Followup to void return functions in CIR

Fix some comments and some formatting.  Change which function prints the
opening `(` of the parameter list of a function type.  No changes in
behavior.

Author: dkolsen-pgi

clang/include/clang/CIR/Dialect/IR/CIRTypes.td

@@ -296,7 +296,7 @@ def CIR_FuncType : CIR_Type<"Func", "func"> {
   }];
 
   let builders = [
-    // Construct with an actual return type or explicit !cir.void
+    // Construct with an actual return type or implicit !cir.void.
     TypeBuilderWithInferredContext<(ins
       "llvm::ArrayRef<mlir::Type>":$inputs, "mlir::Type":$returnType,
       CArg<"bool", "false">:$isVarArg), [{
@@ -317,7 +317,7 @@ def CIR_FuncType : CIR_Type<"Func", "func"> {
     unsigned getNumInputs() const { return getInputs().size(); }
 
     /// Returns the result type of the function as an actual return type or
-    /// explicit !cir.void
+    /// explicit !cir.void.
     mlir::Type getReturnType() const;
 
     /// Returns the result type of the function as an ArrayRef, enabling better

clang/lib/CIR/Dialect/IR/CIRTypes.cpp

@@ -347,12 +347,13 @@ static mlir::ParseResult parseFuncTypeReturn(mlir::AsmParser &p,
   mlir::Type type;
   if (p.parseType(type))
     return mlir::failure();
-  if (isa<cir::VoidType>(type))
+  if (isa<cir::VoidType>(type)) {
     // An explicit !cir.void means also no return type.
     optionalReturnType = {};
-  else
+  } else {
     // Otherwise use the actual type.
     optionalReturnType = type;
+  }
   return p.parseLParen();
 }
 
@@ -361,7 +362,6 @@ static void printFuncTypeReturn(mlir::AsmPrinter &p,
                                 mlir::Type optionalReturnType) {
   if (optionalReturnType)
     p << optionalReturnType << ' ';
-  p << '(';
 }
 
 static mlir::ParseResult
@@ -399,6 +399,7 @@ parseFuncTypeArgs(mlir::AsmParser &p, llvm::SmallVector<mlir::Type> &params,
 static void printFuncTypeArgs(mlir::AsmPrinter &p,
                               mlir::ArrayRef<mlir::Type> params,
                               bool isVarArg) {
+  p << '(';
   llvm::interleaveComma(params, p,
                         [&p](mlir::Type type) { p.printType(type); });
   if (isVarArg) {