[llvm] [mlir] [mlir] Add symbol user attribute interface. (PR #153206)

[Mehdi Amini via llvm-commits]

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@@ -220,6 +220,24 @@ def SymbolUserOpInterface : OpInterface<"SymbolUserOpInterface"> {
   ];
 }
 
+def SymbolUserAttrInterface : AttrInterface<"SymbolUserAttrInterface"> {
+  let description = [{
+    This interface describes an attribute that may use a `Symbol`. This
+    interface allows for users of symbols to hook into verification and other
+    symbol related utilities that are either costly or otherwise disallowed
+    within a traditional operation.
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joker-eph wrote:

Also what are these things that are costly/disallowed?

https://github.com/llvm/llvm-project/pull/153206