GCC warning -Wunused-but-set-parameter in MLIR (<gcc-10 only)

[lipracer]

system:
gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0

summary:

llvm-project/mlir/include/mlir/IR/OperationSupport.h:656:67: warning: parameter ‘rhs’ set but not used [-Wunused-but-set-parameter]
  656 |     bool compareProperties(OpaqueProperties lhs, OpaqueProperties rhs) final {
      |                                                  ~~~~~~~~~~~~~~~~~^~~
llvm-project/mlir/include/mlir/IR/OperationSupport.h: In instantiation of ‘llvm::hash_code mlir::RegisteredOperationName::Model<ConcreteOp>::hashProperties(mlir::OpaqueProperties) [with ConcreteOp = mlir::transform::ApplyExpandOpsPatternsOp]’:
llvm-project/mlir/include/mlir/IR/OperationSupport.h:666:21:   required from here
llvm-project/mlir/include/mlir/IR/OperationSupport.h:666:53: warning: parameter ‘prop’ set but not used [-Wunused-but-set-parameter]
  666 |     llvm::hash_code hashProperties(OpaqueProperties prop) final {

[joker-eph]

This is a gcc issue fixed in gcc 10 I believe: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85827
not sure we should fix it? If someone is interested I would suggest writing a CMake patch that detects gcc < 10 and sets -Wnounused-but-set-parameter flag.

[lipracer]

Thanks, I will create a PR later.

[lipracer]

cmake patch PR.