[Mlir-commits] [mlir] [mlir][tosa] Use explicit namespace for OpTrait. (PR #126286)

[Scott Todd]

https://github.com/ScottTodd created https://github.com/llvm/llvm-project/pull/126286

I'm seeing build errors in a downstream project using torch-mlir that are fixed by this change. See https://github.com/iree-org/iree/pull/19903#discussion_r1946899561 for more context. The build error on MSVC is:
```
C:\home\runner\_work\iree\iree\third_party\llvm-project\mlir\include\mlir/Dialect/Tosa/Utils/ConversionUtils.h(148): error C2872: 'OpTrait': ambiguous symbol
C:\home\runner\_work\iree\iree\third_party\llvm-project\mlir\include\mlir/Dialect/Tosa/IR/TosaOps.h(49): note: could be 'mlir::OpTrait'
C:\home\runner\_work\iree\iree\third_party\torch-mlir\include\torch-mlir/Dialect/Torch/IR/TorchTraits.h(23): note: or       'mlir::torch::Torch::OpTrait'
C:\home\runner\_work\iree\iree\third_party\llvm-project\mlir\include\mlir/Dialect/Tosa/Utils/ConversionUtils.h(148): note: the template instantiation context (the oldest one first) is
C:\home\runner\_work\iree\iree\third_party\torch-mlir\lib\Conversion\TorchToTosa\TosaLegalizeCommon.cpp(126): note: see reference to function template instantiation 'TosaOp mlir::tosa::CreateOpAndInfer<mlir::tosa::MulOp,mlir::Value&,mlir::Value&,mlir::Value&>(mlir::PatternRewriter &,mlir::Location,mlir::Type,mlir::Value &,mlir::Value &,mlir::Value &)' being compiled
        with
        [
            TosaOp=mlir::tosa::MulOp
        ]
C:\home\runner\_work\iree\iree\third_party\torch-mlir\include\torch-mlir/Conversion/TorchToTosa/TosaLegalizeUtils.h(83): note: see reference to function template instantiation 'TosaOp mlir::tosa::CreateOpAndInfer<TosaOp,mlir::Value&,mlir::Value&,mlir::Value&>(mlir::ImplicitLocOpBuilder &,mlir::Type,mlir::Value &,mlir::Value &,mlir::Value &)' being compiled
        with
        [
            TosaOp=mlir::tosa::MulOp
        ]
C:\home\runner\_work\iree\iree\third_party\torch-mlir\include\torch-mlir/Conversion/TorchToTosa/TosaLegalizeUtils.h(76): note: see reference to function template instantiation 'TosaOp mlir::tosa::CreateOpAndInferShape<TosaOp,mlir::Value&,mlir::Value&,mlir::Value&>(mlir::ImplicitLocOpBuilder &,mlir::Type,mlir::Value &,mlir::Value &,mlir::Value &)' being compiled
        with
        [
            TosaOp=mlir::tosa::MulOp
        ]
```

I think the torch-mlir code here is causing the issue, but I'm not sure why builds only started failing now: https://github.com/llvm/torch-mlir/blob/main/include/torch-mlir/Dialect/Torch/IR/TorchTraits.h. Given that `mlir::OpTrait` already exists, torch-mlir should not be creating an ambiguous symbol `mlir::torch::Torch::OpTrait`. So while a better fix would be to the downstream project, being explicit here doesn't seem that unreasonable to me.

>From ef0f3be1bb32d20d13ca7cd7397214c606cfabcb Mon Sep 17 00:00:00 2001
From: Scott Todd <scott.todd0 at gmail.com>
Date: Fri, 7 Feb 2025 10:39:01 -0800
Subject: [PATCH] [mlir][tosa] Use explicit namespace for OpTrait.

---
 mlir/include/mlir/Dialect/Tosa/Utils/ConversionUtils.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mlir/include/mlir/Dialect/Tosa/Utils/ConversionUtils.h b/mlir/include/mlir/Dialect/Tosa/Utils/ConversionUtils.h
index 88c21629286525d..4e2f1b9cb19a91b 100644
--- a/mlir/include/mlir/Dialect/Tosa/Utils/ConversionUtils.h
+++ b/mlir/include/mlir/Dialect/Tosa/Utils/ConversionUtils.h
@@ -145,7 +145,7 @@ TosaOp createOpAndInferShape(ImplicitLocOpBuilder &builder, Type resultTy,
 template <typename TosaOp, typename... Args>
 TosaOp CreateOpAndInferShape(ImplicitLocOpBuilder &builder, Type resultTy,
                              Args &&...args) {
-  if (TosaOp::template hasTrait<OpTrait::SameOperandsAndResultRank>()) {
+  if (TosaOp::template hasTrait<::mlir::OpTrait::SameOperandsAndResultRank>()) {
     // op requires same ranks for tensor operands
     if constexpr (sizeof...(Args) == 2) {
       auto argX = std::get<0>(std::tie(args...));