[mlir] Migrate away from std::nullopt (NFC) #145523

kazutakahirata · 2025-06-24T14:50:27Z

ArrayRef has a constructor that accepts std::nullopt. This
constructor dates back to the days when we still had llvm::Optional.

Since the use of std::nullopt outside the context of std::optional is
kind of abuse and not intuitive to new comers, I would like to move
away from the constructor and eventually remove it.

This patch migrates away from std::nullopt in favor of ArrayRef()
where we use perfect forwarding. Note that {} would be ambiguous for
perfect forwarding to work.

ArrayRef has a constructor that accepts std::nullopt. This constructor dates back to the days when we still had llvm::Optional. Since the use of std::nullopt outside the context of std::optional is kind of abuse and not intuitive to new comers, I would like to move away from the constructor and eventually remove it. This patch migrates away from std::nullopt in favor of ArrayRef<T>() where we use perfect forwarding. Note that {} would be ambiguous for perfect forwarding to work.

llvmbot · 2025-06-24T14:50:58Z

@llvm/pr-subscribers-mlir-core
@llvm/pr-subscribers-mlir
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-mlir-linalg

Author: Kazu Hirata (kazutakahirata)

Changes

ArrayRef has a constructor that accepts std::nullopt. This
constructor dates back to the days when we still had llvm::Optional.

Since the use of std::nullopt outside the context of std::optional is
kind of abuse and not intuitive to new comers, I would like to move
away from the constructor and eventually remove it.

This patch migrates away from std::nullopt in favor of ArrayRef<T>()
where we use perfect forwarding. Note that {} would be ambiguous for
perfect forwarding to work.

Full diff: https://github.com/llvm/llvm-project/pull/145523.diff

8 Files Affected:

(modified) clang/lib/ASTMatchers/Dynamic/Marshallers.h (+1-1)
(modified) mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp (+1-1)
(modified) mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp (+8-8)
(modified) mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp (+2-1)
(modified) mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp (+3-2)
(modified) mlir/test/lib/Dialect/Test/TestPatterns.cpp (+2-2)
(modified) mlir/unittests/IR/OperationSupportTest.cpp (+11-11)
(modified) mlir/unittests/IR/ValueTest.cpp (+6-6)

diff --git a/clang/lib/ASTMatchers/Dynamic/Marshallers.h b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
index 0e640cbada726..d44e42a524f27 100644
--- a/clang/lib/ASTMatchers/Dynamic/Marshallers.h
+++ b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
@@ -1060,7 +1060,7 @@ makeMatcherAutoMarshall(ReturnType (*Func)(), StringRef MatcherName) {
   BuildReturnTypeVector<ReturnType>::build(RetTypes);
   return std::make_unique<FixedArgCountMatcherDescriptor>(
       matcherMarshall0<ReturnType>, reinterpret_cast<void (*)()>(Func),
-      MatcherName, RetTypes, std::nullopt);
+      MatcherName, RetTypes, ArrayRef<ArgKind>());
 }
 
 /// 1-arg overload
diff --git a/mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp b/mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp
index bd2846ac388fd..945d38e929e08 100644
--- a/mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp
+++ b/mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp
@@ -991,7 +991,7 @@ void PDLToPDLInterpPass::runOnOperation() {
       module.getLoc(), pdl_interp::PDLInterpDialect::getMatcherFunctionName(),
       builder.getFunctionType(builder.getType<pdl::OperationType>(),
                               /*results=*/{}),
-      /*attrs=*/std::nullopt);
+      /*attrs=*/ArrayRef<NamedAttribute>());
 
   // Create a nested module to hold the functions invoked for rewriting the IR
   // after a successful match.
diff --git a/mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp b/mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp
index 923f5f67b865a..c2be08ef40f21 100644
--- a/mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp
+++ b/mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp
@@ -310,8 +310,8 @@ static Value createLinalgBodyCalculationForElementwiseOp(
     auto shifted =
         rewriter.create<arith::ShRSIOp>(loc, resultTypes, args[0], subtract)
             ->getResults();
-    auto truncated =
-        rewriter.create<arith::TruncIOp>(loc, i1Ty, shifted, std::nullopt);
+    auto truncated = rewriter.create<arith::TruncIOp>(
+        loc, i1Ty, shifted, ArrayRef<NamedAttribute>());
     auto isInputOdd =
         rewriter.create<arith::AndIOp>(loc, i1Ty, truncated, i1one);
 
@@ -552,20 +552,20 @@ static Value createLinalgBodyCalculationForElementwiseOp(
 
     if (isa<FloatType>(srcTy) && isa<FloatType>(dstTy) && bitExtend)
       return rewriter.create<arith::ExtFOp>(loc, resultTypes, args,
-                                            std::nullopt);
+                                            ArrayRef<NamedAttribute>());
 
     if (isa<FloatType>(srcTy) && isa<FloatType>(dstTy) && !bitExtend)
       return rewriter.create<arith::TruncFOp>(loc, resultTypes, args,
-                                              std::nullopt);
+                                              ArrayRef<NamedAttribute>());
 
     // 1-bit integers need to be treated as signless.
     if (srcTy.isInteger(1) && arith::UIToFPOp::areCastCompatible(srcTy, dstTy))
       return rewriter.create<arith::UIToFPOp>(loc, resultTypes, args,
-                                              std::nullopt);
+                                              ArrayRef<NamedAttribute>());
 
     if (srcTy.isInteger(1) && isa<IntegerType>(dstTy) && bitExtend)
       return rewriter.create<arith::ExtUIOp>(loc, resultTypes, args,
-                                             std::nullopt);
+                                             ArrayRef<NamedAttribute>());
 
     // Unsigned integers need an unrealized cast so that they can be passed
     // to UIToFP.
@@ -583,7 +583,7 @@ static Value createLinalgBodyCalculationForElementwiseOp(
     // All other si-to-fp conversions should be handled by SIToFP.
     if (arith::SIToFPOp::areCastCompatible(srcTy, dstTy))
       return rewriter.create<arith::SIToFPOp>(loc, resultTypes, args,
-                                              std::nullopt);
+                                              ArrayRef<NamedAttribute>());
 
     // Casting to boolean, floats need to only be checked as not-equal to zero.
     if (isa<FloatType>(srcTy) && dstTy.isInteger(1)) {
@@ -690,7 +690,7 @@ static Value createLinalgBodyCalculationForElementwiseOp(
 
     if (isa<IntegerType>(srcTy) && isa<IntegerType>(dstTy) && bitExtend)
       return rewriter.create<arith::ExtSIOp>(loc, resultTypes, args,
-                                             std::nullopt);
+                                             ArrayRef<NamedAttribute>());
 
     if (isa<IntegerType>(srcTy) && isa<IntegerType>(dstTy) && !bitExtend) {
       return rewriter.create<arith::TruncIOp>(loc, dstTy, args[0]);
diff --git a/mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp b/mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp
index 695d43b04cff0..f63af8da28087 100644
--- a/mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp
+++ b/mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp
@@ -111,7 +111,8 @@ static Value getFlatMemref(OpBuilder &rewriter, Location loc, Value source,
       getFlatOffsetAndStrides(rewriter, loc, source, offsetsTemp);
   MemRefType retType = inferCastResultType(base, offset);
   return rewriter.create<memref::ReinterpretCastOp>(loc, retType, base, offset,
-                                                    std::nullopt, std::nullopt);
+                                                    ArrayRef<OpFoldResult>(),
+                                                    ArrayRef<OpFoldResult>());
 }
 
 static bool needFlatten(Value val) {
diff --git a/mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp b/mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp
index 29bc49b78f15d..824201d17b5ab 100644
--- a/mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp
+++ b/mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp
@@ -350,8 +350,9 @@ Value CodeGen::genNonInitializerVar(const ast::VariableDecl *varDecl,
     Value results = builder.create<pdl::TypesOp>(
         loc, pdl::RangeType::get(builder.getType<pdl::TypeType>()),
         /*types=*/ArrayAttr());
-    return builder.create<pdl::OperationOp>(
-        loc, opType.getName(), operands, std::nullopt, ValueRange(), results);
+    return builder.create<pdl::OperationOp>(loc, opType.getName(), operands,
+                                            ArrayRef<StringRef>(), ValueRange(),
+                                            results);
   }
 
   if (ast::RangeType rangeTy = dyn_cast<ast::RangeType>(type)) {
diff --git a/mlir/test/lib/Dialect/Test/TestPatterns.cpp b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
index 9126736d1d175..6b22b171822ae 100644
--- a/mlir/test/lib/Dialect/Test/TestPatterns.cpp
+++ b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
@@ -1014,7 +1014,7 @@ struct TestPassthroughInvalidOp : public ConversionPattern {
               .getResult());
     }
     rewriter.replaceOpWithNewOp<TestValidOp>(op, TypeRange(), flattened,
-                                             std::nullopt);
+                                             ArrayRef<NamedAttribute>());
     return success();
   }
 };
@@ -1030,7 +1030,7 @@ struct TestDropAndReplaceInvalidOp : public ConversionPattern {
   matchAndRewrite(Operation *op, ArrayRef<Value> operands,
                   ConversionPatternRewriter &rewriter) const final {
     rewriter.replaceOpWithNewOp<TestValidOp>(op, TypeRange(), ValueRange(),
-                                             std::nullopt);
+                                             ArrayRef<NamedAttribute>());
     return success();
   }
 };
diff --git a/mlir/unittests/IR/OperationSupportTest.cpp b/mlir/unittests/IR/OperationSupportTest.cpp
index 0dd46fbd3f104..b335c7977cc6d 100644
--- a/mlir/unittests/IR/OperationSupportTest.cpp
+++ b/mlir/unittests/IR/OperationSupportTest.cpp
@@ -32,8 +32,8 @@ TEST(OperandStorageTest, NonResizable) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *useOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                              builder.getIntegerType(16));
   Value operand = useOp->getResult(0);
 
   // Create a non-resizable operation with one operand.
@@ -56,8 +56,8 @@ TEST(OperandStorageTest, Resizable) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *useOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                              builder.getIntegerType(16));
   Value operand = useOp->getResult(0);
 
   // Create a resizable operation with one operand.
@@ -84,8 +84,8 @@ TEST(OperandStorageTest, RangeReplace) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *useOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                              builder.getIntegerType(16));
   Value operand = useOp->getResult(0);
 
   // Create a resizable operation with one operand.
@@ -120,8 +120,8 @@ TEST(OperandStorageTest, MutableRange) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *useOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                              builder.getIntegerType(16));
   Value operand = useOp->getResult(0);
 
   // Create a resizable operation with one operand.
@@ -159,7 +159,7 @@ TEST(OperandStorageTest, RangeErase) {
 
   Type type = builder.getNoneType();
   Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, {type, type});
+      createOp(&context, /*operands=*/ArrayRef<Value>(), {type, type});
   Value operand1 = useOp->getResult(0);
   Value operand2 = useOp->getResult(1);
 
@@ -189,8 +189,8 @@ TEST(OperationOrderTest, OrderIsAlwaysValid) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *containerOp = createOp(&context, /*operands=*/std::nullopt,
-                                    /*resultTypes=*/std::nullopt,
+  Operation *containerOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                                    /*resultTypes=*/ArrayRef<Type>(),
                                     /*numRegions=*/1);
   Region &region = containerOp->getRegion(0);
   Block *block = new Block();
diff --git a/mlir/unittests/IR/ValueTest.cpp b/mlir/unittests/IR/ValueTest.cpp
index 58678224780be..1b6bcb50b49de 100644
--- a/mlir/unittests/IR/ValueTest.cpp
+++ b/mlir/unittests/IR/ValueTest.cpp
@@ -31,8 +31,8 @@ TEST(ValueTest, getNumUses) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *op0 =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *op0 = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                            builder.getIntegerType(16));
 
   Value v0 = op0->getResult(0);
   EXPECT_EQ(v0.getNumUses(), (unsigned)0);
@@ -52,8 +52,8 @@ TEST(ValueTest, hasNUses) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *op0 =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *op0 = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                            builder.getIntegerType(16));
   Value v0 = op0->getResult(0);
   EXPECT_TRUE(v0.hasNUses(0));
   EXPECT_FALSE(v0.hasNUses(1));
@@ -76,8 +76,8 @@ TEST(ValueTest, hasNUsesOrMore) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *op0 =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *op0 = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                            builder.getIntegerType(16));
   Value v0 = op0->getResult(0);
   EXPECT_TRUE(v0.hasNUsesOrMore(0));
   EXPECT_FALSE(v0.hasNUsesOrMore(1));

llvmbot · 2025-06-24T14:50:59Z

@llvm/pr-subscribers-mlir-gpu

Author: Kazu Hirata (kazutakahirata)

Changes

ArrayRef has a constructor that accepts std::nullopt. This
constructor dates back to the days when we still had llvm::Optional.

Since the use of std::nullopt outside the context of std::optional is
kind of abuse and not intuitive to new comers, I would like to move
away from the constructor and eventually remove it.

This patch migrates away from std::nullopt in favor of ArrayRef<T>()
where we use perfect forwarding. Note that {} would be ambiguous for
perfect forwarding to work.

Full diff: https://github.com/llvm/llvm-project/pull/145523.diff

8 Files Affected:

(modified) clang/lib/ASTMatchers/Dynamic/Marshallers.h (+1-1)
(modified) mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp (+1-1)
(modified) mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp (+8-8)
(modified) mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp (+2-1)
(modified) mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp (+3-2)
(modified) mlir/test/lib/Dialect/Test/TestPatterns.cpp (+2-2)
(modified) mlir/unittests/IR/OperationSupportTest.cpp (+11-11)
(modified) mlir/unittests/IR/ValueTest.cpp (+6-6)

diff --git a/clang/lib/ASTMatchers/Dynamic/Marshallers.h b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
index 0e640cbada726..d44e42a524f27 100644
--- a/clang/lib/ASTMatchers/Dynamic/Marshallers.h
+++ b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
@@ -1060,7 +1060,7 @@ makeMatcherAutoMarshall(ReturnType (*Func)(), StringRef MatcherName) {
   BuildReturnTypeVector<ReturnType>::build(RetTypes);
   return std::make_unique<FixedArgCountMatcherDescriptor>(
       matcherMarshall0<ReturnType>, reinterpret_cast<void (*)()>(Func),
-      MatcherName, RetTypes, std::nullopt);
+      MatcherName, RetTypes, ArrayRef<ArgKind>());
 }
 
 /// 1-arg overload
diff --git a/mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp b/mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp
index bd2846ac388fd..945d38e929e08 100644
--- a/mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp
+++ b/mlir/lib/Conversion/PDLToPDLInterp/PDLToPDLInterp.cpp
@@ -991,7 +991,7 @@ void PDLToPDLInterpPass::runOnOperation() {
       module.getLoc(), pdl_interp::PDLInterpDialect::getMatcherFunctionName(),
       builder.getFunctionType(builder.getType<pdl::OperationType>(),
                               /*results=*/{}),
-      /*attrs=*/std::nullopt);
+      /*attrs=*/ArrayRef<NamedAttribute>());
 
   // Create a nested module to hold the functions invoked for rewriting the IR
   // after a successful match.
diff --git a/mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp b/mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp
index 923f5f67b865a..c2be08ef40f21 100644
--- a/mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp
+++ b/mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp
@@ -310,8 +310,8 @@ static Value createLinalgBodyCalculationForElementwiseOp(
     auto shifted =
         rewriter.create<arith::ShRSIOp>(loc, resultTypes, args[0], subtract)
             ->getResults();
-    auto truncated =
-        rewriter.create<arith::TruncIOp>(loc, i1Ty, shifted, std::nullopt);
+    auto truncated = rewriter.create<arith::TruncIOp>(
+        loc, i1Ty, shifted, ArrayRef<NamedAttribute>());
     auto isInputOdd =
         rewriter.create<arith::AndIOp>(loc, i1Ty, truncated, i1one);
 
@@ -552,20 +552,20 @@ static Value createLinalgBodyCalculationForElementwiseOp(
 
     if (isa<FloatType>(srcTy) && isa<FloatType>(dstTy) && bitExtend)
       return rewriter.create<arith::ExtFOp>(loc, resultTypes, args,
-                                            std::nullopt);
+                                            ArrayRef<NamedAttribute>());
 
     if (isa<FloatType>(srcTy) && isa<FloatType>(dstTy) && !bitExtend)
       return rewriter.create<arith::TruncFOp>(loc, resultTypes, args,
-                                              std::nullopt);
+                                              ArrayRef<NamedAttribute>());
 
     // 1-bit integers need to be treated as signless.
     if (srcTy.isInteger(1) && arith::UIToFPOp::areCastCompatible(srcTy, dstTy))
       return rewriter.create<arith::UIToFPOp>(loc, resultTypes, args,
-                                              std::nullopt);
+                                              ArrayRef<NamedAttribute>());
 
     if (srcTy.isInteger(1) && isa<IntegerType>(dstTy) && bitExtend)
       return rewriter.create<arith::ExtUIOp>(loc, resultTypes, args,
-                                             std::nullopt);
+                                             ArrayRef<NamedAttribute>());
 
     // Unsigned integers need an unrealized cast so that they can be passed
     // to UIToFP.
@@ -583,7 +583,7 @@ static Value createLinalgBodyCalculationForElementwiseOp(
     // All other si-to-fp conversions should be handled by SIToFP.
     if (arith::SIToFPOp::areCastCompatible(srcTy, dstTy))
       return rewriter.create<arith::SIToFPOp>(loc, resultTypes, args,
-                                              std::nullopt);
+                                              ArrayRef<NamedAttribute>());
 
     // Casting to boolean, floats need to only be checked as not-equal to zero.
     if (isa<FloatType>(srcTy) && dstTy.isInteger(1)) {
@@ -690,7 +690,7 @@ static Value createLinalgBodyCalculationForElementwiseOp(
 
     if (isa<IntegerType>(srcTy) && isa<IntegerType>(dstTy) && bitExtend)
       return rewriter.create<arith::ExtSIOp>(loc, resultTypes, args,
-                                             std::nullopt);
+                                             ArrayRef<NamedAttribute>());
 
     if (isa<IntegerType>(srcTy) && isa<IntegerType>(dstTy) && !bitExtend) {
       return rewriter.create<arith::TruncIOp>(loc, dstTy, args[0]);
diff --git a/mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp b/mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp
index 695d43b04cff0..f63af8da28087 100644
--- a/mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp
+++ b/mlir/lib/Dialect/GPU/Transforms/DecomposeMemRefs.cpp
@@ -111,7 +111,8 @@ static Value getFlatMemref(OpBuilder &rewriter, Location loc, Value source,
       getFlatOffsetAndStrides(rewriter, loc, source, offsetsTemp);
   MemRefType retType = inferCastResultType(base, offset);
   return rewriter.create<memref::ReinterpretCastOp>(loc, retType, base, offset,
-                                                    std::nullopt, std::nullopt);
+                                                    ArrayRef<OpFoldResult>(),
+                                                    ArrayRef<OpFoldResult>());
 }
 
 static bool needFlatten(Value val) {
diff --git a/mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp b/mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp
index 29bc49b78f15d..824201d17b5ab 100644
--- a/mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp
+++ b/mlir/lib/Tools/PDLL/CodeGen/MLIRGen.cpp
@@ -350,8 +350,9 @@ Value CodeGen::genNonInitializerVar(const ast::VariableDecl *varDecl,
     Value results = builder.create<pdl::TypesOp>(
         loc, pdl::RangeType::get(builder.getType<pdl::TypeType>()),
         /*types=*/ArrayAttr());
-    return builder.create<pdl::OperationOp>(
-        loc, opType.getName(), operands, std::nullopt, ValueRange(), results);
+    return builder.create<pdl::OperationOp>(loc, opType.getName(), operands,
+                                            ArrayRef<StringRef>(), ValueRange(),
+                                            results);
   }
 
   if (ast::RangeType rangeTy = dyn_cast<ast::RangeType>(type)) {
diff --git a/mlir/test/lib/Dialect/Test/TestPatterns.cpp b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
index 9126736d1d175..6b22b171822ae 100644
--- a/mlir/test/lib/Dialect/Test/TestPatterns.cpp
+++ b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
@@ -1014,7 +1014,7 @@ struct TestPassthroughInvalidOp : public ConversionPattern {
               .getResult());
     }
     rewriter.replaceOpWithNewOp<TestValidOp>(op, TypeRange(), flattened,
-                                             std::nullopt);
+                                             ArrayRef<NamedAttribute>());
     return success();
   }
 };
@@ -1030,7 +1030,7 @@ struct TestDropAndReplaceInvalidOp : public ConversionPattern {
   matchAndRewrite(Operation *op, ArrayRef<Value> operands,
                   ConversionPatternRewriter &rewriter) const final {
     rewriter.replaceOpWithNewOp<TestValidOp>(op, TypeRange(), ValueRange(),
-                                             std::nullopt);
+                                             ArrayRef<NamedAttribute>());
     return success();
   }
 };
diff --git a/mlir/unittests/IR/OperationSupportTest.cpp b/mlir/unittests/IR/OperationSupportTest.cpp
index 0dd46fbd3f104..b335c7977cc6d 100644
--- a/mlir/unittests/IR/OperationSupportTest.cpp
+++ b/mlir/unittests/IR/OperationSupportTest.cpp
@@ -32,8 +32,8 @@ TEST(OperandStorageTest, NonResizable) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *useOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                              builder.getIntegerType(16));
   Value operand = useOp->getResult(0);
 
   // Create a non-resizable operation with one operand.
@@ -56,8 +56,8 @@ TEST(OperandStorageTest, Resizable) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *useOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                              builder.getIntegerType(16));
   Value operand = useOp->getResult(0);
 
   // Create a resizable operation with one operand.
@@ -84,8 +84,8 @@ TEST(OperandStorageTest, RangeReplace) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *useOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                              builder.getIntegerType(16));
   Value operand = useOp->getResult(0);
 
   // Create a resizable operation with one operand.
@@ -120,8 +120,8 @@ TEST(OperandStorageTest, MutableRange) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *useOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                              builder.getIntegerType(16));
   Value operand = useOp->getResult(0);
 
   // Create a resizable operation with one operand.
@@ -159,7 +159,7 @@ TEST(OperandStorageTest, RangeErase) {
 
   Type type = builder.getNoneType();
   Operation *useOp =
-      createOp(&context, /*operands=*/std::nullopt, {type, type});
+      createOp(&context, /*operands=*/ArrayRef<Value>(), {type, type});
   Value operand1 = useOp->getResult(0);
   Value operand2 = useOp->getResult(1);
 
@@ -189,8 +189,8 @@ TEST(OperationOrderTest, OrderIsAlwaysValid) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *containerOp = createOp(&context, /*operands=*/std::nullopt,
-                                    /*resultTypes=*/std::nullopt,
+  Operation *containerOp = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                                    /*resultTypes=*/ArrayRef<Type>(),
                                     /*numRegions=*/1);
   Region &region = containerOp->getRegion(0);
   Block *block = new Block();
diff --git a/mlir/unittests/IR/ValueTest.cpp b/mlir/unittests/IR/ValueTest.cpp
index 58678224780be..1b6bcb50b49de 100644
--- a/mlir/unittests/IR/ValueTest.cpp
+++ b/mlir/unittests/IR/ValueTest.cpp
@@ -31,8 +31,8 @@ TEST(ValueTest, getNumUses) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *op0 =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *op0 = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                            builder.getIntegerType(16));
 
   Value v0 = op0->getResult(0);
   EXPECT_EQ(v0.getNumUses(), (unsigned)0);
@@ -52,8 +52,8 @@ TEST(ValueTest, hasNUses) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *op0 =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *op0 = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                            builder.getIntegerType(16));
   Value v0 = op0->getResult(0);
   EXPECT_TRUE(v0.hasNUses(0));
   EXPECT_FALSE(v0.hasNUses(1));
@@ -76,8 +76,8 @@ TEST(ValueTest, hasNUsesOrMore) {
   MLIRContext context;
   Builder builder(&context);
 
-  Operation *op0 =
-      createOp(&context, /*operands=*/std::nullopt, builder.getIntegerType(16));
+  Operation *op0 = createOp(&context, /*operands=*/ArrayRef<Value>(),
+                            builder.getIntegerType(16));
   Value v0 = op0->getResult(0);
   EXPECT_TRUE(v0.hasNUsesOrMore(0));
   EXPECT_FALSE(v0.hasNUsesOrMore(1));

kazutakahirata · 2025-06-25T15:23:08Z

Friendly ping. Thanks!

clang/lib/ASTMatchers/Dynamic/Marshallers.h

ArrayRef has a constructor that accepts std::nullopt. This constructor dates back to the days when we still had llvm::Optional. Since the use of std::nullopt outside the context of std::optional is kind of abuse and not intuitive to new comers, I would like to move away from the constructor and eventually remove it. This patch migrates away from std::nullopt in favor of ArrayRef<T>() where we use perfect forwarding. Note that {} would be ambiguous for perfect forwarding to work.

kazutakahirata requested a review from kuhar June 24, 2025 14:50

llvmbot added clang Clang issues not falling into any other category mlir:core MLIR Core Infrastructure mlir:linalg mlir:gpu mlir mlir:tosa labels Jun 24, 2025

kazutakahirata requested a review from matthias-springer June 24, 2025 14:50

Remove bits that have nothing to do with perfect forwarding

108e1c1

kazutakahirata requested a review from tgymnich June 25, 2025 15:23

River707 approved these changes Jun 25, 2025

View reviewed changes

clang/lib/ASTMatchers/Dynamic/Marshallers.h Outdated Show resolved Hide resolved

Address a comment.

6430141

kazutakahirata merged commit 28f6f87 into llvm:main Jun 25, 2025
7 checks passed

kazutakahirata deleted the cleanup_20250624_nullopt_mlir_ArrayRef branch June 25, 2025 18:49

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