[mlir] Explain required attrs for CallOpInterface in Toy (NFC)

[jjvraw]

Following #123176.

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@llvm/pr-subscribers-mlir

Author: Joshua James Venter (jjvraw)

Changes

Following #123176.

---

Full diff: https://github.com/llvm/llvm-project/pull/141018.diff

1 Files Affected:

• (modified) mlir/docs/Tutorials/Toy/Ch-4.md (+14-1)

diff --git a/mlir/docs/Tutorials/Toy/Ch-4.md b/mlir/docs/Tutorials/Toy/Ch-4.md
index 39e9ecdd92221..1275d36de3531 100644
--- a/mlir/docs/Tutorials/Toy/Ch-4.md
+++ b/mlir/docs/Tutorials/Toy/Ch-4.md
@@ -159,7 +159,20 @@ def GenericCallOp : Toy_Op<"generic_call",
 
 In the above we also use the `DeclareOpInterfaceMethods` directive to
 auto-declare all of the interface methods in the class declaration of
-GenericCallOp. We have already provided the definition in the `extraClassDeclaration`
+`GenericCallOp`. However, using this directive with `CallOpInterface`
+includes methods for handling argument and result attributes. Therefore,
+we need to add these specifically named attributes to our `GenericCallOp`
+definition:
+
+```tablegen
+let arguments = (ins
+  ...
+  OptionalAttr<DictArrayAttr>:$arg_attrs,
+  OptionalAttr<DictArrayAttr>:$res_attrs
+);
+
+
+We have already provided the definition in the `extraClassDeclaration`
 field of the `FuncOp` class:
 
 ```c++

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