Fix #1924: preserve hexadecimal format when converting literal to wider type

ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -60,6 +60,7 @@
     <None Include="TestCases\Correctness\StackTests.il" />
     <None Include="TestCases\Correctness\StackTypes.il" />
     <None Include="TestCases\Correctness\Uninit.vb" />
+    <None Include="TestCases\ILPretty\Issue1922.il" />
     <None Include="TestCases\ILPretty\WeirdEnums.il" />
     <None Include="TestCases\ILPretty\ConstantBlobs.il" />
     <None Include="TestCases\ILPretty\CS1xSwitch_Debug.il" />
@@ -81,6 +82,7 @@
   <ItemGroup>
     <Compile Include="DisassemblerPrettyTestRunner.cs" />
     <Compile Include="TestCases\Correctness\StringConcat.cs" />
+    <Compile Include="TestCases\ILPretty\Issue1922.cs" />
     <Compile Include="TestCases\Ugly\NoLocalFunctions.cs" />
     <Compile Include="TestCases\VBPretty\Issue1906.cs" />
     <Compile Include="TestCases\VBPretty\Select.cs" />

ICSharpCode.Decompiler.Tests/ILPrettyTestRunner.cs

@@ -94,6 +94,12 @@ namespace ICSharpCode.Decompiler.Tests
 			Run();
 		}
 
+		[Test]
+		public void Issue1922()
+		{
+			Run();
+		}
+
 		[Test]
 		public void FSharpUsing_Debug()
 		{

ICSharpCode.Decompiler.Tests/TestCases/ILPretty/Issue1922.cs

@@ -0,0 +1,15 @@
+namespace Issue1922
+{
+	public class Program
+	{
+		public static long fnWorks(int x, int y)
+		{
+			return (((long)y & 0xFFFFFFL) << 24) | ((long)x & 0xFFFFFFL);
+		}
+
+		public static long fnFails(int x, int y)
+		{
+			return ((y & 0xFFFFFFL) << 24) | (x & 0xFFFFFFL);
+		}
+	}
+}

ICSharpCode.Decompiler.Tests/TestCases/ILPretty/Issue1922.il

@@ -0,0 +1,59 @@
+.assembly extern mscorlib
+{
+  .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )
+  .ver 4:0:0:0
+}
+.assembly Issue1922
+{
+  .hash algorithm 0x00008004
+  .ver 1:0:4059:39717
+}
+.module Issue1389.dll
+.imagebase 0x00400000
+.file alignment 0x00000200
+.stackreserve 0x00100000
+.subsystem 0x0003       // WINDOWS_CUI
+.corflags 0x00000003    //  ILONLY 32BITREQUIRED
+
+.class public auto ansi beforefieldinit Issue1922.Program
+	extends [mscorlib]System.Object
+{
+	// Methods
+  .method public hidebysig static int64 fnWorks (int32 x, int32 y) cil managed 
+  {
+    .maxstack 8
+
+    ldarg.1
+    conv.i8
+    ldc.i4 16777215
+    conv.i8
+    and
+    ldc.i4.s 24
+    shl
+    ldarg.0
+    conv.i8
+    ldc.i4 16777215
+    conv.i8
+    and
+    or
+    ret
+  }
+
+  .method public hidebysig static int64 fnFails (int32 x, int32 y) cil managed 
+  {
+    .maxstack 8
+
+    ldarg.1
+    conv.i8
+    ldc.i8 16777215
+    and
+    ldc.i4.s 24
+    shl
+    ldarg.0
+    conv.i8
+    ldc.i8 16777215
+    and
+    or
+    ret
+  }
+} // end of class Issue1922.Program

ICSharpCode.Decompiler/CSharp/TranslatedExpression.cs

@@ -431,8 +431,12 @@ namespace ICSharpCode.Decompiler.CSharp
 			}
 			var rr = expressionBuilder.resolver.WithCheckForOverflow(checkForOverflow).ResolveCast(targetType, ResolveResult);
 			if (rr.IsCompileTimeConstant && !rr.IsError) {
-				return expressionBuilder.ConvertConstantValue(rr, allowImplicitConversion)
+				var convertedResult = expressionBuilder.ConvertConstantValue(rr, allowImplicitConversion)
 					.WithILInstruction(this.ILInstructions);
+				if (convertedResult.Expression is PrimitiveExpression outputLiteral && this.Expression is PrimitiveExpression inputLiteral) {
+					outputLiteral.Format = inputLiteral.Format;
+				}
+				return convertedResult;
 			} else if (rr.IsError && targetType.IsReferenceType == true && type.IsReferenceType == true) {
 				// Conversion between two reference types, but no direct cast allowed? cast via object
 				// Just make sure we avoid infinite recursion even if the resolver falsely claims we can't cast directly: