[float] resultDouble.TryParse(str).

AST.ci

@@ -97,6 +97,7 @@ public enum CiId
 	MathNaN,
 	MathNegativeInfinity,
 	MathPositiveInfinity,
+	DoubleTryParse,
 	StringContains,
 	StringEndsWith,
 	StringIndexOf,
@@ -1372,6 +1373,7 @@ public class CiSystem : CiScope
 		Add(ushortType);
 		CiRangeType# minus1Type = CiRangeType.New(-1, 0x7fffffff);
 		Add(FloatType);
+		DoubleType.Add(CiMethod.NewMutator(CiVisibility.Public, BoolType, CiId.DoubleTryParse, "TryParse", CiVar.New(StringPtrType, "value")));
 		Add(DoubleType);
 		Add(BoolType);
 		CiClass# stringClass = CiClass.New(CiCallType.Normal, CiId.StringClass, "string");

GenCs.cs

@@ -420,6 +420,13 @@ public override void VisitSymbolReference(CiSymbolReference expr, CiPriority par
 	protected override void WriteCall(CiExpr obj, CiMethod method, List<CiExpr> args, CiPriority parent)
 	{
 		switch (method.Id) {
+		case CiId.DoubleTryParse:
+			Write("double.TryParse(");
+			args[0].Accept(this, CiPriority.Argument);
+			Write(", out ");
+			obj.Accept(this, CiPriority.Argument);
+			WriteChar(')');
+			break;
 		case CiId.StringIndexOf:
 		case CiId.StringLastIndexOf:
 			obj.Accept(this, CiPriority.Primary);

Parser.ci

@@ -121,9 +121,7 @@ public class CiParser : CiLexer
 	CiLiteralDouble# ParseDouble!()
 	{
 		double d;
-		bool ok;
-		native { ok = double.TryParse(GetLexeme().Replace("_", ""), out d); }
-		if (!ok)
+		if (!d.TryParse(GetLexeme().Replace("_", "")))
 			ReportError("Invalid floating-point number");
 		CiLiteralDouble# result = new CiLiteralDouble { Line = this.Line, Type = this.Program.System.DoubleType, Value = d };
 		NextToken();

Transpiled.cs

@@ -1267,6 +1267,7 @@ public enum CiId
 		MathNaN,
 		MathNegativeInfinity,
 		MathPositiveInfinity,
+		DoubleTryParse,
 		StringContains,
 		StringEndsWith,
 		StringIndexOf,
@@ -2820,6 +2821,7 @@ internal CiSystem()
 			Add(ushortType);
 			CiRangeType minus1Type = CiRangeType.New(-1, 2147483647);
 			Add(this.FloatType);
+			this.DoubleType.Add(CiMethod.NewMutator(CiVisibility.Public, this.BoolType, CiId.DoubleTryParse, "TryParse", CiVar.New(this.StringPtrType, "value")));
 			Add(this.DoubleType);
 			Add(this.BoolType);
 			CiClass stringClass = CiClass.New(CiCallType.Normal, CiId.StringClass, "string");
@@ -3168,8 +3170,7 @@ void CheckXcrementParent()
 		CiLiteralDouble ParseDouble()
 		{
 			double d;
-			bool ok;
-			 ok = double.TryParse(GetLexeme().Replace("_", ""), out d); if (!ok)
+			if (!double.TryParse(GetLexeme().Replace("_", ""), out d))
 				ReportError("Invalid floating-point number");
 			CiLiteralDouble result = new CiLiteralDouble { Line = this.Line, Type = this.Program.System.DoubleType, Value = d };
 			NextToken();

test/DoubleTryParse.ci

@@ -0,0 +1,8 @@
+public static class Test
+{
+	public static bool Run()
+	{
+		double d;
+		return d.TryParse("5") && d == 5; //FAIL: c cpp java js py swift ts cl
+	}
+}