Attributes sorting order

[greenozon]

Usually if you do export to project serveral times, ILSpy saves types with accompanying attributes in different order
e.g.:

Describe the solution you'd like
It'd be very nice to happen if the order of attributes would be sorted in some order and will be constant from export to export

Such feature was implemented in dnSpy and could be turned ON/OFF in Options:

Overall benefit of this feature would be to have shorter time to find the diff between multiple exports thus making end-users even more happy :)

[MeFisto94]

Was also going to report this issue, but not on the UI level but the nuget pkg/decompiler settings class.
I don't know if IL is preserving attribute order and this is a bug or if the order of attributes is just not defined.
In the latter case, I'd suggest adding a DecompilerSetting "sort attributes in alphabetical order" (or similar) and just sorting the set when rendering the code.

That would greatly help my tooling by reducing faulty diffs (that basically happen on every file that has more than two attributes on an element)

Edit: A simple hack would probably be to sort here:

ILSpy/ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpOutputVisitor.cs

Lines 569 to 572 in 2ed9ad6

	foreach (AttributeSection attr in attributes)
	{
	attr.AcceptVisitor(this);
	}

I don't know the code base at all, but essentially AstNodeCollection seems to preserve the order, so the question is why the AstNode provides the attributes in such an order, so probably sorting makes sense in the parser that populates the AstNode? or have it sort said node afterwards?

[dgrunwald]

ILSpy should alway maintain the order of the attributes from the CustomAttributes metadata table.
I think it's the C# compiler that emits attributes in non-deterministic order. The C# compiler needs to sort the attribute table by the parent metadata token, so my guess is that they're using a non-stable sort for doing that.

[dgrunwald]

Actually I'm not sure who's doing the sorting -- System.Reflection.Metadata also has logic to unstably sort the custom attribute table if they're not already sorted (CustomAttributeTableReader ctor).

[xiaoxiao921]

Temp solution for anyone still intersted in this:

diff --git a/ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpOutputVisitor.cs b/ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpOutputVisitor.cs
index 96d591dab..057a5b385 100644
--- a/ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpOutputVisitor.cs
+++ b/ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpOutputVisitor.cs
@@ -566,7 +566,12 @@ protected virtual void WriteMethodBody(BlockStatement body, BraceStyle style, bo

                protected virtual void WriteAttributes(IEnumerable<AttributeSection> attributes)
                {
-                       foreach (AttributeSection attr in attributes)
+                       var l = attributes.ToList();
+                       l.Sort((a, b) => {
+                               return a.ToString().CompareTo(b.ToString());
+                       });
+
+                       foreach (AttributeSection attr in l)
                        {
                                attr.AcceptVisitor(this);
                        }

Tried implementing cleanly with a IAstTransform without any success, any changes to an ast node child ordering wouldnt save so I just did this quick hack locally instead

[greenozon]

The issue still present... it's a minor one but once you need to compare 2 slightly different assemblies you'll hit the enourmous delta, in fact it's 0, eg:

@dgrunwald could we please get back to this old issue?
Thanks

Expectation - somehow sort the attributes and make it stable each & every run

[testanull]

Thank a random Chinese @xiaoxiao921,
Your solution works perfectly for me!

[siegfriedpammer]

@greenozon now implemented as an option

[testanull]

@greenozon now implemented as an option

Sorry but I have to reopen this issue,
I've tested with commit 8b76879, but this error shows up

I think the reason is because of the inconsistent of attributes NamedArguments' Length and attributes FixedArguments' Length

In TypeSystemAstBuilder.cs#L844

Is this supposed to be a.NamedArguments instead?

[siegfriedpammer]

@testanull thanks for reporting, fixed