T == enum))
 {
            inout( char) idx(        inout( char) );
            inout(wchar) idx(        inout(wchar) );
@@ -2937,7 +2937,7 @@ unittest
 
 /*
  */
-template StaticArrayTypeOf(T)
+template StaticArrayTypeOf(T) if (!is(T == enum))
 {
     inout(U[n]) idx(U, size_t n)( inout(U[n]) );
 
@@ -2968,7 +2968,7 @@ unittest
 
 /*
  */
-template DynamicArrayTypeOf(T)
+template DynamicArrayTypeOf(T) if (!is(T == enum))
 {
     inout(U[]) idx(U)( inout(U[]) );
 
@@ -3008,7 +3008,7 @@ unittest
 
 /*
  */
-template ArrayTypeOf(T)
+template ArrayTypeOf(T) if (!is(T == enum))
 {
     static if (is(StaticArrayTypeOf!T X))
         alias X ArrayTypeOf;
@@ -3024,7 +3024,7 @@ unittest
 
 /*
  */
-template StringTypeOf(T) if (isSomeString!T)
+template StringTypeOf(T) if (!is(T == enum) && isSomeString!T)
 {
     alias ArrayTypeOf!T StringTypeOf;
 }
@@ -3054,7 +3054,7 @@ unittest
 
 /*
  */
-template AssocArrayTypeOf(T)
+template AssocArrayTypeOf(T) if (!is(T == enum))
 {
        immutable(V [K]) idx(K, V)(    immutable(V [K]) );
 
@@ -3286,7 +3286,10 @@ Detect whether we can treat T as one of the built-in string types.
  */
 template isSomeString(T)
 {
-    enum isSomeString = isNarrowString!T || is(T : const(dchar[]));
+    static if (is(T == enum))
+        enum isSomeString = false;
+    else
+        enum isSomeString = isNarrowString!T || is(T : const(dchar[]));
 }
 
 unittest