Extend attributes removal to support values matching (#1935)

* Extend attributes removal to support values matching

This is useful for key/value pair like custom attributes removal

* PR feedback

1 files changed, 23 insertions, 5 deletions

diff --git a/docs/data-formats.md b/docs/data-formats.md
index 91670c8d9..f3a11d981 100644
--- a/docs/data-formats.md
+++ b/docs/data-formats.md
@@ -528,15 +528,15 @@ attributes are applied.
 <attribute fullname="SomecustomAttribute" feature="EnableOptionalFeature" featurevalue="false"/>
 ```
 
-### Special custom attributes
+### Removing custom attributes
 
-Also if the attribute is used in a type, a special property can be used to specify that the type
-is a Custom Attribute and it's instances should be removed by the linker. To do this use `internal="RemoveAttributeInstances"` instead of specifying `fullname` in the attribute as described in the following
-example:
+Any custom attribute can be annotated with a special custom attribute which can be used to specify
+that all instances of the attribute can be removed by the linker. To do this use `internal="RemoveAttributeInstances"`
+instead of specifying `fullname` in the attribute as described in the following example:
 
 ```xml
 <linker>
-  <assembly fullname="*"> 
+  <assembly fullname="*">
     <type fullname="System.Runtime.CompilerServices.NullableAttribute">
       <attribute internal="RemoveAttributeInstances" feature="EnableOptionalFeature" featurevalue="false" />
     </type>
@@ -544,6 +544,24 @@ example:
 </linker>
 ```
 
+In some cases, it's useful to remove only specific usage of the attribute. This can be achieved by specifying the value
+or values of the arguments to match. In the example below only `System.Reflection.AssemblyMetadataAttribute` custom attributes
+with the first argument equal to `RemovableValue` will be removed.
+
+```xml
+<linker>
+  <assembly fullname="*">
+    <type fullname="System.Reflection.AssemblyMetadataAttribute">
+      <attribute internal="RemoveAttributeInstances">
+        <argument type="System.Object">
+          <argument>RemovableValue</argument>
+        </argument>
+      </attribute>
+    </type>
+  </assembly>
+</linker>
+```
+
 Notice that a descriptor file containing the custom attribute type overrides this behavior. In case the
 custom attribute type is being referenced in a descriptor file and in the attribute annotations file
 for removal, the custom attribute will not be removed.