From 2e00285666d38aa6efb024d36966e48febbcb86a Mon Sep 17 00:00:00 2001
From: Siegfried Pammer <siegfriedpammer@gmail.com>
Date: Sat, 4 May 2019 22:44:35 +0200
Subject: [PATCH] Display type information of fixed fields as "Type[Length]" in
 tree view.

---
 .../CSharp/CSharpDecompiler.cs                | 21 +++++++++++++++++++
 .../CSharp/OutputVisitor/CSharpAmbience.cs    |  8 ++++++-
 .../CSharp/Syntax/TypeSystemAstBuilder.cs     |  8 +++----
 3 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs b/ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs
index 41119a828..00791e127 100644
--- a/ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs
+++ b/ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs
@@ -1406,6 +1406,27 @@ namespace ICSharpCode.Decompiler.CSharp
 			return false;
 		}
 
+		internal static bool IsFixedField(MetadataReader metadata, FieldDefinitionHandle handle, out IType type, out int elementCount)
+		{
+			type = null;
+			elementCount = 0;
+			var field = metadata.GetFieldDefinition(handle);
+			foreach (var h in field.GetCustomAttributes()) {
+				var customAttribute = metadata.GetCustomAttribute(h);
+				if (customAttribute.IsKnownAttribute(metadata, KnownAttribute.FixedBuffer)) {
+					var value = customAttribute.DecodeValue(MetadataExtensions.minimalCorlibTypeProvider);
+					if (value.FixedArguments.Length == 2) {
+						if (value.FixedArguments[0].Value is IType trr && value.FixedArguments[1].Value is int length) {
+							type = trr;
+							elementCount = length;
+							return true;
+						}
+					}
+				}
+			}
+			return false;
+		}
+
 		EntityDeclaration DoDecompile(IProperty property, DecompileRun decompileRun, ITypeResolveContext decompilationContext)
 		{
 			Debug.Assert(decompilationContext.CurrentMember == property);
diff --git a/ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpAmbience.cs b/ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpAmbience.cs
index 775cff0b0..6064fbd33 100644
--- a/ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpAmbience.cs
+++ b/ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpAmbience.cs
@@ -137,7 +137,13 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 					writer.Space();
 					writer.WriteToken(Roles.Colon, ":");
 					writer.Space();
-					rt.AcceptVisitor(new CSharpOutputVisitor(writer, formattingPolicy));
+					if (symbol is IField f && CSharpDecompiler.IsFixedField(f.ParentModule.PEFile.Metadata, (System.Reflection.Metadata.FieldDefinitionHandle)f.MetadataToken, out var type, out int elementCount)) {
+						rt = astBuilder.ConvertType(type);
+						new IndexerExpression(new TypeReferenceExpression(rt), astBuilder.ConvertConstantValue(f.Compilation.FindType(KnownTypeCode.Int32), elementCount))
+							.AcceptVisitor(new CSharpOutputVisitor(writer, formattingPolicy));
+					} else {
+						rt.AcceptVisitor(new CSharpOutputVisitor(writer, formattingPolicy));
+					}
 				}
 			}
 
diff --git a/ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs b/ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs
index 714befab6..c31a53c07 100644
--- a/ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs
+++ b/ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs
@@ -176,25 +176,25 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		public bool UseCustomEvents { get; set; }
 
 		/// <summary>
-		/// Controls if unbound type argument names are inserted in the ast or not.
+		/// Controls whether unbound type argument names are inserted in the ast or not.
 		/// The default value is <c>false</c>.
 		/// </summary>
 		public bool ConvertUnboundTypeArguments { get; set;}
 
 		/// <summary>
-		/// Controls if aliases should be used inside the type name or not.
+		/// Controls whether aliases should be used inside the type name or not.
 		/// The default value is <c>true</c>.
 		/// </summary>
 		public bool UseAliases { get; set; }
 
 		/// <summary>
-		/// Controls if constants like <c>int.MaxValue</c> are converted to a <see cref="MemberReferenceExpression"/> or <see cref="PrimitiveExpression" />.
+		/// Controls whether constants like <c>int.MaxValue</c> are converted to a <see cref="MemberReferenceExpression"/> or <see cref="PrimitiveExpression" />.
 		/// The default value is <c>true</c>.
 		/// </summary>
 		public bool UseSpecialConstants { get; set; }
 
 		/// <summary>
-		/// Controls if integral constants should be printed in hexadecimal format.
+		/// Controls whether integral constants should be printed in hexadecimal format.
 		/// The default value is <c>false</c>.
 		/// </summary>
 		public bool PrintIntegralValuesAsHex { get; set; }