Fix #2547: decimal const not removed from static constructor.

ICSharpCode.Decompiler.Tests/TestCases/Pretty/ConstructorInitializers.cs

@@ -36,6 +36,25 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			}
 		}
 
+		public class ClassWithConstant
+		{
+			// using decimal constants has the effect that there is a cctor
+			// generated containing the explicit initialization of this field.
+			// The type is marked beforefieldinit
+			private const decimal a = 1.0m;
+		}
+
+		public class ClassWithConstantAndStaticCtor
+		{
+			// The type is not marked beforefieldinit
+			private const decimal a = 1.0m;
+
+			static ClassWithConstantAndStaticCtor()
+			{
+
+			}
+		}
+
 		public struct SimpleStruct
 		{
 			public int Field1;

ICSharpCode.Decompiler/CSharp/Transforms/TransformFieldAndConstructorInitializers.cs

@@ -18,6 +18,7 @@
 
 using System.Collections.Generic;
 using System.Linq;
+using System.Reflection;
 
 using ICSharpCode.Decompiler.CSharp.Syntax;
 using ICSharpCode.Decompiler.CSharp.Syntax.PatternMatching;
@@ -304,8 +305,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 					var metadata = context.TypeSystem.MainModule.PEFile.Metadata;
 					SRM.MethodDefinition ctorMethodDef = metadata.GetMethodDefinition((SRM.MethodDefinitionHandle)ctorMethod.MetadataToken);
 					SRM.TypeDefinition declaringType = metadata.GetTypeDefinition(ctorMethodDef.GetDeclaringType());
-					if (declaringType.HasFlag(System.Reflection.TypeAttributes.BeforeFieldInit))
-					{
+					bool declaringTypeIsBeforeFieldInit = declaringType.HasFlag(TypeAttributes.BeforeFieldInit);
 					while (true)
 					{
 						ExpressionStatement es = staticCtor.Body.Statements.FirstOrDefault() as ExpressionStatement;
@@ -324,6 +324,9 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 						{
 							fieldOrPropertyDecl.Modifiers |= Modifiers.Unsafe;
 						}
+						// Only move fields that are constants, if the declaring type is not marked beforefieldinit.
+						if (declaringTypeIsBeforeFieldInit || fieldOrProperty is IField { IsConst: true })
+						{
 							if (fieldOrPropertyDecl is FieldDeclaration fd)
 								fd.Variables.Single().Initializer = assignment.Right.Detach();
 							else if (fieldOrPropertyDecl is PropertyDeclaration pd)
@@ -332,7 +335,13 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 								break;
 							es.Remove();
 						}
-						if (staticCtor.Body.Statements.Count == 0)
+						else
+						{
+							break;
+						}
+					}
+					if (declaringTypeIsBeforeFieldInit && staticCtor.Body.Statements.Count == 0)
+					{
 						staticCtor.Remove();
 					}
 				}