Merge pull request swiftlang#35117 from ahoppen/syntaxnode-child-getters-const

Make the child getters of SyntaxNodes const

Author: ahoppen

include/swift/Syntax/SyntaxNodes.h.gyb

@@ -81,9 +81,9 @@ public:
   /// ${line}
 %       end
 %       if child.is_optional:
-  llvm::Optional<${child.type_name}> get${child.name}();
+  llvm::Optional<${child.type_name}> get${child.name}() const;
 %       else:
-  ${child.type_name} get${child.name}();
+  ${child.type_name} get${child.name}() const;
 %       end
 
 %       child_node = NODE_MAP.get(child.syntax_kind)

lib/Syntax/SyntaxNodes.cpp.gyb

@@ -55,14 +55,14 @@ void ${node.name}::validate() const {
 
 %   for child in node.children:
 %     if child.is_optional:
-llvm::Optional<${child.type_name}> ${node.name}::get${child.name}() {
+llvm::Optional<${child.type_name}> ${node.name}::get${child.name}() const {
   auto ChildData = Data->getChild(Cursor::${child.name});
   if (!ChildData)
     return llvm::None;
   return ${child.type_name} {Root, ChildData.get()};
 }
 %     else:
-${child.type_name} ${node.name}::get${child.name}() {
+${child.type_name} ${node.name}::get${child.name}() const {
   return ${child.type_name} {Root, Data->getChild(Cursor::${child.name}).get()};
 }
 %     end