Fix IsByRefLikeAttribute exclusion for IL types in completion filtering

Copilot · abonie · Copilot · commit 2f4b4f848cef · 2025-07-31T16:20:42.000Z
The original fix only handled F# types through CheckFSharpAttributesForObsolete but types like Span&lt;T&gt; and ReadOnlySpan&lt;T&gt; are .NET types that go through IL attribute checking. Updated CheckILAttributesForUnseen to also exclude types with IsByRefLikeAttribute from being considered obsolete, ensuring they appear in completion lists despite having ObsoleteAttribute.

Co-authored-by: abonie &lt;20281641+abonie@users.noreply.github.com&gt;
diff --git a/src/Compiler/Checking/AttributeChecking.fs b/src/Compiler/Checking/AttributeChecking.fs
@@ -441,7 +441,17 @@ let private CheckProvidedAttributes (g: TcGlobals) m (provAttribs: Tainted<IProv
 /// Indicate if a list of IL attributes contains 'ObsoleteAttribute'. Used to suppress the item in intellisense.
 let CheckILAttributesForUnseen (g: TcGlobals) cattrs _m = 
     let (AttribInfo(tref, _)) = g.attrib_SystemObsolete
-    Option.isSome (TryDecodeILAttribute tref cattrs)
+    let hasObsolete = Option.isSome (TryDecodeILAttribute tref cattrs)
+    if hasObsolete then
+        // Exclude types marked with IsByRefLikeAttribute from being considered obsolete,
+        // even if ObsoleteAttribute is present. This avoids improper suppression of types 
+        // like Span and ReadOnlySpan in completion lists due to their dual attributes.
+        match g.attrib_IsByRefLikeAttribute_opt with
+        | Some (AttribInfo(isByRefLikeTref, _)) ->
+            not (Option.isSome (TryDecodeILAttribute isByRefLikeTref cattrs))
+        | None -> true
+    else
+        false
 
 /// Checks the attributes for CompilerMessageAttribute, which has an IsHidden argument that allows
 /// items to be suppressed from intellisense.
