[mlir] Use std::nullopt instead of None in comments (NFC)

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

2 files changed, 5 insertions, 5 deletions

diff --git a/mlir/tools/mlir-tblgen/OpFormatGen.cpp b/mlir/tools/mlir-tblgen/OpFormatGen.cpp
index 07a6ab9..daa4e9d 100644
--- a/mlir/tools/mlir-tblgen/OpFormatGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpFormatGen.cpp
@@ -57,8 +57,8 @@ struct AttributeVariable
     : public OpVariableElement<NamedAttribute, VariableElement::Attribute> {
   using Base::Base;
 
-  /// Return the constant builder call for the type of this attribute, or None
-  /// if it doesn't have one.
+  /// Return the constant builder call for the type of this attribute, or
+  /// std::nullopt if it doesn't have one.
   llvm::Optional<StringRef> getTypeBuilder() const {
     llvm::Optional<Type> attrType = var->attr.getValueType();
     return attrType ? attrType->getBuilderCall() : std::nullopt;
@@ -251,7 +251,7 @@ struct OperationFormat {
   public:
     TypeResolution() = default;
 
-    /// Get the index into the buildable types for this type, or None.
+    /// Get the index into the buildable types for this type, or std::nullopt.
     Optional<int> getBuilderIdx() const { return builderIdx; }
     void setBuilderIdx(int idx) { builderIdx = idx; }
 
@@ -263,7 +263,7 @@ struct OperationFormat {
     const NamedAttribute *getAttribute() const {
       return resolver.dyn_cast<const NamedAttribute *>();
     }
-    /// Get the transformer for the type of the variable, or None.
+    /// Get the transformer for the type of the variable, or std::nullopt.
     Optional<StringRef> getVarTransformer() const {
       return variableTransformer;
     }
diff --git a/mlir/tools/mlir-tblgen/OpPythonBindingGen.cpp b/mlir/tools/mlir-tblgen/OpPythonBindingGen.cpp
index f83908c3..a5ffcc4 100644
--- a/mlir/tools/mlir-tblgen/OpPythonBindingGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpPythonBindingGen.cpp
@@ -71,7 +71,7 @@ class {0}(_ods_ir.OpView):
 /// Each segment spec is either None (default) or an array of integers
 /// where:
 ///   1 = single element (expect non sequence operand/result)
-///   0 = optional element (expect a value or None)
+///   0 = optional element (expect a value or std::nullopt)
 ///   -1 = operand/result is a sequence corresponding to a variadic
 constexpr const char *opClassSizedSegmentsTemplate = R"Py(
   _ODS_{0}_SEGMENTS = {1}