From 67d80c8834dda145ad708a26bca11e498d0517e1 Mon Sep 17 00:00:00 2001
From: Daniel Grunwald <daniel@danielgrunwald.de>
Date: Sun, 27 Jan 2013 18:42:50 +0100
Subject: [PATCH] CompareFloatWithEqualityOperatorIssue: don't show warning
 when comparing with infinities.

---
 .../CompareFloatWithEqualityOperatorIssue.cs  | 16 +++++++++
 ...pareFloatWithEqualityOperatorIssueTests.cs | 35 +++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/CompareFloatWithEqualityOperatorIssue.cs b/ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/CompareFloatWithEqualityOperatorIssue.cs
index 4c67c2ee9f..59beaf9f0a 100644
--- a/ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/CompareFloatWithEqualityOperatorIssue.cs
+++ b/ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/CompareFloatWithEqualityOperatorIssue.cs
@@ -25,6 +25,7 @@
 // THE SOFTWARE.
 
 using System.Collections.Generic;
+using ICSharpCode.NRefactory.Semantics;
 using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
@@ -60,6 +61,19 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 				return IsFloatingPointType (ctx.Resolve (node).Type);
 			}
 
+			bool IsConstantInfinity(AstNode node)
+			{
+				ResolveResult rr = ctx.Resolve(node);
+				if (!rr.IsCompileTimeConstant)
+					return false;
+				if (rr.ConstantValue is float)
+					return float.IsInfinity((float)rr.ConstantValue);
+				else if (rr.ConstantValue is double)
+					return double.IsInfinity((double)rr.ConstantValue);
+				else
+					return false;
+			}
+
 			bool IsNaN (AstNode node, out string floatType)
 			{
 				floatType = "";
@@ -105,6 +119,8 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 				} else if (IsNaN (binaryOperatorExpression.Right, out floatType)) {
 					AddIsNaNIssue (binaryOperatorExpression, binaryOperatorExpression.Left, floatType);
 				} else if (IsFloatingPoint(binaryOperatorExpression.Left) || IsFloatingPoint(binaryOperatorExpression.Right)) {
+					if (IsConstantInfinity(binaryOperatorExpression.Left) || IsConstantInfinity(binaryOperatorExpression.Right))
+						return;
 					AddIssue (binaryOperatorExpression, ctx.TranslateString ("Compare a difference with EPSILON"),
 						script => {
 							// Math.Abs(diff) op EPSILON
diff --git a/ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/CompareFloatWithEqualityOperatorIssueTests.cs b/ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/CompareFloatWithEqualityOperatorIssueTests.cs
index 455d23485a..1276d4f688 100644
--- a/ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/CompareFloatWithEqualityOperatorIssueTests.cs
+++ b/ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/CompareFloatWithEqualityOperatorIssueTests.cs
@@ -94,5 +94,40 @@ class TestClass
 }";
 			Test<CompareFloatWithEqualityOperatorIssue> (input, 4, output);
 		}
+		
+		
+		[Test]
+		public void TestPositiveInfinity ()
+		{
+			var input = @"
+class TestClass
+{
+	void TestMethod (double x, float y)
+	{
+		bool test = x == System.Double.PositiveInfinity;
+		bool test2 = x != double.PositiveInfinity;
+		bool test3 = y == float.PositiveInfinity;
+		bool test4 = x != float.PositiveInfinity;
+	}
+}";
+			Test<CompareFloatWithEqualityOperatorIssue> (input, 0);
+		}
+		
+		[Test]
+		public void TestNegativeInfinity ()
+		{
+			var input = @"
+class TestClass
+{
+	void TestMethod (double x, float y)
+	{
+		bool test = x == System.Double.NegativeInfinity;
+		bool test2 = x != double.NegativeInfinity;
+		bool test3 = y == float.NegativeInfinity;
+		bool test4 = x != float.NegativeInfinity;
+	}
+}";
+			Test<CompareFloatWithEqualityOperatorIssue> (input, 0);
+		}
 	}
 }