Add special case for negative zero in CSharpOutputVisitor.

ICSharpCode.NRefactory.CSharp/OutputVisitor/CSharpOutputVisitor.cs

@@ -1057,6 +1057,12 @@ namespace ICSharpCode.NRefactory.CSharp
 					}
 					return;
 				}
+				if (f == 0 && 1 / f == float.NegativeInfinity) {
+					// negative zero is a special case
+					// (again, not a primitive expression, but it's better to handle
+					// the special case here than to do it in all code generators)
+					formatter.WriteToken("-");
+				}
 				formatter.WriteToken(f.ToString("R", NumberFormatInfo.InvariantInfo) + "f");
 				lastWritten = LastWritten.Other;
 			} else if (val is double) {
@@ -1075,6 +1081,12 @@ namespace ICSharpCode.NRefactory.CSharp
 					}
 					return;
 				}
+				if (f == 0 && 1 / f == double.NegativeInfinity) {
+					// negative zero is a special case
+					// (again, not a primitive expression, but it's better to handle
+					// the special case here than to do it in all code generators)
+					formatter.WriteToken("-");
+				}
 				string number = f.ToString("R", NumberFormatInfo.InvariantInfo);
 				if (number.IndexOf('.') < 0 && number.IndexOf('E') < 0) {
 					number += ".0";

ICSharpCode.NRefactory.Tests/CSharp/CSharpOutputVisitorTests.cs

@@ -138,5 +138,14 @@ namespace ICSharpCode.NRefactory.CSharp
 			             "case 3: {\n$int a = 3;\n$return a;\n}\n" +
 			             "default:\n$break;\n}\n", type);
 		}
+		
+		[Test]
+		public void ZeroLiterals()
+		{
+			AssertOutput("0.0", new PrimitiveExpression(0.0));
+			AssertOutput("-0.0", new PrimitiveExpression(-0.0));
+			AssertOutput("0f", new PrimitiveExpression(0f));
+			AssertOutput("-0f", new PrimitiveExpression(-0f));
+		}
 	}
 }