[NFC] Fix -Wrange-loop-analysis warnings.

[dan-zheng]

Summary

Remove unnecessary & from loop variables.

Fix warnings: "loop variable is always a copy because the range does not
return a reference".

[240/2862] Building CXX object tools/mlir/tools/mlir-tblgen/CMakeFiles/mlir-tblgen.dir/TypeDefGen.cpp.o
llvm-project/mlir/tools/mlir-tblgen/TypeDefGen.cpp:50:25: warning: loop variable 'typeDef' is always a copy because the range of type 'llvm::iterator_range<llvm::mapped_iterator<std::__1::__wrap_iter<llvm::Record **>, (lambda at llvm-project/mlir/tools/mlir-tblgen/TypeDefGen.cpp:40:16), mlir::tblgen::TypeDef> >' does not return a reference [-Wrange-loop-analysis]
    for (const TypeDef &typeDef : defs)
                        ^
llvm-project/mlir/tools/mlir-tblgen/TypeDefGen.cpp:50:10: note: use non-reference type 'mlir::tblgen::TypeDef'
    for (const TypeDef &typeDef : defs)
         ^~~~~~~~~~~~~~~~~~~~~~~~
llvm-project/mlir/tools/mlir-tblgen/TypeDefGen.cpp:64:23: warning: loop variable 'typeDef' is always a copy because the range of type 'llvm::iterator_range<llvm::mapped_iterator<std::__1::__wrap_iter<llvm::Record **>, (lambda at llvm-project/mlir/tools/mlir-tblgen/TypeDefGen.cpp:40:16), mlir::tblgen::TypeDef> >' does not return a reference [-Wrange-loop-analysis]
  for (const TypeDef &typeDef : defs)
                      ^
llvm-project/mlir/tools/mlir-tblgen/TypeDefGen.cpp:64:8: note: use non-reference type 'mlir::tblgen::TypeDef'
  for (const TypeDef &typeDef : defs)
       ^~~~~~~~~~~~~~~~~~~~~~~~
2 warnings generated.

[1934/2862] Building CXX object tools...Files/toyc-ch4.dir/mlir/MLIRGen.cpp.o
llvm-project/mlir/examples/toy/Ch4/mlir/MLIRGen.cpp:139:22: warning: loop variable 'name_value' is always a copy because the range of type 'detail::zippy<detail::zip_shortest, ArrayRef<unique_ptr<VariableExprAST, default_delete<VariableExprAST> > > &, MutableArrayRef<BlockArgument> >' does not return a reference [-Wrange-loop-analysis]
    for (const auto &name_value :
                     ^
llvm-project/mlir/examples/toy/Ch4/mlir/MLIRGen.cpp:139:10: note: use non-reference type 'std::__1::tuple<const std::__1::unique_ptr<toy::VariableExprAST, std::__1::default_delete<toy::VariableExprAST> > &, mlir::BlockArgument &>'
    for (const auto &name_value :
         ^~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.

[1940/2862] Building CXX object tools...Files/toyc-ch5.dir/mlir/MLIRGen.cpp.o
llvm-project/mlir/examples/toy/Ch5/mlir/MLIRGen.cpp:139:22: warning: loop variable 'name_value' is always a copy because the range of type 'detail::zippy<detail::zip_shortest, ArrayRef<unique_ptr<VariableExprAST, default_delete<VariableExprAST> > > &, MutableArrayRef<BlockArgument> >' does not return a reference [-Wrange-loop-analysis]
    for (const auto &name_value :
                     ^
llvm-project/mlir/examples/toy/Ch5/mlir/MLIRGen.cpp:139:10: note: use non-reference type 'std::__1::tuple<const std::__1::unique_ptr<toy::VariableExprAST, std::__1::default_delete<toy::VariableExprAST> > &, mlir::BlockArgument &>'
    for (const auto &name_value :
         ^~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.

[dan-zheng]

Fix clang-tidy invalid case style warnings ([readability-identifier-naming]).

[dan-zheng]

@jpienaar: thanks for reviewing! It seems that LLVM.CodeGen/XCore::threads.ll is a flaky test failure, so this patch should be ready to land. Could you please help merge it?

mlir/examples/toy/Ch2/mlir/MLIRGen.cpp

mlir::FuncOp mlirGen(FunctionAST &funcAST) {
 
     // Let's start the body of the function now!
     // In MLIR the entry block of the function is special: it must have the same
     // argument list as the function itself.
     auto &entryBlock = *function.addEntryBlock();
     auto protoArgs = funcAST.getProto()->getArgs();
 
     // Declare all the function arguments in the symbol table.
-    for (const auto &name_value :
+    for (const auto name_value :
          llvm::zip(protoArgs, entryBlock.getArguments())) {
       if (failed(declare(std::get<0>(name_value)->getName(),
                          std::get<1>(name_value))))
         return nullptr;
     }
 
     // Set the insertion point in the builder to the beginning of the function
     // body, it will be used throughout the codegen to create operations in this

mlir/examples/toy/Ch3/mlir/MLIRGen.cpp

mlir::FuncOp mlirGen(FunctionAST &funcAST) {
 
     // Let's start the body of the function now!
     // In MLIR the entry block of the function is special: it must have the same
     // argument list as the function itself.
     auto &entryBlock = *function.addEntryBlock();
     auto protoArgs = funcAST.getProto()->getArgs();
 
     // Declare all the function arguments in the symbol table.
-    for (const auto &name_value :
+    for (const auto name_value :
          llvm::zip(protoArgs, entryBlock.getArguments())) {
       if (failed(declare(std::get<0>(name_value)->getName(),
                          std::get<1>(name_value))))
         return nullptr;
     }
 
     // Set the insertion point in the builder to the beginning of the function
     // body, it will be used throughout the codegen to create operations in this

mlir/examples/toy/Ch4/mlir/MLIRGen.cpp

mlir::FuncOp mlirGen(FunctionAST &funcAST) {
 
     // Let's start the body of the function now!
     // In MLIR the entry block of the function is special: it must have the same
     // argument list as the function itself.
     auto &entryBlock = *function.addEntryBlock();
     auto protoArgs = funcAST.getProto()->getArgs();
 
     // Declare all the function arguments in the symbol table.
-    for (const auto &name_value :
+    for (const auto name_value :
          llvm::zip(protoArgs, entryBlock.getArguments())) {
       if (failed(declare(std::get<0>(name_value)->getName(),
                          std::get<1>(name_value))))
         return nullptr;
     }
 
     // Set the insertion point in the builder to the beginning of the function
     // body, it will be used throughout the codegen to create operations in this

mlir/examples/toy/Ch5/mlir/MLIRGen.cpp

mlir::FuncOp mlirGen(FunctionAST &funcAST) {
 
     // Let's start the body of the function now!
     // In MLIR the entry block of the function is special: it must have the same
     // argument list as the function itself.
     auto &entryBlock = *function.addEntryBlock();
     auto protoArgs = funcAST.getProto()->getArgs();
 
     // Declare all the function arguments in the symbol table.
-    for (const auto &name_value :
+    for (const auto name_value :
          llvm::zip(protoArgs, entryBlock.getArguments())) {
       if (failed(declare(std::get<0>(name_value)->getName(),
                          std::get<1>(name_value))))
         return nullptr;
     }
 
     // Set the insertion point in the builder to the beginning of the function
     // body, it will be used throughout the codegen to create operations in this

mlir/examples/toy/Ch6/mlir/MLIRGen.cpp

mlir::FuncOp mlirGen(FunctionAST &funcAST) {
 
     // Let's start the body of the function now!
     // In MLIR the entry block of the function is special: it must have the same
     // argument list as the function itself.
     auto &entryBlock = *function.addEntryBlock();
     auto protoArgs = funcAST.getProto()->getArgs();
 
     // Declare all the function arguments in the symbol table.
-    for (const auto &name_value :
+    for (const auto name_value :
          llvm::zip(protoArgs, entryBlock.getArguments())) {
       if (failed(declare(std::get<0>(name_value)->getName(),
                          std::get<1>(name_value))))
         return nullptr;
     }
 
     // Set the insertion point in the builder to the beginning of the function
     // body, it will be used throughout the codegen to create operations in this

mlir/examples/toy/Ch7/mlir/Dialect.cpp

static mlir::LogicalResult verifyConstantForType(mlir::Type type,
   auto attrValue = opaqueValue.dyn_cast<ArrayAttr>();
   if (!attrValue || attrValue.getValue().size() != resultElementTypes.size())
     return op->emitError("constant of StructType must be initialized by an "
                          "ArrayAttr with the same number of elements, got ")
            << opaqueValue;
 
   // Check that each of the elements are valid.
   llvm::ArrayRef<mlir::Attribute> attrElementValues = attrValue.getValue();
-  for (const auto &it : llvm::zip(resultElementTypes, attrElementValues))
+  for (const auto it : llvm::zip(resultElementTypes, attrElementValues))
     if (failed(verifyConstantForType(std::get<0>(it), std::get<1>(it), op)))
       return mlir::failure();
   return mlir::success();
 }
 
 /// Verifier for the constant operation. This corresponds to the `::verify(...)`
 /// in the op definition.
 static mlir::LogicalResult verify(ConstantOp op) {

mlir/examples/toy/Ch7/mlir/MLIRGen.cpp

mlir::FuncOp mlirGen(FunctionAST &funcAST) {
 
     // Let's start the body of the function now!
     // In MLIR the entry block of the function is special: it must have the same
     // argument list as the function itself.
     auto &entryBlock = *function.addEntryBlock();
     auto protoArgs = funcAST.getProto()->getArgs();
 
     // Declare all the function arguments in the symbol table.
-    for (const auto &name_value :
+    for (const auto name_value :
          llvm::zip(protoArgs, entryBlock.getArguments())) {
       if (failed(declare(*std::get<0>(name_value), std::get<1>(name_value))))
         return nullptr;
     }
 
     // Set the insertion point in the builder to the beginning of the function
     // body, it will be used throughout the codegen to create operations in this
     // function.

mlir/tools/mlir-tblgen/TypeDefGen.cpp

if (defs.empty())
     return;
 
   StringRef dialectName;
   if (selectedDialect.getNumOccurrences() == 0) {
     if (defs.empty())
       return;
 
     llvm::SmallSet<Dialect, 4> dialects;
-    for (const TypeDef &typeDef : defs)
+    for (const TypeDef typeDef : defs)
       dialects.insert(typeDef.getDialect());
     if (dialects.size() != 1)
       llvm::PrintFatalError("TypeDefs belonging to more than one dialect. Must "
                             "select one via '--typedefs-dialect'");
 
     dialectName = (*dialects.begin()).getName();
   } else if (selectedDialect.getNumOccurrences() == 1) {
     dialectName = selectedDialect.getValue();
   } else {
     llvm::PrintFatalError("Cannot select multiple dialects for which to "
                           "generate types via '--typedefs-dialect'.");
   }
 
-  for (const TypeDef &typeDef : defs)
+  for (const TypeDef typeDef : defs)
     if (typeDef.getDialect().getName().equals(dialectName))
       typeDefs.push_back(typeDef);
 }
 
 namespace {
 
 /// Pass an instance of this class to llvm::formatv() to emit a comma separated
 /// list of parameters in the format by 'EmitFormat'.