[mlir][llvm] Fix compiler error on GCC 9

[unterumarmung]

Summary

This patch fixes the following compiler error:

error: declaration of ‘mlir::LLVM::cconv::CConv mlir::LLVM::detail::CConvAttrStorage::CConv’ changes meaning of ‘CConv’ [-fpermissive]

CConv as a member variable name was shadowing CConv as an enumeration,
hence the compiler error.

[ftynse]

mlir/include/mlir/Dialect/LLVMIR/LLVMAttrDefs.td

42

This name was capitalized at a request in the review of the original patch. Is there another way to fix it? Perhaps use the fully qualified type name when necessary to disambiguate?

[alexbatashev]

mlir/include/mlir/Dialect/LLVMIR/LLVMAttrDefs.td

42

Maybe this would satisfy everybody?

[unterumarmung]

mlir/include/mlir/Dialect/LLVMIR/LLVMAttrDefs.td

42

Perhaps use the fully qualified type name when necessary to disambiguate?

This wouldn't work. The error is attached to the member variable declaration, so we need to change the name.

42

I'd go with @alexbatashev's suggestion

[ftynse]

mlir/include/mlir/Dialect/LLVMIR/LLVMAttrDefs.td

42

Works for me.

[unterumarmung]

Address review comments

[unterumarmung]

@alexbatashev @ftynse thank you for the quick review! If you have no further objections, could someone please approve the revision?

mlir/include/mlir/Dialect/LLVMIR/LLVMAttrDefs.td

def LinkageAttr : LLVM_Attr<"Linkage"> {
   );
   let hasCustomAssemblyFormat = 1;
 }
 
 // Attribute definition for the LLVM Linkage enum.
 def CConvAttr : LLVM_Attr<"CConv"> {
   let mnemonic = "cconv";
   let parameters = (ins
-    "CConv":$CConv
+    "CConv":$CallingConv
   );
   let hasCustomAssemblyFormat = 1;
 }
 
 def LoopOptionsAttr : LLVM_Attr<"LoopOptions"> {
   let mnemonic = "loopopts";
 
   let description = [{

mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td

 }
 
 def CConv : DialectAttr<
     LLVM_Dialect,
     CPred<"$_self.isa<::mlir::LLVM::CConvAttr>()">,
     "LLVM Calling Convention specification"> {
   let storageType = "::mlir::LLVM::CConvAttr";
   let returnType = "::mlir::LLVM::cconv::CConv";
-  let convertFromStorage = "$_self.getCConv()";
+  let convertFromStorage = "$_self.getCallingConv()";
   let constBuilderCall =
           "::mlir::LLVM::CConvAttr::get($_builder.getContext(), $0)";
 }
 
 class LLVM_Builder<string builder> {
   string llvmBuilder = builder;
 }
 

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

if (!elem) {
     return {};
   }
   Linkage linkage = *elem;
   return LinkageAttr::get(parser.getContext(), linkage);
 }
 
 void CConvAttr::print(AsmPrinter &printer) const {
   printer << "<";
-  if (static_cast<uint64_t>(getCConv()) <= cconv::getMaxEnumValForCConv())
-    printer << stringifyEnum(getCConv());
+  if (static_cast<uint64_t>(getCallingConv()) <= cconv::getMaxEnumValForCConv())
+    printer << stringifyEnum(getCallingConv());
   else
-    printer << "INVALID_cc_" << static_cast<uint64_t>(getCConv());
+    printer << "INVALID_cc_" << static_cast<uint64_t>(getCallingConv());
   printer << ">";
 }
 
 Attribute CConvAttr::parse(AsmParser &parser, Type type) {
   StringRef convName;
 
   if (parser.parseLess() || parser.parseKeyword(&convName) ||
       parser.parseGreater())