[NFC] Extract a function to canonicalize an individual FunctionType::Param.

Author: rjmccall

include/swift/AST/Types.h

@@ -3103,6 +3103,8 @@ class AnyFunctionType : public TypeBase {
         return true;
       return false;
     }
+
+    Param getCanonical(CanGenericSignature genericSig) const;
 
     ParameterTypeFlags getParameterFlags() const { return Flags; }
 

lib/AST/Type.cpp

@@ -1606,14 +1606,19 @@ getCanonicalParams(AnyFunctionType *funcType,
                    SmallVectorImpl<AnyFunctionType::Param> &canParams) {
   auto origParams = funcType->getParams();
   for (auto param : origParams) {
-    // Canonicalize the type and drop the internal label to canonicalize the
-    // Param.
-    canParams.emplace_back(param.getPlainType()->getReducedType(genericSig),
-                           param.getLabel(), param.getParameterFlags(),
-                           /*InternalLabel=*/Identifier());
+    canParams.emplace_back(param.getCanonical(genericSig));
   }
 }
 
+AnyFunctionType::Param
+AnyFunctionType::Param::getCanonical(CanGenericSignature genericSig) const {
+  // Canonicalize the type and drop the internal label to canonicalize the
+  // Param.
+  return Param(getPlainType()->getReducedType(genericSig),
+               getLabel(), getParameterFlags(),
+               /*InternalLabel=*/Identifier());
+}
+
 CanType TypeBase::computeCanonicalType() {
   assert(!hasCanonicalTypeComputed() && "called unnecessarily");